PEPTIDE-BASED SYNTHETIC CHLORIDE ION TRANSPORTERS FIELD OF THE INVENTION The present invention relates to the field of human therapy. In particular, the present invention relates to novel synthetic peptide-based chloride ion transporter and to compositions thereof, as well as methods of treating, reducing, inhibiting or controlling chloride ion channel related diseases. BACKGROUND OF THE INVENTION Cell penetrating peptides (CPPs) or protein transduction domains (PTDs) are small peptides with less than 30 amino acid residues and of the appropriate size, charge and, polarity to pass through the cellular membrane. The main characteristics of these peptides include their ability to cross the cellular membrane using both endocytosis and energy-independent pathways, their high cellular permeability rates and their low cell toxicity and safety associated with little to no immunological response. Currently, more than 1800 different CPPs have been reported and the vast majority of them have been experimentally tested for different applications. CPPs are classified according to the type of cargo, their physicochemical properties (cationic, hydrophobic, amphipathic), their internalization mechanism and their structural features (linearity or cyclic nature). Cell penetrating peptides have been used for transporting various materials (peptides, proteins, DNA, RNA, etc.) through biological barriers such as plasma membranes (JP Richard, et.al., Journal of Biological Chemistry, 2003, 278, pp 585). Despite the diversity of pathways and cell types targeted by CPP-based therapies, there are still no FDA approved CPP-conjugated drugs and several clinical trials have been discontinued to date. The problems associated with the use of CPP-conjugated drugs include: (1) in vivo stability issues due to susceptibility to proteolytic degradation; (2) immunogenicity issues; (3) poor efficiency due to the drug’s failure to escape from endosomes after being internalized by cells; (4) toxicity due to the degradation of moieties; and (5) toxicity or poor efficiency due to the CPP’s lack of site specificity. (L Gomes dos Reis, D Traini, Expert Opinion on Drug Delivery, 2020, 17(5), pp 647; J Habault, JL Poyet, Recent Advances in Cell Penetrating Peptide-Based Anticancer Therapies, Molecules, 2019, 24 (5), pp 927). Intensive research efforts have been devoted to developing synthetic ion channels using artificial compounds. The main strategies are related to the synthesis of unimolecular channels or the design of self-assembled supramolecular channels. These synthetic ion transporters or ion channels could complement the impaired or lost function of cellular ion channels (N Busschaert, PA Gale, Angewandte Chemie International Edition 2013, 52, pp 1374) and thus be used for the treatment of channelopathies and related diseases. Various artificial chloride transporters were developed with different molecular masses ranging from small organic molecules to supramolecular systems. These compounds either passively diffuse through the membrane with the chloride ion or form a channel in the membrane, facilitating passive ion transport. The general drawback of these compounds is their toxicity. It has been shown that some transporters increase intracellular sodium chloride concentrations, enhance cellular reactive oxygen species (ROS) levels, trigger the release of cytochrome c from the mitochondria and induce caspase activation, all of which results in apoptosis (SK Ko, et.al., Nat Chem 2014, 6, pp 885). Respiratory diseases such as chronic obstructive pulmonary disease (COPD), asthma, cystic fibrosis (CF), bronchiectasis, tuberculosis, and lung cancer are leading causes of death, with numbers increasing yearly. There is an unmet need for new therapies for lung-related diseases as this has been recognised as the largest therapeutic failure. The field of bioactive molecules (peptides, proteins, and nucleic acids) is an area in which potential new treatments for respiratory diseases could be developed (L Gomes dos Reis, D Traini, Expert Opinion on Drug Delivery, 2020, 17(5), pp 647). CF is the most common autosomal recessive genetic disease characterized by multi-organ pathology and significantly decreased life expectancy caused by the impaired function or expression of cystic fibrosis transmembrane conductance regulator (CFTR). In CF, chloride transport is impaired due to genetic mutations of the CFTR gene leading to absent, or diminished function of the CFTR protein (BP O'Sullivan, SD Freedman, Lancet, 2009, 373, pp 1891). Recent therapeutic developments have significantly enhanced the life expectancy of patients with CF, yet the average age of death (usually caused by respiratory failure) is still 31.4 years (A Orenti, et al, ECFSPR Annual Report, 2016). In addition, 31% of the CF patients have chronic lung infections caused by Pseudomonas aeruginosa, whilst 83% of all CF patients need pancreatic enzyme replacement therapy, resulting in a significant burden to both the patients and healthcare systems. Oral delivery of such therapeutic agents would be desirable, though this remains an unsolved challenge for drug formulators and drug delivery experts due to instability of the peptide-based bioactives in the GI tract, their low permeability and extremely rapid clearance (S Gupta et.al., Drug Delivery, 2013, 20, pp 237-246). Although cystic fibrosis is a systemic disease affecting – among others – the lungs, the digestive system and the reproductive system, lung infections and lung complications are the primary cause of death, accounting for up to 85% of the cases. (C Martin, et.al, Journal of Cystic Fibrosis, 2016, 15, pp 204-212). Abnormal mucus viscosity and production is known to contribute to CF pathogenesis (C Ehre et al, The International Journal of Biochemistry & Cell Biology, 2014, 52, pp 136–145). Moreover, hyper-concentrated mucus with increased airway adhesion is known to induce CF-like disease in animal models (M Mall et al, Nature Medicine, 2004, 10, pp 487–493). Analysis of the bronchoalveolar lavage fluid of young CF patients indicated that abnormally viscous mucus accumulation, with increased total mucin and inflammatory factor concentrations, drives the early pathogenesis of CF disease (CR Esther et al, Science Translational Medicine, 2019, 11, pp 1-11). The increase in mucus viscosity is due to the decreased cellular secretion of chloride ions, which results in an impaired fluid secretion and increased apical sodium absorption by the airway epithelial cells (H Li et.al., Current Opinion in Pharmacology, 2017, 34, pp 91-97). These alterations in ion transport ultimately result in the acidification and decreased height of the apical airway surface liquid. In CF patients, cilial movement is impaired due to these alterations and the viscous mucus layer cannot be removed from the smaller airways. This results in chronic cough and increased probability and frequency of lung infections. Hydration therapy has been demonstrated to correct CF sputum samples to near-normal viscoelasticity, reinforcing the clinical findings that administration of hydrating agents yields beneficial results in patients with CF (BE Tildy and DF Rogers, Pharmacology, 2015, 95, pp 117-132). Therefore, a synthetic chloride ion transporter administered directly to the lungs could alleviate the symptoms associated with the highly viscous mucus layer (independent of the mutation causing the disease) by increasing the electrolyte levels of the layer and thus facilitating water transport out of the epithelial cells. Ultimately, this could lead to improved rheological properties of the mucus layer (D Schieppati, et.al, Respiratory Medicine, 2019, 153, pp 52-59). This is supported by the analysis of mucus samples, where it was shown that diluting (hydrating) mucus by a factor of 2 from 5.2% to 2.6% decreased the complex viscosity by a factor of eight (DB Hill et al, European Respiratory Journal, 2018, 52, pp 1-11). Whilst VX (or ‘caftor’) CFTR modulators such as ivacaftor, lumacaftor, tezacaftor, elexacaftor and their combinations, as found in the marketed drug products Kalydeco, Orkambi, Symdeko and Trikafta, are effective in improving chloride ion transport, their use is limited to certain mutations of the CFTR gene. Moreover, there are numerous patients found to either not respond to or not tolerate such caftor therapies. Treatment of these patients is an unmet medical need, in which synthetic chloride ion transporters may play a major role. Also, combining these universally effective ion channel transporters with established cystic fibrosis treatments, may result in improved therapeutic outcomes. There is thus a significant need for synthetic chloride ion transporters that could be potentially utilized in channel replacement therapy to treat diseases associated with dysregulated anion transport, particularly those involving chloride ion. SUMMARY OF THE INVENTION In a first aspect, the invention provides a compound according to Formula I: T – Z – [Peptide] (I) or a pharmaceutically acceptable salt thereof, wherein: T is a chloride ion binding moiety; and Z is a linker having a chain length of from 8 to 30 atoms in the shortest linear path, the chain of atoms including at least 2 heteroatoms selected from O, S and N; and the peptide comprises a cell penetrating peptide (CPP), a retro-analogue of a CPP, an inverso-analogue of a CPP or a retro-inverso-analogue of a CPP, or a variant thereof having at least 70% sequence identity thereto, wherein a variant of an inverso-analogue or a retro-inverso-analogue of a CPP comprises at least one D-amino acid, and wherein the -OH at the C-terminus of the peptide is optionally substituted by Ra, wherein Ra is selected from -NH ₂ , -O-C _1-6 alkyl, -NHC _1-6 alkyl, and -NH-NH _2, provided the compound is not

. In embodiments, the chain length for Z is from 9 to 30 atoms in the shortest linear path. In other words, in embodiments of the first aspect, the invention provides a compound according to Formula I: T – Z – [Peptide] (I) or a pharmaceutically acceptable salt thereof, wherein: T is a chloride ion binding moiety; and Z is a linker having a chain length of from 9 to 30 atoms in the shortest linear path, the chain of atoms including at least 2 heteroatoms selected from O, S and N; and the peptide comprises a cell penetrating peptide (CPP), a retro-analogue of a CPP, an inverso-analogue of a CPP or a retro-inverso-analogue of a CPP, or a variant thereof having at least 70% sequence identity thereto, wherein a variant of an inverso-analogue or a retro-inverso-analogue of a CPP comprises at least one D-amino acid, and wherein the -OH at the C-terminus of the peptide is optionally substituted by Ra, wherein Ra is selected from -NH ₂ , -O-C _1-6 alkyl, -NHC _1-6 alkyl, and -NH-NH ₂ . In a second aspect, the invention provides a compound according to Formula I, T – Z – [Peptide] (I) or a pharmaceutically acceptable salt thereof, wherein: T is a chloride ion binding moiety; and Z is a C _1-12 alkylene, C _5-12 cycloalkylene, C _2-30 heteroalkylene, or C _6-12 aralkylene, each optionally substituted with from 1-6 substituents independently selected from -OH, =O, -NO ₂ , -NH ₂ and halo; and the -OH at the C-terminus of the peptide is optionally substituted by Ra, wherein Ra is selected from NH ₂ , -O-C _1-6 alkyl, -NHC _1-6 alkyl, and -NH-NH ₂ ; and wherein the peptide is a retro-analogue, an inverso-analogue or a retro-inverso-analogue of a cell penetrating peptide (CPP) or a variant thereof having at least 70% sequence identity thereto, wherein a variant of an inverso-analogue or a retro-inverso-analogue of a CPP comprises at least one D-amino acid. In a third aspect, the invention provides a compound according to Formula I, T – Z – [Peptide] (I) or a pharmaceutically acceptable salt thereof, wherein: T is a chloride ion binding moiety; and Z is a C _1-12 alkylene, C _5-10 cycloalkylene, C _2-30 heteroalkylene, or C _6-10 aralkylene, optionally substituted with from 1-6 substituents independently selected from -OH, =O, -NO ₂ , -NH ₂ and halo; and the -OH at the C-terminus of the peptide is optionally substituted by Ra, wherein Ra is selected from NH2, -O-C1-6alkyl, -NHC1-6alkyl, and -NH-NH2; and wherein the peptide comprises a cell-penetrating peptide (CPP) having at least 70% sequence identity to a mitochondria-targeting sequence (MTS), SEQ ID NO: 12 or SEQ ID NO: 20, or to an inverso-analogue, a retro-analogue or a retro-inverso-analogue thereof. Further embodiments of these aspects of the invention are described in the Detailed Description of the invention. The disclosure also includes the following subject matter disclosed in the form of the following numbered “points”. 1. A compound of Formula (A):

Peptide or pharmaceutically acceptable stereoisomers, enantiomers, diastereomers, racemic mixtures, polymorphs, tautomers, solvates, salts, esters, prodrugs or combinations thereof, wherein, n= 0-10; k= 1-200; The peptide component comprises two or more amino acids which may comprise D and/or L amino acids, optionally in any proportion. The sequence of the peptide can be read and synthesized from left side to right side, but also from right side to left side, which opposite sequence can be called retro peptide containing compounds. X= H, C1-10 alkyl or cycloalkyl, aryl, protecting group, C1-10 acyl, biotin, fluorescent and radioactive tracer, alkyl, cycloalkyl and acyl groups substituted with N, O, S, P, Se, Si, As or halides; Y= O, S, NH, CH ₂ , N-OR; Z= C1-10 alkyl or cycloalkyl, aryl, protecting group, C1-10 acyl, biotin, fluorescent and radioactive tracer, alkyl, cycloalkyl and acyl groups substituted with N, O, S, P, Se, Si, As or halides; R= H, OH, O-alkyl, NH, N-alkyl, SH, S-alkyl, alkyl, alkenyl, alkynyl, NH-NH2, R2 = H, C1-10 alkyl or cycloalkyl, aryl, these substituted with N, O, S, P, Se, Si, As or halides, and form a ring system, and glycosylated; and R3 = H, C1-10 alkyl or cycloalkyl, aryl, these ideally substituted with N, O, S, P, Se, Si, As or halides, and may form ideally a ring system, and may be glycosylated, and stereoisomers including enantiomers, diastereomers, racemic mixtures, mixtures of enantiomers or combinations thereof, as well as polymorphs, tautomers, solvates, salts, esters and prodrugs thereof. 2. The compound as recited in Point 1, wherein said peptide domain comprises one or more positively charged residues. 3. The compound as recited in Points 1 or 2, wherein said peptide domain comprises arginine or lysine side-chains. 4. The compound as recited in any of Points 1 to 3, wherein said peptide domain comprises one or more cell membrane penetrating domains (CPPs), such as cationic, amphipathic, hydrophobic or amphiphilic CPPs, selected from the group consisting of SP, pVEC, poly-arginine (arginine stretch), transportan, TAT, and penetratin, or variants thereof having at least 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81% 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, or 95% identity to any of SEQ ID NOs: 16, 17, 18, 19, 24 or 25, and having cell penetrating activity, preferably selected from: residue 48-60 of TAT or penetratin, or variants thereof. 5. A compound as recited in any of Point 1 to 4, wherein said compound is compound no. 10871 (Table 1), optionally wherein the molecular weight (MW) of the compound is 2630.1 Daltons. 6. A compound as recited in Point 5, wherein said compound is selected from pharmaceutically acceptable stereoisomers, enantiomers, diastereomers, racemic mixtures, polymorphs, tautomers, solvates, salts, esters, prodrugs or combinations thereof. 7. A compound as recited in any of Point 1 to 4, wherein said compound is compound no. 10875 (Table 1), optionally wherein the molecular weight (MW) of the compound is 2747.2 Daltons. 8. A compound as recited in Point 7, wherein said compound is selected from pharmaceutically acceptable stereoisomers, enantiomers, diastereomers, racemic mixtures, polymorphs, tautomers, solvates, salts, esters, prodrugs or combinations thereof. 9. A compound as recited in any of Points 1 to 4, wherein said compound is compound no. 10890 (Table 1), wherein each amino acid of said peptide component is in its D-configuration, optionally wherein the molecular weight (MW) of the compound is 2630.1 Daltons. 10. A compound as recited in Point 9, wherein said compound is selected from pharmaceutically acceptable stereoisomers, enantiomers, diastereomers, racemic mixtures, polymorphs, tautomers, solvates, salts, esters, prodrugs or combinations thereof. 11. A compound as recited in any of Point 1 to 4, wherein said compound is compound no. 10891 (Table 1), wherein each amino acid of said peptide component is in its D-configuration, optionally wherein the molecular weight (MW) of the compound is 2630.1 Daltons. 12. A compound as recited in Point 11, wherein said compound is selected from pharmaceutically acceptable stereoisomers, enantiomers, diastereomers, racemic mixtures, polymorphs, tautomers, solvates, salts, esters, prodrugs or combinations thereof. 13. A compound as recited in any of Points 1 to 12, wherein said compound does not induce apoptosis or necrosis when applied to a cell or cell layer at a concentration range between about 0.1 nM to about 10,000 µM, or between about 1 nM to about 1,000 µM. 14. A compound as recited in any of Points 1 to 13, wherein said compound decreases the intracellular chloride ion concentration, when applied to HEK-293 cells at a concentration between about 0.1 nM to about 10,000 µM, or between about 1 nM to about 1,000 µM, optionally in a dose- dependent manner. 15. A compound as recited in any of Points 1 to 13, wherein the application of said compound to a cell or cell layer increases epithelial short circuit current at 10 to 100 μM concentration range which remains partially sustained for at least a 10-minute period, optionally in an acute setting. 16. A compound as recited in any of Points 1 to 13, wherein said compound in acute application upstream significantly increases the transient response of Ca2+-activated Cl- channel (CaCC) when activated by UTP, a purinergic agonist. 17. A compound as recited in any of Points 1 to 13, wherein the activity of said compound is independent of the presence of functional CFTR in the membrane or CFTR mutation status. 18. A compound as recited in any of Points 1 to 13, wherein the application of said compound to a suitable cell or cell layer such as airway epithelial cells, increases residual epithelial short circuit current indicating basal levels of Cl- ion transport, independent of CFTR involvement, as well as an increase in said compounds dose-dependent CaCC activity induced by UTP. 19. A compound as recited in any of Points 1 to 13, wherein said compounds weakly interact with mucus, facilitating the rapid transit of a compound of the invention through the mucus. 20. A compound as recited in any of Points 1 to 13, wherein the transit time for said compound through a 100μm mucus layer is less than 5 minutes, or less than 3 minutes, thus enabling the rapid penetration of the compound to or through an apical or epithelial cell membrane. 21. A compound as recited in any of Points 1 to 13, wherein the application of said compound to a suitable cell layer such as airway epithelial cells, increases the airway surface liquid height. 22. A pharmaceutical composition comprising a compound as recited in any of Points 1 to 21, and a pharmaceutically acceptable excipient or carrier, suitably comprising one or more said pharmaceutically acceptable excipients or carriers 23. A pharmaceutical composition comprising a compound as recited in any of Points 1 to 21 wherein said pharmaceutical composition is formulated for a route of administration selected from: oral, pulmonary, rectal, colonic, parenteral, intracisternal, intravaginal, intraperitoneal, ocular, otic, buccal, nasal, and topical administration; and/or formulated as a dosage form selected from the group consisting of liquid dispersions, gels, aerosols, ointments, creams, lyophilized formulations, tablets, capsules; and/or presented as a dosage form selected from the group consisting of controlled release formulations, fast melt formulations, delayed release formulations, extended release formulations, pulsatile release formulations, and mixed immediate release and controlled release formulations; and/or presented as an enema formulation, iontophoretic application, coating an implantable medical device; liquid formulations comprising solutions or suspensions suitable for pulmonary delivery or inhalation via a pMDI, soft mist inhaler, nebulizer or such like; dry powder formulations suitable for pulmonary delivery or inhalation via dry powder delivery device; or combinations thereof. 24. A pharmaceutical composition according to Point 22 or 23, for use in the manufacture of a medicament. 25. A pharmaceutical composition according to any of Points 22-24, for use in the treatment, reduction, inhibition, control of viscous sputum or lowering the viscosity of mucus associated with cystic fibrosis in a human subject, wherein said pharmaceutical composition increases the electrolyte content of said viscous mucus or sputum, such as chloride and/or bicarbonate ions, optionally wherein said pharmaceutical composition is administered to the lungs of said human subject by pulmonary or aerosol delivery as a solution or suspension in a liquid vehicle via a device such as a pMDI, soft mist inhaler or nebulizer, or as a dry powder via a single or multi-dose dry powder inhaler, wherein said devices are well known to those skilled in the art. 26. A compound as recited in any of Points 1 to 21 or a pharmaceutical composition as recited in any of Points 22-23 for use in therapy. 27. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-23 for use in the treatment of diseases associated with chloride ion channel mutations that are involved in processes including the regulation of the membrane potential and excitability of neurons, skeletal, cardiac and smooth muscle, cell volume regulation, transepithelial ion transport, the acidification of intercellular and extracellular compartments, the cell cycle and different forms of cell death. 28. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25 for use in the treatment of a disease associated with chloride ion channel mutations, wherein the disease is selected from: myotonia congenita Becker, Myotonia congenita Thomsen, Dystrophia myotonica 1, dystrophia myotonica 2, childhood absence epilepsy type 3, juvenile absence epilepsy, juvenile myoclonic epilepsy, epilepsy with grand mal seizures on awakening, Bartter Syndrome, Bartter syndrome with sensorineurial deafness, Dent's disease, autosomal dominant osteopetrosis, autosomal recessive osteopetrosis, cystic fibrosis, idiopathic chronic pancreatitis, bronchiectasis, congenital bilateral absence of vas deferens, Best's disease, adult-onset vitelliform macular dystrophy, concentric annular macular dystrophy, cataract, juvenile myoclonic epilepsy, childhood absence epilepsy type 2, generalized epilepsy with febrile seizures, severe myoclonic epilepsy in infancy, insomnia and hereditary hyperekplexia. 29. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25 for use in the treatment of a disease associated with chloride ion channel mutations, wherein the chloride ion channel is selected from: voltage-gated chloride channel family (CLC), transmitter-gated GABA _A , glycine receptors, calcium-activated (CaCC) or calcium- dependent chloride ion channel (Ca-CIC), high (maxi) conductance chloride ion channel, cystic fibrosis transmembrane conductance regulator (CFTR), and volume-regulated channel mutations. 30. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-23 for use in the treatment of a disease associated with voltage-sensitive chloride intracellular channel (CLIC) mutations. 31. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25 for use in the treatment of a disease associated with voltage-sensitive chloride intracellular channel (CLIC) mutations, wherein the voltage-sensitive chloride intracellular channel (CLIC) mutation is selected from the group of CLIC-1, CLIC-2, hCLIC-Ka (rCLIC-K1), hCLIC- Kb (rCLIC-K2); CLIC-3 to CLIC-5, and CLIC-6 and CLIC-7 chloride ion channel mutations. 32. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25 for use in the treatment of a disease associated with voltage-sensitive chloride intracellular channel (CLIC) mutations, wherein the disease is selected from: muscle, skeletal and bone diseases; kidney diseases, ear diseases, central nervous (CNS) diseases, eye diseases, gastrointestinal diseases, pulmonary diseases, cardiac diseases and liver diseases. 33. A compound as recited in any of Points 1 to 21 or a pharmaceutical composition as recited in any of Points 22-25 for use in the treatment of a disease associated with voltage-sensitive chloride intracellular channel (CLIC) mutations, selected from: recessive and dominant myotonia, leukodystrophy, aldosteronism, diabetes insipidus, Bartter disease, Gilteman disease, CNS and retina degeneration, mental retardation, epilepsy, Dent’s disease, proteinuria, impaired renal endocytosis, osteopetrosis, pulmonary hypertension, cardiac dysfunction, Alzheimer’s disease, respiratory and gastrointestinal diseases, including asthma, chronic obstructive pulmonary disease, cystic fibrosis, pneumonia, colon colitis, cystic fibrosis intestinal mucous disease, ulcerative colitis, and gastrointestinal parasitic infection. 34. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25 for use in the treatment of a disease associated with transmitter-gated GABA _A or glycine receptor mutations. 35. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25 for use in the treatment of a diseases associated with calcium-activated chloride ion channel mutations (CaCC or CaCIC). 36. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25 for use in the treatment of a disease associated with calcium-activated chloride ion channel mutations, selected from: cystic fibrosis, dry mouth and dry eye syndromes, asthma, diarrhea, hypertension, neuropathic pain and cancers. 37. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25 for use in the treatment of a disease associated with high (maxi) conductance chloride ion channel mutations. 38. A compound as recited in any of Points 1 to 21, or a composition as recited in any of Points 22-25 for use in the treatment of diseases associated with high (maxi) conductance chloride ion channel mutations, wherein said mutation is found in neurons, glia cells, cardiac muscle cells, lymphocytes, epithelia, macula densa cells of the kidney and human placenta syncytiotrophoblasts. 39. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25 for use in the treatment of a disease associated with volume-activated chloride channel mutations. 40. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25 for use in the treatment of a disease associated with cystic fibrosis transmembrane conductance regulator (CFTR) mutations. 41. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25 for use in the treatment of CFTR-mediated diseases selected from cystic fibrosis, asthma, smoke induced COPD, chronic bronchitis, rhinosinusitis, constipation, pancreatitis, pancreatic insufficiency, male infertility caused by congenital bilateral absence of the vas deferens (CBAVD), mild pulmonary disease, idiopathic pancreatitis, allergic bronchopulmonary aspergillosis (ABPA), liver disease, hereditary emphysema, mucopolysaccharidoses, chloride channelopathies such as myotonia congenita (Thomson and Becker forms), Bartter's syndrome type III, Dent's disease, hyperekplexia, epilepsy, Primary Ciliary Dyskinesia (PCD), an inherited disorders of the structure and/or function of cilia, including PCD with situs inversus (also known as Kartagener syndrome), PCD without situs inversus and ciliary aplasia. 42. A method of treating, reducing, inhibiting or controlling viscous sputum or lowering the viscosity of mucus associated with cystic fibrosis in a human subject, wherein said method comprises administration of a compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25 wherein said method increases the electrolyte content of said viscous mucus or sputum, such as chloride and/or bicarbonate ions, optionally wherein said pharmaceutical composition is administered to the lungs of said human subject by pulmonary or aerosol delivery as a solution or suspension in a liquid vehicle via a device such as a pMDI, soft mist inhaler or nebulizer, or as a dry powder via a single or multi-dose dry powder inhaler. 43. A method of treating, reducing, inhibiting or controlling at least one sign or symptom of cystic fibrosis in a human subject, wherein said method comprises administration of a therapeutically effective amount of one or more compounds as recited in any of Points 1 to 21 or a pharmaceutical composition as recited in any of Points 22-25 to the human subject, optionally in combination with one or more therapeutic agents, wherein said sign or symptom is associated with the airways or respiratory system and includes one or more of the following: abnormally viscous mucus accumulation; increased total mucin content; elevated inflammatory factor concentration; decreased cellular secretion of chloride ions; impaired fluid secretion; increased apical sodium absorption by airway epithelial cells; acidification and decreased height of the apical airway surface liquid; chronic cough; chronic lung infection, and combinations thereof. 44. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22-25, or a method according to Points 42 or 43, for use in the treatment of diseases associated with chloride ion channel mutations or channelopathies which results in one or more of the following: (i) a reduction in the viscosity of the mucus in the lungs, optionally in the presence or absence of any CFTR mutation, (ii) a reduction or delay in disease progression, (iii), reduction in symptom severity relative to therapy in the absence of administration of a compound as claimed herein; (iv), an improvement in breathing or respiratory performance as measured by one or more of FEV1, PEF, FVC, and such like, (v) an improvement in patient reported outcomes, (v) a reduction in the risk of lung infection due to bacteria and/or virus and/or fungus, relative to therapy in the absence of administration of a compound as claimed herein. 45. A compound as recited in any of Points 1 to 21, or a pharmaceutical composition as recited in any of Points 22 to 25, or a method according to Points 42 or 43, for use in the treatment of diseases associated with chloride ion channel mutations or channelopathies, such as CF, wherein said therapeutically effective amount is between about 1 ng and about 5 g, or between about 10 ng and 1 g, or between about 1 mcg and about 500 mg, or between about 10 mcg and about 100 mg, per dose or administration. The term “peptide”, as used herein, refers to a polymer of amino acid residues. The peptide may be, or may have, a sequence which corresponds to, a fragment of a longer protein. The term also applies to amino acid polymers in which one or more amino acid residues is a modified residue, or a non- naturally occurring residue, such as an artificial chemical mimetic of a corresponding naturally- occurring amino acid, as well as to naturally occurring amino acid polymers. The terms “peptide”, “peptide domain” and “peptide component” are used interchangeably herein. The term “retro-analogue”, as used herein, refers to an isomer of a parent peptide in which the order of amino acid has been reversed compared to the parent peptide. The term “inverso-analogue”, as used herein, refers to an isomer of a parent peptide in which one or more D-amino acids are used instead of the corresponding L-amino acid. In preferred embodiments, all of the amino acids in an inverso-analogue are D-amino acids. The term “retro-inverso-analogue”, as used herein, refers to an isomer of a parent peptide in which the order of amino acids has been reversed compared to the parent peptide, and one or more D- amino acids is used instead of the corresponding L-amino acid. Preferably, all of the amino acids in a retro-inverso-analogue are D-amino acids. The term “variant” as used herein means a functional variant, having the same function as the non- variant. In the context of a peptide or a protein, a variant may have sequence alternations compared to the non-variant sequence but retains the biological activity of the non-variant sequence. In particular, a functional variant of one of the proteins, peptides or amino acid sequences disclosed herein has at least 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity to the reference protein, peptide or amino acid sequence, and additionally has the same function as that protein, peptide or amino acid sequence, preferably, cell-penetrating activity. When the peptide is a variant of an inverso-analogue or a retro-inverso-analogue of a CPP, the peptide comprises at least one D-amino acid. The term “sequence identity”, as used herein indicates the percentage of amino acid residues which are the same between two or more sequences, when the sequences are compared and aligned for maximum correspondence. The identity between sequences is determined over the full length of the peptides to be compared or a specified subsequence thereof, and can be determined using the local homology algorithm of Smith and Waterman (1981, Adv. Appl. Math. 2: 482), the homology alignment algorithm of Needleman and Wunsch (1970, J. Mol. Biol. 48: 4430, the search for similarity method of Pearson and Lipman (1988, Proc. Natl. Acad. Sci., USA, 85: 2444), or computerized implementations of these algorithms (GAP, BESTFIT, FASTA, and TFASTA in the Wisconsin Genetics Software Package, Genetics Computer Group, 575 Science Dr., Madison, Wis.), or by manual alignment and visual inspection. Other examples of algorithms that are suitable for determining percent sequence identity are the BLAST and BLAST 2.0 algorithms. It is preferred that the percentage “sequence identity” between two sequences is determined using EMBOSS Needle Pairwise Sequence Alignment (Rice et al., Trends Genet.2000 Jun;16(6):276-7; Nucleic Acids Res. 2019 Jul 2;47(W1):W636-W641) using default parameters. In particular, EMBOSS Needle can be accessed on the internet using the URL: https://www.ebi.ac.uk/Tools/psa/emboss_needle/. The term “mitochondria-targeting sequence”, as used herein, refers to a short peptide chain which directs the transport of a protein to a mitochondria of a cell, and which is often found at the N- terminus of the protein. Mitochondria-targeting sequences (MTSs) are made up of an alternating pattern of hydrophobic and positively charged amino acids, and form an amphipathic helix. MTSs are known to be a sub-type of CPPs. The MTS in the compounds of the invention may be any MTS known to the person skilled in the art. Example MTSs are detailed in Cho et al., (BBA – Molecular basis of Disease 1866 (2020) 165808). The term “poly-arginine” as used herein includes a peptide chain containing more than one amino acid residue, wherein all of the amino acid residues in the chain are arginine. The term “pharmaceutical composition”, as used herein, means a pharmaceutical preparation suitable for administration to an intended human or animal subject for therapeutic purposes. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph showing the cytotoxicity and viability data for compounds of the invention in human bronchial/tracheal epithelial cells, compared to controls and a previously-identified synthetic ion transporter (compound no.10871). Figure 2 is a graph showing the results of Two-Electrode Voltage-Clamp (TEVC) recording using compounds of the invention, compared to a previously-identified synthetic ion transporter (reference compound no.10871). Figure 3 presents the results of the intracellular chloride ion measurements that shows the maximal responses of each cell in Reference Example 1. Figure 4 is a graph showing the results of the stability study using compound no.10871, compound no.10890 (which comprises an inverso-peptide) and compound no.10891 (which comprises a retro- inverso-peptide). Figure 5 is graph showing that the baseline electrophysiological characteristics of compound no. 10871 falls within acceptable parameters in CF W1282X/R1162X HBE cultures. Figure 6 is a graph showing the acute activity of compound no. 10871 in CF W1282X/R1162X HBE cultures of Reference Example 3. Figure 7 is a graph showing the chronic activity of compound no.10871 (Reference Example 3). BRIEF DESCRIPTION OF THE SEQUENCE LISTING SEQ ID NO: 1 (GRKKRRQRRRPPQ) is a fragment of HIV-TAT consisting of residues 48-60 of TAT. SEQ ID NO: 2 (RKKRRQRRR) is a fragment of HIV-TAT consisting of residues 49-57 of TAT SEQ ID NO: 3 (YGRKKRRQRRRP) is a fragment of HIV-TAT consisting of residues 47-58 of TAT. SEQ ID NO: 4 (GRKKRRQRRRPPQ) is a fragment of HIV-TAT comprising residues 48-60 of TAT. SEQ ID NO: 5 (RQIKIWFQNRRMKWKK) is the amino acid sequence of penetratin. SEQ ID NO: 6 (RQIKIFFQNRRMKWKK) is a variant of penetratin having a W-to-F amino acid substitution at position 6 of SEQ ID NO: 5, referred to herein as “penetratin variant W48F”. SEQ ID NO: 7 (RQIKIWFQNRRMKFKK) is a variant of penetratin having a W-to-F amino acid substitution at position 14 of SEQ ID NO: 5, referred to herein as “penetratin variant W56F”. SEQ ID NO: 8 (RQIKIWFQNRRMKFKK) is the amino acid sequence of a variant of penetratin (SEQ ID NO: 5). SEQ ID NO: 9 (GWTLNSAGYLLGKINLKALAALAKKIL) is the amino acid of transportan. SEQ ID NO: 10 (GWYLNSAGYLLGKCINLKALAALAKKIL) is the amino acid sequence of transportan-27. SEQ ID NO: 11 (GWYLNSAGYLLGKCINLKALAAL) is the amino acid sequence of transportan-22. SEQ ID NO: 12 (KETWWETWWTEWSQPKKKRKV) is the amino acid sequence of Pep-1. SEQ ID NO: 13 (KETWFETWFTEWSQPKKKRKV) is the amino acid sequence of Pep-2. SEQ ID NO: 14 (YARAAARQARA) is the amino acid sequence of PTD4. SEQ ID NO: 15 (RRRRRRR) is the amino acid sequence of R7 poly-arginine. SEQ ID NO: 16 (LLIILRRRIRKQAHAHSK) is the amino acid sequence of pVEC. SEQ ID NO: 17 (MLRAALSTARRGPRLSRLL) is the amino acid sequence of a mitochondria- targeting sequence (MTS) derived from human mitochondria-oriented aldehyde dehydrogenase. SEQ ID NO: 18 (MVSAL) is a MTS derived from mitochondrial human malate dehydrogenase. SEQ ID NO: 19 (MSVLTPLLLRGLTGSARRLPVPRAKIHSL) is a MTS derived from subunit IV of human cytochrome c oxidase. SEQ ID NO: 20 (GALFLGFLGAAGSTMGAWSQPKKKRKV) is the amino acid sequence of MPG. SEQ ID NO: 21 (RQIKIWFQNRRMKWKK) is the amino acid sequence of the inverso-analogue of penetratin. SEQ ID NO: 22 (KKWKMRRNQFWIKIQR) is the amino acid sequence of the retro-analogue of penetratin. SEQ ID NO: 23 (KKWKMRRNQFWIKIQR ) is the amino acid sequence of the retro-inverso- analogue of penetratin. DETAILED DESCRIPTION OF THE INVENTION The present invention arises because novel synthetic chloride ion transporters have been found, demonstrating surprising biological properties. Cell-penetrating peptides (CPPs) are small oligopeptides typically comprising between 5 and 30 amino acid residues. They are generally positively charged and are known to possess a random conformation in aqueous environment. However, in the non-polar cell membrane, they show a tendency to fold into helical conformations (C Bechara, S Sagan, FEBS Letters, 2013, 587, pp 1693). They can pass through membranes either by a direct pathway or by a vesicular mode via endocytosis. Cell-penetrating peptides (CPPs) are known to transport various cargos ranging from small organic molecules to gene encoding DNAs (JP Richard, et.al, Journal of Biological Chemistry, 2003, 278, pp 585). Synthetic ion transporters or ion channels could mimic the function of natural ion channels, thus rendering the unmet clinical need for channel replacement therapy feasible (N Busschaert, PA Gale, Angewandte Chemie International Edition, 2013, 52, pp 1374.). The development of lipid-bilayer chloride ion transporters for potential use in channel replacement therapy for the treatment of diseases caused by dysregulation of anion transport, such as cystic fibrosis (CF), is an area of current interest. In CF, the impaired chloride transportation is the main cause of the illness affected by the monogenic mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel (BP O'Sullivan, SD Freedman, Lancet, 2009, 373, pp 1891). CPP-based treatments may be combined with currently used therapies in CF, as the mechanism of action of each is completely different and result in synergy. CPP-based therapies can enhance the effect of mucolytic drugs and airway clearance techniques, as the application of CPP-based therapies may increase the hydration of mucus. Synergistic effects are found in the combined application with VX compounds, as CPP-based chloride ion transport is independent from the presence of functional CFTR in the membrane. Various synthetic chloride transporters have been developed, with different molecular masses ranging from small organic molecules to supramolecular systems. These compounds either passively diffuse through the membrane with the chloride ion or form a channel in the membrane, opening the way for passive ion transport (N Busschaert, PA Gale, Angewandte Chemie International Edition 2013, 52, pp 1374). Chloride ion channels are a functionally and structurally diverse group of anion selective channels involved in processes including the regulation of the excitability of neurons, skeletal, cardiac and smooth muscle, cell volume regulation, transepithelial salt transport, the acidification of internal and extracellular compartments, the cell cycle and apoptosis. Chloride ion channels can be classified as members of the voltage-sensitive CLIC subfamily, transmitter-gated GABA _A , and glycine receptors, calcium-activated chloride ion channels (CaCIC) such as TMEM16A, high (maxi) conductance chloride ion channels, the cystic fibrosis transmembrane conductance regulator (CFTR), and volume-regulated channels. The mammalian CLIC family contains 9 members that fall into three groups; CLIC-1, CLIC-2, hCLIC-Ka (rCLIC-K1) and hCLIC-Kb (rCLIC-K2); CLIC-3 to CLIC-5, and CLIC-6 and CLIC-7. CLIC-1 and CLIC-2 are plasma membrane chloride channels. ClC-Ka and ClC-Kb are also plasma membrane channels (largely expressed in the kidney and inner ear) when associated with barttin (BSND, Q8WZ55. The localisation of the remaining members of the CLIC family is likely to be predominantly intracellular in vivo, although they may traffic to the plasma membrane in overexpression systems. Numerous recent reports indicate that CLIC-4, CLIC-5, CLIC-6 and CLIC-7 (and by inference CLIC-3) function as Cl-/H+ antiporters (secondary active transport), rather than classical Cl- channels. The activity of CLIC-5 as a Cl-/H+ exchanger is important for renal endocytosis. (“Chloride channels.” British Journal of Pharmacology 2009, vol.158, Suppl 1: S130-S134). The role of CLICs in tubulogenesis and angiogenesis is well established (GR Shubha, P Neel J., S Harpreet, Frontiers in Physiology, 2020, Vol.11, pp 96). One of the most significant pathological roles discovered for CLICs was their involvement in pulmonary hypertension (PH). PH is characterized by a loss of vasodilator influences in the pulmonary circulation, which results in pathogenic vasoconstriction, and remodeling of small intrapulmonary arteries, leading to eventual right heart failure. CLIC4 was found to be highly expressed in the pulmonary vascular endothelium of PH patients. In the heart, CLICs are extensively expressed in several types of cells. CLIC1, CLIC4, and CLIC5 were localized in adult cardiomyocytes, and further CLIC4 and CLIC5 were localized to mitochondrial membranes. CLIC5 is the first chloride channel to be identified up to the molecular level in the inner membrane of cardiac mitochondria. The first member of the CLIC family to directly implicate them in cardiac dysfunction was CLIC2. A mutation in CLIC2 (c.303C>G, p.H101Q) was found to be associated with X-linked intellectual disability (ID), atrial fibrillation, cardiomegaly, congestive heart failure (CHF), and seizures. CLIC2 is known to interact with ryanodine receptor (RyR) proteins and inhibit its activity. In blood cells, CLIC1 is known to promote platelet function, promote adhesive functions in platelets as well as endothelial cells, and is critical for vascular repair and angiogenesis. One of the major physiological roles of CLIC5 is implicated in hearing impairment. At molecular levels, CLIC5 is shown to work with cytoskeletal elements such as radixin, protein tyrosine phosphatase receptor Q, taperin, and myosin VI. These interactions are essential to stabilize membrane-cytoskeletal attachments at the base of the hair bundle. Absence of CLIC5 compromises the stability of hair bundles either by disrupting cytoskeletal filaments or by disrupting chloride ion transport in hair cells, resulting in the progressive loss of integrity of these vital structures. Chloride intracellular ion channel proteins are known to be present in neurons and astrocytes. At the functional level, CLIC1 is characterized for its role in Alzheimer’s disease (AD) where it is present in activated microglia. CLCA1 is a member of the CLCA (calcium-activated chloride channel regulator) family and plays an essential role in goblet cell mucus production from the respiratory tract epithelium. CLCA1 also regulates Ca2+-dependent Cl− transport that involves the channel protein transmembrane protein 16A (TMEM16A) and its accessary molecules. CLCA1 modulates epithelial cell chloride current and participates in the pathogenesis of mucus hypersecretory-associated respiratory and gastrointestinal diseases, including asthma, chronic obstructive pulmonary disease, cystic fibrosis, pneumonia, colon colitis, cystic fibrosis intestinal mucous disease, ulcerative colitis, and gastrointestinal parasitic infection. The Ca2+-activated chloride ion channels (CaCCs) are found in almost all species ranging from invertebrates to mammals, and the ubiquitous expression of CaCCs indicates a variety of functions important for physiology, including regulation of epithelial Cl– secretion, excitability of neuronal and cardiac cells, smooth muscle contraction and nociception. The molecular identity of the Ca2+- activated chloride ion channels (CaCCs)remained elusive until anoctamin 1 (ANO1) and anoctamin 2 (ANO2) were identified as CaCCs in 2008. ANO1 and ANO2 possess the same properties as endogenous CaCCs. These properties include anion selectivity, submicromolar sensitivity to intracellular Ca2+, voltage activation at low Ca2+ concentrations and inhibition by the pharmacological agents niflumic acid (NFA) and 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) (J Berg, H Yang, LY Jan, J Cell Sci.2012;125(Pt 6), pp 1367-1371). ANO1, as a CaCC, is primarily expressed in epithelial cells, smooth muscle cells and sensory neurons. ANO2, also as a CaCC, is expressed in the olfactory sensory neurons, photoreceptor synaptic terminals, hippocampal pyramidal neurons, thalamocortical neurons, and inferior olive neurons in the brain. Other ANOs family members including ANO6 and ANO7 were onetime considered to be CaCCs12, but evidence shows that ANOs3–7 neither generate Ca2+-activated Cl– currents nor traffic into membrane, indicating that they are endoplasmic reticulum proteins (Y Liu, Z Liu, K Wang, Acta Pharmaceutica Sinica B., 2020). ANO1 high expression or hyperactivity can cause inflammatory diseases such as asthma and diarrhea. Outward flow of Cl− through the activation of ANO1 in smooth muscle cells causes depolarization and smooth muscle contraction. ANO1 high expression or hyperactivity is responsible for asthma diarrhea, and hypertension. In DRG sensory neurons, activation of ANO1 by intracellular Ca2+ or heat causes Cl− efflux and increases neuronal excitability for induction of neuropathic pain. The functional coupling between TRPV1 and ANO1 is also involved in nociception. In cancer cells, ANO1 upregulation promotes cell proliferation and migration, whereas ANO1 downregulation induces apoptosis through multiple signaling pathways, including EGFR/MAPK signaling pathway, CaMKII/MAPK signaling pathway, TGF-β signaling pathway and NF-κB signaling pathway. Pharmacological activation of ANO1 by activators or potentiators may serve as a therapeutic strategy for treatment of CF, dry mouth and dry eye syndromes, and inhibition of ANO1 by inhibitors may be beneficial for ANO1 related channelopathies including asthma, diarrhea, hypertension, neuropathic pain and cancers. Maxi Cl− channels are high conductance, anion selective, channels initially characterised in skeletal muscle and subsequently found in many cell types including neurons, glia, cardiac muscle, lymphocytes, secreting and absorbing epithelia, macula densa cells of the kidney and human placenta syncytiotrophoblasts. CFTR, a 12TM, ABC type protein, is a cAMP-regulated epithelial cell membrane chloride ion channel involved in normal fluid transport across various epithelia. The most common mutation in CFTR (i.e. the deletion mutant, ΔF508) results in impaired trafficking of CFTR and reduces its incorporation into the plasma membrane causing cystic fibrosis. Channels carrying the ΔF508 mutation that do traffic to the plasma membrane demonstrate gating defects. In addition to acting as an anion channel per se, CFTR may act as a regulator of several other conductances including inhibition of the epithelial Na channel (ENaC), calcium-activated chloride channels (CaCC) and Volume-regulated anion channel (VRAC), activation of the outwardly rectifying chloride channel (ORCC), and enhancement of the sulphonylurea sensitivity of the renal outer medullary potassium channel (ROMK2). CFTR also regulates TRPV4, which provides the Ca2+ signal for regulatory volume decrease (RVD) in airway epithelia. The activities of CFTR and the chloride-bicarbonate exchangers SLC26A3 (DRA) and SLC26A6 (PAT1) are mutually enhanced by a physical association between the regulatory (R) domain of CFTR and the STAS domain of the SCL26 transporters, an effect facilitated by PKA-mediated phosphorylation of the R domain of CFTR. Volume activated chloride channels (VSOAC) participate in regulatory volume decrease (RVD) in response to cell swelling. VRAC may also be important for several other processes including the regulation of membrane excitability, transcellular Cl- transport, angiogenesis, cell proliferation, necrosis, apoptosis, glutamate release from astrocytes, insulin release from pancreatic β cells and resistance to the anti-cancer drug, cisplatin. Currently more than 2000 CFTR gene mutations have been described, whereas only 159 mutations have been characterized in terms of disease liability (R Bolia, et al., J Paediatr Child Health, 2018, 54, pp 609). The most common mutation type in 85% of patients worldwide is the deletion of phenylalanine at position 508 (F508del), however to date mutations are classified into seven different groups according to the CFTR defect caused (K De Boeck, MD Amaral, Lancet Respir Med, 2016, 4, pp 662). Class I mutations, which include frameshift, splicing or nonsense mutations that introduce premature termination codons; Class II mutations, which lead to misfolding and impaired protein biogenesis at the endoplasmic reticulum (ER); Class V mutations which result in reduced synthesis due to promoter or splicing abnormalities; and Class VI mutations that destabilize the CFTR channel in post-ER compartments and/or at the plasma membrane. Whereas Class III and IV mutations impair the gating and channel pore conductance respectively, thus selectively compromising CFTR function. In Class VII mutations, no mRNA can be detected. Current clinical treatment of CF is based on CFTR modulator therapy. CFTR modulators include ivacaftor (Kalydeco®), lumacaftor/ivacaftor (Orkambi®), tezacaftor/ivacaftor (Symdeko®), and elexacaftor/tezacaftor/ivacaftor (Trikafta™). These drugs can increase the open state probability of CFTR and thus increase the ion efflux through the channel pore, or can promote the CFTR protein folding. Although these drugs have beneficial effects, their clinical use is restricted to patient populations with specific types of CFTR gene mutations. Channel replacement therapy with synthetic chloride ion transporters based on CPPs could overcome the severe limitation of current treatments, since such synthetic chloride transporters may promote chloride efflux across biological barriers even in the complete absence of CFTR protein. Therefore, chloride channel replacement therapy may provide mutation independent treatment, also known as pangenotypic, since the CFTR protein is not needed for chloride ion transport, and could therefore be used early in patients, whereby their patient-specific mutations do not have to be characterized prior to commencement of such therapies (as is the current standard of care). In addition, there are several patients with extremely rare mutations, which are not yet classified under the current mutation classes. CPP-based treatment may be applied in these patients without any clear restrictions. Synthetic chloride ion transporter compounds of the present invention either passively diffuse through the membrane with the chloride ion or form a channel in the membrane, opening the way for passive ion transport. Synthetic chloride ion transporters can be used in a mutation-independent way. Thus all CF patients may be treated using the compounds according to the invention. Compounds described herein include those having the general formula A as follows:

wherein, n= 0-10; k= 1-200; The peptide part comprises two or more amino acids which may comprise D and/or L amino acids, in any proportion. The sequence of peptide part can be read and synthesized from left side to right side, but also from right side to left side which opposite sequence can be called retro peptide containing compounds X= H, C1-10 alkyl or cycloalkyl, aryl, protecting group, C1-10 acyl, biotin, fluorescent and radioactive tracer, alkyl, cycloalkyl and acyl groups can be substituted with N, O, S, P, Se, Si, As or halides; Y= O, S, NH, CH ₂ , N-OR; Z= C1-10 alkyl or cycloalkyl, aryl, protecting group, C1-10 acyl, biotin, fluorescent and radioactive tracer, alkyl, cycloalkyl and acyl groups can be substituted with N, O, S, P, Se, Si, As or halides; R= H, OH, O-alkyl, NH, N-alkyl, SH, S-alkyl, alkyl, alkenyl, alkynyl, NH-NH2; R2 = H, C1-10 alkyl or cycloalkyl, aryl, these ideally substituted with N, O, S, P, Se, Si, As or halides, and may form ideally a ring system, and may be glycosylated, further including pharmaceutically acceptable stereoisomers, enantiomers, diastereomers, racemic mixtures, polymorphs, tautomers, solvates, salts, esters, prodrugs or combinations thereof. R3= H, C1-10 alkyl or cycloalkyl, aryl, these ideally substituted with N, O, S, P, Se, Si, As or halides, and may form ideally a ring system, and may be glycosylated, further including pharmaceutically acceptable stereoisomers, enantiomers, diastereomers, racemic mixtures, polymorphs, tautomers, solvates, salts, esters, prodrugs or combinations thereof. In a first aspect, the invention provides a compound according to Formula I: T – Z – [Peptide] (I) or a pharmaceutically acceptable salt thereof, wherein: T is a chloride ion binding moiety; and Z is a linker having a chain length of from 8 to 30 atoms in the shortest linear path, the chain of atoms including at least 2 heteroatoms selected from O, S and N; and the peptide comprises a cell penetrating peptide (CPP), a retro-analogue of a CPP, an inverso-analogue of a CPP or a retro-inverso-analogue of a CPP, or a variant thereof having at least 70% sequence identity thereto, wherein a variant of an inverso-analogue or a retro-inverso-analogue of a CPP comprises at least one D-amino acid, and wherein the -OH at the C-terminus of the peptide is optionally substituted by Ra, wherein Ra is selected from -NH ₂ , -O-C _1-6 alkyl, -NHC _1-6 alkyl, and -NH-NH _2, provided the compound is not

. In embodiments, the chain length for Z is from 9 to 30 atoms in the shortest linear path. In other words, in embodiments of the first aspect, the invention may provide a compound according to Formula I: T – Z – [Peptide] (I) or a pharmaceutically acceptable salt thereof, wherein: T is a chloride ion binding moiety; and Z is a linker having a chain length of from 9 to 30 atoms in the shortest linear path, the chain of atoms including at least 2 heteroatoms selected from O, S and N; and the peptide comprises a cell penetrating peptide (CPP), a retro-analogue of a CPP, an inverso-analogue of a CPP or a retro-inverso-analogue of a CPP, or a variant thereof having at least 70% sequence identity thereto, wherein a variant of an inverso-analogue or a retro-inverso-analogue of a CPP comprises at least one D-amino acid, and wherein the -OH at the C-terminus of the peptide is optionally substituted by Ra, wherein Ra is selected from -NH ₂ , -O-C _1-6 alkyl, -NHC _1-6 alkyl, and -NH-NH ₂ . As recited herein, T is a chloride ion binding moiety. As used herein, the term “chloride ion binding moiety” refers to a chemical structure that contains at least one functional group that is capable of binding chloride ions (e.g. by dative coordination). Urea and thiourea are examples of functional groups that are capable of coordinating chloride ions. Thioureas bind chloride ions particularly strongly and so chemical structures that contain one or more thiourea groups are particularly preferred as the chloride ion binding moiety at T, according to the invention. In preferred embodiments, T is 1 , wherein X is a C _6-10 aryl group (preferably phenyl), optionally substituted with from 1 to 3 substituents, each substituent independently selected from NO ₂ , CN, halo, C _1-4 alkyl, C _1-4 alkoxy and C _1-3 haloalkyl; and Y1 is S or O. In other words, the compound may thus be a compound of Formula 1* [I*] or pharmaceutically acceptable salt thereof, wherein Z, X1, Y1 and [peptide] as are defined according to any embodiment of the first aspect disclosed herein. Any embodiments or limitations described herein in respect of Formula I or Formula Ia may thus apply to Formula I*. As defined above in relation to Formula I, Z is a linker having a chain length of from 8 to 30 atoms in the shortest linear path, the chain of atoms including at least 2 heteroatoms selected from O, S and N. Z may for instance have a chain length of from 9 to 30 atoms in the shortest linear path. By way of clarification, the following illustration indicates the atom numbering principle applied in the present application with respect to exemplary compounds of formula I, for the purpose of calculating the number of chain atoms in linker Z. In the above illustration, the thiourea-containing group represents the chloride ion binding moiety T of formula I, and the atoms linking said group T with the N terminus of the peptide represent the linker. In the above example, which illustrates the groups T and Z of compound number 10875 (table 1), the linker Z has a chain length of 13 atoms. The linker acts to both bind together, and physically separate the chloride ion binding moiety and the peptide. As demonstrated in the examples, it has been surprisingly found that heteroatom- containing linkers of the type claimed and length defined in the first aspect (especially polyethylene glycol-containing linkers) provide improved therapeutic effects compared to comparative compounds having different linkers, for instance shorter chain non-heteroatom containing linkers or longer chain heteroatom-containing linkers. The linker may be acyclic (unbranched or branched) or may include cyclic moieties. When a cyclic moiety forms part of the chain backbone (e.g. a cycloalkyl group), the number of atoms in the chain is calculated according to the shortest linear chain of atoms joining T and the peptide. Typically, however, the linker is acyclic, preferably unbranched. Moreover, also with reference to the above illustration, we clarify what it means for the chain of atoms to include heteroatoms. In the above illustration, according to the convention described in this application, the linker Z has specifically 3 heteroatoms in the chain of atoms, namely the oxygen atom 3, oxygen atom 6, and nitrogen atom 9. The number of heteroatoms in the chain as defined in accordance with the present invention is thus intended to refer to the heteroatoms in the chain backbone. The linker in the illustration above also contains 2 x =O groups (i.e. at positions numbered 10 and 13 in the illustration above). These are not heteroatoms in the chain of atoms, but substituents that are pendant to the chain of atoms. In embodiments, Z may have a chain length of from 9-28 atoms. Z may have a chain length of from 9-20 atoms. Z may have a chain length of from 9-16 atoms. Z may have a chain length of from 9- 14 atoms. Z may have a chain length of from 9-13 atoms. In embodiments, Z may have a chain length of from 10-28 atoms. Z may have a chain length of from 10-20 atoms. Z may have a chain length of from 10-16 atoms. Z may have a chain length of from 10-14 atoms. Z may have a chain length of from 10-13 atoms. Z may have a chain length of from 12-28 atoms. Z may have a chain length of from 12-20 atoms. Z may have a chain length of from 12-16 atoms. Z may preferably have a chain length of from 12- 14 atoms, e.g.13 atoms. Z may have a chain length of from 20-30 atoms. Z may have a chain length of from 22-28 atoms. Z may have a chain length of from 26-28 atoms. Z may for instance have a chain length of 27 atoms. According to Z defined herein, the chain of atoms includes at least 2 heteroatoms selected from O, S and N. This means that the chain of atoms linking T and the peptide moiety contains these atoms in the backbone. In embodiments, the chain of atoms may include up to 10 heteroatoms selected from O, S and N. The chain of atoms may include at least 3 or 4 heteroatoms selected from O, S and N. In embodiments, the chain of atoms includes from 2 to 8 heteroatoms selected from O, S and N, e.g. 2, 3, 4, 5, 6, 7, or 8. Typically the heteroatoms are selected from O and N, and may include both. Z may therefore include ether and / or amine moieties. Preferably O and N atoms are included, preferably wherein the N is provided as part of an –NH- group. In addition to containing heteroatoms in the chain, Z encompasses linkers containing pendant heteroatom-containing functional groups bonded to the chain, such as -OH, =O, -NO2, -NH2 or halo, typically =O. In embodiments, there are no additional pendant groups. In embodiments, 1-6 such pendant substituents may be present, such as 1-4, e.g. 2-4. Typically there are such pendant substituents. The substituents may in some embodiments be independently selected from -OH, =O, -NH ₂ and halo, such as from -OH, =O, and -NH ₂ , e.g. –OH and =O, preferably =O. Preferably the substituent(s) are each =O. In some embodiments there is one substituent, which is =O. In some embodiments, there is no substitution. The chain may thus be a heteroalkylene chain, optionally substituted with from one to six (e.g. 2- 4) substituents selected from -OH, =O, -NO2, -NH2 and halo. Z may thus be a C _9-30 heteroalkylene, optionally substituted with from 1-6 (e.g.2-4) substituents selected from -OH, =O, -NO ₂ , -NH ₂ or halo. The substituents may in some embodiments be independently selected from -OH, =O, -NH ₂ and halo, such as from -OH, =O, and -NH ₂ , e.g. –OH and =O, preferably =O. Preferably the substituent(s) are each =O. In some embodiments there is one substituent, which is =O. In some embodiments, there is no substitution. If one or more substituents are present, they are most preferably =O, e.g. there may be from 1-6 such as 2-4 =O substituents. Preferably, the linker Z contains one or more amide moieties (e.g. -NH-C(O)-) and / or ethylene glycol moieties (i.e. -CH2-CH2-O-). Most preferably, the linker contains both amide and ethylene glycol moieties, such as polyethylene glycol moieties (“PEG”). Z may be –Z1C(O)-, wherein Z1 is C _8-28 heteroalkylene optionally substituted with from 1-5 substituents (e.g. 1-3 substituents) independently selected from -OH, =O, -NO ₂ , -NH ₂ or halo, preferably =O. The Z1 group may thus be unsubstituted. Typically however it is substituted. In preferred embodiments, Z is: . In particularly preferred embodiments, Z is In an especially preferred embodiment, Formula I is according to the following formulae, wherein the peptide is as defined according to the first aspect or any embodiment thereof Preferably formula I in the first aspect is as follows: wherein the peptide is as defined according to the first aspect or any embodiment thereof. In some embodiments, the peptide consists of a CPP, a retro-analogue of a CPP, an inverso- analogue of a CPP or a retro-inverso-analogue of a CPP, or a variant thereof having at least 70% sequence identity thereto, wherein a variant of an inverso-analogue or a retro-inverso-analogue of a CPP comprises at least one D-amino acid. In a second aspect, the invention provides a compound according to Formula I, T – Z – [Peptide] (I) or a pharmaceutically acceptable salt thereof, wherein: T is a chloride ion binding moiety; and Z is a C _1-12 alkylene, C _5-12 cycloalkylene, C _2-30 heteroalkylene, or C _6-12 aralkylene, each optionally substituted with from 1-6 substituents independently selected from -OH, =O, -NO ₂ , -NH ₂ and halo; and the -OH at the C-terminus of the peptide is optionally substituted by Ra, wherein Ra is selected from NH ₂ , -O-C _1-6 alkyl, -NHC _1-6 alkyl, and -NH-NH ₂ ; and wherein the peptide is a retro-analogue, an inverso-analogue or a retro-inverso-analogue of a cell penetrating peptide (CPP) or a variant thereof having at least 70% sequence identity thereto, wherein a variant of an inverso-analogue or a retro-inverso-analogue of a CPP comprises at least one D-amino acid. T may include a urea and / or thiourea group, preferably a thiourea. In preferred embodiments, T is , wherein X1 is a C _6-10 aryl group (preferably phenyl), optionally substituted with from 1 to 3 substituents, each substituent independently selected from NO ₂ , CN, halo, C _1-4 alkyl, C _1-4 alkoxy and C _1-3 haloalkyl; and Y1 is S or O, preferably S. In other words, the compound may thus be a compound of Formula 1* or pharmaceutically acceptable salt thereof, wherein Z, X1, Y1 and [peptide] as are defined according to any embodiment of the second aspect herein. Any embodiments or limitations described herein in respect of Formula I or Formula Ia may thus apply to Formula I*. Z may typically be C _1-12 alkylene or C _2-30 heteroalkylene, optionally substituted with from 1-6 substituents (e.g. 2-4 substituents) independently selected from -OH, =O, -NO ₂ , -NH ₂ and halo, preferably =O. When Z is C _1-12 alkylene, it may be C _2-8 alkylene optionally substituted with from 1-2 substituents independently selected from -OH, =O, -NO2, -NH2 or halo, preferably =O. For example, Z may be C _2-8 alkylene substituted with only one =O group. It may be C ₃ alkylene substituted with only one =O group. It may be C ₆ alkylene substituted with only one =O group. The alkylene is preferably linear (unbranched) alkylene, e.g. wherein C ₃ alkylene is n-propylene, and C ₆ alkylene is n-hexylene. Z according to the second aspect may be defined according to the first aspect or any embodiment thereof. When Z is optionally substituted C _2-30 heteroalkylene, Z may comprise one or more amide moieties and / or one or more ethylene glycol moieties, preferably both amide and ethylene glycol moieties. In embodiments, Z may be C _8-28 heteroalkylene, optionally substituted as described above. Z may be C _8-20 heteroalkylene, optionally substituted as described above. Z may be C _8-16 heteroalkylene, optionally substituted as described above. Z may be C8-14heteroalkylene, optionally substituted as described above. Z may be C _8-13 heteroalkylene, optionally substituted as described above. In embodiments, Z may be C _9-28 heteroalkylene, optionally substituted as described above. Z may be C _9-20 heteroalkylene, optionally substituted as described above. Z may be C _9-16 heteroalkylene, optionally substituted as described above. Z may be C _9-14 heteroalkylene, optionally substituted as described above. Z may be C9-13heteroalkylene, optionally substituted as described above. In embodiments, Z may be C _10-28 heteroalkylene, optionally substituted as described above. Z may be C _10-20 heteroalkylene, optionally substituted as described above. Z may be C _10-16 heteroalkylene, optionally substituted as described above. Z may preferably be C _10-14 heteroalkylene, optionally substituted as described above, e.g. C ₁₃ heteroalkylene, optionally substituted as described above. Z may be C _12-28 heteroalkylene, optionally substituted as described above. Z may be C _{12- 20} heteroalkylene, optionally substituted as described above. Z may be C _12-16 heteroalkylene, optionally substituted as described above. Z may be C _12-14 heteroalkylene, optionally substituted as described above, e.g. C ₁₃ heteroalkylene, optionally substituted as described above. Where Z is substituted, it may contain from 1-6 substituents independently selected from -OH, =O, -NO2, -NH2 or halo, typically =O. In embodiments, there are from 1-4 substituents, such as 1, 2, 3, or 4. The substituents may in some embodiments be independently selected from -OH, =O, -NH ₂ and halo, such as -OH, =O, and -NH2, e.g. –OH or =O, preferably =O. Preferably the substituent(s) are each =O. In some embodiments there is one substituent, which is =O. In some embodiments, there is no substitution. Z may be selected from Z may be –Z1C(O)-, wherein Z1 is C _1-10 alkylene, C _5-10 cycloalkylene, C _2-28 heteroalkylene, or C _6-10 aralkylene, preferably C _1-10 alkylene or C _2-28 heteroalkylene, wherein the alkylene and heteroalkylene groups are each optionally substituted with from 1-5 substituents (e.g. 1-4 substituents) independently selected from -OH, =O, -NO ₂ , -NH ₂ or halo, preferably =O. Z1 may be C _1-10 alkylene, C _5-10 cycloalkylene, C _2-10 heteroalkylene, or C _6-10 aralkylene. Z1 may be C _2-6 alkylene, for example C _2-5 alkylene. It may be C ₂ alkylene. It may be C ₅ alkylene. The alkylene is preferably linear (unbranched) alkylene, e.g. wherein C ₂ alkylene is ethylene, and C ₅ alkylene is n-pentylene. Z1 may be C _2-28 heteroalkylene, optionally substituted as described above. Z1 may be C _{2- 20} heteroalkylene, optionally substituted as described above. Z1 may be C _2-16 heteroalkylene, optionally substituted as described above. Z1 may be C _2-14 heteroalkylene, optionally substituted as described above. Z1 may be C _2-12 heteroalkylene, optionally substituted as described above. Z1 may be C _11-28 heteroalkylene, optionally substituted as described above. Z1 may be C _{11- 20} heteroalkylene, optionally substituted as described above. Z1 may be C _11-16 heteroalkylene, optionally substituted as described above. Z1 may be C _11-14 heteroalkylene, optionally substituted as described above. Z1 may preferably be C ₁₂ heteroalkylene, optionally substituted as described above. Z1 may be In a preferred embodiment of the second aspect, the compound of Formula I is according to Formula Ia, or a pharmaceutically-acceptable salt thereof, wherein X1 is a C _6-10 aryl group, optionally substituted with from 1 to 3 substituents, each substituent independently selected from NO ₂ , CN, halo, C _1-4 alkyl, C _1-4 alkoxy and C _1-3 haloalkyl; Y1 is S or O; and Z1 is as defined above according to the second aspect or any embodiment thereof described herein; and the peptide is as defined above for the second aspect or any embodiment thereof described herein. In both the first and second aspect, the CPP may be penetratin, MPG, a MTS, HIV-TAT, a peptide comprising positions 48-60 or 49-57 of HIV-TAT, transportan, herpes simplex virus protein VP22, Pep-1, Pep-2, PTD4, SP, pVEC or poly-arginine, or a variant or a translocationally-active homologue or fragment thereof. In both the first and the second aspect, the CPP may have at least 70% sequence identity to any one of SEQ ID NOs: 1-20. For example, the CPP may have at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to any one of SEQ ID NOs: 1-20. In some embodiments, the CPP comprises or consists of one of SEQ ID NOs: 1-20. Thus, the peptide may have at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to a retro-analogue of any one of SEQ ID NOs: 1-20, or to an inverso- analogue or a retro-inverso-analogue of any one of SEQ ID NOs: 1-20 wherein the peptide comprises at least one D-amino acid. In some embodiments, the peptide comprises or consists of an inverso-analogue, a retro-analogue or a retro-inverso-analogue of any one of SEQ ID NOs: 1-20. The peptide may have at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to an inverso-analogue or a retro-inverso-analogue of any one of SEQ ID NOs: 1-20, wherein the peptide comprises at least one D-amino acid. For example, the peptide may comprise or consist of an inverso-analogue or a retro-inverso-analogue of any one of SEQ ID NOs: 1-20. In preferred embodiments, all of the amino acids of the inverso-analogue or retro-inverso-analogue are D-amino acids. In both the first and the second aspect, the CPP may have at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to one of SEQ ID NOs: 5, 12 and 17-20, preferably to one of SEQ ID NOs: 5, 12, 17 and 20. In some embodiments, the CPP has at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to SEQ ID NO: 5. In some embodiments, the CPP comprises or consists of one of SEQ ID NO: 5, and 17-20, preferably one of SEQ ID NOs: 5, 12, 17 and 20. In some embodiments, the CPP comprises or consists of SEQ ID NO: 5. Thus, the peptide may have at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to a retro-analogue of any one of SEQ ID NOs: 5, 12 and 17-20, or to an inverso-analogue or retro-inverso-analogue of any one of SEQ ID NOs: 5, 12 and 17-20 wherein the peptide comprises at least one D-amino acid. Preferably, the peptide has at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to an inverso-analogue or a retro-inverso-analogue of any one of SEQ ID NOs: 5, 12 and 17-20, wherein the peptide comprises at least one D-amino acid. In some embodiments, the peptide may have at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% sequence identity to a retro-analogue of any one of SEQ ID NOs: 5, 12, 17 and 20; or to an inverso-analogue or retro-inverso-analogue of any one of SEQ IDNOs: 5, 12, 17 and 20, wherein the peptide comprises at least one D-amino acid. Preferably, the peptide has at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to an inverso-analogue or retro-inverso- analogue of any one of SEQ ID NOs: 5, 12, 17 and 20, wherein the peptide comprises at least one D-amino acid. In some embodiments, the peptide has at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to a retro-analogue of SEQ ID NO: 5; or to an inverso-analogue or a retro- inverso-analogue of SEQ ID NO: 5, wherein the peptide comprises at least one D-amino acid. In some embodiments, the peptide has at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to an inverso-analogue or a retro-inverso-analogue of SEQ ID NO: 5, wherein the peptide comprises at least one D-amino acid. In some embodiments, the peptide comprises or consists of an inverso-analogue, a retro-analogue or a retro-inverso analogue, preferably an inverso-analogue or a retro-inverso-analogue, of any one of SEQ ID NOs: 5, 12, 17-20. In some embodiments, the peptide comprises or consists of an inverso-analogue, a retro-analogue or a retro-inverso analogue, preferably an inverso-analogue or a retro-inverso-analogue, of one of SEQ IDNOs: 5, 12, 17 and 20. In some embodiments, the peptide comprises or consists of an inverso-analogue, a retro- analogue or a retro-inverso analogue, preferably an inverso-analogue or a retro-inverso-analogue, of SEQ ID NO: 5. In the first aspect, the peptide may have at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to any one of SEQ ID NOs: 5, 12, 17-21 and 23, preferably to any one of SEQ ID NOs: 5, 12, 21 and 23. In some preferred embodiments, the peptide comprises or consists of any one of SEQ ID NOs: 5, 12, 17-21 and 23, preferably one of SEQ ID NOs: 5, 12, 21 and 23. In some embodiments, the peptide comprises or consists of SEQ ID NO: 5. In the second aspect, the peptide may have at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to any one of SEQ ID NOs: 21-23. In some embodiments, the peptide comprises or consists of any one of SEQ ID NOs: 21-23, and, more preferably, comprises or consists of SEQ ID NO: 21 or 23. In the first aspect, the compound may be compound no. 10875 or 10907 (Table 1), or a pharmaceutically acceptable salt thereof. In the second aspect, the compound may be compound no. 10890 or compound no. 10891 (Table 1), or a pharmaceutically acceptable salt thereof. In a third aspect, the invention provides a compound according to Formula I, T – Z – [Peptide] (I) or a pharmaceutically acceptable salt thereof, wherein: T is a chloride ion binding moiety; and Z is a C1-12alkylene, C5-10cycloalkylene, C2-30heteroalkylene, or C6-10aralkylene, optionally substituted with from 1-6 substituents independently selected from -OH, =O, -NO ₂ , -NH ₂ and halo; and the -OH at the C-terminus of the peptide is optionally substituted by Ra, wherein Ra is selected from NH ₂ , -O-C _1-6 alkyl, -NHC _1-6 alkyl, and -NH-NH ₂ ; and wherein the peptide comprises a cell-penetrating peptide (CPP) having at least 70% sequence identity to a mitochondria-targeting sequence (MTS), SEQ ID NO: 12 or SEQ ID NO: 20, or to an inverso-analogue, a retro-analogue or a retro-inverso-analogue thereof. T may include a urea and / or thiourea group, preferably thiourea. In preferred embodiments, T is wherein X1 is a C _6-10 aryl group (preferably phenyl), optionally substituted with from 1 to 3 substituents, each substituent independently selected from NO ₂ , CN, halo, C _1-4 alkyl, C _1-4 alkoxy and C _1-3 haloalkyl; and Y1 is S or O, preferably S. In other words, the compound may thus be a compound of Formula 1* or pharmaceutically acceptable salt thereof, wherein Z, X1, Y1 and [peptide] as are defined according to any embodiment of the third aspect herein. Any embodiments or limitations described herein in respect of Formula I or Formula Ia may thus apply to Formula I*. Z may typically be C _1-12 alkylene or C _2-30 heteroalkylene, optionally substituted with from 1-6 substituents (e.g. 2-4 substituents) independently selected from -OH, =O, -NO ₂ , -NH ₂ and halo, preferably =O. When Z is C _1-12 alkylene, it may be C _2-8 alkylene optionally substituted with from 1-2 substituents independently selected from -OH, =O, -NO ₂ , -NH ₂ or halo, preferably =O. For example, Z may be C _2-8 alkylene substituted with only one =O group. It may be C ₃ alkylene substituted with only one =O group. It may be C ₆ alkylene substituted with only one =O group. The alkylene is preferably linear (unbranched) alkylene, e.g. wherein C ₃ alkylene is n-propylene, and C ₆ alkylene is n-hexylene. When Z is optionally substituted C2-30heteroalkylene, Z may comprise one or more amide moieties and / or one or more ethylene glycol moieties, preferably both amide and ethylene glycol moieties. In embodiments, Z may be C _8-28 heteroalkylene, optionally substituted as described above. Z may be C _8-20 heteroalkylene, optionally substituted as described above. Z may be C _8-16 heteroalkylene, optionally substituted as described above. Z may be C _8-14 heteroalkylene, optionally substituted as described above. Z may be C8-13heteroalkylene, optionally substituted as described above. In embodiments, Z may be C _9-28 heteroalkylene, optionally substituted as described above. Z may be C _9-20 heteroalkylene, optionally substituted as described above. Z may be C _9-16 heteroalkylene, optionally substituted as described above. Z may be C _9-14 heteroalkylene, optionally substituted as described above. Z may be C _9-13 heteroalkylene, optionally substituted as described above. In embodiments, Z may be C _10-28 heteroalkylene, optionally substituted as described above. Z may be C _10-20 heteroalkylene, optionally substituted as described above. Z may be C _10-16 heteroalkylene, optionally substituted as described above. Z may preferably be C _10-14 heteroalkylene, optionally substituted as described above. Z may be C _12-28 heteroalkylene, optionally substituted as described above. Z may be C _{12- 20} heteroalkylene, optionally substituted as described above. Z may be C _12-16 heteroalkylene, optionally substituted as described above. Z may be C _12-14 heteroalkylene, optionally substituted as described above, e.g. C ₁₃ heteroalkylene, optionally substituted as described above. Where Z is substituted, it may contain from 1-6 substituents independently selected from -OH, =O, -NO2, -NH2 or halo, typically =O. In embodiments, there are from 1-4 substituents, such as 1, 2, 3, or 4, preferably wherein the substituent(s) are each =O. The substituents may in some embodiments be independently selected from -OH, =O, -NH ₂ and halo, such as from -OH, =O, and -NH ₂ , e.g. – OH and =O, preferably =O. Preferably the substituent(s) are each =O. In some embodiments there is one substituent, which is =O. In some embodiments, there is no substitution. Z may be selected from Z may be –Z1C(O)-, wherein Z1 is C _1-10 alkylene, C _5-10 cycloalkylene, C _2-28 heteroalkylene, or C _6-10 aralkylene, preferably C _1-10 alkylene or C _2-28 heteroalkylene, wherein the alkylene and heteroalkylene groups are each optionally substituted with from 1-5 substituents (e.g. 1-4 substituents) independently selected from -OH, =O, -NO ₂ , -NH ₂ or halo, preferably =O. Z1 may be C _1-10 alkylene, C _5-10 cycloalkylene, C _2-10 heteroalkylene, or C _6-10 aralkylene. Z1 may be C _2-6 alkylene, for example C _2-5 alkylene. It may be C ₂ alkylene. It may be C ₅ alkylene. The alkylene is preferably linear (unbranched) alkylene, e.g. wherein C2alkylene is ethylene, and C ₅ alkylene is n-pentylene. Z1 may be C _2-28 heteroalkylene, optionally substituted as described above. Z1 may be C _{2- 20} heteroalkylene, optionally substituted as described above. Z1 may be C _2-16 heteroalkylene, optionally substituted as described above. Z1 may be C _2-14 heteroalkylene, optionally substituted as described above. Z1 may be C _2-12 heteroalkylene, optionally substituted as described above. Z1 may be C _11-28 heteroalkylene, optionally substituted as described above. Z1 may be C _{11- 20} heteroalkylene, optionally substituted as described above. Z1 may be C _11-16 heteroalkylene, optionally substituted as described above. Z1 may be C _11-14 heteroalkylene, optionally substituted as described above. Z1 may preferably be C ₁₂ heteroalkylene, optionally substituted as described above. Z1 may be In a preferred embodiment of the third aspect, the compound of Formula I is according to Formula Ia, or a pharmaceutically-acceptable salt thereof, wherein X1 is a C _6-10 aryl group, optionally substituted with from 1 to 3 substituents, each substituent independently selected from NO ₂ , CN, halo, C _1-4 alkyl, C _1-4 alkoxy and C _1-3 haloalkyl; Y1 is S or O; and Z1 is as defined above according to the third aspect or any embodiment thereof described herein; and the peptide is as defined above for the third aspect or any embodiment thereof described herein. In an exemplary embodiment of the third aspect, Formula I is according to the following formulae, wherein the peptide is as defined according to the third aspect or any embodiment thereof . In some embodiments of the third aspect, the peptide comprises a CPP having at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to a MTS, SEQ ID NO: 12 or SEQ ID NO: 20. In some embodiments, the peptide consists of a CPP having at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to a MTS, SEQ ID NO: 12 or SEQ ID NO: 20. In some embodiments, the peptide comprises or consists of a CPP which has 100% sequence identity to a MTS, SEQ ID NO: 12 or SEQ ID NO: 20. In the third aspect, the MTS may be any one of SEQ ID NOs: 17-19. In some embodiments, the MTS is SEQ ID NO: 17. Thus, in some embodiments, the peptide comprises a CPP which has at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%, or 100%, sequence identity to SEQ ID NO: 17 or SEQ ID NO: 20. In some embodiments, the peptide consists of a CPP which has at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% sequence identity to SEQ ID NO: 17 or SEQ ID NO: 20. In some embodiments, the peptide comprises or consists of a CPP which has 100% sequence identity to SEQ ID NO: 17 or SEQ ID NO: 20. In some embodiments, the peptide comprises or consists of SEQ ID NO: 17 or SEQ ID NO: 20. In the third aspect, the compound may be compound no.10884, compound no.10887 or compound no.10889 (Table 1), or a pharmaceutically acceptable salt thereof. According to any of the inventive compounds described in the first, second or third aspects herein, T is a chloride ion binding moiety. Urea and thiourea are examples of functional groups that are capable of coordinating chloride ions. Thioureas bind chloride ions particularly strongly and so chemical structures that contain one or more thiourea groups are particularly preferred as the chloride ion binding moiety at T, according to the invention. In preferred embodiments according to any of the aspects of the invention disclosed herein, T is wherein X1 is a C _6-10 aryl group (preferably phenyl), optionally substituted with from 1 to 3 substituents, each substituent independently selected from NO ₂ , CN, halo, C _1-4 alkyl, C _1-4 alkoxy and C _1-3 haloalkyl; and Y1 is S or O, wherein S is preferred. In other words, the compound according to any aspect described herein may thus be a compound of Formula 1* or pharmaceutically acceptable salt thereof, wherein Z, X1, Y1 and [peptide] as are defined according to any aspect or embodiment herein. Any embodiments or limitations described herein in respect of Formula I or Formula Ia may thus apply to Formula I*. In accordance with any of the aspects and embodiments described herein, X1 may be a C _6-10 aryl group (preferably phenyl), optionally substituted with from 1 to 3 substituents, each substituent independently selected from NO2, CN, halo, C1-4alkyl, C1-4alkoxy and C1-3haloalkyl. In embodiments, the C _6-10 aryl group in X1 may be phenyl, optionally substituted with from 1 to 3 substituents, each substituent independently selected from NO ₂ , CN, halo, C _1-4 alkyl, C _1-4 alkoxy, and C _1-3 haloalkyl. The C _1-4 alkyl, C _1-4 alkoxy, and C _1-3 haloalkyl are typically methyl, methoxy and trifluoromethyl (i.e. CF ₃ ). In preferred embodiments, the C _6-10 aryl group in X1(e.g. phenyl) is substituted. There may be three substituents. There may be two substituents. There may be one substituent. The substituent(s) may in some embodiments be independently selected from CN, halo, C _1-4 alkyl, C _1-4 alkoxy, and C _{1- 3} haloalkyl. The C _1-4 alkyl, C _1-4 alkoxy, and C _1-3 haloalkyl are typically methyl, methoxy and trifluoromethyl (i.e. CF ₃₎ . The substituent(s) may be independently selected from CN, halo (e.g. F), methyl, methoxy and CF ₃ . In some exemplary embodiments, the substituents at X1 are each halo, e.g. F, such as in the case of bis- or tris-fluoro substituted phenyl. In some exemplary embodiments, the substituents are each C _1-4 alkyl, e.g. methyl, such as in the case of tris-methyl substituted phenyl. In some exemplary embodiments, the substituents are each C _1-4 alkoxy, e.g. methoxy, such as in the case of bis-methoxy substituted phenyl. In some exemplary embodiments, the substituents are each C _1-3 haloalkyl, e.g. trifluoromethyl, such as in the case of bis-trifluoromethyl substituted phenyl. Where the substituent is or includes CN, the CN may be the sole substituent, e.g. in the case of mono-cyano substituted phenyl. According to any aspect or embodiment herein, X1 may be X1 may preferably be Y1 is preferably S. In any compounds of the invention, the -OH at the C-terminus of the peptide domain may be substituted by Ra, wherein Ra is selected from -NH ₂ , -O-C _1-6 alkyl, -NHC _1-6 alkyl, and -NH-NH ₂ . Substitution by Ra in this context is intended to refer to the -OH part of the carboxylic acid end of the peptide being notionally replaced by the Ra moiety. In the case of Ra being –NH ₂ for instance, the C-terminus of the peptide would end in a carboxamide moiety, i.e. -C(=O)-NH ₂ , instead of a conventional carboxylic acid moiety. It is intended that CPPs substituted in this way have cell- penetrating activity. In typical embodiments, the -OH at the C-terminus of the peptide domain is substituted by Ra. In all of the above aspects and embodiments of the invention, the C-terminus of the peptide is preferably substituted by -NH ₂ . The peptide of the compounds described herein may comprise one or more positively charged residues. The peptide of the compounds described herein may contain arginine or lysine side-chains. The peptide of the compounds described herein are cell membrane penetrating peptides (CPPs), such as cationic, amphipathic, hydrophobic or amphiphilic CPPs. The peptide of the compounds described herein may be a cell membrane penetrating peptide having at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% to, or is selected from (i.e. has 100% sequence identity to), one or more of the following: a) HIV-TAT protein or a translocationally active derivative thereof, such as residue 48 to 60 of TAT: GRKKRRQRRRPPQ (SEQ ID NO:1), b) the TAT 49-57 peptide: RKKRRQRRR (SEQ ID NO: 2), c) YGRKKRRQRRRP (SEQ ID NO: 3) (a longer peptide containing TAT49-57), d) GRKKRRQRRRPPQ (SEQ ID NO: 4) (a longer peptide containing TAT49-57), e) penetratin having the sequence RQIKIWFQNRRMKWKK (SEQ ID NO:5), f) penetratin variant W48F having the sequence RQIKIFFQNRRMKWKK (SEQ ID NO: 6), g) penetratin variant W56F having the sequence RQIKIWFQNRRMKFKK (SEQ ID NO: 7), h) penetratin variant having the sequence RQIKIWFQNRRMKFKK (SEQ ID NO: 8), i) transportan having the sequence GWTLNSAGYLLGKINLKALAALAKKIL (SEQ ID NO: 9), j) transportan-27 having the sequence GWYLNSAGYLLGK(e- Cys)INLKALAALAKKIL (SEQ ID NO: 10), k) transportan-22 having the sequence GWYLNSAGYLLGK(e-Cys)INLKALAAL (SEQ ID NO: 11), l) herpes simplex virus protein VP22 or a translocationally-active homologue thereof from a different herpes virus such as MDV protein UL49, m) Pep-1, having the sequence KETWWETWWTEWSQPKKKRKV (SEQ ID NO: 12), n) Pep-2, having the sequence KETWFETWFTEWSQPKKKRKV (SEQ ID NO: 13), o) PTD4, having the sequence YARAAARQARA (SEQ ID NO: 14), p) R7 poly-arginine, having the sequence RRRRRRR (SEQ ID NO: 15), q) pVEC, having the sequence LLIILRRRIRKQAHAHSK (SEQ ID NO: 16), r) a MTS derived from human mitochondria-oriented aldehyde dehydrogenase, having the sequence MLRAALSTARRGPRLSRLL (SEQ ID NO: 17), s) a MTS derived from mitochondrial malate dehydrogenase, having the sequence MVSAL (SEQ ID NO: 18), t) a MTS derived from subunit IV of human cytochrome c oxidase, having the sequence MSVLTPLLLRGLTGSARRLPVPRAKIHSL (SEQ ID NO: 19), u) MPG, having the sequence GALFLGFLGAAGSTMGAWSQPKKKRKV (SEQ ID NO: 20), or v) an inverso-analogue, a retro-analogue or a retro-inverso-analogue of one of a)-u). In some embodiments, said peptide of the compounds described herein may be TAT having the amino acid sequence of SEQ ID NO: 1, or a variant thereof, having at least 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81 % 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, or 95% identity to SEQ ID NO: 1 and having cell penetrating activity; or penetratin having the amino acid sequence of SEQ ID NO: 5, or a variant thereof having at least 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81% 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, or 95% identity to SEQ ID NO: 5 and having cell penetrating activity. In some embodiments, said peptide of the compounds described herein may comprise or consist of the amino acid sequence of any one of SEQ ID NOs: 2 to 4, or 6 to 13, or a sequence which is at least 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 85%, 90%, 91%, 92%, 93%, 94%, or 95% identical to any one of SEQ ID NOs: 2 to 4 or 6 to 13, and having cell penetrating activity. In some embodiments of the invention, said peptide comprises or consists of one or more cell membrane penetrating domains selected from the group consisting of a MTS, MPG, Pep-1, Pep-2, SP, pVEC, poly-arginine (arginine stretch), transportan, TAT, and penetratin, or variants thereof having at least having at least 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81% 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, or 95% identity to any of SEQ ID NOs: 1 to 20, and having cell penetrating activity, preferably selected from: residue 48-60 of TAT or penetratin, or variants thereof. Pharmaceutically acceptable salts In some embodiments of the invention, said salts can be prepared from any compound of the invention having functionality capable of forming salts, for example a base functionality. Pharmaceutically acceptable salts can be prepared with organic or inorganic acids. Compounds of the invention that contain one or more basic functional groups are capable of forming pharmaceutically acceptable salts with pharmaceutically acceptable organic and inorganic acids. These salts can be prepared in situ during the final isolation and purification of the compounds of the invention, or by separately reacting a purified compound of the invention in its free base form with a suitable organic or inorganic acid, and isolating the salt thus formed. Examples of pharmaceutically acceptable salts include but are not limited to sulfate, pyrosulfate, bisulfate, sulfite, bisulfite, phosphate, monohydrogenphosphate, dihydrogenphosphate, metaphosphate, pyrophosphate, chloride, bromide, iodide, acetate, propionate, decanoate, caprylate, acrylate, formate, isobutyrate, caprate, heptanoate, propiolate, oxalate, malonate, succinate, suberate, sebacate, fumarate, maleate, butyne-1,4-dioate, hexyne-1,6-dioate, benzoate, chlorobenzoate, methylbenzoate, dinitrobenzoate, hydroxybenzoate, methoxybenzoate, phthalate, terephthalate, sulfonate, xylene sulfonate, phenylacetate, phenylpropionate, phenylbutyrate, citrate, lactate, β-hydroxybutyrate, glycolate, tartrate, methanesulfonate, propanesulfonate, naphthalene-1- sulfonate, naphthalene-2-sulfonate, mandelate, adipate, alginate, mucate, aspartate, benzenesulfonate, butyrate, camphorate, camphorsulfonate, cyclopentanepropionate, digluconate, dodecylsulfate, ethanesulfonate, glucoheptanoate, glycerophosphate, hemisulfate, hexanoate, hydrochloride, hydrobromide, hydroiodide, 2-hydroxyethanesulfonate, 2-napthalenesulfonate, nicotinate, nitrate, palmoate, pectinate, persulfate, picrate, pivalate, salicylate, thiocyanate, tosylate, arginate and undecanoate. See, for example, Berge et al. "Pharmaceutical Salts", J. Pharm. Sci. 66:1-19 (1977) and the like. Acids commonly employed to form pharmaceutically acceptable salts include but are not limited to inorganic acids such as hydrogen bisulfide, hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid and phosphoric acid, as well as organic acids such as paratoluenesulfonic acid, salicylic acid, tartaric acid, bitartaric acid, ascorbic acid, maleic acid, besylic acid, fumaric acid, gluconic acid, glucuronic acid, formic acid, glutamic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, lactic acid, oxalic acid, para-bromophenylsulfonic acid, carbonic acid, succinic acid, citric acid, benzoic acid and acetic acid. Other acids, such as oxalic, while not in themselves pharmaceutically acceptable, may be employed in the preparation of salts useful as intermediates in obtaining the compounds of the invention and their pharmaceutically acceptable acid addition salts. In some embodiments, pharmaceutically acceptable acid addition salts include those formed with mineral acids such as hydrochloric acid and hydrobromic acid, and especially those formed with organic acids such as trifluoroacetic acid and maleic acid. Solvates & hydrates The compounds of this disclosure may exist in unsolvated or solvated forms. The term “solvate” includes molecular complexes comprising a given compound (or salt) and one or more pharmaceutically acceptable solvent molecules such as water or C1-6 alcohols, e.g. ethanol. The term “hydrate” means a “solvate” where the solvent is water. Amorphous & crystalline forms The compounds of the invention may exist in solid states from amorphous through to crystalline forms. All such solid forms are included within the invention. Isomeric forms Compounds of the invention may exist in one or more geometrical, optical, enantiomeric, diastereomeric and tautomeric forms, including but not limited to cis- and trans-forms, E- and Z- forms, R-, S- and meso-forms, keto- and enol-forms. All such isomeric forms are included within the invention, except where indicated otherwise. The isomeric forms may be in isomerically pure or enriched form, as well as in mixtures of isomers (e.g. racemic or diastereomeric mixtures). Isotopic labeling The disclosure includes pharmaceutically acceptable isotopically-labelled compounds of the invention wherein one or more atoms are replaced by atoms having the same atomic number, but an atomic mass or mass number different from the atomic mass or mass number usually found in nature. Isotopically-labelled compounds (such as deuterated variants) can generally be prepared by conventional techniques known to those skilled in the art or by processes analogous to those described herein using an appropriate isotopically-labelled reagent in place of the non-labelled reagent previously employed. Chemical group definitions: “Aryl” as mentioned herein is intended to include monocyclic or polycyclic fused ring aromatic groups (depending on the number of carbon atoms present). Preferred is phenyl. The term “alkyl” is intended to include straight (i.e. linear) or branched, saturated, acyclic hydrocarbyl groups. Methyl is preferred. The term “halogen” (or “halo”) includes fluorine, chlorine, bromine and iodine. In preferred examples, halo is F. The term “alkylene” includes divalent, straight or branched, saturated, acyclic hydrocarbyl groups. In typical embodiments the alkylene is straight (i.e. linear / not branched). Examples include ethylene (C ₂ -alkylene) and n-pentylene (a C ₅ -alkylene). The term “cycloalkylene” includes divalent, saturated, hydrocarbyl groups containing at least 1 saturated carbocyclic group. The cycloalkylene group may consist solely of a saturated carbocyclic group, or may contain additional non-cyclic carbon atoms in the chain, provided at least 1 saturated carbocyclic group is present, such as in the case of The term “heteroalkylene” includes alkylene groups in which at least one carbon atom is notionally replaced by a heteroatom, independently selected from S, O or N, provided at least one alkylene carbon atom remains. The number of carbon atoms that may be notionally replaced by heteroatoms is dependent on the length of the heteroalkylene chain. However, in suitable embodiments, up to 10, 9, 8, 7, 6, or 5 carbon atoms may be replaced by a heteroatom. In typical embodiments up to three carbon atoms may be replaced, in one embodiment up to two carbon atoms, in another embodiment one carbon atom, are each notionally replaced independently by O, S or N, typically N or O and most typically O, provided at least one of the alkylene carbon atoms remains. Examples of heteroalkylene groups thus include ethers, such as polyethers, and secondary amines. In exemplary compounds of the invention, the heteroalkylene group, if present, is typically linked to the remaining parts of the compound via carbon atoms. Linear (non-branched) heteroalkylene groups are preferred. It will be appreciated that notional replacement of carbon atom in an alkylene group with a heteroatom such as N, O and S will usually mean also notionally losing at least one hydrogen atom, since N, O and S form fewer bonds than carbon. Notional replacement of a carbon by N, O or S will therefore typically result in notional replacement of a CH ₂ with NH, O, or S respectively, i.e. to form secondary amines, ethers or thioethers respectively. By way of clarification, in relation to the above mentioned heteroatom containing groups, where a numerical of carbon atoms is given, for instance C _2-10 heteroalkylene, what is intended is a group based on C _2-10 alkylene in which one or more of the 2-10 chain carbon atoms is replaced by O or N, provided at least one carbon remains. Accordingly, a C _2-10 heteroalkylene group, for example, will contain less than 2-10 chain carbon atoms. The term “aralkylene” refers to an alkylene group notionally substituted with an aryl group in the chain. Examples include , wherein a phenyl group has been notionally substituted into the alkylene carbon chain (this structure is an example of a C ₇ -aralkylene). In the absence of any specific indication, the alkylene and aryl moieties of the aralkylene may be spatially orientated in the compound from left to right in either order, e.g, -aryl-alkylene- or -alkylene-aryl-. In some embodiments of the invention, the compounds described herein do not induce apoptosis or necrosis when applied to a cell or cell layer at a concentration range between about 0.1 nM to about 10,000 µM, or between about 1 nM to about 1,000 µM, wherein said cell layer comprises airway epithelial cells. In some embodiments, the application of said compound to a Xenopus laevis oocyte increases the current between the oocyte internal and external part using a two-electrodes voltage clamp setup perfusing the external part with Cl-free buffer at a concentration between 0.1nM to 10mM, 1nM to 1mM, 100nM to 20μM, 100nM to 15μM, 1μM to 20μM, 1μM to 15μM, 100 nM to 10 μM or 1μM to 10μM, optionally in a dose-dependent manner. In some embodiments of the invention, the compounds of the present invention are amphipathic. In some embodiments of the invention, the compounds of the present invention decrease the intracellular (Cl-) chloride ion concentration in a dose-dependent manner, optionally when applied into or onto an epithelial surface. In some embodiments of the invention, apical application in an Ussing Chamber of 10 to 100 μM solutions comprising compounds of the present invention to a cell layer increases epithelial short circuit current (Isc) compared to vehicle control, a substantial improvement over the current CFTR modulator therapies (e.g. Trikafta) for this genotype, under acute conditions. In some embodiments of the invention, increased epithelial short circuit current can be induced by compounds of the present invention when applied to a cell or cell layer at a concentration of, for example, 10 to 100 μM, wherein said increase remains sustained for at least a 10-minute period, optionally in an acute setting. In some embodiments of the invention, acute application of compounds of the present invention upstream significantly increase the transient response of Ca2+-activated Cl- channel (CaCC) when activated by UTP, a purinergic agonist. In some embodiments of the invention, the activity of the compounds of the present invention is independent of CFTR. In some embodiments, the application of the compounds of the present invention promotes mucin complex formation and/or release, mucin, optionally emerging from the epithelial surface. In some embodiments, the application of the compounds of the present invention increases residual epithelial short circuit current indicating basal levels of Cl- ion transport, independent of CFTR involvement, as well as an increase in dose-dependent CaCC activity of said compounds, when induced by UTP. In some embodiments, the compounds of the present invention weakly interact with mucus, as demonstrated by a rapid transit through a mucus layer comprising 2% or 4% or more solids content. In another embodiment, the penetration time for compounds of the present invention through a 100μm mucus layer is less than 5 minutes, or less than 3 minutes, thus enabling the rapid penetration of the compound to or through an apical or epithelial cell membrane, optionally wherein said mucus layer comprises 2% or 4% or more solids content. In some embodiments, the application of the compounds of the present invention increases the airway surface liquid height (ASL). Increasing the height of the ASL may be indicative of increased water content primarily via an increased secretion due to Cl- ion concentration and subsequent water retention. Increased water content will decrease the viscosity of the mucus and will thus make it easier to transport excess mucus out of the lungs. In a fourth aspect, the invention provides a pharmaceutical composition comprising any compound of the invention or a pharmaceutically-acceptable salt thereof, and a pharmaceutically-acceptable carrier, diluent or excipient. In some embodiments, the pharmaceutical composition comprises one or more additional therapeutic agents. In a fifth aspect, the invention provides a kit comprising any compound of the invention or a pharmaceutically-acceptable salt thereof, or a pharmaceutical composition of the invention, the kit optionally comprising a label providing instructions for use of the compound, salt or composition. In a sixth aspect, the invention provides a compound, or pharmaceutically-acceptable salt thereof, of the invention, or a pharmaceutical composition of the invention, for use in the treatment of a disease or condition. In a seventh aspect, the invention provides a method of treatment of a disease or condition, wherein the method comprises administering a therapeutically effective amount of a compound, or a pharmaceutically-acceptable salt thereof, of the invention, or a pharmaceutical composition of the invention, to a patient in need thereof. In an eighth aspect, the invention provides use of a compound, or pharmaceutically-acceptable salt thereof, of the invention, or a pharmaceutical composition of the invention for the manufacture of a medicament for the treatment of a disease or condition. The disease or condition may be associated with a chloride ion channel mutation or with a mutation in genes encoding chloride ion channels (i.e. a channelopathy) which lead to abnormal, deficient or absent chloride ion channel function. In particular, Figure 2 shows that the compounds of the invention have chloride ion transporter function. The chloride ion channel mutation may be selected from a voltage-sensitive CLIC, transmitter-gated GABA _A , glycine receptors, calcium-activated chloride ion channel (CaCC), high (maxi) conductance chloride ion channel, cystic fibrosis transmembrane conductance regulator (CFTR) and a volume-regulated channel mutation. In some embodiments, the disease or condition is associated with more than one CFTR mutation, including Class I (e.g. G542X, W1282X, R553X, Glu831X), Class II (e.g. F508del, N1303K, I507del), Class III (e.g. G551D, S549N, V520F), Class IV (e.g. R117H, D1152H, R374P), or Class V mutations (e.g.3849+10kbC>T, 2789+5G>A, A455E). The disease or condition may be selected from myotonia congenita Becker, Myotonia congenita Thomsen, Dystrophia myotonica 1, dystrophia myotonica 2, childhood absence epilepsy type 3, juvenile absence epilepsy, juvenile myoclonic epilepsy, epilepsy with grand mal seizures on awakening, Bartter Syndrome, Bartter syndrome with sensorineurial deafness, Dent's disease, autosomal dominant osteopetrosis, autosomal recessive osteopetrosis, cystic fibrosis, idiopathic chronic pancreatitis, bronchiectasis, congenital bilateral absence of vas deferens, Best's disease, adult-onset vitelliform macular dystrophy, concentric annular macular dystrophy, cataract, childhood absence epilepsy type 2, generalized epilepsy with febrile seizures plus, severe myoclonic epilepsy in infancy, insomnia, hereditary hyperekplexia, recessive and dominant myotonia, leukodystrophy, aldosteronism, diabetes insipidus, Bartter disease, Gilteman disease, CNS and retina degeneration, mental retardation, epilepsy, proteinuria, impaired renal endocytosis, osteopetrosis, pulmonary hypertension, cardiac dysfunction, neurodegenerative diseases such as Alzheimer’s disease, associated respiratory and gastrointestinal diseases, including asthma, chronic obstructive pulmonary disease, cystic fibrosis, pneumonia, colon colitis, cystic fibrosis intestinal mucous disease, ulcerative colitis, gastrointestinal parasitic infection. dry mouth and dry eye syndromes, diarrhea, hypertension, neuropathic pain, cancer, smoke induced COPD, chronic bronchitis, rhinosinusitis, constipation, pancreatitis, pancreatic insufficiency, male infertility caused by congenital bilateral absence of the vas deferens (CBAVD), mild pulmonary disease, idiopathic pancreatitis, allergic bronchopulmonary aspergillosis (ABPA), liver disease, hereditary emphysema, hereditary hemochromatosis, coagulation-fibrinolysis deficiencies, such as protein C deficiency, Type 1 hereditary angioedema, lipid processing deficiencies, such as familial hypercholesterolemia, Type 1 chylomicronemia, abetalipoproteinemia, lysosomal storage diseases, such as I-cell disease/pseudo-Hurler, mucopolysaccharidoses, Sandhof/Tay-Sachs, Crigler-Najjar type II, polyendocrinopathy/hyperinsulemia, Diabetes mellitus, Laron dwarfism, myleoperoxidase deficiency, primary hypoparathyroidism, melanoma, glycanosis CDG type 1, congenital hyperthyroidism, osteogenesis imperfecta, hereditary hypofibrinogenemia, ACT deficiency, Diabetes insipidus (DI), neurophyseal DI, neprogenic DI, Charcot-Marie Tooth syndrome, Perlizaeus-Merzbacher disease, Parkinson's disease, amyotrophic lateral sclerosis, progressive supranuclear plasy, Pick's disease, several polyglutamine neurological disorders such as Huntington's, spinocerebullar ataxia type I, spinal and bulbar muscular atrophy, dentatorubal pallidoluysian, and myotonic dystrophy, as well as spongiform encephalopathies, such as hereditary Creutzfeldt-Jakob disease (due to prion protein processing defect), Fabry disease, Straussler- Scheinker syndrome, COPD, dry-eye disease, or Sjogren's disease, Osteoporosis, Osteopenia, bone healing and bone growth (including bone repair, bone regeneration, reducing bone resorption and increasing bone deposition), Gorham's Syndrome, Bartter's syndrome type III, hyperekplexia, lysosomal storage disease, Angelman syndrome, and Primary Ciliary Dyskinesia (PCD), an inherited disorders of the structure and/or function of cilia, including PCD with situs inversus (also known as Kartagener syndrome), PCD without situs inversus and ciliary aplasia. In some embodiments, the disease or condition is a respiratory disease, preferably COPD, asthma, bronchiectasis, pneumonia or cystic fibrosis. In some embodiments of the invention, there is provided a method of treating a disease or condition associated with a chloride ion channel mutation, preferably wherein the chloride ion channel is involved in a process including the regulation of the excitability of neurons, skeletal, cardiac and smooth muscle, cell volume regulation, transepithelial salt transport, the acidification of internal and extracellular compartments, the cell cycle and apoptosis, by administering a therapeutically effective amount of a compound, or a pharmaceutically-acceptable salt thereof, or a pharmaceutical composition according to the invention described herein, preferably selected from compound nos. 10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907, or a variant or mixtures thereof, to a human subject in need thereof. The disease or condition associated with a chloride ion channel mutations may be selected from the group of myotonia congenita Becker, Myotonia congenita Thomsen, Dystrophia myotonica 1, dystrophia myotonica 2, childhood absence epilepsy type 3, juvenile absence epilepsy, juvenile myoclonic epilepsy, epilepsy with grand mal seizures on awakening, Bartter Syndrome, Bartter syndrome with sensorineurial deafness, Dent's disease, autosomal dominant osteopetrosis, autosomal recessive osteopetrosis, cystic fibrosis, idiopathic chronic pancreatitis, bronchiectasis, congenital bilateral absence of vas deferens, Best's disease, adult-onset vitelliform macular dystrophy, concentric annular macular dystrophy, cataract, juvenile myoclonic epilepsy, childhood absence epilepsy type 2, generalized epilepsy with febrile seizures plus, severe myoclonic epilepsy in infancy, insomnia and hereditary hyperekplexia. The chloride ion channel mutation may be selected from the group of: voltage-sensitive CLIC, transmitter-gated GABA _A , glycine receptors, calcium-activated chloride ion channel (CaCC), high (maxi) conductance chloride ion channel, cystic fibrosis transmembrane conductance regulator (CFTR), and volume-regulated channel mutations. In some embodiments of the invention, there is provided a method of treating a disease or condition associated with a voltage-sensitive chloride intracellular channel (CLIC) mutation, wherein the method comprises administering a therapeutically effective amount of a compound, or a pharmaceutically-acceptable salt thereof, or a pharmaceutical composition according to the invention described herein, preferably selected from compound nos. 10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907or a variant or mixtures thereof, to a human subject in need thereof. The voltage-sensitive chloride intracellular channel (CLIC) mutation may be selected from the group of CLIC-1, CLIC-2, hCLIC-Ka (rCLIC-K1), hCLIC-Kb (rCLIC-K2); CLIC-3 to CLIC-5, and CLIC-6 and CLIC-7 chloride ion channel mutations. The voltage-sensitive chloride intracellular channel (CLIC)-associated disease or condition may be selected from the group of muscle, skeletal and bone diseases, kidney diseases, ear diseases, central nervous (CNS) diseases, eye diseases, gastrointestinal diseases, pulmonary diseases, cardiac diseases and liver diseases. The voltage-sensitive chloride intracellular channel (CLIC)-associated disease or condition may be selected from the group consisting of: recessive and dominant myotonia, leukodystrophy, aldosteronism, diabetes insipidus, Bartter disease, Gilteman disease, CNS and retina degeneration, mental retardation, epilepsy, Dent’s disease, proteinuria, impaired renal endocytosis, osteopetrosis, pulmonary hypertension, cardiac dysfunction, Alzheimer’s disease, associated respiratory and gastrointestinal diseases, including asthma, chronic obstructive pulmonary disease, cystic fibrosis, pneumonia, colon colitis, cystic fibrosis intestinal mucous disease, ulcerative colitis, and gastrointestinal parasitic infection. In some embodiments of the invention, there is provided a method of treating a disease or condition associated with a transmitter-gated GABA _A and glycine receptor mutation. In some embodiments of the invention, there is provided a method of treating a disease or condition associated with a calcium-activated chloride ion channel mutation, wherein the method comprises administering a therapeutically effective amount of a compound, or a pharmaceutically-acceptable salt thereof, or a pharmaceutical composition according to the invention described herein, preferably selected from compound nos. 10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907 or a variant or mixtures thereof, to a human subject in need thereof. The calcium-activated chloride ion channel-associated disease or condition may be selected from: cystic fibrosis, dry mouth and dry eye syndromes, asthma, diarrhea, hypertension, neuropathic pain and cancers. In some embodiments of the invention, there is provided a method of treating a disease or condition associated with a high (maxi) conductance chloride ion channel mutation, wherein the method comprises administering a therapeutically effective amount of a compound, or a pharmaceutically- acceptable salt thereof, or a pharmaceutical composition according to the invention described herein, preferably selected from compound nos.10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907 or a variant or mixtures thereof, to a human subject in need thereof. In some embodiments of the invention, there is provided a method of treating a disease or condition associated with a high (maxi) conductance chloride ion channel mutation, wherein the mutation is found in neurons cells, glia cells, cardiac muscle cells, lymphocytes, epithelia, macula densa cells of the kidney and human placenta syncytiotrophoblasts. In some embodiments of the invention, there is provided a method of treating a disease or condition associated with volume-activated chloride channel mutations, wherein the method comprises administering a therapeutically effective amount of a compound, or a pharmaceutically-acceptable salt thereof, or a pharmaceutical composition according to the invention described herein, preferably selected from compound nos. 10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907 or a variant or mixtures thereof, to a human subject in need thereof. In some embodiments of the invention, there is provided a method of treating a disease or condition associated with cystic fibrosis transmembrane conductance regulator (CFTR) mutations, wherein the method comprises administering a therapeutically effective amount of a compound, or a pharmaceutically-acceptable salt thereof, or a pharmaceutical composition according to the invention described herein, preferably selected from compound nos.10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907 or a variant or mixtures thereof, to a human subject in need thereof. In some embodiments, the compounds, or the pharmaceutically-acceptable salts thereof, and the pharmaceutical compositions of the present invention are for use in the treatment, or are for use in the manufacture of a medicament for the treatment, of a CFTR-mediated disease selected from cystic fibrosis, asthma, smoke induced COPD, chronic bronchitis, rhinosinusitis, constipation, pancreatitis, pancreatic insufficiency, male infertility caused by congenital bilateral absence of the vas deferens (CBAVD), mild pulmonary disease, idiopathic pancreatitis, allergic bronchopulmonary aspergillosis (ABPA), liver disease, hereditary emphysema, hereditary hemochromatosis, coagulation-fibrinolysis deficiencies, such as protein C deficiency, Type 1 hereditary angioedema, lipid processing deficiencies, such as familial hypercholesterolemia, Type 1 chylomicronemia, abetalipoproteinemia, lysosomal storage diseases, such as I-cell disease/pseudo-Hurler, mucopolysaccharidoses, Sandhof/Tay-Sachs, Crigler-Najjar type II, polyendocrinopathy/hyperinsulemia, Diabetes mellitus, Laron dwarfism, myleoperoxidase deficiency, primary hypoparathyroidism, melanoma, glycanosis CDG type 1, congenital hyperthyroidism, osteogenesis imperfecta, hereditary hypofibrinogenemia, ACT deficiency, Diabetes insipidus (DI), neurophyseal DI, neprogenic DI, Charcot-Marie Tooth syndrome, Perlizaeus-Merzbacher disease, neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, progressive supranuclear plasy, Pick's disease, several polyglutamine neurological disorders such as Huntington's, spinocerebullar ataxia type I, spinal and bulbar muscular atrophy, dentatorubal pallidoluysian, and myotonic dystrophy, as well as spongiform encephalopathies, such as hereditary Creutzfeldt-Jakob disease (due to prion protein processing defect), Fabry disease, Straussler-Scheinker syndrome, COPD, dry-eye disease, or Sjogren's disease, Osteoporosis, Osteopenia, bone healing and bone growth (including bone repair, bone regeneration, reducing bone resorption and increasing bone deposition), Gorham's Syndrome; chloride channelopathies such as myotonia congenita (Thomson and Becker forms), Bartter's syndrome type III, Dent's disease, hyperekplexia, epilepsy, Gitelman, lysosomal storage disease, Angelman syndrome, and Primary Ciliary Dyskinesia (PCD), an inherited disorders of the structure and/or function of cilia, including PCD with situs inversus (also known as Kartagener syndrome), PCD without situs inversus and ciliary aplasia. In some embodiments, there is provided a method of treating one of these CFTR-mediated diseases, wherein the method comprises administering a compound, or a pharmaceutically-acceptable salt thereof, or a pharmaceutical composition of the invention to a patient in need thereof. In some embodiments of the invention, the compounds, a pharmaceutically-acceptable salt thereof, and the pharmaceutical compositions of the present invention are for use in the treatment of, or are for use in the manufacture of a medicament for the treatment of, cystic fibrosis patients presenting with one or more CFTR mutations, including Class I (e.g. G542X, W1282X, R553X, Glu831X), Class II (e.g. F508del, N1303K, I507del), Class III (e.g. G551D, S549N, V520F), Class IV (e.g. R117H, D1152H, R374P), or Class V mutations (e.g.3849+10kbC>T, 2789+5G>A, A455E). The CF patient may present as a homozygotes or heterozygotes for any such CFTR mutation, e.g. F508del homozygote. In some embodiments of the invention, the compounds, or the pharmaceutically-acceptable salts thereof, or the pharmaceutical compositions, of the present invention are for use in the treatment of, or are for use in the manufacture of a medicament for the treatment of, a channelopathy, wherein channelopathies are a heterogeneous group of disorders resulting from the dysfunction of ion channels located in the membranes of all cells and many cellular organelles, including diseases of the respiratory system (e.g., cystic fibrosis) and the urinary system (e.g., Bartter syndrome). The present invention includes methods of treating any of the disease or conditions disclosed herein using any of the compounds, or pharmaceutically-acceptable salts thereof, or pharmaceutical compositions disclosed herein. The present invention also includes use of any of the compounds, or pharmaceutically-acceptable salts thereof, or pharmaceutical compositions disclosed herein for the treatment of any disease or condition disclosed herein. The present invention also includes use of any of the compounds, or pharmaceutically-acceptable salts thereof, or pharmaceutical compositions disclosed herein for the manufacture of a medicament for the treatment of any of the diseases or conditions disclosed herein. The medicament may be in any of the dosage forms disclosed herein, and/or may be administered by any route disclosed herein. In the methods of treatment of a disease or condition, uses for treatment of a disease of condition, and uses for manufacture of a medicament for treatment of a disease of condition, of the present invention, the treatment of the disease or condition may comprise the administration of more than one compound, or pharmaceutically-acceptable salt thereof, or pharmaceutical composition of the invention. The treatment of the disease or condition may comprise the administration of one or more additional therapeutic agents, in addition to the compound, or pharmaceutically-acceptable salt thereof, or pharmaceutical composition of the invention. The additional therapeutic agent may be administered simultaneously (separately or in a single composition) or sequentially with the compound, or pharmaceutically-acceptable salt thereof, or pharmaceutical composition of the invention. When the compound, or pharmaceutically-acceptable salt thereof, or pharmaceutical composition is administered simultaneously with, but separately from, the one or more additional therapeutic agents, the compound, or pharmaceutically-acceptable salt thereof, or pharmaceutical composition and the one or more therapeutic agents are administered one after the other, in either order. The treatment disclosed herein may also include reducing, inhibiting or controlling the disease or condition, preferably treating, reducing, inhibiting or controlling at least one sign or symptom of the disease or condition. For example, the treatment of cystic fibrosis includes reducing, inhibiting or controlling cystic fibrosis in a subject, preferably treating, reducing, inhibiting or controlling at least one sign or symptom of cystic fibrosis in a subject. When the disease is cystic fibrosis, the sign or symptom may be associated with the airways or respiratory system and may include one or more of the following: abnormally viscous mucus accumulation; increased total mucin content; elevated inflammatory factor concentration; decreased cellular secretion of chloride ions; impaired fluid secretion; increased apical sodium absorption by airway epithelial cells; acidification and decreased height of the apical airway surface liquid; chronic cough; chronic lung infection, and combinations thereof. The compounds, and pharmaceutically-acceptable salts thereof, of the invention may be prepared by elongating a desired peptide chain on a suitable gel resin such as TentaGel (R) RAM resin with a Rink amide linker. The coupling of the desired peptide chain to the channel-targeting moiety is preferably performed in two steps, namely, by dissolving Fmoc protected amino acid, the uronium coupling agent O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (HATU) and N,N-diisopropylethylamine (DIPEA) in N,N-dimethylformamide (DMF) as solvent, under three hours of shaking in the first step and then the second coupling is performed with amino acid, HATU and DIPEA; then the resin is washed with DMF, methanol and DCM, and the washing is preferably followed by a deprotection step using 2% DBU and 2% piperidine in DMF in two steps with 15 and 5 minutes reaction times. After the coupling of the amino acids, the thiourea element is created, whereby the free N-terminus is reacted with specific isothiocyanates under alkaline conditions in DMF. After the completion of the sequence and thiourea construct the cleavage was carried out with TFA/water/dl-dithiothreitol (DTT)/TIS at 0 °C for 1 hour. In some embodiments of the invention, the peptide has at least 70% to an inverso-analogue or a retro-inverso-analogue of a CPP, or comprises or consists of an inverso-analogue or a retro-inverso- analogue of a CPP. In some embodiments of the invention, the peptide comprises two or more amino acids, and may comprise D and/or L amino acids in any proportion. In some embodiments, the peptide comprises at least 1, at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13, at least 14 or at least 15 D-amino acid. In some embodiments, all of the amino acids of the peptide are D-amino acids. In particular, Figure 4 shows that analogues of CPPs which comprise at least one D-amino acid have greater stability than CPPs which do not comprise any D-amino acids. More specifically, Figure 4 shows that an inverso-analogue of a CPP is more resistant to degradation by gastric enzymes, such as trypsin, than the parent peptide which does not contain any D-amino acids. Figure 2 shows that an inverso-analogue of a CPP retains ion transport activity. Thus, compounds of the invention in which the peptide comprises one or more D-amino acids are expected to be useful for oral administration to a subject. It is also expected that these compounds will enable a more controlled effect on the patient, due to a combination of similar or slightly lower activity (Figure 2) but improved resistance to gastric enzymes (Figure 4), which provides for a longer half-life. In some embodiments of the invention, the peptide comprises a sequence of amino acids which is read and/or synthesized from the left side to right side. In other words, in these embodiments, the peptide is an analogue of a parent peptide, in which the order of amino acids is reversed compared to the parent peptide (i.e. the peptide of the compound is a retro-analogue). Preferably, these peptides comprise one or more D-amino acids. For example, these peptides comprise at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13, at least 14 or at least 15 D-amino acids. Preferably, all of the amino acids in these peptides are D-amino acids. Figure 4 shows that a compound comprising a retro-inverso-analogue of a CPP is more stable than compounds comprising the corresponding parent CPP. In particular, the retro-inverso-analogue of the CPP is more resistant to degradation by gastric enzymes, such as trypsin, than the parent CPP. In addition, Figure 2 shows that compounds in which the peptide is a retro-inverso-analogue of a CPP retains ion transport activity. Thus, it is expected that compounds in which the peptide comprises the reverse order of amino acids compared to the parent CPP, and particularly, retro-inverso-analogues of a CPP, are useful for oral administration. It is also expected that these compounds will enable a more controlled effect on the patient, due to a combination of similar or slightly lower activity (Figure 2) but improved resistance to gastric enzymes (Figure 4), which provides for a longer half-life. In some embodiments of the invention, the peptide comprises a sequence of amino acids which is read and/or synthesized from the right side to left side, where compounds of the invention comprising said opposite sequence may be referred to as retro-peptide containing compounds. In some embodiments of the invention, the peptide comprises between 1 and 200 amino acids, or between 2 and 100 amino acids, or between 5 and 50 amino acids, or between 10 and 25 amino acids, preferably in a linear configuration. In some embodiments of the invention, the peptide comprises between 2 and 250 amino acids, or between 5 and 50 amino acids, or between 10 and 25 amino acids, in a cyclic configuration, whereby said “cyclic peptides” are more resistant to cleavage. In some embodiments of the invention, there is provided a method of treating a chloride ion channelopathy in a subject in need thereof, wherein said method comprises administration of a therapeutically effective amount of one or more compounds, or a pharmaceutically-acceptable salt thereof, or a pharmaceutical composition disclosed herein, to the subject, optionally in combination with one or more therapeutic agents, preferably by administering a therapeutically effective amount of one of compound nos.10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907, or a variant or mixtures thereof, to a human subject in need thereof. In some embodiments of the invention, there is provided a method of treating a CFTR-mediated disease selected from cystic fibrosis, asthma, COPD, smoke induced COPD, and chronic bronchitis fibrosis in a subject in need thereof, wherein said method comprises administration of a therapeutically effective amount of one or more compounds, or pharmaceutically-acceptable salts thereof, or pharmaceutical compositions disclosed herein to the subject, optionally in combination with one or more therapeutic agents, preferably wherein said CFTR-mediated diseases is cystic fibrosis, preferably by administering a therapeutically effective amount of compound nos. 10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907, or a variant or mixtures thereof, to a human subject in need thereof. In some embodiments of the invention, there is provided a method of treating cystic fibrosis in a human subject in need thereof, wherein said method comprises administration of a therapeutically effective amount of one or more compounds, or pharmaceutically-acceptable salts thereof, or pharmaceutical compositions disclosed herein, to the human subject, optionally in combination with one or more therapeutic agents, preferably by administering a therapeutically effective amount of compound nos. 10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907, or a variant or mixtures thereof, to a human subject in need thereof. In some embodiments of the invention, there is provided a method of treating, reducing, inhibiting or controlling cystic fibrosis in a subject, wherein said method comprises simultaneously, separately or sequentially administering to the subject, (i) one or more therapeutic agents, and, (ii) a therapeutically effective amount of one or more compounds, or pharmaceutically-acceptable salts thereof, or pharmaceutical compositions disclosed herein, preferably by administering a therapeutically effective amount of compound nos. 10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907, or a variant thereof, to a human subject in need thereof. In some embodiments of the invention, there is provided a method of treating, reducing, inhibiting or controlling at least one sign or symptom of cystic fibrosis in a subject, wherein said method comprises administration of a therapeutically effective amount of one or more compounds, or pharmaceutically-acceptable salts thereof, or a pharmaceutical composition disclosed herein, to the human subject, optionally in combination with one or more therapeutic agents, wherein said sign or symptom is associated with the airways or respiratory system and includes one or more of the following: abnormally viscous mucus accumulation; increased total mucin content; elevated inflammatory factor concentration; decreased cellular secretion of chloride ions; impaired fluid secretion; increased apical sodium absorption by airway epithelial cells; acidification and decreased height of the apical airway surface liquid; chronic cough; chronic lung infection, and combinations thereof. Preferably said method involves administering a therapeutically effective amount of a compound according to the invention described herein, such as compound nos. 10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907, or a variant or mixtures thereof, to a human subject in need thereof. In some embodiments of the invention, there is provided a compound, or a pharmaceutically- acceptable salt thereof, or a pharmaceutical composition of the invention for use in the treatment, reduction, inhibition or control of viscous sputum or lowering the viscosity of mucus associated with cystic fibrosis in a human subject, wherein said pharmaceutical composition increases the electrolyte content of said viscous mucus or sputum, such as chloride and/or bicarbonate ions, optionally wherein said pharmaceutical composition is administered to the lungs of said human subject by pulmonary or aerosol delivery as a solution or suspension in a liquid vehicle via a device such as a pMDI, soft mist inhaler or nebulizer, or as a dry powder via a single or multi-dose dry powder inhaler, wherein said devices are known to those skilled in the art. Preferably said compound is, or said composition comprises, one of compound nos.10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907, or a variant thereof. In some embodiments of the invention, there is provided a method of treating, reducing, inhibiting or controlling viscous sputum or lowering the viscosity of mucus associated with cystic fibrosis in a human subject, wherein said method comprises administration of a compound, or a pharmaceutically-acceptable salt thereof, or a pharmaceutical composition, according to the invention described herein to the human subject, wherein said method increases the electrolyte content of said viscous mucus or sputum, such as chloride and/or bicarbonate ions, optionally wherein said pharmaceutical composition is administered to the lungs of said human subject by pulmonary or aerosol delivery as a solution or suspension in a liquid vehicle via a device such as a pMDI, soft mist inhaler or nebulizer, or as a dry powder via a single or multi-dose dry powder inhaler, wherein said devices are known to those skilled in the art.. Preferably, said method involves administering a therapeutically effective amount of a compound, or a pharmaceutically-acceptable salt thereof, or a pharmaceutical composition, according to the invention described herein, such as, or comprising, compound no. 10871, 10875, 10884, 10887, 10889, 10890, 10891 or 10907, or a variant or mixtures thereof, to a human subject in need thereof. Further aspects In some embodiments of the invention, there is provided a complex comprising a cell-penetrating peptide (CPP) covalently linked to one or several chemical entities via an X-NH-C(=Y)-NH- moiety at the N-terminal end of the amino acid sequence of said CPP. In some embodiments of the invention, there is provided a complex comprising a cell-penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP to one or several chemical entities via a linker component, preferably wherein said chemical entity is selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, preferably wherein said complex is amphipathic. In some embodiments of the invention, there is provided a complex comprising a cell-penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP to one or several chemical entities via a linker component selected from: an acetyl, an aromatic, a fatty acid, a cholesterol, a poly-ethylene glycol, a nuclear localization signal, nuclear export signal, an antibody, a polysaccharide and a targeting molecule, wherein said chemical entity is preferably selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group. In a further embodiment of the invention, is provided a complex comprising a cell-penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP to one or several chemical entities via a linker component selected from: an acetyl, an aromatic, a fatty acid, a cholesterol, a poly-ethylene glycol, a nuclear localization signal, nuclear export signal, an antibody, a polysaccharide and a targeting molecule, and wherein said chemical entity is preferably selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, wherein said complex is for use in the treatment of channelopathies, which are a heterogeneous group of disorders resulting from the dysfunction of ion channels located in the membranes of all cells and many cellular organelles, including diseases of the respiratory system (e.g., cystic fibrosis) and the urinary system (e.g., Bartter syndrome). In some embodiments of the invention, there is provided a complex comprising a cell-penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP to one or several chemical entities via a linker component, wherein said chemical entity is preferably selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, preferably wherein said complex is amphipathic, optionally wherein said complex is for use in the manufacture of a medicament. In some embodiments of the invention, there is provided a complex comprising a cell-penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP to one or several chemical entities via a linker component, wherein said chemical entity is preferably selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, preferably wherein said complex is amphipathic, wherein said complex is for use in the treatment of chloride channelopathies. In some embodiments of the invention, there is provided a method of treating a chloride ion channelopathy in a subject in need thereof, wherein said method comprises administration of a therapeutically effective amount of a complex comprising a cell-penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP to one or several chemical entities, via a linker component selected from: an acetyl, an aromatic, a fatty acid, a cholesterol, a poly-ethylene glycol, a nuclear localization signal, nuclear export signal, an antibody, a polysaccharide and a targeting molecule, wherein said chemical entity is selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, to a human subject in need thereof. In yet further aspects of the present disclosure, there is provided a method of treating a CFTR- mediated disease selected from cystic fibrosis, asthma, COPD, smoke induced COPD, and chronic bronchitis fibrosis in a subject in need thereof, wherein said method comprises administration of a therapeutically effective amount of a complex comprising a cell-penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP to, one or several chemical entities via a linker component selected from an acetyl, an aromatic, a fatty acid, a cholesterol, a poly-ethylene glycol, a nuclear localization signal, nuclear export signal, an antibody, a polysaccharide and a targeting molecule, wherein said chemical entity is selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, optionally where said method provides said complex administered in combination with one or more therapeutic agents, to a human subject in need thereof. In a further aspect of the disclosure, there is provided a method of treating cystic fibrosis in a human subject in need thereof, wherein said method comprises administration of a therapeutically effective amount of a complex comprising a cell-penetrating peptide (CPP) covalently linked via the N- terminal end of the amino acid sequence of said CPP to one or several chemical entities via a linker component selected from an acetyl, an aromatic, a fatty acid, a cholesterol, a poly-ethylene glycol, a nuclear localization signal, nuclear export signal, an antibody, a polysaccharide and a targeting molecule, wherein said chemical entity is selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, to a human subject in need thereof. Alternatively, said one or more chemical entities are selected from an acetyl, an aromatic, a fatty acid, a cholesterol, a poly-ethylene glycol, a nuclear localization signal, nuclear export signal, an antibody, a polysaccharide and a targeting molecule, and wherein said linker is selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group. In a further aspect of the disclosure, there is provided a method of treating, reducing, inhibiting or controlling cystic fibrosis in a subject, wherein said method comprises simultaneously, separately or sequentially administering to the subject, (i) one or more therapeutic agents, and, (ii) a therapeutically effective amount of a complex comprising a cell-penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP to one or several chemical entities via a linker, wherein said chemical entity is selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, preferably wherein said complex is amphipathic and administered to a human subject in need thereof. In a further aspect of the disclosure, there is provided a method of treating, reducing, inhibiting or controlling at least one sign or symptom of cystic fibrosis in a subject, wherein said method comprises administration of a therapeutically effective amount a complex comprising a cell- penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP via a linker to, one or several chemical entities preferably selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, preferably wherein said complex is amphipathic, to the human subject, optionally in combination with one or more therapeutic agents, wherein said sign or symptom is associated with the airways or respiratory system and includes one or more of the following: abnormally viscous mucus accumulation; increased total mucin content; elevated inflammatory factor concentration; decreased cellular secretion of chloride ions; impaired fluid secretion; increased apical sodium absorption by airway epithelial cells; acidification and decreased height of the apical airway surface liquid; chronic cough; chronic lung infection, and combinations thereof. In a further aspect of the disclosure, there is provided a method of treating, reducing, inhibiting or controlling at least one sign or symptom of cystic fibrosis in a subject, wherein said method comprises simultaneously, separately or sequentially administering to the subject, (i) one or more therapeutic agents, and, (ii) a therapeutically effective amount of one or more compounds disclosed herein, wherein said sign or symptom is associated with the airways or respiratory system and includes one or more of the following: abnormally viscous mucus accumulation; increased total mucin content; elevated inflammatory factor concentration; decreased cellular secretion of chloride ions; impaired fluid secretion; increased apical sodium absorption by airway epithelial cells; acidification and decreased height of the apical airway surface liquid; chronic cough; chronic lung infection, and combinations thereof. Preferably, said method involves administering a therapeutically effective amount of one or more complexes comprising a cell-penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP via a linker to one or several chemical entities p selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, preferably wherein said complex is amphipathic and administered to a human subject in need thereof. In a further aspect of the disclosure, there is provided a pharmaceutical composition for use in the treatment, reduction, inhibition or control of viscous sputum or lowering the viscosity of mucus associated with cystic fibrosis in a human subject, wherein said pharmaceutical composition increases the electrolyte content of said viscous mucus or sputum, such as chloride and/or bicarbonate, optionally wherein said pharmaceutical composition is administered to the lungs of said human subject by pulmonary or aerosol delivery as a solution or suspension in a liquid vehicle via a device such as a pMDI, soft mist inhaler or nebulizer, or as a dry powder via a single or multi- dose dry powder inhaler, wherein said devices are known to those skilled in the art.. Preferably said composition comprises a complex comprising a cell-penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP via a linker to one or several chemical entities selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, preferably wherein said complex is amphipathic. In a further aspect of the disclosure, there is provided a method of treating, reducing, inhibiting or controlling viscous sputum or lowering the viscosity of mucus associated with cystic fibrosis in a human subject, wherein said method comprises administration of a compound according to the invention described herein to a human subject in need thereof, wherein said method increases the electrolyte content of said viscous mucus or sputum, such as chloride and/or bicarbonate ions, optionally wherein said pharmaceutical composition is administered to the lungs of said human subject by pulmonary or aerosol delivery as a solution or suspension in a liquid vehicle via a device such as a a pMDI, soft mist inhaler or nebulizer, or as a dry powder via a single or multi-dose dry powder inhaler. Preferably, said method involves administering a therapeutically effective amount of a complex comprising a cell-penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP to one or several chemical entities via a linker, wherein said chemical entity is selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, optionally wherein said complex is amphipathic. The disclosure also provides a complex as described herein, for use in the treatment of a disease associated with chloride ion channel mutations or channelopathies, wherein the disease is selected from: myotonia congenita Becker, Myotonia congenita Thomsen, Dystrophia myotonica 1, dystrophia myotonica 2, childhood absence epilepsy type 3, juvenile absence epilepsy, juvenile myoclonic epilepsy, epilepsy with grand mal seizures on awakening, Bartter Syndrome, Bartter syndrome with sensorineurial deafness, Dent's disease, autosomal dominant osteopetrosis, autosomal recessive osteopetrosis, cystic fibrosis, idiopathic chronic pancreatitis, bronchiectasis, congenital bilateral absence of vas deferens, Best's disease, adult-onset vitelliform macular dystrophy, concentric annular macular dystrophy, cataract, juvenile myoclonic epilepsy, childhood absence epilepsy type 2, generalized epilepsy with febrile seizures plus, severe myoclonic epilepsy in infancy, insomnia and hereditary hyperekplexia. In some preferred embodiments of the invention, there is provided a compound, or a pharmaceutically-acceptable salt thereof, or complex or pharmaceutical composition or a method or use as described herein, for the treatment of a disease associated with a chloride ion channel mutation or channelopathy, wherein administration of said compound, or pharmaceutically- acceptable salt thereof, complex or pharmaceutical composition, or the method or the use results in one or more of the following: (i) a reduction in the viscosity of the mucus in the lungs, optionally in the presence or absence of any CFTR mutation, (ii) a reduction or delay in disease progression, (iii), reduction in symptom severity relative to therapy in the absence of administration of a compound as claimed herein; (iv), an improvement in breathing or respiratory performance, as measured by one or more of FEV1, PEF, FVC, and such like, (v) an improvement in patient reported outcomes, (v) a reduction in the risk of lung infection due to bacteria and/or virus and/or fungus, relative to therapy in the absence of administration of a compound as claimed herein, In some preferred embodiments of the invention, there is provided a compound, or a pharmaceutically-acceptable salt thereof, a complex, a pharmaceutical composition, a method or use as described herein, for the treatment of cystic fibrosis in a human subject in need thereof, wherein said treatment comprises administration of a therapeutically effective amount of a compound, or a pharmaceutically-acceptable salt thereof, or a pharmaceutical composition as described herein, or of a complex comprising a cell-penetrating peptide (CPP) covalently linked via the N-terminal end of the amino acid sequence of said CPP to one or several chemical entities via a linker component selected from an acetyl, an aromatic, a fatty acid, a cholesterol, a poly-ethylene glycol, a nuclear localization signal, nuclear export signal, an antibody, a polysaccharide and a targeting molecule, wherein said chemical entity is selected from a thiourea, (thio)ureido, (hydroxy)guanidino, ethylenediamine or acylthiourea group, to a human subject in need thereof, optionally wherein administration of said compound, or pharmaceutically-acceptable salt thereof, complex or pharmaceutical composition, or the method or use, results in one or more of the following: (i) a reduction in the viscosity of the mucus in the lungs, optionally in the presence or absence of any CFTR mutation, (ii) a reduction or delay in disease progression, (iii), reduction in symptom severity relative to therapy in the absence of administration of a compound as claimed herein; (iv), an improvement in breathing or respiratory performance as measured by one or more of FEV1, PEF, FVC, and such like, (v) an improvement in patient reported outcomes, (v) a reduction in the risk of lung infection due to bacteria and/or virus and/or fungus, relative to therapy in the absence of administration of a compound as claimed herein. In some preferred embodiments of the invention, there is provided a compound, or a pharmaceutically-acceptable salt thereof, a complex or a pharmaceutical composition, or a method or use, as described herein, optionally wherein said compound, or pharmaceutically-acceptable salt thereof, complex or pharmaceutical composition is administered to the lungs of said human subject by pulmonary or aerosol delivery as a solution or suspension in a liquid vehicle via a device such as a a pMDI, soft mist inhaler or nebulizer, or as a dry powder via a single or multi-dose dry powder inhaler. In some embodiments of the invention, there is provided a compound, or a pharmaceutically- acceptable salt thereof, a complex or a pharmaceutical composition, or a method or use, as described herein, wherein said compound or complex is preferably selected from, or the pharmaceutical composition comprises a compound or complex selected from, compound nos. 10871, 10875, 10884, 10887, 10889, 10890, 10891 and 10907, or a variant or combination thereof, optionally wherein said compound, complex or pharmaceutical composition is administered to a human subject by via a route of administration selected from: oral, pulmonary, rectal, colonic, parenteral, intracisternal, intravaginal, intraperitoneal, ocular, otic, buccal, nasal, and topical administration, preferably oral. A therapeutically effective amount, as disclosed herein, may be between about 1 ng and about 5 g, preferably between about 10 ng and 1g. EXAMPLES EXAMPLE 1 With Fmoc chemistry the peptide chain was elongated on TentaGel R RAM resin (0.19 mmol/g) (E Bayer, Angew. Chem. Int. Ed., 1991, 30, pp 113.) with a Rink amide linker on a 0.4 mmol scale manually. The coupling was performed in two steps. In the first step 3 equivalents of Fmoc protected amino acid, 3 equivalents of the uronium coupling agent O-(7-azabenzotriazol-1-yl)-N,N,N′,N′- tetramethyluronium hexafluorophosphate (HATU) (LA Carpino, Am. Chem. Soc., 1993, 115, pp 4379.) and 6 equivalents N,N-diisopropylethylamine (DIPEA) was used in N,N- dimethylformamide (DMF) as solvent with three hours of shaking. The second coupling was performed with 1 equivalent amino acid, 1 equivalent HATU and 2 equivalents of DIPEA. After the coupling steps, the resin was washed 3 times with DMF, once with methanol and 3 times with DCM. By these coupling conditions no truncated sequences was observed. The deprotection step was performed with 2% DBU and 2% piperidine in DMF in two steps with 15 and 5 minutes reaction times. The resin was washed with the same solvents as described previously. After the coupling of the amino acids, the thiourea element was created. The free N-terminus was reacted with specific isothiocyanates under alkaline conditions in DMF. After the completion of the sequence and thiourea construct, the cleavage was carried out with TFA/water/dl-dithiothreitol (DTT)/TIS at 0 °C for 1 h. The cleavage has been performed with TFA/water/DL-dithiothreitol (DTT)/TIS (90/5/2.5/2.5) at 0 °C for 1 h. The purification was performed by reverse-phase HPLC, using a Phenomenex Luna C18100 Ǻ 10 μm column (10 mm x 250 mm). The HPLC apparatus was made by JASCO and the solvent system used was as follows: 0.1% TFA in water; 0.1% TFA, 80% acetonitrile in water; linear gradient was used during 60 min, at a flow rate of 4.0 mL min-1, with detection at 206 nm. The fractions purity was determined by analytical HPLC using a JASCO HPLC system with a Phenomenex Luna C18100 Ǻ 5 μm column (4.6 mm x 250 mm) and the pure fractions were pooled and lyophilized. The purified peptides were characterized by mass spectrometry. For HCl salt preparation, the TFA salts of the peptides were dissolved in distilled water at 5 mg/mL concentration. Then using continuous stirring Amberlite IRA 410 chloride anion exchange resin was added to the solution at 20x excess compared to the amount of TFA salts and was stirred for 1 hour at 300 rpm. After 1 hour the suspensions were filtered through a porosity 3 glass filter. The remained resin was then washed with 0.1 N HCl and distilled water. The filtrates were then lyophilized in order to obtain solid HCl salt. In the Examples and Reference Examples below, TFA salt forms of the compounds were used. Reference compounds not presently claimed, and exemplary compounds according to the present invention, were produced and are described below, e.g. in Table 1: Table 1

The following reference examples (not presently claimed) are also provided: Reference Formula (II): The molecular weight (MW) of the compound is 2548.1 Da; Reference Formula (III): The molecular weight (MW) of the compound is 2548.1 Da; Reference Formula (IV): The molecular weight (MW) of the compound is 2536.2 Da; Reference Formula (V):

The molecular weight (MW) of the compound is 2630.1 Da; Reference Formula (VI): The molecular weight (MW) of the compound is 2530.1 Da; Reference Formula (VII): The molecular weight (MW) of the compound is 2554.2 Da; Reference Formula (VIII): The molecular weight (MW) of the compound is 2519.1 Da; Reference Formula (IX): The molecular weight (MW) of the compound is 2588.0 Da; Reference Formula (X): The molecular weight (MW) of the compound is 2656.2 Da; Reference Formula (XI): The molecular weight (MW) of the compound is 2650.1 Da; Reference Formula (XII): The molecular weight (MW) of the compound is 2662.1 Da; Example 2 Cytotoxicity of compounds and effect on viability of human bronchial/tracheal epithelial cells To investigate the cytotoxic effect of the compounds of Example 1, and their effect on the viability of human bronchial/tracheal epithelial cells, LAE-F cells were initially seeded at 10K cells per well in a 96 well plate format and allowed to grow to 75% confluence. After cells reached confluency, media was removed and cells were treated with one of eight treatment articles at 6 different concentrations (10uM, 2uM, 1uM, 0.5uM, 0.2uM, and 0.1uM) and incubated for 24 hours. After 24 hours, condition media was collected and used to detect LDH following the manufacturer’s instructions (Cayman Chemical, Cat#: 601170). Treatments were compared to the following controls: H ₂ O vehicle, DMSO vehicle, untreated cells. Compound 10871, which is described in PCT/IB2020/061590, was included as a comparative reference. None of the compounds tested showed significant toxicity in human bronchial/tracheal epithelial cells (Figure 1). Example 3 Regulation of ion channels or transporters expressed or added in/to Xenopus laevis oocytes Two-Electrode Voltage-Clamp (TEVC) recording in Xenopus laevis oocytes provides a powerful method to investigate the functions and regulation of ion channels or transporters expressed or added in/to Xenopus laevis oocytes. The plasma membrane of the oocyte is impaled by two microelectrodes, one for voltage sensing and the other one for current injection. Solutions used for the experiments were 3 M KCl (internal), Cl-free (external: in bath, then perfusion of cells with 5ml/cell). The compounds of Example 1 were dissolved in 93 mM Na-aspartate, 5 mM KCl, 1.8 mM CaCl2, 1 mM MgCl2, 5 mM HEPES, 50 μg/ml Pen.-Strept, pH 7.4 to make 10 μM solutions. The negative control was penetratin, while the positive control was Compound no. 10871 (which has been identified in PCT application no. PCT/IB2020/061590 as having chloride ion transporter function). For each tested compound, the signal (uA) from each tested compound was normalised against the positive control and is shown as a percentage of the signal from the positive control in Table 2 and Figure 2 (Oocyte% = percentage of the signal (uA)– baseline (negative control) compared to positive control was determined). If the oocyte% was higher than 100%, then the test compound was considered as having a higher chloride ion transport capability compared to the positive control. If the oocyte % was less than 80%, then the test compound was considered to have a lower chloride ion transport capability than the positive control (it should be noted that these test compounds still have chloride ion transporter functionality). Table 2 shows that compound no. 10875, which has a heteroatom containing linker, shows unexpectedly improved chloride ion transport activity compared to reference compound 10871. As shown by comparison to inventive compound 10907, longer heteroatom containing linkers as claimed still show notable chloride ion transport activity compared to compound no. 10871. However, very long chain heteroatom linkers not presently claimed, such as in reference compound no.10908 on the other hand show much lower ion transport activity. Compounds according to the first aspect thus demonstrate surprisingly improved activity compared to linkers which do not contain heteroatoms in the linker chain backbone, or which contain chain lengths outside the claimed range. Table 2: results of Two-Electrode Voltage-Clamp (TEVC) recording

Reference Example 1 Effect of reference compounds on the intracellular Cl- level in 2D HEK 293 cells in extracellular Cl- free media To assess the biological activity of the reference compounds, changes of intracellular Cl- level were measured by loading HEK-293 cells with 5μM N-(Ethoxycarbonylmethyl)-6-Methoxyquinolinium Bromide (MQAE; ThermoFisher; Catalog number: E3101) for 30 min in the presence of 0.05% Pluronic F-127. Cells were bathed with Cl- free external solution and treated with different concentrations of the reference compounds disclosed herein, at 37°C, at the perfusion rate of 2-3 ml/min. Region of interests (ROIs) were determined by the xcellence softver (Olympus) and changes of Cl- were determined by exciting the cells with an MT20 light source equipped with a 340/11 nm excitation filter. Excitation and emission wavelengths were separated by a 400 nm beam splitter and the emitted light was captured by a Hamamatsu ORCA- ER CCD camera. One measurement per second was obtained. During further analysis the fluorescence signals were normalized to the initial fluorescence intensity (F ₁ /F ₀ ) and expressed as normalized MQAE fluorescence. The maximal fluorescent intensity changes were calculated. Notably, the increase of normalised fluorescent intensity represents a decrease in the intracellular Cl- concentration. Reference Compounds of Formulae (II), (III), (V), (VI), (VI), and (VIII) were tested and displayed different characteristics in the intracellular Cl- measurements. The results are shown in Figure 3. Reference Example 2 Rheological and Electrophysiological Evaluation of Reference Compound no.10871 Evaluation of ion transport in W1282X/R1162X CFTR primary airway cultures. Cells were brought out of cryopreservation, expanded, and fully differentiated. Cultures were then treated (‘apical’) with compound no. 10871 chronically for 24 hours prior to assessment in Ussing chambers. Cultures were also exposed to the same concentrations acutely for assessment. Compound no. 10871 was tested at different concentrations in both scenarios. Changes in short circuit current (Isc) were measured in response to agonists and inhibitors of ion channels to determine the amplitude of Cl- transport necessary to effect mucociliary clearance in the lung. Basolateral culture medium was collected and stored pre- and post- treatment. Apical Krebs Bicarbonate Ringer (KBR) buffer from the chamber was collected for mucin analysis. To complement these Ussing chamber measurements, the re-adsorption rate of the airway surface liquid (ASL) was tested to verify the efficacy of compound no.10871 in preventing the underlying airway defect engendered by CFTR dysfunction: hyper-absorption of the ASL. Measurements of the height of the ASL layer were taken over a 48-hour period via confocal microscopy. Finally, since compound no. 10871 is intended to be an inhaled compound, the penetration of compound no.10871 through mucus layers mimicking healthy, mild CF, and severe CF were taken. “ACUTE” Bioelectrics: Following equilibration, 100µM Amiloride was introduced to the apical chamber to inhibit ENaC (Na absorption). At steady state compound no. 10871 at different concentrations was introduced to induce Cl- transport. Forskolin (10µM bilateral), CFTR inhibitor- 172 (10µM apical), and UTP (100µM apical) were added at 10-15 minute intervals to assess subsequent impact of the compound on cAMP-induced current and Clack current. “CHRONIC” Bioelectrics: Bioelectric measurements were performed in the presence of Formula (XVI) (identical to concentrations used chronically). Compound no. 10871 at different concentrations was added apically after a short period of incubation in bilateral KBR solution. Forskolin (10µM bilateral), CFTR inhibitor-172 (10µM apical), and UTP (100µM apical) were added at 10 to15 minute intervals to assess subsequent impact of the compound on cAMP-induced current and CaCC activity. Electrophysiological Results Baseline measurements suggest that all mucus-producing and ciliated epithelial cultures used in this experiment had intact and functional epithelium at the time of the assay. Well differentiated epithelial cultures tolerated compound no. 10871 at the concentrations tested. All cultures designated for acute experiments (N=16) were assessed for baseline characteristics to demonstrate the bioelectric features of untreated cultures of this genotype (W1282X/R1162X). A 2-tailed student’s t-test was used to determine statistical significance in chronically treated cohorts (1, 10, and 100μM, N=4 per group) compared to chronic control group (0μM compound no.10871, N=4) (see Figure 5). A decrease in the electrochemical gradient (i.e.: PD) was observed in cultures treated chronically at 100μM vs 0μM control, (-20.5+/-3.5 v. 35.4+/- 1.9, p=0.009). This represents 58% of potential difference found in controls, (or a reduction of 42%). Transepithelial resistance was reduced by 30% in 100μM compound no.10871-treated cultures, (control 699.8+/- 14.6, 100uM 487.9+/-54.4, p=0.009), which may indicate the activation of an ion channel or ‘creation’ of pores without agonist effect. We did not observe leaking or liquid transport (i.e.: wet cultures) demonstrating the epithelial barrier is intact. There was no difference observed in the activity of ENaC channels (amiloride) in chronic treatment groups. A potential dose related increase was observed in residual current following inhibition of sodium channel activity in chronically treated cultures, becoming significant at concentrations of 10μM (- 0.15+/-0.36 p=0.023) and 100μM (2.16+/-0.63, p=0.002) compared to control (-1.53+/-0.28). The 240% increase may indicate constitutive activity under these conditions. “ACUTE” responses were evaluated by testing compound no. 10871 at increasing concentrations in 5mL of Krebs Bicarbonate Ringers (KBR) solution in the apical hemi-chamber to induce an increase in short circuit current (Isc). Compound no.10871 acutely activated short circuit current independent of CFTR and may induce purinergic activation of Ca2+-activated chloride channels. At 10μM (0.16 +/-0.01, p=0.000007) and 100μM (2.20+/-0.21 p=0.000042) acutely administered compound no. 10871 to the apical hemi-chamber, induced a small yet significant increase in Isc compared to control (-0.012+/-0.006). Additionally, compound no.10871 at higher concentrations, particularly at 100μM, demonstrated at least some sustained activity and/or prolonged residence time in the cell membrane, a favorable kinetic for therapeutic purposes. Compound no. 10871 increased the UTP-induced activity of CaCC by 1.7-fold at 10μM (2.26+/-0.29, p=0.018662061) and 2-fold at 100μM (2.57+/-0.24, p=0.002583508) (see Figure 6). The sustained amplitude of Isc following purinergic activation of CaCC was quite minimal, yet statistically significant. Neither forskolin nor CFTRinh-172 had a significant effect in these cultures due to the absence of CFTR protein in the cultures. Reference Compound no.10871 CHRONIC Treatment Following 24-hour treatment with reference compound no. 10871, a residue on the surface of cultures treated with 100μM compound no.10871 was observed. Electrophysiology was performed in the presence of equivalent compound no.10871 in the apical chamber. Cultures from the chronic studies were removed from the Ussing chambers and repurposed/stored for further histological examination or nucleic acid analysis. A temporary decrease in short circuit current was observed when compound no.10871 was added acutely at 100μM (-5.213+/-1.024, p=0.0020) compared to control (0.118+/-0.098 [slope corrected value]). The short circuit current partially recovered after 10 minutes and did not have a significant effect on changes in current following inhibition of ENaC with amiloride. A dose dependent increase in measured residual current [(10μM) -0.156+/-0.355, p=0.023, (100μM) 2.163+/-0.628, p=0.002, Control -1.534+/-0.282] was observed indicating possible increase in constitutive activity. At 100μM, compound no.10871 decreased cAMP activity in these cultures (-0.344+/-0.306, p=0.006) compared to control (0.923+/-0.052). There was minimal change in CFTR inhibition in all groups, except at 100μM (-0.938+/-0.065, p=0.026) compared to control (-0.614+/-0.088) which may be a non-specific effect due to the presumed absence of CFTR in these cultures. Compound no.10871 enhanced purinergic activation of CaCC in a dose-dependent manner. Compound no. 10871 induced a 1.2-, a 1.5-, and a 2.3-fold increase in response to UTP in cultures treated at 1uM (1.379+/- 0.016, p=0.002), 10uM (1.697+/- 0.179, p=0.024) and 100uM (2.647+/- 0.088, p=0.0000045) compared to control (1.145+/- 0.040) (see Figure 7). Mucus Migration Studies The ability of reference compound no.10871 to permeate mucus was determined by measuring the diffusion of fluorescently labeled compound no. 10871 molecules in both buffer and mucus prepared to concentrations that mimic healthy patient mucus (2% solids), mild CF patient mucus (4% solids), and severe CF mucus (8% solids). The diffusion of compound no. 10871 in buffer (PBS) was measured against an 80/20 glycerol/water mixture which served as a control. Images of each the diffusion of Cy5 labeled compound no. 10871 in 2 and 4% HBE mucus were taken and analyzed. In 2% mucus, the smear in the intensity pattern was wider than in 4% mucus, indicating that the concentration of mucus did have some effect on the penetration of mucus by compound no. 10871. Fitting the intensity patterns to a Gaussian distribution, the diffusion coefficient and effective viscosity “felt” by compound no. 10871 in each mucus concentration were determined (see Table 3). In mucus, the diffusion coefficient of compound no. 10871 increased with the solids content/ concentration of mucus. Since the diameter of compound 10871 is well below the polymeric spacing, or mesh size of mucus, this decrease in diffusion coefficient indicated that the compounds is interacting with its environment and effectively “feels” a progressively higher viscosity at each mucus concentration. The effective viscosity in 4 and 8% mucus was increased 2-3 times above the viscosity of buffer, while macroscopic measurements of the viscosity of mucus at these concentrations is 100 – 1000 times higher than buffer. Correspondingly, it may have been anticipated that the compound of compound no. 10871 may have taken 2 to -3 times longer to penetrate a 100μm mucus layer compared to water, but the compound was able to traverse the layer in < 2.5 minutes. Table 3. Effective viscosity and penetration time of reference compound no. 10871 as a function of mucus concentration. ASL Re-adsorption The height of the airway surface liquid (ASL) was measured by confocal microscopy after the addition of 20μL of buffer containing rhodamine-labeled dextran. In acute studies, a transient effect of 10μM reference compound no. 10871 at 24 hours was noted, where the height of the ASL was increased above baseline at this time point. Additionally, all tested concentrations of compound no. 10871 were shown to decrease the level of ASL re-absorption at 48 hours. As with the acute exposures, statistical significance was not demonstrated in chronically treated cultures, however, a significant effect of dosing cultures was found on ASL height. The mean ASL height was increased at 48 hours for all concentrations. Example 4 Stability of inverso- and retro-inverso-peptide compounds Compound nos.10871 (reference compound), 10890 and 10891 were tested for their stability in the presence of the gastric enzyme trypsin. The compounds were dissolved in 0.1% acetic acid at 0.2 mg/mL concentration. Trypsin enzyme was dissolved in 0.001M HCl at 1 mg/mL concentration. Then 0.5 mL samples and 0.5 mL HEPES buffer consisting of 50 mM pH 7.4 HEPES and 9 mg/ml NaCl, and 0.01 mL trypsin solution were pipetted in one tube. The samples were incubated at 37°C. The chemical stability of the samples was tested at 15 minutes and 70 minutes, using HPLC-UV (the compounds were detected at 271nm). The %recovery was calculated as the area under the peak for each compound compared to the area under the peak of the control (reference compound 10871 in the absence of trypsin), and the results are shown in Figure 4. Compound no. 10891 and Compound no. 10890 showed high resistance against enzymatic degradation, while Reference Compound no. 10871 significantly degraded within 15 minutes (Figure 4).