GENERATION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 61/681,916, filed on August 10, 2012, which is incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention is directed to a method of quenching singlet and triplet electronic excited states of photodegradable pigments with conjugated fused tricyclic compounds having electron withdrawing groups. More particularly, it has been found that conjugated fused tricyclic compounds having electron withdrawing groups quench the singlet and triplet excited states of pigments, such as porphyrin compounds, by accepting or dontating an electron, thereby returning the pigments back to their ground state to reduce the formation of free radical (singlet state) oxygen and/or other reactive oxygen species and radical compounds that are damaging to skin cells. Porphyrin compounds, for example, reach an excited state when excited by visible radiation at a wavelength in the range of about 290 to about 800 nm, e.g., sunlight, and when the excited porphyrin compound is reacted with a conjugated fused tricyclic compound having electron withdrawing groups, the excited porphyrin compound, and other photolabile pigments, are returned to their ground state before interacting with cellular oxygen, thereby generating substantially less singlet state oxygen, and preventing oxidative stress to skin cells.

BACKGROUND AND PRIOR ART

[0003] Endogenous pigments are substances in living matter that absorb visible light. They may also absorb UV radiation. These substances are produced either within tissues and serve a physiological function, or they are by-products of the metabolic process. Endogenous pigments can be classified into non-hematogenous pigments and hematogenous (i.e., blood derived) pigments. Non-hematogenous pigments include, e.g., melanins, flavins, pterins, and urocanic acid. Melanins are derived from tyrosine, and include eumelaninm pheomelanin, and

neuromelanin. Flavins are a group of organic compounds based on pteridine, formed by the tricyclic heteronuclear organic ring isoalloxazine. Examples of flavins include riboflavin, flavin mononucleotide, flavoproteins, and flavin adenine dinucleotide. Pterins are heterocyclic compounds composed of a pteridine ring system, with a keto group and an amino group on positions 4 and 2, respectively. Examples of pterins include pteridine, biopterin,

tetrahydrobiopterin, molybdopterin, cyanopterin, tetrahydromethanopterin, and folic acid.

Urocanic acid is an intermediate in the catabolism of L-histidine. Hematogenous pigments include, e.g., hemoglobin, bile pigments, and porphyrins. Hemoglobin is a basic, conjugated protein that is responsible for the transportation of oxygen and carbon dioxide within the blood stream. It is composed of protein, globin, and heme— four molecules of heme are attached to each molecule of globin.

Heme B group of hemoglobin complexed to four interior nitrogen atoms

Bile pigments are the metabolic products of heme, and include bilirubin (yellow, tetrapyrrolic breakdown product) and biliverdin (green, tetrapyrrolic breakdown product).

[0004] Porphyrins are a group of organic compounds, mainly naturally occurring, but also can be exogenous. Porphyrins are heterocyclic macrocycles composed of four modified pyrrole subunits interconnected at their a carbon atoms via methine bridges (=CH-), as shown in Formula (I). Porphyrins are aromatic. That is, they obey Hiickel's rule for aromaticity, possessing 4n+2 π electrons (n=4 for the shortest cyclic path) delocalized over the macrocycle. Thus, porphyrin macrocycles are highly conjugated systems and typically have very intense absorption bands in the visible region and may be deeply colored. The macrocycle has 26 π electrons in total. The parent porphyrin is porphine, and substituted porphines are called porphyrins. The porphyrin compounds that have their singlet and triplet excited states quenched by the conjugated, fused tricyclic compound having electron withdrawing groups include any porphyrin compound that includes the moiety of Formula (I) (and derivatives and tautomers thereof), as shown in Formula la, particularly protoporphyrin IX, Formula lb.

(I) la lb

Structure of porphine,

the simplest porphyrin

[0005] A porphyrin without a metal-ion in its cavity is a free base. Some iron-containing porphyrins are called hemes, the pigment in red blood cells. As previously discussed, heme is a cofactor of the protein hemoglobin. Heme-containing proteins, or hemoproteins, are found extensively in nature. Hemoglobin and myoglobin are two 0 ₂ -binding proteins that contain iron porphyrins. Various cytochromes are also hemoproteins.

[0006] The absorption of visible light (at about 400 to about 800 nm and UV of about 290 to about 400 nm) by a porphyrin compound causes the excitation of an electron in the porphyrin molecule from an initially occupied, lower energy orbital to a higher energy, previously unoccupied orbital. The energy of the absorbed photon is used to energize an electron and cause it to "jump" to a higher energy orbital. See Turro, Modern Molecular Photochemistry, 1991. Two excited electronic states derive from the electronic orbital configuration produced by visible light absorption. In one state, the electron spins are paired (antiparallel) and in the other state the electron spins are unpaired (parallel). The state with paired spins has no resultant spin magnetic moment, but the state with unpaired spins possesses a net spin magnetic moment. A state with paired spins remains a single state in the presence of a magnetic field, and is termed a singlet state. A state with unpaired spins interacts with a magnetic field and splits into three quantized states, and is termed a triplet state.

[0007] In the electronically excited state, the porphyrin molecule can transfer its excited state energy to oxygen contained in blood and/or skin cells, thereby generating cell-damaging singlet excited state oxygen (hereinafter "singlet oxygen"), or free radical oxygen. To photo stabilize the excited state of the porphyrin molecule so that it does not generate cell-toxic singlet oxygen, the excited state of the porphyrin molecule must be returned to the ground state before it transfers its excited state energy to nearby oxygen molecule.

[0008] On the other hand, the excited state of porphyrins has also been intentionally harnassed to administer photodynamic therapy (PDT). Protoporphyrin IX (C ₃₄ H ₃₄ N ₄ O ₄ ) is used in PDT, for example, as a treatment for basal cell carcinoma (BCC), which is the most common form of skin cancer in humans. The PDT treatment involves applying a photosensitizer precursor, such as aminolevulinic acid (ALA) to the cancerous cells, waiting a few hours for the ALA to be taken up by the cells and converted to protoporphyrin IX, and then irradiating the cancerous cells with light in the wavelength of about 380 to about 650 nm which excites the protoporphyrin IX to a singlet excited state after which it intersystem crosses to a triplet excited state thereby making it reactive with oxygen, thereby generating cytotoxic singlet oxygen that kills cancerous and pre-cancerous cells.

SUMMARY

[0009] In one aspect, the disclosure provides a method of quenching excited state energy from a photodegradable pigment compound that has been excited by exposure to and absorption of light having a wavelength in the wavelength range of about 290 to about 800 nm, comprising reacting the photodegraded pigment in its excited states with a conjugated fused tricyclic compound having electron withdrawing groups of Formula (II) or a salt thereof:

wherein: sel

B 1 , B2 , D 1 , and 2 are each independently selected from the group consisting of F, CI, Br, I, CF ₃ , CC1 ₃ , NR ³ 3 ⁺ , N0 ₂ , CN, C(=0)R ⁴ , C(=0)OR ¹ , S0 ₂ R ⁵ , aryl, and—

C=CHR ⁶ ; each m independently is 0, 1, 2, 3, or 4; n is 0 or 1 ; each R ¹ is independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, and aryl;

R is selected from the group consisting of H, alkyl, cycloalkyl, alkenyl, alkynyl, and aryl; each R is independently selected from the group consisting of H and Ci-C6 alkyl; each R ⁴ is independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, and aryl; each R ⁵ is independently selected from the group consisting of H, O ^" , OH, NH ₂ , and CI; and, each R ⁶ is independently selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, and aryl.

[0010] In another aspect, the disclosure provides a method of suppressing the generation of singlet oxygen and/or other reactive oxygen species or radical compounds by an excited pigment when mammalian-contained pigment is exposed to light, thereby exciting the pigment to an excited state, by quenching the excited state of the pigment compound with a conjugated fused tricyclic compound having electron withdrawing groups of Formula (II) or a salt thereof. Other oxygen species presented from forming include free radical oxygen, superoxide anion, peroxide, hydroxyl radical, and hydroxyl ion.

[0011] In yet another aspect, the invention provides a method of protecting skin from oxidative stress caused by the generation of free radical oxygen comprising coating the skin with a pigment excited state quencher capable of accepting or donating an electron from or to a pigment compound in the excited state and returning the excited pigment compound to its ground state, said pigment quencher comprising a conjugated fused tricyclic compound having electron withdrawing groups of Formula (II) or a salt thereof.

[0012] In still another aspect, the invention provides a method of protecting healthy cells adjacent to cancerous or pre-cancerous cells undergoing photodynamic therapy comprising applying a composition comprising a pigment excited state quencher compound to said adjacent cells to reduce the generation of free radical oxygen and other reactive oxygen species from said healthy cells while the photodynamic therapy generates free radical oxygen from said cancerous or pre-cancerous cells with a conjugated fused tricyclic compound having electron withdrawing groups of Formula (II) or a salt thereof.

[0013] In some exemplary embodiments of any of the above aspects, the pigment compound is a porphyrin compound comprising a porphyrin moiety of Formula (I) or a derivative or tautomer thereof:

[0014] In another aspect, the invention provides a cosmetic or dermatological composition for coating a skin surface to protect the skin from getting damaging amounts of singlet oxygen when skin cell-contained or blood-contained porphyrin compounds are exposed to sunlight, or other visible light comprising a compound of Formula lib, lie, lid, He, Ilf, Ilg, IHi, Ili, Ilj, Ilk, III, Urn, Iln, or a combination thereof:

Formula Mb Formula lie Formula Me

Formula llg Formula llh Formula 11 J Formula Mm

Formula lln

wherein: each R ¹ is independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, and aryl; and,

R is selected from the group consisting of H, alkyl, cycloalkyl, alkenyl, alkynyl, and aryl. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 shows absorption spectra of the compound of Formula Ilai (Figure la), Formula Ilbi (Figure lc), Formula IIci (Figure Id), Formula Ilfi (Figure Ie), and a mixture of Formulae Ildi and Ilei (Figure If) in acetonitrile and alkoxy crylene (Figure lb) in acetonitrile.

[0016] Figure 2 shows an absorption spectrum (Figure 2a) and a fluorescence spectrum (Figure 2b) of protoporphyrin IX in acetonitrile. λεχ = 510 nm.

[0017] Figure 3 shows fluorescence decay traces monitored at 690 nm using time correlated single photon counting of the compound of Formula Ilai (Figure 3 a) and alkoxy crylene (Figure 3b) in acetonitrile solutions in the absence and presence of different amounts of stabilizers, λεχ = 490 nm.

[0018] Figure 4 is a graph showing the determination of k _q , the bimolecular rate constant for quenching of protoporphyrin IX fluorescence by Formula Ilai and alkoxy crylene using the experimental data shown in Figure 3 (Figure 4a), and Formula Ilbi, IIci, a mixture of Ildi and Ilei, and Ilfi (Figure 4b). The graphs depict inverse fluorescence lifetime vs. quencher

(stabilizer) concentration.

[0019] Figure 5 is a graph showing a transient absorption spectrum (Figure 5a) of an argon saturated acetonitrile solution of protoporphyrin IX recorded 0.1 to 1.5 μ8 after pulsed laser excitation (355 nm, 5 ns pulse width). Selected kinetic traces at different observation wavelengths are also included (Figs, b, c).

[0020] Figure 6a) is a graph showing determination of k _q , the bimolecular rate constant for quenching of protoporphyrin IX triplet states by the compounds of Formula Ilai and alkoxy crylene. Figures 6b), 6c), 6d), and 6e) are graphs showing the determination of k _q , the bimolecular rate constant for quenching of protoporphyrin IX triplet states by the compounds of Formulae Ilbi, IIci, a mixture of Ildi and Ilei, and Ilfi. The graphs depict inverse inverse triplet state lifetime measured at 440 nm by laser flash photolysis vs. quencher (stabilizer)

concentration.

[0021] Figure 7 shows luminescence excitation (Figure 7b) and emission (Figure 7c) spectra of the compound of Formula Ilai in an ethanol matrix at 77 K. Room temperature absorption spectrum (Figure 7a) of Formula Ilai in ethanol solution is also shown. [0022] Figure 8 shows a singlet oxygen phosphorescence spectrum (Figure 8a) and a decay trace (Figure 8b) generated by photoexcitation (532 nm) of tetrapenylporphyrin in air saturated CC1 ₄ solutions using steady-state lamp excitation (Figure 8a) or pulsed laser excitation (Figure 8b).

[0023] Figure 9 shows determination of singlet oxygen quenching rate constants k _q by the stabilizers. The graph depicts inverse phosphorescence lifetime vs. quencher (stabilizer) concentration.

[0024] Figure 10 is a graph showing singlet oxygen phosphorescence decay traces generated by pulsed laser excitation (355 nm) of protoporphyrin IX in air saturated DMSO-d6 solutions in the absence and presence of the compound of Formula Ilai.

[0025] Figure 11 is a graph showing singlet oxygen phosphorescence decay traces generated by pulsed laser excitation (355 nm) of protoporphyrin IX in air saturated DMSO-d6 solutions in the absence and presence of the alkoxy crylene compound at different concentrations.

[0026] Figure 12 shows singlet oxygen phosphorescence spectra generated by photoexcitation of Formula Ilai (Figure 12b) or alkoxy crylene (Figure 12b) at 355 nm in benzophenone in air saturated CC1 ₄ solutions. The concentrations were adjusted to have an absorbance of 0.3 at 355 nm. Figure 12 b is an amplification of Figure 12a.

[0027] Figure 13 is a graph showing an absorption spectrum and a singlet oxygen

phosphorescence excitation spectrum (monitored at 1270 nm) of alkoxy crylene in air saturated CCI ₄ solutions.

[0028] Figure 14 shows singlet oxygen phosphorescence decay traces monitored at 1270 nm generated by pulsed laser excitation at 355 nm (Figures 14a and 14c) or 532 nm (Figures 14b and 14d) of protoporphyrin IX (25 μΜ) in air saturated DMSO-d6 solutions in the absence and presence of the compound of Formula Ilai and the alkoxy crylene compound.

[0029] Figure 15 shows the structures of protoporphyrin IX and protoporphyrin IX dimethyl ester.

[0030] Figure 16 shows singlet oxygen phosphorescence decay traces monitored at 1270 nm generated by pulsed laser excitation at 355 nm (Figures 16a and 16c) or 532 nm (Figures 16b and 16d) of protoporphyrin IX dimethyl ester (25 μΜ), and monitored at 1270 nm generated by pulsed laser excitation at 532 nm of protoporphyrin IX dimethyl ester (17 μΜ) (Figures 16e, 16f, 16g, 16h, 16i, and 16j) in air saturated CDC1 ₃ solutions in the absence and presence of the compound of Formulae Ilai, Ilbi, Ilci, a mixture of Ildi and Ilei, Ilfi and the alkoxy crylene compound, commercially available as SolaStay ^® S I (The HallStar Company).

[0031] Figure 17 shows a Stern- Volmer plot of singlet oxygen phosphorescence data from decay traces generated by pulsed laser excitation at 355 nm (Figures 14a and 14c) or 532 nm (Figures 14b and 14d)) of protoporphyrin IX (25 μΜ) in air saturated DMSO-d ₆ solutions in the absence and presence of the compound of Formula Ilai and the alkoxy crylene compound (Fig. 17a), and at 532 nm (Figure 16e, 16f, 16g, 16h, 16i, and 16j) of protoporphyrin IX dimethyl ester (17 μΜ) in air saturated CDCI ₃ solutions in the absence and presence of the compound of Formulae Ilai, Ilbi, Ilci, a mixture of Ildi and Ilei, and Ilf, and the alkoxy crylene compound (Fig. 17b and 17c)i.

[0032] Figure 18 shows the structures of additional specific compounds in accordance with Formula (II).

[0033] Figure 19 shows the redox potential of protoporphyrin IX (Fig. 19a), Formula Ilai (Fig. 19b), Ilbi (Fig. 19c), Ilfi (Fig. 19d), Ilci (Fig. 19e), a mixture of Ildi and Ilei (Fig. 19f), and alkoxy crylene (Fig. 19g).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Quite surprisingly, it has been found that conjugated fused tricyclic compounds having electron withdrawing groups will quench electronically excited pigments, such as porphyrin molecules, caused when the pigment (e.g., a porphyrin) is excited by absorption of visible light. As a result, the excited state of photodegradable pigments, such as porphyrin molecules, particularly protoporphyrin IX, is returned to the ground state, thereby reducing the generation of singlet oxygen and protecting mammalian skin from oxidative stress, which would otherwise develop from sunlight-induced production of singlet state oxygen. Accordingly, by applying one or more of the conjugated fused tricyclic compounds having electron withdrawing groups, in a dermatologically or cosmetically acceptable carrier, onto mammalian skin, e.g., human skin, the skin will not suffer from oxidative stress due to the generation of potentially cytotoxic singlet oxygen and other reactive oxygen species. Thus, the compositions and methods described herein advantageously quench the excited state reached by pigments, such as porphyrins, particularly protoporphyrin IX, thereby significantly reducing the generation of singlet oxygen and other reactive oxygen species in cells, and thereby preventing oxidative stress.

[0035] Ranges may be expressed herein as from "about" or "approximately" one particular value and/or to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment.

Definitions

[0036] The term "alkyl" refers to straight chained and branched saturated hydrocarbon groups containing one to thirty carbon atoms, for example, one to thirty carbon atoms, one to twenty carbon atoms, and/or one to ten carbon atoms. The term C _n means the alkyl group has "n" carbon atoms. For example, C ₄ alkyl refers to an alkyl group that has 4 carbon atoms. CrC ₇ alkyl refers to an alkyl groups having a number of carbon atoms encompassing the entire range (i.e., 1 to 7 carbon atoms), as well as all subgroups (e.g., 1-6, 2-7, 1-5, 3-6, 1, 2, 3, 4, 5, 6, and 7 carbon atoms). Nonlimiting examples of alkyl groups include, methyl, ethyl, w-propyl, isopropyl, w-butyl, sec-butyl (2-methylpropyl), i-butyl (1,1-dimethylethyl), 3,3-dimethylpentyl, and 2-ethylhexyl. Unless otherwise indicated, an alkyl group can be an unsubstituted alkyl group or a substituted alkyl group. When the term "alkyl" is in parenthesis (e.g., (alkyl)acrylate), then the alkyl group is optional.

[0037] The term "alkenyl" is defined identically as "alkyl" except for containing at least one carbon-carbon double bond, e.g., ethenyl, 1-propenyl, 2-propenyl, and butenyl. Unless otherwise indicated, an alkenyl group can be an unsubstituted alkenyl group or a substituted alkenyl group.

[0038] The term "alkynyl" is defined identically as "alkyl" except for containing at least one carbon-carbon triple bond, e.g., ethynyl, 1-propynyl, 2-propynyl, and butynyl. Unless otherwise indicated, an alkynyl group can be an unsubstituted alkynyl group or a substituted alkynyl group.

[0039] The term "cycloalkyl" as used herein refers to an aliphatic cyclic hydrocarbon group containing three to eight carbon atoms (e.g., 3, 4, 5, 6, 7, or 8 carbon atoms). The term C _n means the cycloalkyl group has "n" carbon atoms. For example, C ₅ cycloalkyl refers to a cycloalkyl group that has 5 carbon atoms in the ring. C5-C8 cycloalkyl refers to cycloalkyl groups having a number of carbon atoms encompassing the entire range (i.e., 5 to 8 carbon atoms), as well as all subgroups (e.g., 5-6, 6-8, 7-8, 5-7, 5, 6, 7, and 8 carbon atoms). Nonlimiting examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Unless otherwise indicated, a cycloalkyl group can be an unsubstituted cycloalkyl group or a substituted cycloalkyl group.

[0040] The term "heterocycloalkyl is defined similarly as cycloalkyl, except the ring contains one to three heteroatoms independently selected from the group consisting of oxygen, nitrogen, and sulfur. Nonlimiting examples of heterocycloalkyl groups include piperdine, tetrahydrofuran, tetrahydropyran, dihydrofuran, morpholine, thiophene, and the like. Cycloalkyl and

heterocycloalkyl groups can be saturated or partially unsaturated ring systems optionally substituted with, for example, one to three groups, independently selected from the group consisting of alkyl, alkyleneOH, C(0)NH ₂ , NH ₂ , oxo (=0), aryl, haloalkyl, halo, and OH.

Heterocycloalkyl groups optionally can be further N-substituted with alkyl, hydroxyalkyl, alkylenearyl, or alkyleneheteroaryl.

[0041] The term "cycloalkenyl" is defined identically as "cycloalkyl" except for containing at least one double bond, e.g., cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, and cyclooctenyl. Unless otherwise indicated, a cycloalkenyl group can be an unsubstituted cycloalkenyl group or a substituted cycloalkenyl group.

[0042] The term "aryl" as used herein refers to monocyclic or polycyclic (e.g., fused bicyclic and fused tricyclic) carbocyclic aromatic ring systems. Examples of aryl groups include, but are not limited to, phenyl, naphthyl, tetrahydronaphthyl, phenanthrenyl, biphenylenyl, indanyl, indenyl, anthracenyl, and fluorenyl. Unless otherwise indicated, an aryl group can be an unsubstituted aryl group or a substituted aryl group.

[0043] The term "heteroaryl" as used herein refers to monocyclic or polycyclic (e.g., fused bicyclic and fused tricyclic) aromatic ring systems, wherein one to four-ring atoms are selected from the group consisting of oxygen, nitrogen, and sulfur, and the remaining ring atoms are carbon, said ring system being joined to the remainder of the molecule by any of the ring atoms. Nonlimiting examples of heteroaryl groups include, but are not limited to, pyridyl, pyrazinyl, pyrimidinyl, pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, tetrazolyl, oxazolyl, isooxazolyl, thiadiazolyl, oxadiazolyl, furanyl, quinolinyl, isoquinolinyl, benzoxazolyl, benzimidazolyl, and benzothiazolyl. Unless otherwise indicated, a heteroaryl group can be an unsubstituted heteroaryl group or a substituted heteroaryl group.

[0044] The term "hydroxy" or "hydroxyl" as used herein refers to an "— OH" group.

[0045] The term "alkoxy" or "alkoxyl" as used herein refers to an "— O-alkyl" group.

O

[0046] The term "ester" as used herein refers to a group of the general Formula: %A OR wherein R is an alkyl group or a cycloalkyl group.

[0047] The term "ether" as used herein refers to a Q-C30 alkyl group that includes at least one oxygen atom inserted within the alkyl group.

[0048] The term "amino" as used herein refers a— NH ₂ or— NH— group, wherein each hydrogen in each Formula can be replaced with an alkyl, cycloalkyl, aryl, heteroaryl, or heterocyclo alkyl group.

[0049] The term "carboxy" or "carboxyl" as used herein refers to a "-COOH" group.

[0050] The term "carboxylic ester" as used herein refers to a "-(C=0) O-alkyl" group.

[0051] The term "sulfhydryl" as used herein refers to a "— SH" group.

[0052] The term "halo" as used herein refers to a halogen (e.g., F, CI, Br, or I).

[0053] The term "cyano" as used herein refers to a— C≡N group, also designated— CN.

[0054] A "substituted" alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, alkoxyl, ester, ether, or carboxylic ester refers to an alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, alkoxyl, ester, ether, or carboxylic ester having at least one hydrogen radical that is substituted with a non-hydrogen radical (i.e., a substitutent). Examples of non-hydrogen radicals (or substituents) include, but are not limited to, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, ether, aryl, heteroaryl, heterocycloalkyl, heterocycloalkyl, hydroxyl, oxy (or oxo), alkoxyl, ester, thioester, acyl, carboxyl, cyano, nitro, amino, amido, sulfur, and halo. When a substituted alkyl group includes more than one non-hydrogen radical, the substituents can be bound to the same carbon or two or more different carbon atoms.

[0055] The term "hydroxyalkyl" as used herein refers to an alkyl group that is substituted with a hydroxyl group. [0056] The term "carboxyalkyl" as used herein refers to an alkyl group that is substituted with a carboxyl group.

[0057] The term "esteralkyl" as used herein refers to an alkyl group that is substituted with an ester group.

[0058] The term "sulfhydrylalkyl" as used herein refers to an alkyl group that is substituted with a sulfhydryl group.

[0059] The term "photogenerated reactive oxygen" as used herein refers to singlet oxygen or free radical oxygen, superoxide anion, peroxide, hydroxyl radical, hydroxyl ion, and other reactive oxygen species that are generated when a photodegradable pigment is excited by light having a wavelength of 290 nm to 800 nm.

Embodiments

[0060] The conjugated fused tricyclic compounds having electron withdrawing groups capable of quenching the excited state energy of pigments, such as the porphyrins compounds of Formulae (I) and la, are the compounds of Formula (II) or a salt thereof:

Formula (II)

Conjugated fused tricyclic compounds having electron withdrawing groups wherein:

A is selected from the group consisiting of O, S, C=0, C=S, ;

B 1 , B2 , D 1 , and 2 are each independently selected from the group consisting of F, CI, Br, I, CF ₃ , CC1 ₃ , NR ³ 3 ⁺ , N0 ₂ , CN, C(=0)R ⁴ , C(=0)OR ¹ , S0 ₂ R ⁵ , aryl, and— C=CHR ⁶ ;

each m independently is 0, 1, 2, 3, or 4;

n is 0 or 1 ; each R is independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, and aryl;

R is selected from the group consisting of H, alkyl, cycloalkyl, alkenyl, alkynyl, and aryl; each R is independently selected from the group consisting of H and C -C alkyl;

each R ⁴ is independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, and aryl;

each R ⁵ is independently selected from the group consisting of H, O ^" , OH, NH ₂ , and CI; and, each R ⁶ is independently selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, and aryl.

[0061] In some embodiments:

B 1 and B2" are each independently selected from the group consisting of CF ₃ , CC1 ₃ , NR 3 ₃ + , N0 ₂ , CN, C(=0)R ⁴ , C(=0)OR ¹ , S0 ₂ R ⁵ , aryl, and— C=CHR ⁶ ;

D 1 and 2 are each independently selected from the group consisting of F, CI, Br, I, CF ₃ , CC1 ₃ , NR ³ /, N0 ₂ , CN, C(=0)R ⁴ , C(=0)OR ¹ , S0 ₂ R ⁵ , aryl, and— C=CHR ⁶ ; each m independently is 0, 1, or 2; n is 0 or 1 ; each R ¹ is independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, and aryl;

R is selected from the group consisting of H, alkyl, cycloalkyl, alkenyl, alkynyl, and aryl; each R is independently selected from the group consisting of H and Ci-C6 alkyl; each R ⁴ is independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, and aryl; each R ⁵ is independently selected from the group consisting of H, O ^" , OH, NH ₂ , and CI; and, each R ⁶ is independently selected from the group consisting of alkyl, alkenyl, alkynyl, and aryl. [0062] In some embodiments:

B 1 and B2" are each independently selected from the group consisting of CN, C(=0)R 4 , D 1 and 2 are each independently selected from the group consisting of F, CI, Br, CF ₃ , CC1 ₃ , MR ³ , N0 ₂ , CN, C(=0)R ⁴ , C(=0)0R ¹ , and S0 ₂ R ⁵ ; each m independently is 0, 1, or 2; n is 0 or 1 ; each R ¹ is independently selected from the group consisting of H, C C ₂ o alkyl, C C ₂ o alkenyl, C C ₂ o alkynyl, and aryl;

R is selected from the group consisting of H, alkyl, cycloalkyl, alkenyl, alkynyl, and aryl; each R is independently selected from the group consisting of H and Ci-C4 alkyl; each R ⁴ is independently selected from the group consisting of H, C C ₂ o alkyl, C C ₂ o alkenyl, C C ₂ o alkynyl, and aryl; and, each R ⁵ is independently selected from the group consisting of H, O ^" , OH, NH ₂ , and CI.

[0063] In some of these embodiments, both B 1 and B2 are are CN, both B 1 and W2 are C(=0)OR ¹ , or one of B ¹ and B ² is CN and the other is C(=0)OR ¹ , wherein each R ¹ is independently selected from the group consisting of H, C Cio alkyl C Cio alkenyl, C Cio alkynyl, and aryl.

[0064] In some embodiments where R ¹ , R ² , and/or R ⁴ is alkenyl, then the double bond can be internal or terminal. In some exemplary embodiments, the double bond is terminal. For i 2 4 ¾^

example, R , R , and/or R can be, e.g., ⁰ , wherein o is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,

12, 13, 14, 15, 16, 17, 18, 19, or 20. In some embodiments, o is 9.

[0065] In some embodiments where one of B 1 and B2 i·s CN and the other i ·s the compounds of Formula (II) include the compounds of Formula Ila, lib, lie, lid, He, Ilf, and Ilg:

Formula Me Formula I If Formula llg , and mixtures thereof.

[0066] In some of these embodiments, R ¹ is H, Q.C30 alkyl, Ci-Cio alkyl, or Q.Qo alkyl. In some exemplary embodiments, R ¹ can include H, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, or decyl. For example, R ¹ can include, but is not limited to, H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, or 2-ethylhexyl.

[0067] In some of these embodiments, R ² is H, Q.C30 alkyl, Ci-Cio alkyl, or Q.Qo alkyl. In some exemplary embodiments, R can include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, or decyl. For example, R can include, but is not limited to, H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, or 2-ethylhexyl.

[0068] In some exemplary embodiments where one of B 1 and B 2 is CN and the other is C(=0)OR ¹ , the compound of Formula (II) is selected from the group consisting of:

Formula lldi , and mixtures thereof.

[0069] In some embodiments where both of B 1 and B2 are C(=0)OR 1 , the compounds of Formula (II) include the compounds of Formula Ilh, Hi, IIj, Ilk, III, Ilm, and Iln:

Formula Ilh Formula Mi Formula IIj Formula Ilk , and mixtures thereof.

[0070] In some of these embodiments, R ¹ is H, Q-C30 alkyl, C C ₂ o alkyl, or C Cio alkyl. In some exemplary embodiments, R ¹ can include H, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, or decyl. For example, R can include, but is not limited to, H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, or 2-ethylhexyl.

[0071] In some of these embodiments, R ² is H, Q-C30 alkyl, Ci-C2o alkyl, or Ci-Cw alkyl. .

In some exemplary embodiments, R can include H, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, or decyl. For example, R can include, but is not limited to, H, methyl, ethyl, propyl, isopropyl, or 2-ethylhexyl.

1 2 1

[0072] In some exemplary embodiments where both of B and B are C(=0)OR , the compound of Formula (II) is selected from the group consisting of:

Formula llki

and mixtures thereof.

[0073] The photodegradable pigments described herein can include exogenous pigments, such as exogenous porphyrin compounds, or endogenous pigments, such as non-hematogenous pigments, hematogenous (i.e., blood derived) pigments, or mixtures thereof.

[0074] In some embodiments, the endogenous photodegradable pigment is a nonhematogenous pigment, such as, for example, melanins, flavins, pterins, urocanic acid.

[0075] In some of these embodiments, the photodegradable non-hematogenous pigment is a melanin, such as, for example, eumelanin, pheomelanin, neuromelanin, or mixtures thereof. [0076] In some of these embodiments, the photodegradable non-hematogenous pigment is a flavin, such as, for example, riboflavin, flavin mononucleotide, a flavoprotein, flavin adenine dinucleotide.

[0077] In some of these embodiments, the photodegradable non-hematogenous pigment is a pterin, such as, for example, pteridine, biopterin, tetrahydrobiopterin, molybdopterin, cyanopterin, tetrahydromethanopterin, folic acid, and combinations thereof.

[0078] In some of these embodiments, the photodegradable non-hematogenous pigment is urocanic acid.

[0079] In some embodiments, the photodegradable endogenous pigment is a hematogenous pigment. The hematogenous pigment can include, for example, hemoglobin, bile pigments, porphyrins, and mixtures thereof.

[0080] In some embodiments, the photodegradable hematogenous pigment is hemoglobin.

[0081] In some embodiments, the photodegradable hematogenous pigment is a bile pigment. In some embodiments, the bile pigment is bilirubin, biliverdin, or a mixture thereof.

[0082] In some embodiments, the photodegradable hematogenous pigment is a porphyrin. In other embodiments, the pigment is an exogenous porphyrin. The porphyrin compounds described herein include a porphyrin moiety of Formula (I) or a derivative or tautomer thereof:

[0083] In some embodiments, the porphyrin moiety of Formula la is:

or a multimer thereof, wherein:

R ^7a , R ^7b , R ^7c , R ^7d , R ^7e , R ^7f , R ^7g , R ^7h are each independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, hydroxyl, alkoxyl, carboxyl, carboxylic ester, amino, sulfhydryl, aryl, and heteroaryl; and,

R ^a , R , R ^c , R , and R ⁶ are each independently selected from the group consisting of

H, alkyl, alkenyl, alkynyl, hydroxyl, alkoxyl, carboxyl, carboxylic ester, amino, sulfhydryl, aryl, and heteroaryl.

[0084] In some embodiments, R ^7a , R ^7b , R ^7c , R ^7d , R ^7e , R ^7f , R ^7g , R ^7h are each independently selected from the group consisting of H, C C ₆ unsubstituted alkyl, C C ₆ hydroxyalkyl, C C ₆ carboxyalkyl, CrC ₆ esteralkyl, CrC ₆ sulfhydrylalkyl CrC ₆ alkenyl, amino, aryl, and heteroaryl.

[0085] In some exemplary embodiments, R ^7a , R ^7b , R ^7c , R ^7d , R ^7e , R ^7f , R ^7g , R ^7h are each independently selected from the group consisting of H, C C ₄ unsubstituted alkyl, C C ₄

hydroxyalkyl, CrC ₄ carboxyalkyl, CrC ₄ esteralkyl, CrC ₆ sulfhydrylalkyl, CrC ₄ alkenyl, aryl, and heteroaryl. For example, R ^7a , R ^7b , R ^7c , R ^7d , R ^7e , R ^7f , R ^7g , R ^7h can each independently be selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, iso- butyl, tert-butyl, ethenyl, 1-propenyl, 2-propenyl, 1-hydroxyethyl, 2-hydroxyethyl, phenyl, acetic acid, methyl acetate, ethyl acetate, propionic acid, methyl propanate, ethylpropanate, and

[0086] In some embodiments, R ^a , R , R ^c , R , and R ⁶ are each independently selected from the group consisting of H, C -C alkyl, C -C alkenyl, aryl, and heteroaryl. In some exemplary embodiments, R ^8a , R ^8b , R ^8c , R ^8d , and R ^8e are each independently selected from the group consisting of H, C C ₄ alkyl, CrC ₄ alkenyl, phenyl, naphthyl, and pyridyl. For example, R ^8a , R ^8b , R ^8c , R ^8d , and R ^8e can each independently be selected from the group consisting of H, phenyl, hydroxyphenyl, dihydroxyphenyl, trihydroxyphenyl, methoxyphenyl, dimethoxyphenyl, trimethoxyphenyl, carboxyphenyl, trimethylanilinium, naphthyl, sulfonatophenyl, pyridyl, and N-methylpyridyl.

[0087] In some embodiments, R ^7a , R ^7b , R ^7c , R ^7d , R ^7e , R ^7f , R ^7g , R ^7h are each independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, hydroxyl, alkoxyl, carboxyl, carboxylic ester, amino, sulfhydryl, aryl, and heteroaryl; and R ^a , R , R ^c , R , and R ⁶ are each independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, hydroxyl, alkoxyl, carboxyl, carboxylic ester, amino, sulfhydryl, aryl, and heteroaryl.

[0088] In other embodiments, R ^7a , R ^7b , R ^7c , R ^7d , R ^7e , R ^7f , R ^7g , R ^7h are each independently selected from the group consisting of H, C C ₆ unsubstituted alkyl, C C ₆ hydroxyalkyl, C C ₆ carboxyalkyl, CrC ₆ esteralkyl, CrC ₆ sulfhydrylalkyl CrC ₆ alkenyl, amino, aryl, and heteroaryl; and R ^8a , R ^8b , R ^8c , R ^8d , and R ^8e are each independently selected from the group consisting of H, C -C alkyl, C -C alkenyl, aryl, and heteroaryl.

[0089] In yet other embodiments, R ^7a , R ^7b , R ^7c , R ^7d , R ^7e , R ^7f , R ^7g , R ^7h are each independently selected from the group consisting of H, C C ₄ unsubstituted alkyl, C C ₄ hydroxyalkyl, C C ₄ carboxyalkyl, C C ₄ esteralkyl, Ci-Ce sulfhydrylalkyl, C C ₄ alkenyl, aryl, or heteroaryl; and R ^8a , R ^8b , R ^8c , R ^8d , and R ^8e are each independently selected from the group consisting of H, C C ₄ alkyl, CrC ₄ alkenyl, phenyl, naphthyl, and pyridyl.

[0090] In still other embodiments, R ^7a , R ^7b , R ^7c , R ^7d , R ^7e , R ^7f , R ^7g , R ^7h are each independently selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, iso- butyl, tert-butyl, ethenyl, 1-propenyl, 2-propenyl, 1-hydroxyethyl, 2-hydroxyethyl, phenyl, acetic acid, methyl acetate, ethyl acetate, propionic acid, methyl propanate, ethylpropanate, and ; and R , R , R , R , and R ^8e are each independently selected from the group consisting of H, phenyl, hydroxyphenyl, dihydroxyphenyl, trihydroxyphenyl, methoxyphenyl, dimethoxyphenyl, trimethoxyphenyl, carboxyphenyl, trimethylanilinium, naphthyl,

sulfonatophenyl, pyridyl, and N-methylpyridyl.

[0091] All porphyrin compounds that are excited by visible light are returned to their ground state by the conjugated fused tricyclic compounds having electron withdrawing groups described herein. The porphyrin compounds include, but are not limited to, 5-azaprotoporphyrin IX, bis- porphyrin, coproporphyrin III, deuteroporphyrin, deuteroporphyrin IX dichloride, diformyl deuteroprophyrin IX, dodecaphenylporphyrin, hematoporphyrin, hematoporphyrin IX, hematoporphyrin monomer, hematoporphyrin dimer, hematoporphyrin derivative,

hematoporphyrin derivative A, hematoporphyrin IX dihydrochloride, hematoporphyrin dihydrochloride, mesoporphyrin, mesoporphyrin IX, monohydroxyethylvinyl deuteroporphyrin, 5,10,15,20-tetra(o-hydroxyphenyl)porphyrin, 5,10,15,20-tetra(m-hydroxyphenyl)porphyrin, 5,10,15,20-tetra(p-hydroxyphenyl) porphyrin, 5,10,15,20-tetrakis(3-methoxyphenyl)-porphyrin, 5,10,15,20-tetrakis(3,4-dimethoxyphenyl)porphyrin, 5,10,15,20-tetrakis(3,5- dimethoxyphenyl)porphyrin, 5,10,15,20-tetrakis(3,4,5-trimethoxyphenyl)porphyrin,

2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporph yrin, porphyrin c, protoporphyrin, protoporphyrin IX, tetra-(4-N-carboxyphenyl)-porphine, tetra-(3-methoxyphenyl)-porphine, tetra-(3-methoxy-2,4-difluorophenyl)-porphine, 5, 10, 15,20-tetrakis(4-N-methylpyridyl)porphine, tetra-(4-N-methylpyridyl)-porphine tetrachloride, tetra-(3-N-methylpyridyl)-porphine, tetra-(2- N-methylpyridyl)-porphine, tetra(4-N,N,N-trimethylanilinium)porphine, tetra-(4-N,N,N"- trimethylamino-phenyl)porphine tetrachloride, tetranaphthaloporphyrin, tetraphenylporphyrin, tetra-(4-sulfonatophenyl)-porphine, 4-sulfonatophenylporphine, uroporphyrin, uroporphyrin III, uroporphyrin IX, and uroporphyrin I, and esters thereof.

[0092] In some embodiments, the porphyrin compound is an ester selected from the group consisting of 5-azaprotoporphyrin dimethylester, coproporphyrin III tetramethylester, deuteroporphyrin IX dimethylester, diformyl deuteroporphyrin IX dimethylester,

hematoporphyrin IX dimethylester, mesoporphyrin dimethylester, mesoporphyrin IX

dimethylester, monoformyl-monovinyl-deuteroporphyrin IX dimethylester, protoporphyrin dimethylester, and protoporphyrin IX dimethylester.

[0093] In some exemplary embodiments, the porphyrin compound is selected from the group consisting of coproporphyrin III, coproporphyrin III tetramethylester, deuteroporphyrin, deuteroporphyrin IX dichloride, deuteroporphyrin IX dimethylester, hematoporphyrin, hematoporphyrin IX, hematoporphyrin derivative, hematoporphyrin derivative A,

hematoporphyrin IX dihydrochloride, hematoporphyrin dihydrochloride, hematoporphyrin IX dimethylester, mesoporphyrin, mesoporphyrin dimethylester, mesoporphyrin IX, mesoporphyrin IX dimethylester, protoporphyrin, protoporphyrin IX, protoporphyrin dimethylester,

protoporphyrin IX dimethylester, uroporphyrin, uroporphyrin III, uroporphyrin IX, and uroporphyrin I.

[0094] For example, the porphyrin compound can include protoporphyrin IX,

deuteroporphyrin IX dichloride, deuteroporphyrin IX dimethylester, hematoporphyrin, hematoporphyrin IX, hematoporphyrin derivative, mesoporphyrin dimethylester, mesoporphyrin IX, or mesoporphyrin IX dimethylester.

[0095] In some embodiments, the porphyrin compound exists as a free base. In other embodiments, the porphyrin compound is chelated to a metal. In some embodiments, the metal has a 2+ or 3+ oxidation state. In some embodiments, the metal can include, for example, beryllium, magnesium, aluminum, calcium, strontium, barium, radium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, lead, and platinum.

[0096] A particularly useful porphyrin compound is protoporphyrin IX having the structure (lb):

[0097] Thus, one aspect provides a method of quenching excited state energy from an photodegradable pigment compound that has been excited by absorption of light having a wavelength in the wavelength range of about 290 to about 800 nm, comprising reacting the pigment compound with a conjugated fused tricyclic compound having electron withdrawing groups of Formula (II) or a salt thereof:

, as previously defined above.

[0098] In some exemplary embodiments of this aspect, the photodegradable pigment compound includes a porphyrin compound comprising a porphyrin moiety of Formula (I) or a derivative or tautomer thereof: , as previously defined above.

[0099] Another aspect provides a method of suppressing the generation of singlet oxygen by an excited pigment when a mammalian-contained pigment is exposed to light, thereby exciting the pigment to an excited state, by quenching the excited state of the pigment compoundwith a conjugated fused tricyclic compound having electron withdrawing groups of Formula (II) or a salt thereof:

, as previously defined above.

[00100] In some exemplary embodiments of this aspect, the pigment compound includes a porphyrin compound comprising a porphyrin moiety of Formula (I) or a derivative or tautomer thereof:

, as previously defined above.

[00101] Yet another aspect provides a method of protecting skin from oxidative stress caused by the generation of free radical oxygen comprising contacting, preferably coating the skin with an pigment excited state quencher capable of accepting or donating an electron from or to an pigment compound in the excited state and returning the excited pigment compound to its ground state, said pigmnet quencher comprising a conjugated fused tricyclic compound having electron withdrawing groups of Formula (II) or a salt thereof: , as previously defined above.

[00102] In some exemplary embodiments of this aspect, the pigment compound includes a porphyrin compound comprising a porphyrin moiety of Formula (I) or a derivative or tautomer thereof:

, as previously defined above.

[00103] Still another aspect provides a method of protecting healthy cells adjacent to cancerous or pre-cancerous cells undergoing photodynamic therapy comprising applying a coating composition containing a pigment excited state quencher compound to said adjacent cells to reduce the generation of free radical oxygen and other reactive oxygen species from said healthy cells while the photodynamic therapy generates free radical oxygen from said cancerous or pre-cancerous cells, with a conjugated fused tricyclic compound having electron withdrawing groups of Formula (II) or a salt thereof:

, as previously defined above.

[00104] In some exemplary embodiments of this aspect, the pigment compound includes a porphyrin compound comprising a porphyrin moiety of Formula (I) or a derivative or tautomer thereof:

, as previously defined above. [00105] In accordance with one important embodiment, a conjugated fused tricyclic compound having electron withdrawing groups of Formula (II), Ila, lib, lie, lid, He, Ilf, Ilg, Ilh, Ili, Ilj, Ilk, III, Urn, Iln, or a combination thereof is included in a cosmetic or dermatological composition for contacting, and preferably coating a skin surface to protect the skin from contacting damaging amounts of singlet oxygen and other reactive oxygen species which, without the presence of the conjugated fused tricyclic compound having electron withdrawing groups, would be generated when skin cell-contained or blood-contained porphyrin compounds, particularly protoporphyrin IX, are exposed to sunlight, or other visible light. In another embodiment, the cosmetic or dermatological composition can also include a UVA filter and/or UVB filter compound and/or a broad-band filter compound for protection of the skin from UVA and/or UVB wavelengths.

[00106] The conjugated fused tricyclic compounds having electron withdrawing groups of Formula (II) can be used to suppress the generation of other reactive oxygen speices or radical compounds. Some of these reactive oxygen species include, for example, free radical oxygen, superoxide anion, peroxide, hydroxyl radical, and hydroxyl ion. It should be understood that throughout this disclosure whenever singlet state oxygen or free radical oxygen is described as being suppressed, these other oxygen species also may be suppressed.

[00107] The conjugated fused tricyclic compound having electron withdrawing groups of Formula (II) can be included in the cosmetic or dermatological composition in an amount of about 0.01% by weight to about 20% by weight, preferably from about 0.1 to about 20% by weight, more preferably from about 0.1% to about 10% by weight, in each case based on the total weight of the composition.

[00108] The total amount of one or more water-soluble UV filter substances in the finished cosmetic or dermatological compositions is advantageously chosen from the range of about 0.01% by weight to about 20% by weight, preferably from about 0.1% to about 20% by weight, more preferably from about 0.1% to about 10% by weight, in each case based on the total weight of the composition.

[00109] Preferred UV filter compounds, and photo stabilizers for the UV filter compounds, are disclosed in published PCT application WO 2009/020676, hereby incorporated by reference for preferred water-soluble, organic and particulate UV filter compounds. [00110] In some embodiments, the UV filter compound is a benzotriazle compound having the structure

[00111] The cosmetic or dermatological compositions can include an additional photoactive compound. In some embodiments, the additional photoactive compound is selected from the group consisting of p-aminobenzoic acid and salts and derivatives thereof; anthranilate and derivatives thereof; salicylate and derivatives thereof; cinnamic acid and derivatives thereof; dihydroxycinnamic acid and derivatives thereof; camphor and salts and derivatives thereof; trihydroxycinnamic acid and derivatives thereof; dibenzalacetone naptholsulfonate and salts and derivatives thereof; benzalacetophenone naphtholsulfonate and salts and derivatives thereof; dihydroxy-naphthoic acid and salts thereof; o-hydroxydiphenyldisulfonate and salts and derivatives thereof; p-hydroxdydiphenyldisulfonate and salts and derivatives thereof; coumarin and derivatives thereof; diazole derivatives; quinine derivatives and salts thereof; quinoline derivatives; hydroxyl- substituted benzophenone derivatives; naphthalate derivatives; methoxy- substituted benzophenone derivatives; uric acid derivatives; vilouric acid derivatives; tannic acid and derivatives thereof; hydroquinone; benzophenone derivatives; 1, 3, 5- triazine derivatives; phenyldibenzimidazole tetrasulfonate and salts and derivatives thereof; terephthalyidene dicamphor sulfonic acid and salts and derivatives thereof; methylene bis-benzotriazolyl tetramethylbutylphenol and salts and derivatives thereof; bis-ethylhexyloxyphenol

methoxyphenyl triazine and salts, diethylamino hydroxyl benzoyl and derivatives thereof; and combinations of the foregoing.

[00112] The cosmetic or dermatological composition may include a cinnamate ester, such as 2-ethylhexyl p-methoxycinnamate, isoamyl p-methoxycinnamate, and a combination thereof. For example, the cinnamate ester can be 2-ethylhexyl p-methoxycinnamate. In some of these embodiments, the cinnamate ester is present in the composition in an amount in a range of about 0.1 wt.% to about 15 wt.%, based on the total weight of the composition.

[00113] The cosmetic or dermatological composition also may include about 0.1 to about 10 wt.% of a triplet quencher selected from the group consisting of octocrylene, methyl benzylidene camphor, diethylhexyl 2,6-naphthalate, and combinations thereof.

[00114] The cosmetic or dermatological composition also may include about 0.1 to about 10 wt.% of a singlet quencher such as an alkoxy crylene (e.g., ethylhexyl methoxy crylene), a copolymer of adipic acid and neopentyl glycol that is terminated with cyanodiphenyl propenoic acid, and mixtures thereof.

[00115] The cosmetic or dermatological compositions may have conventional additives and solvents used for the treatment, care and cleansing of skin and/or the hair and as a make-up product in decorative cosmetics.

[00116] For use in protecting skin from oxidative stress, the cosmetic and/or dermatological compositions can contain about 0.01 wt. % to about 20 wt.% conjugated fused tricyclic compound(s) having electron withdrawing groups and the composition is applied to the skin and/or the hair in a sufficient quantity in the manner customary for cosmetics.

[00117] The cosmetic and dermatological compositions described herein can comprise cosmetic auxiliaries such as those conventionally used in such preparations, e.g. preservatives, bactericides, perfumes, antifoams, dyes, pigments which have a coloring effect, thickeners, moisturizers and/or humectants, fats, oils, waxes or other conventional constituents of a cosmetic or dermatological composition, such as alcohols, polyols, polymers, foam stabilizers,

electrolytes, organic solvents or silicone derivatives.

[00118] An additional content of antioxidants is generally preferred. According to the invention, favorable antioxidants which can be used are any antioxidants suitable or conventional for cosmetic and/or dermatological applications.

[00119] The antioxidants are particularly advantageously chosen from the group consisting of amino acids (e.g. glycine, histidine, tyrosine, tryptophan) and derivatives thereof, imidazoles (e.g. urocanic acid) and derivatives thereof, peptides such as D,L-camosine, D-carnosine, L- carnosine and derivatives thereof (e.g. anserine), carotenoids, carotenes (e.g. a-carotene, β- carotene, lycopene) and derivatives thereof, chlorogenic acid and derivatives thereof, lipoic acid and derivatives thereof (e.g. dihydrolipoic acid), aurothioglucose, propylthiouracil and other thiols (e.g. thioredoxin, glutathione, cysteine, cystine, cystamine and the glycosyl, N-acetyl, methyl, ethyl, propyl, amyl, butyl and lauryl, palmitoyl, oleyl, .gamma.-linoleyl, cholesteryl and glyceryl esters thereof) and salts thereof, dilauryl thiodipropionate, distearyl thiodipropionate, thiodipropionic acid and derivatives thereof (esters, ethers, peptides, lipids, nucleotides, nucleosides and salts) and sulfoximine compounds (e.g. buthionine sulfoximines, homocysteine sulfoximine, buthionine sulfones, penta-, hexa-, heptathionine sulfoximine) in very low tolerated doses (e.g. pmol to μιηοΐ/kg), and also (metal) chelating agents (e.g. a-hydroxy fatty acids, palmitic acid, phytic acid, lactoferrin), a-hydroxy acids (e.g. citric acid, lactic acid, malic acid), humic acid, bile acid, bile extracts, bilirubin, biliverdin, EDTA, EGTA and derivatives thereof, unsaturated fatty acids and derivatives thereof (e.g. .gamma.-linolenic acid, linoleic acid, oleic acid), folic acid and derivatives thereof, ubiquinone and ubiquinol and derivatives thereof, vitamin C and derivatives (e.g. ascorbyl palmitate, Mg ascorbyl phosphate, ascorbyl acetate), tocopherols and derivatives (e.g. vitamin E acetate), vitamin A and derivatives (vitamin A palmitate) and coniferyl benzoate of gum benzoin, rutinic acid and derivatives thereof, a- glycosylrutin, ferulic acid, furfurylideneglucitol, carnosine, butylhydroxytoluene,

butylhydroxyanisole, nordihydroguaiaretic acid, trihydroxybutyro-phenone, uric acid and derivatives thereof, mannose and derivatives thereof, zinc and derivatives thereof (e.g. ZnO, ZnS0 ₄ ), selenium and derivatives thereof (e.g. selenomethionine), stilbenes and derivatives thereof (e.g. stilbene oxide, trans- stilbene oxide) and the derivatives (salts, esters, ethers, sugars, nucleotides, nucleosides, peptides and lipids) of said active ingredients which are suitable according to the invention.

[00120] Thus, in some embodiments, the cosmetic or dermatological composition can include one or more oxidation-sensitive or UV-sensitive ingredients selected from the group consisting of retinoid compounds, carotenoid compounds, lipoic acid and derivatives thereof, vitamin E and derivatives thereof, vitamin F and derivatives thereof, and dioic acid in an amount from about 0.0001 wt to about 10 wt , based on the total weight of the composition.

[00121] Advantageous hydrophilic active ingredients which (individually or in any combinations with one another) are stabilized by their use together with one or more conjugated fused tricyclic compounds having electron withdrawing groups include those listed below: biotin; carnitine and derivatives; creatine and derivatives; folic acid; pyridoxine; niacinamide; polyphenols (in particular flavonoids, very particularly alpha-glucosylrutin); ascorbic acid and derivatives; Hamamelis; Aloe Vera; panthenol; and amino acids.

[00122] Particularly advantageous hydrophilic active ingredients for the purposes of the present invention are also water-soluble antioxidants, such as, for example, vitamins.

[00123] The amount of hydrophilic active ingredients (one or more compounds) in the compositions is preferably about 0.0001% to about 10% by weight, particularly preferably about 0.001% to about 5% by weight, based on the total weight of the composition.

[00124] Particularly advantageous compositions are also obtained when antioxidants are used as additives or active ingredients. According to the invention, the cosmetic or dermatological compositions advantageously comprise one or more antioxidants. Favorable, but nevertheless optional antioxidants which may be used are all antioxidants customary or suitable for cosmetic and/or dermatological applications.

[00125] The amount of antioxidants (one or more compounds) in the compositions is preferably about 0.001% to about 30% by weight, particularly preferably about 0.05% to about 20% by weight, in particular about 0.1% to about 10% by weight, based on the total weight of the composition.

[00126] If vitamin E and/or derivatives thereof are the antioxidant or antioxidants, it is advantageous to choose their respective concentrations from the range from about 0.001% to about 10% by weight, based on the total weight of the composition.

[00127] If vitamin A or vitamin A derivatives, or carotenes or derivatives thereof are the antioxidant or antioxidants, it is advantageous to choose their respective concentrations from the range from about 0.001% to about 10% by weight, based on the total weight of the composition.

[00128] It is particularly advantageous when the cosmetic or dermatological compositions, according to the present invention, comprise further cosmetic or dermatological active ingredients, preferred active ingredients being additional antioxidants which can further protect the skin against additional oxidative stress. [00129] Advantageous further active ingredients are natural active ingredients and/or derivatives thereof, such as e.g. ubiquinones, retinoids, carotenoids, creatine, taurine and/or β- alanine.

[00130] Compositions according to the invention, which comprise e.g. known antiwrinkle active ingredients, such as flavone glycosides (in particular a-glycosylrutin), coenzyme Q10, vitamin E and/or derivatives and the like, are particularly advantageously suitable for the prophylaxis and treatment of cosmetic or dermatological changes in skin, as arise, for example, during skin aging (such as, for example, dryness, roughness and formation of dryness wrinkles, itching, reduced refatting (e.g. after washing), visible vascular dilations (teleangiectases, couperosis), flaccidity and formation of wrinkles and lines, local hyperpigmentation,

hypopigmentation and abnormal pigmentation (e.g. age spots), increased susceptibility to mechanical stress (e.g. cracking) and the like). In addition, they are advantageously suitable against the appearance of dry or rough skin.

[00131] The cosmetic or dermatological compositions can include triazines, benzotriazoles, latex particles, organic pigments, inorganic pigments, and mixtures thereof.

[00132] Preferred particulate UV filter substances for the purposes of the present invention are inorganic pigments, especially metal oxides and/or other metal compounds which are slightly soluble or insoluble in water, especially oxides of titanium (Ti0 ₂ ), zinc (ZnO), iron (e.g. Fe ₂ 0 ₃ ), zirconium (Zr0 ₂ ), silicon (Si0 ₂ ), manganese (e.g. MnO), aluminum (A1 ₂ 0 ₃ ), cerium (e.g.

Ce ₂ 0 ₃ ), mixed oxides of the corresponding metals, and mixtures of such oxides, and the sulfate of barium (BaS0 ₄ ).

[00133] Zinc oxides for the purposes of the present invention may also be used in the form of commercially available oily or aqueous predispersions. Zinc oxide particles and predispersions of zinc oxide particles which are suitable according to the invention are distinguished by a primary particle size of <300 nm and can be obtained under the following proprietary names from the stated companies:

Proprietary name Coating Manufacturer

Z-Cote HP1 2% Dimethicone BASF

Z-Cote / BASF ZnO NDM 5% Dimethicone H&R

ZnO Neutral / H&R

MZ-300 / Tayca Corporation

MZ-500 / Tayca Corporation

MZ-700 / Tayca Corporation

MZ-303S 3% Methicone Tayca Corporation

MZ-505S 5% Methicone Tayca Corporation

MZ-707S 7% Methicone Tayca Corporation

MZ-303M 3% Dimethicone Tayca Corporation

MZ-505M 5% Dimethicone Tayca Corporation

MZ-707M 7% Dimethicone Tayca Corporation

Z-Sperse Ultra ZnO (>=56%)/Ethylhexyl Collaborative

Hydroxystearate Benzoate/ Laboratories

Dimethicone/ Cyclomethicone

Samt-UFZO- ZnO (60%)/Cyclomethicone/ Miyoshi Kasei

450/D5 (60%) Dimethicone

[00134] Particularly preferred zinc oxides for the purposes of the invention are Z-Cote HP1 and Z-Cote from BASF and zinc oxide NDM from Haarmann & Reimer.

[00135] Titanium dioxide pigments of the invention may be in the form of both the rutile and anatase crystal modification and may for the purposes of the present invention advantageously be surface-treated ("coated"), the intention being for example to form or retain a hydrophilic, amphiphilic or hydrophobic character. This surface treatment may consist of providing the pigments by processes known per se with a thin hydrophilic and/or hydrophobic inorganic and/or organic layer. The various surface coatings may for the purposes of the present invention also contain water.

[00136] Inorganic surface coatings for the purposes of the present invention may consist of aluminum oxide (A1 ₂ 0 ₃ ), aluminum hydroxide Al(OH) or aluminum oxide hydrate (also:

alumina, CAS No.: 1333-84-2), sodium hexametaphosphate (NaP0 ₃ ) ₆ , sodium metaphosphate (NaP0 ₃ ) _n , silicon dioxide (Si0 ₂ ) (also: silica, CAS No.: 7631-86-9), or iron oxide (Fe ₂ 0 ₃ ). These inorganic surface coatings may occur alone, in combination and/or in combination with organic coating materials. [00137] Organic surface coatings for the purposes of the present invention may consist of vegetable or animal aluminum stearate, vegetable or animal stearic acid, lauric acid,

dimethylpolysiloxane (also: dimethicones), methylpolysiloxane (methicones), simethicones (a mixture of dimethylpolysiloxane with an average chain length of from about 200 to about 350 dimethylsiloxane units and silica gel) or alginic acid. These organic surface coatings may occur alone, in combination and/or in combination with inorganic coating materials.

[00138] Coated and uncoated titanium dioxides may be used in the form of commercially available oily or aqueous predispersions. It may be advantageous to add dispersion aids and/or solubilization mediators.

[00139] Suitable titanium dioxide particles and predispersions of titanium dioxide particles for addition to the compositions described herein are obtainable under the following proprietary names from the stated companies:

Additional

ingredients of the

Proprietary name Coating predispersion Manufacturer

MT-150W None Tayca Corporation

MT-150A None Tayca Corporation

MT-500B None Tayca Corporation

MT-600B None Tayca Corporation

MT-100TV Aluminum Tayca Corporation

hydroxide

Stearic acid

MT-100Z Aluminum Tayca Corporation

hydroxide

Stearic acid

MT-100T Aluminum Tayca Corporation

hydroxide

Stearic acid

MT-500T Aluminum Tayca Corporation

hydroxide

Stearic acid

MT-100S Aluminum Tayca Corporation

hydroxide

Lauric acid

MT-100F Stearic acid Iron — Tayca Corporation

oxide

MT-100SA Alumina Silica Tayca Corporation

MT-500SA Alumina Silica Tayca Corporation

MT-600SA Alumina Silica Tayca Corporation Additional

ingredients of the

Proprietary name Coating predispersion Manufacturer

MT-100SAS Alumina Silica Tayca Corporation

Silicone

MT-500SAS Alumina Silica Tayca Corporation

Silicone

MT-500H Alumina Tayca Corporation MT-100AQ Silica Tayca Corporation

Aluminum

hydroxide

Alginic acid

Eusolex T Water Merck KgaA

Simethicone

Eusolex T-2000 Alumina Merck KgaA

Simethicone

Eusolex T-Olio F Silica C ₁₂ -15 Merck KgaA

Dimethylsilate Alkylbenzoate

Water Calcium Poly- hydroxystearate

Silica

Dimethylsilate

Eusolex T-Olio P Water Octyl Palmitate Merck KgaA

Simethicone PEG-7

Hydrogenated

Castor Oil

Sorbitan Oleate

Hydrogenated

Castor Oil

Beeswax Stearic

acid

Eusolex T-Aqua Water Alumina Phenoxyethanol Merck KgaA

Sodium Sodium

metaphosphate Methylparabens

Sodium

metaphosphate

Eusolex T-45D Alumina Isononyl Merck KgaA

Simethicone Isononanuate

Polyglyceryl

Ricinoleate

Kronos 1171 None Kronos

(Titanium dioxide

171)

Titanium dioxide P25 None Degussa

Titanium dioxide Octyltri- Degussa

T805 methylsilane Additional

ingredients of the

Proprietary name Coating predispersion Manufacturer

(Uvinul Ti0 ₂ )

UV-Titan X610 Alumina — Kemira

Dimethicone

UV-Titan X170 Alumina — Kemira

Dimethicone

UV-Titan X161 Alumina Silica — Kemira

Stearic acid

UV-Titan M210 Alumina — Kemira

UV-Titan M212 Alumina Glycerol Kemira

UV-Titan M262 Alumina — Kemira

Silicone

UV-Titan Ml 60 Alumina Silica — Kemira

Stearic acid

Tioveil AQ 10PG Alumina Silica Water Propylene Solaveil Uniquema

glycol

Mirasun TiW 60 Alumina Silica Water Rhone-Poulenc

[00140] Preferred titanium dioxides are distinguished by a primary particle size between about 10 nm to about 150 nm.

[00141] Titanium dioxides particularly preferred for the compositions described herein are MT-100 Z and MT-100 TV from Tayca Corporation, Eusolex T-2000 from Merck and titanium dioxide T 805 from Degussa.

[00142] Further advantageous pigments are latex particles. Latex particles which are advantageously included in the compositions described herein are described in the following publications: U.S. Pat. No. 5,663,213 and EP 0 761 201. Particularly advantageous latex particles are those formed from water and styrene/acrylate copolymers and available for example under the proprietary name "Alliance SunSphere" from Rohm & Haas.

[00143] An advantageous organic pigment for addition to the compositions described herein is 2,2'-methylenebis(6-(2H-benzotriazol-2-yl)-4-( 1 , 1 ,3,3-tetramethylbutyl-)phenol) (INCI: bis- octyltriazol), which is obtainable under the proprietary name Tinosorb® M from CIBA- Chemikalien GmbH.

EXAMPLES [00144] Initially planned experiments involved the effects of the photoprotecting conjugated fused tricyclic compounds having electron withdrawing groups of Formula (II) and the alkoxy crylene photo stabilizer in the examples of this assignee's US Patent No. 7,597,825 (hereby incorporated by reference in its entirety) on singlet oxygen generation from the following photosensitizers: protoporphyrin IX; riboflavin; retinol; ADMHP; and melanin after UV light exposure (355 nm). The hypothesis is that the compound of Formula (II) and the alkoxy crylene photo stabilizers disclosed in the examples of this assignee's US Patent No. 7,597,825 act as excited state quenchers for porphyrin compounds and subsequently should prevent or significantly reduce singlet oxygen formation when the porphyrin compounds are exposed to light.

[00145] UV and visible light absorption spectra were recorded to investigate to what extent the stabilizers itself absorb UV light. Figure 1 reveals that the stabilizers are strong UV absorbers with large extinction coefficients (molar absorptivity) of 16,200 M -1 cm -1 (RX- 13949; max = 334 nm) and 13,200 M -1 cm -1 (SolaStaySl; max = 336 nm). The compound with the oxygen bridge (Formula Ilbi) caused a bathocromic shift of the UV absorption of the lowest energy band. The compound with the sulfur bridge (Formula Ilfi) shifted the lowest energy band further into the visible region.

[00146] Because of the strong absorption of the two compounds at 355 nm, the initially selected excitation wavelength for the sensitizers for the planned singlet oxygen experiments, the stabilizers would compete for the excitation photons of the excited porphyrin compound. This would lead to a reduced singlet oxygen generation from the sensitizers, but not by excited state quenching of the sensitizers by the stabilizers. To perform meaningful experiments, the sensitizer needs to be excited at a wavelength where the two compounds do not absorb.

Protoporphyrin IX has weak absorption bands above 450 nm, where the two compounds are transparent (Figure 2).

[00147] Photoexcitation in these absorption bands generates singlet excited states which deactivate to the ground state or intersystem cross to the triplet state. The two compounds could target the singlet excited states and/or the triplet states. Fluorescence lifetime measurements are a convenient way to measure singlet state quenching by the stabilizers (see this assignee's US Patent No. 7,776,614). Protoporphyrin IX decay traces were recorded in the absence and presence of difference of the two compounds (Figure 3). The experiments show that the compound of Formula Ilai significantly quenches the protoporphyrin IX fluorescence (reduces fluorescence lifetime; Figure 3). However, the alkoxy crylene compound of US Patent No. 7,597,825 caused no reduction in fluorescence lifetime, even at high concentrations, such as 0.1 M (Figure 3).

[00148] Data, such as the collected data shown in Figure 3, were used to determine the bimolecular quenching rate constant for singlet excited state quenching by alkoxy crylene and compounds Ilai, Ilbi, IIci, a mixture of Ildi and Ilei, and Ilfi. The quenching rate constant can be directly extracted from the slope of the plot of the inverse fluorescence lifetime vs. the concentration of the two compounds (Figure 4). The data reveal a high quenching rate constant with the compound of Formula Ilai, Ilbi, IIci, and the mixture of Ildi and Ilei (close to the diffusion limit) but no observable quenching with the alkoxy crylene compound.

[00149] To investigate if triplet states of protoporphyrin IX are quenched, laser flash photolysis experiments were performed. In these experiments, a deoxygenated acetonitrile solution of protoporphyrin IX is excited with short laser pulses from a Nd-YAG laser (355 nm, 5 ns pulse width). Difference absorption kinetic traces were recorded at different observation wavelength (300 to 800 nm) and from these a transient absorption spectrum was constructed (Figure 5a). This difference spectrum shows ground state depletion at 400 nm (where protoporphyrin IX absorbs strongly; see Figure 2). In addition, two bands are observed at 320 and 440 nm, which are assigned to the triplet-triplet absorption of protoporphyrin IX. The triplet absorption decayed with a lifetime of 52 μ8 with subsequent recovery of the ground state absorption (Figure 5b and c, respectively).

[00150] The triplet absorption kinetics at 440 nm can be utilized to obtain triplet quenching rate constants by the stabilizers. Triplet decay traces at 440 nm were recorded in the presence of different amounts of alkoxy crylene, Formula Ilai, Ilbi, IIci, a mixture of Ildi and Ilei, and Ilfi. The decay traces were fitted to a first-order kinetics. The plot of these pseudo-first-order rate constants (inverse decay lifetime) vs. the concentration of the two compounds gives directly the bimolecular triplet quenching rate constant from the slope (Figure 6).

[00151] The triplet quenching rate constant for Formula Ilai is three orders of magnitude smaller than singlet excited state quenching by the compound of Formula Ilai. However, since the triplet lifetime (52 μ8) is more than three orders of magnitude larger than the singlet excited state lifetime (13 ns), the smaller rate constant for triplet quenching is compensated by the longer triplet lifetime. This makes protoporphyrin IX triplet state quenching by the compound of Formula Ilai more efficient than singlet excited state quenching. Similar to the fluorescence quenching experiments, no triplet quenching was observed by the alkoxy crylene compound. Similarly, the triplet excited state quenching of ΡΡΓΧ varies over three orders of magnitude for Formula Ilbi, Ilci, a mixture of Ildi and Ilei, and Ilfi. Interestingly, Formula Ilci was the most efficient quencher— the ΡΡΓΧ triplet state quenching is almost as fast as the singlet state quenching.

[00152] Because Formula Ilci contains a ketone functionality, intersystem crossing into the triplet state could be promoted after photoexcitation due to spin-orbit coupling. Stabilizer triplet states could generate singlet oxygen. Low-temperature luminescence experiments in a ethanol matrix at 77 K were performed in search for phosphorescence of potential triplet states. Only a very weak luminescence was observed with maximum at 492 nm and a quantum yield of less than 1%. Because the excitation spectrum of this luminescence did not match the absorption spectrum, it can be concluded that this luminescence is probably caused by an impurity and no long-lived triplet states of Formula Ilci are formed.

[00153] The biomolecular quenching rate constants for singlet excited state (k _q ^s ) and triplet excited state (k _q ) quenching of ΡΡΓΧ by stabilizers in acetonitrile solutions at room temperature is shown in Table 1, as well and the Stern- Volmer rate constants (discussed in more detail below).

[00154] Table 1

[00155] The quenching mechanism of protoporphyrin IX singlet excited states and triplet states by the compound of Formula (II) is not clear. A simple energy transfer mechanism would depend on the singlet and triplet energies of the compound of Formula (II) and protoporphyrin IX. To obtain information on excited state energies of the stabilizer, luminescence experiments were performed. The compound of Formula Ilai in ethanol solution did not give detectable fluorescence at room temperature. However, weak luminescence was observed of the compound of Formula Ilai in a frozen ethanol matrix at 77 K. The luminescence with maximum at 575 nm (Figure 7c) originates from the compound of Formula Ilai, because the luminescence excitation spectrum (Figure 7b) matches well the absorption spectrum of the compound of Formula Ilai (Figure 5a). The luminescence lifetime could not be determined, because of the weak signal intensity. However, attempts to record time resolved luminescence spectra suggests that the lifetime is shorter than the microsecond time scale. This suggests that the luminescence at 575 nm is not a typical phosphorescence and probably is the fluorescence. If the luminescence at 575 nm is the fluorescence, then the Stoke' s shift is unusually large. Independent of the assignment of the luminescence to the fluorescence or phosphorescence, this excited state energy is higher than singlet and triplet energies of protoporphyrin IX and rules out a simple energy transfer quenching mechanism. Another possible quenching mechanism is electron transfer quenching which would depend on the redox potentials of the protoporphyrin and the two quencher compounds.

[00156] Singlet oxygen quenching by the compound of Formula (II) is another possible photoprotection mechanism. A convenient way to generate singlet oxygen is by photoexcitation of tetraphenylporphyrin (TPP) in the presence of dissolved oxygen. Figure 8 shows a typical singlet oxygen phosphorescence spectrum (Figure 8a) and its decay trace (Figure 8b). The solvent CCl ₄ was selected, because it is known that the singlet oxygen has a long lifetime in this solvent (ms time scale), which makes the measurement of quenching kinetics easier. Singlet oxygen phosphorescence decay traces, such as shown in Figure 8b, were recorded in the presence of different quencher concentrations. After fitting the decay traces to a first-order kinetic model, the bimolecular quenching constants were determined from the plots shown in Figure 9. The singlet oxygen quenching rate constants of both compounds are relatively low. The slightly higher rate constant for the alkoxy crylene compound is consistent with the additional substituents compared to the compound of Formula Ilai.

singlet oxygen

[00157] Finally, an example of the originally planned experiment was performed, where singlet oxygen was generated by pulsed laser excitation in the UV (355 nm) by protoporphyrin IX. Protoporphyrin IX was selected on the basis of its high extinction coefficient (Figure 2). The solvent DMSO-d6 was selected because of good solubility of the sensitizer and stabilizers. The deuterated form of DMSO was used because of the longer singlet oxygen lifetime in deuterated solvents compared to solvents containing hydrogen. Figure 10 and 11 show kinetic traces of singlet oxygen phosphorescence generated from photoexcitation of protoporphyrin IX. In the presence of small amounts (250 μΜ) of the compound of Formula Ilai (Figure 10) or the alkoxy crylene compound (Figure 11) there was significantly reduced singlet oxygen

phosphorescence. However, the reduced amount of generated singlet oxygen in the presence of the alkoxy cylene compound is probably caused by competitive excitation light absorption, where most of the light is absorbed by the compound of Formula Ilai or the two compounds and not by protoporphyrin IX. Excited state quenching of the protoporphyrin IX by the two compounds is unlikely to occur at these low stabilizer concentrations (μΜ). As shown in Figure 4 and 6, much higher stabilizer concentrations are needed (mM) for excited sensitizer state quenching of porphyrin compounds (sensitizers).

[00158] To investigate to what extent the stabilizers can generate singlet oxygen upon direct UV photolysis, singlet oxygen phosphorescence measurements were performed under photolysis at 355 nm. For these experiments CC1 ₄ was selected as solvent, because of the long lifetime of singlet oxygen in this solvent, which makes these experiments easier to perform. Weak singlet oxygen signals were observed upon photolysis at 355 nm (Figure 12). Using benzophenone as reference (quantum yield of singlet oxygen generation: 0.35) the low quantum yields of singlet oxygen generation were estimated: compound of Formula Ilai: 0.015 and alkoxy crylene:

-0.001.

[00159] To ensure that the observed weak singlet oxygen signals truly originated from the two compounds and not from possible impurities in the sample or solvent, singlet oxygen

phosphorescence excitation spectra were recorded. Because the excitation spectrum resembles the absorption spectrum (Figure 13), it can be concluded that the major amount of observed weak singlet oxygen phosphorescence was generated from the compound of Formula (II). However, no match of the excitation spectrum with the absorption spectrum was observed for the alkoxy crylene compound, which suggests that the observed very weak singlet oxygen originated mostly from impurities.

[00160] In conclusion, the mechanism of photoprotection by the compound of Formula (II) and the non-fused alkoxy crylene compound is probably dominated by their strong light absorption and fast deactivation to the ground state. However, excited state quenching, as shown for protoporphyn IX with the compound of Formula Ilai, should provide additional

photoprotection.

[00161] In the previous experiments, singlet oxygen was generated by pulsed laser excitation in the UV spectral region (355 nm) of protoporphyrory IX. The singlet oxygen generation was mostly suppressed by addition of small amounts of the compound of Formula Ilai or the alkoxy crylene compound (Figure 14a and 14c). This was explained by a simple optical screening mechanism, where the compound of Formula Ilai and alkoxy crylene absorb the UV light.

[00162] In the new experiments, laser excitation was performed with visible light at 532 nm, where the compound of Formula Ilai and the alkoxy crylene compound are transparent. No suppression of singlet oxygen generation was observed by the presence of the alkoxy crylene compound even at high concentrations (37 mM) (Figure Id). The absence of singlet oxygen suppression with 532 nm excitation supports the optical screening mechanism with 355 nm excitation. In the presence of the compound of Formula Ilai at concentrations above 3 mM the amount of generated singlet oxygen was reduced (Figure 14b). This reduction is probably caused by protoporphyrin IX excited state quenching by the compound of Formula Ilai. In the previous experiments it was shown that protoporphyrin IX singlet and triplet excited states are quenched by the compound of Formula Ilai, but not by the alkoxy crylene compound.

[00163] The above-described experiments with protoporphyrin IX were performed in DMSO- d ₆ , a solvent with a relatively short singlet oxygen lifetime, because the polar protoporphyrin IX is not soluble enough is solvents with long singlet oxygen lifetimes, such as CDCI ₃ and CC1 ₄ . Solvents with long singlet oxygen lifetimes make singlet oxygen phosphorescence measurements significantly easier to perform.

[00164] Singlet oxygen phosphorescence experiments were performed to investigate if the large differences in triplet quenching rate constants have an impact on the observed singlet oxygen yields. The dimethyl ester derivative of PPIX (MePPIX, Figure 15) was selected as sensitizer, because of better solubility in a solvent with long singlet oxygen lifetime (CDCI ₃ ). The excited state properties of protoporphyrin IX should not be effected by the methyl ester functionality. Air saturated CDCI ₃ of MePPIX were excited with a pulsed Nd- YAG laser with visible light at 532 nm, where the stabilizers are mostly transparent. Figure 16 shows the generated kinetic traces of singlet oxygen phosphorescence in the absence and presence of stabilizers. Comparison of these kinetic traces shows major differences for the different stabilizers. The non-bridged stabilizer, alkoxy crylene did not suppress singlet oxygen generation. The lack of singlet oxygen suppression is consistent with the lack of observable quenching of singlet or triplet excited states of ΡΡΓΧ by alkoxy crylene. The bridged stabilizers suppressed singlet oxygen generation to different degrees with Ilci showing the largest suppression.

[00165] The singlet oxygen phosphorescence experiments shown in Figure 3 using the dimethyl ester derivative of protoporphyrin IX in CDCI ₃ are qualitatively similar to those shown in Figure 14 using protopophyrin IX in DMSO-d ₆ . Although singlet oxygen phosphorescence detection was easier in CDCI ₃ , decomposition of protoporphyrin IX dimethyl ester by singlet oxygen caused a larger error in phosphorescence intensity, which was especially visible in Figure 16d compared to Figure 14d. The longer singlet oxygen lifetime in CDCI ₃ makes the

chromophore more sensitive to oxidative damage.

[00166] To demonstrate that the suppression of singlet oxygen generation from

photoexcitation at 532 nm is caused by singlet excited state quenching of protoporphyrin IX by the compound of Formula (II), Stern- Volmer analysis of the data in Figure 14b and Figure 16 was performed. The singlet oxygen phosphorescence intensity in the absence of stabilizer (i.e, the compound of Formulae Ilai, Ilbi, Ilci, a mixture of Ildi and Ilei, or Ilfi) (I ₀ ) divided by the singlet oxygen phosphorescence intensity in the presence of stabilizer (i.e., the compound of Formulae Ilai, Ilbi, Ilci, the mixture of Ildi and Ilei, or Ilfi) (I) was plotted against the Formula (II) concentration (Figure 17). From the slope of these plots (Stern- Volmer constant) and the lifetime of the quenched excited state, the bimolecular quenching constant can be extracted. If the excited state, which is quenched by the compound of Formula Ilai (which causes a reduction in singlet oxygen production) is the singlet excited state of protoporphyrin IX then, using the previously measured fluorescence lifetime in acetonitrile (xf = 12.7 ns) a quenching rate constant of 2.4 x 10 ⁹ M ^' V ¹ is estimated. This rate constant is in the same order of the previously measured rate constant using fluorescence quenching (5.3 x 10 ⁹ M ^' V ¹ ) which indicates that singlet excited state quenching of protoporphyrin by the compound of Formula Ilai is predominantly causing the suppression of singlet oxygen generation. The rate constant derived from singlet oxygen phosphorescence quenching (Figure 17) is only half of the more directly derived rate constant from fluorescence quenching, which could be caused by the difference in solvents or by some contribution of protoporphyrin triplet quenching by the compound of Formula Ilai. If the suppression of singlet oxygen generation would be entirely caused by triplet protoporphyrin IX quenching by the compound of Formula Ilai, the rate constant from the Stern-

Volmer plot (Figure 4) would be ~ 3 x 10 7 M -1 s - ^" 1 considering a protoporphyrin IX triplet lifetime of ~ 1μ8 in air saturated DMSO. This rate constant is 5 times higher than the directly measured rate constant by laser flash photolysis (6.1 x 10 ⁶ M ^' V ¹ ). This suggests that protoporphyrin IX triplet quenching by the compound of Formula (II) makes only a minor contribution to the suppression of singlet oxygen generation under these conditions. It must be noted that protoporphyrin IX triplet lifetime of ~ 1μ8 in air saturated DMSO was only estimated based on the directly measured triplet lifetime in air saturated acetonitrile and considering the different oxygen concentration in DMSO compared to acetonitrile. If necessary, the protoporphyrin IX triplet lifetime in air saturated DMSO can easily be measured by laser flash photolysis.

[00167] The Stern- Volmer constants are in direct correlation with the singlet oxygen suppression efficiency. Table 1 (above) summarizes the Stern- Volmer constants and PPIX singlet and triplet state quenching rate constants. Three different ranges of Stern- Volmer constants were observed. For alkoxy crylene and compound Ilfi, only negligible singlet oxygen suppression and low Stern- Volmer constants were observed, which is probably caused by the low PPIX singlet and triplet quenching rate constants of these stabilizers. For compounds Ilai, Ilbi, and the mixture of Ildi and Ilei, Stern- Volmer constants of about 30 M ^"1 were observed. For these three stabilizers, high PPIX singlet quenching rate constants (about 5 x 10 ⁹ M ^' V ¹ ) but low triplet quenching rate constants (< 10 ⁹ M ^' V ¹ ) were observed. Here, the singlet oxygen suppression is probably dominated by PPIX singlet excited state quenching by these stabilizers. The highest Stern- Volmer constant was observed for compound IIci (240 M ^"1 ). Because of the very high PPIX triplet quenching rate constant by compound IIci (3.2 x 10 ⁹ M ^' V ¹ ), the singlet oxygen suppression is probably dominated by triplet quenching. To prove this switch in mechanism and kinetic control of singlet oxygen suppression, additional kinetic parameters would need to be determined, which are easily accessible by laser flash photolysis and time correlated single photon counting. These kinetic parameters include the MePPIX triplet and singlet lifetimes in air saturated and oxygen free CDC1 ₃ and the bimolecular quenching constant by oxygen.

[00168] The complex quenching reaction mechanism of protoporhyrin IX excited states is summarized in Scheme 1.

[00169] Scheme 1: Quenching mechanism of protoporphyrin IX excited states

orp [00170] Additional conjugated fused tricyclic compounds having electron withdrawing groups having Formulas Ilai, Ilbi, Ilci, Ildi, and Ilei were tested against the alkoxy crylene compound as shown in Figures 18 and 19.

[00171] The redox potential of protoporphyrin IX, Formula Ilai, Ilbi, Ilci, a mixture of Ildi and Ilei, Ilfi, and alkoxy crylene were determined with respect to a Ag/AgCl reference electrode. For these experiments, dimethylsulfoxide (DMSO) and tetrabutylammonium perchlorate (TBAP) were obtained from Sigma Aldrich and used as received. Acetone was obtained from Fisher Scienfitic. Solutions of 0.01 M (10 mM) of protoporphyrin IX, Formula Ilai, Ilbi, Ilci, a mixture of Ildi and Ilei, Ilfi, and alkoxy crylene were prepared by dissolving measured amounts in a supporting electrolyte of 0.1 M TBAP in DMSO; the total volume of each sample solution was 15 mL. Platinum wires (BASi MW-1032) of diameter 0.5 mm were employed for both the working electrode (WE) and counter electrode (CE). A dry- solvent tolerant Ag/AgCl reference electrode (RE) was obtained from eDAQ (Model ET072). The WE and CE were cleaned prior to each by first rinsing in acetone, then DI, followed by soaking in -50% aqueous H ₂ SO ₄ for 10-20 minutes and then a final DI rinse. The RE electrode was cleaned prior to each use by an acetone rinse followed by DI rinse. Each sample solution was prepared in a fresh glass vial which had been rinsed with DI then acetone and allowed to dry. Immediately after preparing each solution, it was purged with pure N ₂ gas for 15-20 minutes with the electrodes in place. Voltammetry data was collected shortly afterwards with an EG&G PAR 263 A Potentiostant/Galvanostat operated using a Labview-based control program. Scans were performed at various potential ranges between +2.0V and -2.0V (vs Ag/AgCl); all scan rates were constant at 200 mV/s.

[00172] The voltammograms for protoporphyrin IX appear to show the presence of two distinct redox couples (Figure 19a). The first redox couple has a large reduction peak at -1255 mV and a smaller oxidation peak at -610 mV (two much smaller oxidation peaks are present at - 202 mV and +164 mV which may also be associated with this couple); the redox potential for this couple is thus estimated as -932 mV. The second redox couple has a reduction peak near - 1741 mV and an oxidation peak near -1152 mV; this yields a redox potential of approximately - 1446 mV.

[00173] The voltammograms for Formula Ilai also show the presence of two distinct redox couples (Figure 19b). The first redox couple has a reduction peak at -757 mV and an oxidation peak at -560 mV; the redox potential for this couple is thus estimated as -658 mV. The second redox couple has a reduction peak at -1297 mV and an oxidation peak at -1102 mV; the redox potential is approximately -1199 mV.

[00174] The voltammograms for Formula Ilbi show the presence of two distinct redox couples (Figure 19c). The first redox couple has a reduction peak at -864 mV and an oxidation peak at - 706 mV; the redox potential for this couple is thus estimated as -785 mV. The second redox couple has a reduction peak at -1537 mV and oxidation peaks at -1466 mV (small) and +430 mV (large); the redox potential is estimated as -1501 mV.

[00175] The voltammograms for Formula Ilfi show the presence of two distinct redox couples (Figure 19d). The first redox couple has a reduction peak at -969 mV and an oxidation peak at - 782 mV; the redox potential for this couple is thus estimated as -875 mV. The second redox couple has a reduction peak at -1409 mV and oxidation peaks at -1286 mV (small) and +434 mV (large); the redox potential is estimated as -1347 mV.

[00176] The voltammogram for Formula Ilci shows the presence of only one distinct redox couple (Figure 19e). This couple has a reduction peak at -656 mV and an oxidation peak at -300 mV; the redox potential is thus estimated as -493 mV.

[00177] The voltammogram for the mixture of Formula Ildi and Formula Ilei also shows the presence of only one distinct redox couple (Figure 19f). This couple has a reduction peak at -545 mV and an oxidation peak at +54 mV; the redox potential for this couple is thus estimated as - 245 mV.

[00178] The voltammograms for alkoxy crylene show the presence of two distinct redox couples (Figure 19g). The first redox couple has a reduction peak at -1183 mV and an oxidation peak at -1038 mV; the redox potential for this couple is thus estimated as -1110 mV. The second redox couple has a reduction peak at -1751 mV and an oxidation peak at +318 mV; the redox potential is estimated as -694 mV.