FIELD OF INVENTION:

The present invention relates to novel 5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)- benzylidene]-thiazolidine-2,4-dione compounds of general formula (I), their pharmaceutically acceptable salts, solvates their synthesis and uses thereof, to pharmaceutical compositions containing compounds and to the use of such compounds and composition in medicines either alone or in combination with other compounds.

BACKGROUND AND PRIOR ART:

Diabetes mellitus is a chronic multifactorial metabolic disease resulting from insulin deficiency or insulin resistance, characterized by elevated blood glucose level or hyperglycaemia. Diabetes is a life-long disease and there is no permanent cure. Diabetes mellitus, in the 21 ^st century is considered to be the main threat to human health [Thareja, S.; Aggarwal, S.; Bhardwaj, T. R.; Kumar, M. Protein tyrosine phosphatase IB inhibitors: a molecular level legitimate approach for the management of diabetes mellitus. Med. Res. Rev. 2012, 32, 459-517; Zimmet, P.; Alberti, K. G.; Shaw, J. Global and societal implications of the diabetes epidemic. Nature 2001, 414, 782-787; Schwarz, J.; Bornstein, S. R.; Schulze, J. Prevention of type 2 diabetes: what challenges do we have to address? J. Public Health 2005, 13, 303-308]. Globally, diabetes has shadowed the spread of 'modern lifestyle' and can be linked to an increasingly overweight and sedentary population [Vats, R. K.; Kumar, V.; Kothari, A. Emerging targets for diabetes mellitus. Curr. Sci. 2005, 88, 241-249]. The prevalence of diabetes worldwide was 285 million in the year 2010, present data shows 387 million people worldwide have diabetes in the year 2014, and it is estimated that it will reach 592 million by the year 2035 [Verma, S. K.; Thareja, S. Molecular docking assisted 3D-QSAR study of benzylidene-2, 4- thiazolidinedione derivatives as PTP IB inhibitors for the management of Type-2 diabetes mellitus. RSC Adv. 2016, 6, 33857-33867]. Diabetes is threatening on account of development of many severe complications namely cardiac abnormalities, atherosclerosis, microangiopathy, nephropathy, neuropathy, retinopathy and cataracts [Chung, S. S.; Chung, S. K. Aldose reductase in diabetic microvascular complications. Curr. Drug Targets 2005, 6, 475-486; Suzen, S.; Buyukbingol, E. Recent studies of aldose reductase enzyme inhibition for diabetic complications. Curr. Med. Chem. 2003, 10, 1329-1352]. Protein tyrosine phosphatase IB (PTP IB) is a ubiquitously expressed intracellular enzyme which causes negative regulation of insulin receptor as well as leptin signaling system emerged as a potential target for the management of type 2 diabetes [Lund, I. K.; Bilestup, N. Mechanism of PTP IB mediated inhibition of leptin signaling. J. Mol. End. 2005, 15, 339-351; Forsell, P. A. L.; Boie, Y.; Montalibet, J.; Collins, S.; Kennedy, B. P. Genomic characterization of the human and mouse protein tyrosine phosphatase- IB genes. Gene 2000, 260, 145-153]. It has been involved in down- regulation of receptor tyrosine kinase activity following stimulation of the insulin or leptin receptors [Kennedy, B. P.; Ramachandran, C. Protein tyrosine phosphatase IB in diabetes. Biochem. Pharmacol. 2000, 60, 877- 883; By on, J. C; Kusari, J.; Kusari, A. B. Protein tyrosine phosphatase IB acts as a negative regulator of insulin signal transduction. Mol. Cell. Biochem. 1998, 182, 101-108]. Various studies on PTP IB knockout mice provided significant support for the view that PTP IB is a key regulator of insulin signalling [Elchebly, M.; Payette, P.; Michaliszyn, E.; Cromlish, W.; Collins, S.; Loy, A. L. Increased insulin sensitivity and obesity resistance in mice lacking the protein tyrosine phosphatase- IB gene. Science 1999, 283, 1544-1548]. Therefore, PTP IB inhibitors could potentially ameliorate insulin resistance and normalize plasma glucose and insulin levels without inducing hypoglycemia, and could, therefore, be a major advancement in the treatment of T2DM [Zhang, Z. Y.; Lee, S. Y. PTP IB inhibitors as potential therapeutics in the treatment of Type 2 diabetes. Expert Opin. Invest. Drugs 2003, 12, 223-233; Sachan, N.; Thareja, S.; Aggarwal, R.; Kadam, S. S.; Kulkarni, V. M. Substituted biphenyl ethanones as antidiabetic agents: synthesis and in-vivo screening. Int. J. Pharm Tech Res. 2009, 1, 1625-1631]. Thiazolidine-2,4-dione is an important heterocyclic system that exhibit a range of pharmacological activities such as anti-hyperglycemic, anti-inflammatory, anticancer, anti-microbial among others. The broad spectrum of pharmacological activity is due to the analogues obtained by substitution at free -NH and methylene group in the thiazolidine-2,4-dione moiety. The structural variation at the said free ends of thiazolidine-2,4-dione moiety has led to the development of biologically active molecules against a broad spectrum of protein targets, but not limited to, such as Peroxisome Proliferator activated receptor (PPARy), Aldose reductase (ALR2), Cyclooxygenase (COX-2) and PTP IB.

Thiazolidinediones (TZDs) which are oral insulin-sensitizing agents act by indirectly enhancing peripheral insulin sensitivity, thereby lowering the levels of both glucose and insulin [Bhattarai, B. R.; Kafle, B.; Hwang, J. S.; Khadka, D.; Lee, S. M.; Kang, J. S.; Ham, S. W.; Han, I. O.; Park, H.; Cho, H. Thiazolidinedione derivatives as PTP IB inhibitors with antihyperglycemic and antiobesity effects. Bioorg. Med. Chem. Lett. 2009, 19, 6161-6165]. A major benefit of the thiazolidinediones is that unlike sulfonylurea derivatives, a-glucosidase inhibitors, or insulin, they influence insulin resistance. Of the thiazolidinedione compounds, ciglitazone, troglitazone, englitazone, pioglitazone, and rosiglitazone have been clinically examined as potential antidiabetic compounds but all are suffering from various side effects thus withdrawn (except Pioglitazone) from the market [Maccari, R.; Paoli, P.; Ottana, R.; Jacomelli, M.; Ciurleo, R.; Manao, G.; Steindl, T.; Langer, T.; Vigorita, M. G.; Camici, G. 5-Arylidene-2,4-thiazolidinediones as inhibitors of protein tyrosine phosphatases. Bioorg. Med. Chem. 2007, 15, 5137- 5149]. Pioglitazone is the only TZD available for clinical use in the management of T2DM. There has been speculation that the toxicity observed with the thiazolidinedione class of molecules is due to its binding to peroxisome proliferator activator receptor (PPAR) belonging to the steroid/ thyroid/retinoid receptor super family of ligand-activated transcription factors [Lohray, B. B.; Bhushan, V.; Reddy, A. S.; Rao, P. B.; Reddy, N. J.; Harikishore, P.; Haritha, N.; Vikramadityan, R. K.; Chakrabarti, R.; Rajagopalan, R.; Katneni, K. Novel euglycemic and hypolipidemic agents: pyridyl and quinolinyl containing thiazolidinediones. J. Med. Chem. 1999, 42, 2569-2581]. Development of an orally bioavailable and specific PTP IB inhibitors is not an easy task due to poor cell permeability of the small molecules exhibiting high affinity with PTP lBdue to their hydrophilic nature. A first-in-class PTP IB inhibitor has yet to be discovered; however, extensive research is under way to develop a potential blockbuster drug.

There are various patented and non-patented literature disclosing Thiazolidine-2,4- dione compounds and their synthesis, few of them are referred below.

Article titled "Design and synthesis of novel thiazolidine-2,4- diones as hypoglycemic agents" by P. Datar et al. published in J. Saudi Chem. Soc. 2016, 20, S196-S201 disclose Thiazolidine-2,4-diones derivatives having carboxylic ester appendages at N-3 and 5-substituted benzylidene for treatment in diabetes. The synthesis of compounds disclosed in said article is as shown below:

Scheme Reagents: (a) Piperidine, Ethanol, CH3-COOH; (b) NaH, Ethyl bromoacetate, Dry DMF; (c) Cone. HC1, Glacial acetic acid. Article titled "Design and synthesis of a novel 5-(aminomethylene)thiazolidine- 2,4-dione derivatives as potent hepatitis-B virus polymerase inhibitors" by Wei- Guo Li in Bangladesh J. Pharmacol. 2015, 10, 271-78 reported a series of substituted 5- (aminomethylene)thiazolidine-2,4-diones. The synthetic procedure (Scheme 1) comprises of reaction of thiazolidine-2,4-dione (1) with triethyl orthoformate in the presence of Ac ₂ 0 at reflux temperature to obtain 5- (ethoxymethylene)thiazolidine-2,4-dione (2) followed by condensation with various secondary amines in ethanol at reflux temperature to afford substituted 5- (aminomethylene)thiazolidine-2,4-diones (4) as shown in Table 1 of said article. Scheme 1:

Ankush Garg et al. reported the synthesis of a series of 5-substituted-arylidene-3- substitutedbenzyl-thiazolidine-2,4-dione derivatives (Scheme 2) through Knoevenagel condensation and evaluated their anti-diabetic potential [Garg, A.; Chawla, P.; Saraf, S. A. Syntheses of some novel 5-Substituted-arylidene-3- substituted-benzyl-thiazolidine-2,4-dione analogues as anti-hyperglycemic agents. Int. J. Drug Dev. Res. 2012, 4, 141-146].

Scheme 2:

WO2010082212 discloses N-Biphenylacyl-thiazolidine-2,4-dione derivatives of general formula (I);

(I)

wherein the variables Ri to R ₆ , Zi and Z2 are as described. The compounds of general formula (I) are used in the treatment of hyperglycemia, hypertension, PTP IB inhibition, insulin resistance and exhibit anti-cancer activity. The general synthesis of said derivatives of formula (I) is shown below:

Scheme 3:

Biphenyl moiety was selected as pharmacophore and it was considered of interest to design molecules having biphenyl moiety. It is also evident from the literature that biphenyl compounds exhibited potent PTP IB activity because of extended interaction of additional phenyl ring with the surface near the active site of the enzyme and thus constitute suitable pharmacophore. Extensive survey of literature revealed that biphenyl containing molecules exhibit potential antidiabetic property. The main mechanism of action of all such compounds have been attributed to inhibition of PTP IB which play an important role in insulin signaling associated with T2DM and insulin resistance [Malamas, M. S.; Sredy, J.; Moxham, C; Katz, A.; Xu, W.; McDevitt, R.; Adebayo, F. O.; Sawicki, D. R.; Seestaller, L.; Sullivan, D.; Taylor, J. R. Novel Benzofuran and Benzothiophene Biphenyls as Inhibitors of Protein Tyrosine Phosphatase IB with Antihyperglycemic Properties. J. Med. Chem. 2000, 43, 1293-1310; Murthy, V. S.; Kulkarni, V. M. 3D-QSAR CoMFA and CoMSIA on protein tyrosine phosphatase IB inhibitors. Bioorg. Med. Chem. 2002, 10, 2267-2282; Ahn, J H.; Cho, S. Y.; Ha, J. D.; Chu, S. Y.; Jung, S. H.; Jung, Y. S.; Baek, J. Y.; Choi, I. K.; Shin, E. Y.; Kang, S. K.; Kim, S. S.; Cheon, H. G.; Yang, S. D.; Choi, J. K. Synthesis and PTP IB inhibition of 1, 2-naphthoquinone derivatives as potent anti-diabetic agents. Bioorg. Med. Chem. Lett. 2002, 12, 1941- 1946; Shim, Y. S.; Kim, K. C; Chi, D. Y.; Lee, K. H.; Cho, H. Formylchromone derivatives as a novel class of protein tyrosine phosphatase IB inhibitors. Bioorg. Med. Chem. Lett. 2003, 13, 2561-2563; Arabaci, G.; Yi, T.; Fu, H.; Porter, M. E.; Beebe, K. D.; Pei, D. a-Bromoacetophenone derivatives as neutral protein tyrosine phosphatase inhibitors: structure-Activity relationship. Bioorg. Med. Chem. Lett. 2002, 12, 3047-3050; Guertin, K. R.; Setti, L.; Qi, L.; Dunsdon, R. M.; Dymock, B. W.; Jones, P. S.; Overton, H.; Taylor, M; Williams, G; Sergi, J. A.; Wang, K.; Peng, Y.; Renzetti, M.; Boyce, R.; Falcioni, F.; Garippa, R.; Olivier, A. R. Identification of a novel class of orally active pyrimido[5,4-3][l,2,4]triazine-5,7- diamine-based hypoglycemic agents with protein tyrosine phosphatase inhibitory activity. Bioorg. Med. Chem. Lett. 2003, 13, 2895-2898]. Molecular modeling studies on PTP IB with biphenyl derivatives have also suggested that active site of PTP IB is highly hydrophobic and biphenyl moiety is favourable due to its favourable interaction with hydrophobic residues of PTP IB [Murthy, V.S.; Kulkarni, V.M. Molecular modelling of protein tyrosine phosphatases IB (PTP IB) Inhibitors. Bioorg. Med. Chem. 2002, 10, 897-906]. It also provides sufficient lipophilicity to cross intracellular barrier and active against intracellular targets such as PTP IB [Tarn, S.; Saiah, E. Recent advances in the discovery and development of PTP IB inhibitors. Drugs Future 2008, 133, 175-185].

Recently, it has been also reported that arylidene-2,4-TZD derivatives with N- substitution are of particular interest as PTP IB enzyme inhibitors making them devoid of side effects associated with glitazones [Maccari, R.; Paoli, P.; Ottana, R.; Jacomelli, M.; Ciurleo, R.; Manao, G.; Steindl, T.; Langer, T.; Vigorita, M. G.; Camici, G. 5-Arylidene-2,4-thiazolidinediones as inhibitors of protein tyrosine phosphatases. Bioorg. Med. Chem. 2007, 15, 5137-5149; Maccari, R.; Ottana, R.; Ciurleo, R.; Paoli, P.; Manao, G.; Camici, G.; Laggner, C; Langer, T. Structure- Based Optimization of Benzoic Acids as Inhibitors of Protein Tyrosine Phosphatase IB and Low Molecular Weight Protein Tyrosine Phosphatase. Chem. Med. Chem. 2009, 4, 957-962; Ottana, R.; Maccari, R.; Ciurleo, R.; Paoli, P.; Jacomelli, M.; Manao, G.; Camici, G.; Laggner, C; Langer, T. 5-Arylidene-2-phenylimino-4- thiazolidinones as PTP IB and LMW-PTP inhibitors. Bioorg. Med. Chem. 2009, 17, 1928-1937].

The present inventors felt that there exists a scope to develop novel series of thiazolidine-2, 4-dione over the art having potential activity for treatment of diabetes. The present invention provides novel series of 5-[4-(2-biphenyl-4-yl-2- oxo-ethoxy)-benzylidene]-thiazolidine-2,4-dione compounds with N- substitution at thiazolidine ring which can be used in pharmaceutical compositions for efficient treatment of diabetes and having broad spectrum of activity against various protein targets, but not limited to, such as Peroxisome Proliferator activated receptor (PPARy), Aldose reductase (ALR2), Cyclooxygenase (COX-2), Protein tyrosine phosphatase IB (PTP IB).

SUMMARY OF THE INVENTION

One of the objective of the present invention is to provide novel series of 5-[4-(2- biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazolidine-2,4-di ones with N- substitution at TZD ring, their synthesis pharmaceutical compositions thereof having antidiabetic activities.

In accordance with the above, the present invention provides library of 5-[4-(2- biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazolidine-2,4-di one compounds of general formula (I) or its pharmaceutically acceptable salts, solvates, isomers, enantiomers thereof;

(I)

wherein;

Ri is independently selected from hydrogen, (un)-substituted or substituted linear or branched alkyl, ketones, acids, esters or alkoxy, (un)-substituted or substituted aryl or (un)-substituted or substituted alkylaryl;

R.2 is independently selected from hydrogen, (un)-substituted or substituted linear or branched alkyl, -CN, -SO3H, (un)-substituted or substituted amines or acids; Zi and Z2 independently represent hydrogen or together form a chemical bond. In another aspect, the present invention provides a process for synthesis of library of 5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazolidin e-2,4-dione compounds of general formula (I);

(I)

wherein;

Ri is independently selected from hydrogen, (un)-substituted or substituted linear or branched alkyl, ketones, acids, esters or alkoxy, (un)-substituted or substituted aryl or (un)-substituted or substituted alkylaryl;

R2 is independently selected from hydrogen, (un)-substituted or substituted linear or branched alkyl, -CN, -S03H, (un)- substituted or substituted amines or acids; Zi and Z2 independently represent hydrogen or together form a chemical bond; which comprises at least one of the following reactions;

(i) Knoevanagel condensation of 4-(2-Biphenyl-4-yl-2-oxo-ethoxy)- benzaldehyde of formula (IV) with thiazolidine-2,4 dione (VII) to obtain 5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazolidin e-2,4- dione (I _a );

(ii) N-alkylation of 5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]- thiazolidine-2,4-dione (I _a ) in presence of base and solvent to obtain compounds (Ib-j), (Ii) and (I _m ); or

(iii) N-acylation of 5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]- thiazolidine-2,4-dione (I _a ) in presence of base and solvent to obtain compounds (Ik);

(iv) Acid hydrolysis of compound (Im) of step (ii) to yield compound (In). The rocess is shown in Scheme 4 below:

In another aspect, the compounds of formula (I) of the present invention comprise;

1. (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazol idine-2,4- dione (I _a ); 2. Z)-5-[4-(2-Biphenyl-4yl-2-oxo-ethoxy)-benzylidene]-3-methyl- thiazolidine-2,4-dione (¾);

3. (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-ethyl - thiazolidine-2,4-dione (I _c );

4. (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-(2-ch loroethyl) thiazolidine-2,4-dione (Id);

5. (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-(2-br omoethyl)- thiazolidine-2,4-dione (I _e );

6. (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-propy l- thiazolidine-2,4-dione (If);

7. (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-(3- chloropropyl)- thiazolidine-2,4-dione (I );

8. (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-(3- bromopropyl)-thiazolidine-2,4-dione (Ih);

9. (Z)-5-[4-(2-Biphenyl-4yl-2-oxo-ethoxy)-benzylidene]-3-butyl- thiazolidine-2,4-dione (¾);

10. 4-[(Z)-5-{4-(2-Biphenyl-4yl-2-oxo-ethoxy)-benzylidene}-thiaz olidine-2,4- dione-3-yl- methylj-benzoic acid (Ij);

11. 3-Acetyl-(Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene ]- thiazolidine-2,4-dione (Ik);

12. Methyl 2-[(Z)-5-{4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene}- thiazolidine-2,4-dione-3-yl] acetate (Ii);

13. Ethyl 2-[(Z)-5-{4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene}- thiazolidine-2,4-dione-3-yl] acetate (I _m );

14. [(Z)-5-{4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene}-thiazo lidine-2,4- dione]-acetic acid (I _n ).

DESCRIPTION OF FIGURES:

Fig 1 depict In vivo anti-hyperglycemic activity of 5-[4-(2-biphenyl-4-yl-2-oxo- ethoxy)-benzylidene]-thiazolidine-2,4-dione compounds of formula ( ) in streptozotocin-nicotinamide (STZ-NA) induced diabetic mice. Fig 2 depict graphical presentation of change in body weight after treatment with 5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazolidin e-2,4-dione derivatives (I _a -n) in diabetic mice.

Fig 3 depict (A) Histopathology of pancreas of non-diabetic group; (B) diabetic control group; (C) pioglitazone treated group; and (D) compound ¾ treated group.

DETAILED DESCRIPTION OF THE INVENTION:

Throughout the disclosure the following terms, unless otherwise indicated, shall be understood to have the following meanings:

In the present specification, the term T2DM means type 2 diabetes mellitus which is non-insulin dependent diabetes mellitus and is a disorder that is characterized by elevated blood glucose in relation to insulin resistance and relative insulin deficiency.

PTP IB is a non-trans membranous cytosolic enzyme and is a negative regulator of insulin and leptin signalling cascades.

TZDs means 2,4-thiazolidinediones or thiazolidinedione.

PPARs is peroxisome proliferator activated receptors which are a group of nuclear receptor proteins that function as a transcription factors regulating the expression of genes and plays an important roles in the regulation of cellular differentiation, development and metabolism (carbohydrate, lipid, and protein) of higher organisms.

STZ means streptozocin, is a naturally occurring chemical that is particularly toxic to the insulin-producing beta cells of the pancreas in mammals. It is used in medical research to produce an animal model for hyperglycemia.

NA is nicotinamide, administration of NA partially protects insulin-secreting cells against STZ.

The compounds of this invention may contain asymmetric carbon atom and some of the compounds of this invention may contain one or more asymmetric centres and may thus give rise to stereoisomers and diastereomers. Although the compound of formula (I) is not noticeable with any stereo centres, the present invention includes such stereoisomers and diastereomers, as well as the racemic and resolved, enantiomerically pure R and S stereoisomers, as well as other mixture of the R and S stereoisomers. It will also be apparent to those skilled in the art that certain compounds of formula I may exhibit geometrical isomerism. Geometrical isomers include the cis-trans and Z-E forms of compounds of the invention. So the present invention comprises the individual geometrical isomers and stereoisomers.

Such isomers or diastereomers can be separated from their mixtures, by the application or adaptation of known methods, for example chromatographic techniques and recrystallisation techniques, or they are separately prepared from the appropriate isomers of their intermediates. All forms are within the scope of the invention.

The present invention relates to library of 5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)- benzylidene]-thiazolidine-2,4-dione compounds of general formula (I) or its pharmaceutically acceptable salts, solvates, isomers, enantiomers thereof;

(I)

wherein;

Ri is independently selected from hydrogen, (un)-substituted or substituted linear or branched alkyl, ketones, acids, esters or alkoxy, (un)-substituted or substituted aryl or (un)-substituted or substituted alkylaryl;

R2 is independently selected from hydrogen, (un)-substituted or substituted linear or branched alkyl, -CN, -SO3H, (un)-substituted or substituted amines or acids; Zi and Z2 independently represent hydrogen or together form a chemical bond. The compounds of general formula (I) comprises;

Table 1:

acetic acid

In another embodiment, the present invention discloses a process for preparation of library of 5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazolidin e-2,4- dione compounds of general formula (I);

(I)

wherein;

Ri is independently selected from hydrogen, (un)-substituted or substituted linear or branched alkyl, ketones, acids, esters or alkoxy, (un)- substituted or substituted aryl or (un)-substituted or substituted alkylaryl; R.2 is independently selected from hydrogen, (un)-substituted or substituted linear or branched alkyl, -CN, -SO3H, (un)-substituted or substituted amines or acids; Zi and Z2 independently represent hydrogen or together form a chemical bond; which comprises at least one of the following reactions;

(i) Knoevanagel condensation of 4-(2-Biphenyl-4-yl-2-oxo-ethoxy)- benzaldehyde of formula (IV) with thiazolidine-2,4 dione (VII) to obtain 5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazolidin e-2,4- dione (I _a );

(ii) N-alkylation of 5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]- thiazolidine-2,4-dione (I _a ) in presence of base and solvent to obtain compounds (Ib-j), (Ii) and (I _m );

(iii) N-acylation of 5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]- thiazolidine-2,4-dione (I _a ) in presence of base and solvent to obtain compound (Ik);

(iv) Acid hydrolysis of compound of formula (Im) to yield compound (In).

The knoevanagel condensation of thiazolidine-2,4 dione (VII) with 4-(2-Biphenyl- 4-yl-2-oxo-ethoxy)-benzaldehyde of formula (IV) was carried out in ethanol under reflux conditions containing catalytic amount of piperidine to obtain 5-[4-(2- biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazolidine-2,4-di one (I _a ).

The N-alkylation of step (ii) was performed using alkylating agent selected from (un)-substituted or substituted linear or branched Ci to C12 halides, halo substituted linear or branched esters such as methylchloroacetate, ethylchloroacetate, halo substituted aliphatic or aromatic carboxylic acids or anhydrides. The base is selected from alkali or alkaline earth metal carbonates; the solvent is selected from polar aprotic solvent such as THF, acetone, DMF and the like.

The N-acylation of step (iii) was carried out using acylating agents selected from carboxylic acids, anhydrides, acyl chlorides to obtain compound (Ik). The acylation is carried out in presence of organic bases such as pyridine, 4- Dimethylaminopyridine (DMAP), triethylamine (TEA), 4-picoline, N-methyl morpholine and the like. The solvent is selected from glacial acetic acid, lower alcohols, dioxane, acetonitrile and the like.

The 4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzaldehyde of formula (IV) used in the Knoevanagel condensation was obtained by Friedel Craft's acylation of biphenyl using chloroacetyl chloride in presence of AlCh and anhydrous CS2 as solvent followed by reaction with p-hydroxybenzaldehyde in base and solvent. The intermediate thiazolidine-2,4 dione (III) was obtained by condensation of alpha- chloroacetic acid with thiourea.

In another embodiment, the present invention provides pharmaceutical composition comprising the compounds of general formula (I) or is pharmaceutically acceptable salts, their isomers, enantiomers, solvates along with pharmaceutically employed excipients which may be associated therewith such as insulin resistance, activation of peroxisome proliferator activated receptor (PPAR)-a and -γ, DPP -IV (Dipeptidyl peptidase-IV) inhibition, inhibition of aldose reductase enzyme for the management of diabetic complications, dyslipidemia, hyperglycemia, hypertension, anti-inflammatory, analgesic, antioxidant, antibacterial, antifungal, antitubercular, anticancer, anticonvulsant, antidepressant, antiarrhythmic, antihypertensive, anti-HIV, anti-epimastigote, antihyperlipidemic, muscarinic receptor 1 agonist, follicle stimulating hormone (FSH) receptor agonist, and sphingosine-1 -phosphate (S1P1) agonist activity, and anti-plasmodial activity. . The composition can be formulated as tablets, capsules, powders, syrups, solutions, suspensions and such like or as parenteral injectable.

The pharmaceutical composition of compounds of general formula (I) or its pharmaceutically acceptable salts, their isomers, enantiomers, solvates along with pharmaceutically employed excipients are administered in an effective therapeutic amount to a subject in need either orally or parenterally. The active compound of general formula (I) will be present in such pharmaceutical compositions in amounts sufficient to provide the desired dosage amount. The compounds of general formula (I), for oral administration, can be combined with a suitable solid or liquid carrier or diluent and other pharmaceutically acceptable excipients to form capsules, tablets, powders, syrups, solutions, suspensions and the like. For parenteral administration, the compounds can be combined with sterile aqueous or organic media to form injectable solutions.

In an embodiment, the in vitro PTP IB inhibitory activities of 5-[4-(2-biphenyl-4- yl-2-oxo-ethoxy)-benzylidene]-thiazolidine-2,4-dione compounds (I _a -n) were evaluated against Suramin as standard (Table 1). The compound (¾) exhibited the enhanced ICso inhibitory activity at 5.897μΜ.

In another embodiment, the in vivo anti-hyperglycemic activity of 5-[4-(2-biphenyl- 4-yl-2-oxo-ethoxy)-benzylidene]-thiazolidine-2,4-dione compounds (I _a -n) were studied in streptozotocin-nicotinamide (STZ-NA) induced diabetic mice (Fig 1 and Table 3). Compound ¾ exhibited potent glucose lowering activity as compared to reference standard Pioglitazone at all-time intervals.

In yet another embodiment, the change in body weight of diabetic mice was measured (Fig 2 and Table 4). In control mice, decrease in body weight was observed during the 7 days' treatment period which could be attributed to diabetes. Pioglitazone treatment resulted in increase in body weight. The most potent anti- hyperglycemic compound (¾) showed marginal increase in the body weight, which indicates beneficial effect of the ¾ administration.

The following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purpose of illustrative discussion of preferred embodiments of the invention.

Examples: Example 1: Synthesis of l-Biphenyl-4-yl-2-chloroethanone (III)

A mixture of biphenyl (II) (7.7 g, 50.0 mmol) and finely powdered anhydrous aluminium chloride (6.6 g, 50.0 mmol) in presence of anhydrous carbon disulphide (55.0 mL) was placed in three necked round bottom flask fitted with a dropping funnel. Chloroacetyl chloride (4.0 mL, 50.0 mmol) was added drop wise at room temperature with continuous stirring under anhydrous conditions. The reaction mixture was further stirred for 5 hr, poured slowly with stirring into a solution of hydrochloric acid in water (5% v/v). The separated product was filtered, washed with water repeatedly, dried and crystallised from methanol to get l-biphenyl-4-yl- 2-chloroethanone (III) (10.07 g, 87.4 %) m. p. l26-128°C.

Analysis:

R _f : 0.58 (CHCh: MeOH : : 9.9:0.1)

IR (KBr): 3044, 2942, 1688, 1599 and 762 cm ^"1

¾ NMR (CDCb): δ 4.72 (s, 2H, -CH2CI), 7.39 (t, 1Η, -CH arom), 7.45 (t, 2Η, - CH arom), 7.60 (d, 2Η, -CH arom), 7.68 (d, 2Η, -CH arom) and 8.00 ppm (d, 2Η, -CH arom).

Example 2: Synthesis of 4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzaldehyde (IV)

A mixture of l-biphenyl-4-yl-2-chloroethanone (III) (2.31 g, 10.0 mmol), 4- hydroxybenzaldehyde (1.22 g, 10.0 mmol) and anhydrous potassium carbonate (2.76 g, 20.0 mmol) in acetonitrile (90.0 mL) was refluxed for 12 hr. The solvent was evaporated under reduced pressure to obtain the residue. The residue was poured onto crushed ice with stirring. The separated product was filtered, washed with water and dried. It was crystallized from methanol to yield 4-(2-biphenyl-4- yl-2-oxo-ethoxy)-benzaldehyde (IV) (2.71 g, 86.0 %) m. p. 140-142°C.

Analysis:

R _f : 0.52 (CHC13 : MeOH : : 9.8:0.2)

IR (KBr): 3031, 2892, 1693, 1602, 1261 and 762 cm ^"1

¾ NMR (CDCI3): δ 5.42 (s, 2H, -CH ₂ O-),7.05 (d, 2Η, -CH arom), 7.43 (t, 1Η, -CH arom), 7.47 (t, 2H, -CH arom), 7.63 (d, 2Η, -CH arom), 7.73 (d, 2Η, -CH arom), 7.84 (d, 2Η, -CH arom), 8.06 (d, 2Η, -CH arom) and 9.95 ppm (s, 1Η, -CHO).

Example 3: Synthesis of 2,4-Thiazolidinedione (VII)

A mixture of chloroacetic acid (V) (56.4g, 0.6 mol) and thiourea (VI) (45.6g, 0.6 mol) was dissolved in water (125.0 mL), stirred for 15 min. To this was added drop wise concentrated hydrochloric acid (60.0 mL). The reaction mixture was refluxed for 18 hr and cooled in an ice bath. The product separated as white needles was filtered, washed repeatedly with water, dried and crystallised from methanol to yield 2,4-thiazolidinedione (VII) (62.58 g, 88.2 %) m. p. 123-25°C.

Analysis:

R _f : 0.48 (CHCh : MeOH : : 9: 1)

IR (KBr): 3459, 2946, 1735, 1678 and 1651 cm ^"1

¾ NMR (DMSO-rf ₆ ): δ 3.98 (s, 2H, -CH ₂ ) and 1 1.80 ppm (br s, 1Η, -NH).

Example 4: Synthesis of (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]- thiazolidine-2,4-dione (I _a )

A mixture of 4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzaldehyde (IV) (3.16g, 10.0 mmol) and 2,4-thiazolidinedione (VII) (1.17 g, 10.0 mmol) was refluxed in presence of catalytic amount of piperidine (0.25 mL) for 36 hr in absolute ethanol (80.0 mL) (Knoevenagel condensation). The solvent was removed under reduced pressure to get the residue and poured onto crushed ice with stirring. The product so obtained was filtered, washed with hydrochloric acid (5%), dried and crystallised from methanol to yield (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)- benzylidene]-thiazolidine-2,4-dione (I _a ) ( 3.15 g, 76.1%) m. p. 208-210°C.

Analysis:

R _f : 0.48 (CHCh : MeOH : : 9: 1)

IR (KBr): 341 1, 3046, 2922, 1742, 1685, 1598 and 1238 cm ^"1

¾ NMR (CDCb): δ 5.55 (s, 2H, -CH ₂ 0-), 7.07 (d, 2Η, -CH arom), 7.40 (t, 1Η, -

CH arom), 7.46 (t, 2Η, -CH arom), 7.48 (t, 2Η, -CH arom), 7.66 (d, 2Η, -CH arom), 7.70 (s, 1H, -CH=), 7.76 (d, 2Η, -CH arom), 8.09 (d, 2Η, -CH arom) and 12.25 ppm (s, 1Η, -NH exchangeable with D2O)

¹³ C NMR (CDCI3): δ 193.32 (-C=0), 168.18 (-C=0, TZD), 167.80 (-C=0, TZD), 13 1.97 (C ₆ H ₅ -CH=C-), 121.19 (-C-C=0-), 70.54(-CH ₂ O-), 159.79, 146.29, 139.38, 133.06, 132.05, 129.16, 128.76, 128.59, 127.38, 127.24, 126.51 and 1 15.62 ppm (C, arom)

Mass (APCI): 416 (M ⁺ +l).

Example 5: Synthesis of (Z)-5-[4-(2-Biphenyl-4yl-2-oxo-ethoxy)-benzylidene]- 3-methyl-thiazolidine-2,4-dione (l _b )

A mixture of (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazol idine- 2,4-dione (I _a ) (0.83 g, 2.0 mmol), methyl bromide (R ₂ -Br) (0.17 mL, 3.0 mmol) and anhydrous potassium carbonate (1.38 g, 10.0 mmol) in acetone (50.0 mL) was refluxed for 24 hr. The solvent was recovered under reduced pressure and the residue so obtained was poured onto crushed ice with stirring. The precipitated product was filtered, washed with water, dried and crystallised using methanol to yield (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-methy l- thiazolidine-2, 4-dione (I _b ) (0.70 g, 81.2 %) m. p. 175-178°C.

Analysis:

R _f : 0.52 (CHCh : MeOH : : 9: 1)

IR (KBr): 3031, 2931, 1736, 1682, 1593, 1229 cm ^"1

¾ NMR (DMSO-rf ₆ ): δ 3.23 (s, 3H, -NCH3), 5.49 (s, 2Η, -CH2O-), 7.06 (d, 2Η, - CH arom), 7.43 (t, 1Η, -CH arom), 7.44 (t, 2Η, -CH arom), 7.48 (t, 2Η, -CH arom), 7.65 (d, 2Η, -CH arom), 7.75 (s, 1Η, -CH=), 7.85 (d, 2Η, -CH arom) and 8.08 (d, 2Η, -CH arom)

¹³ C NMR (DMSO-rf ₆ ): δ 192.04 (-C=0), 167.43 (-C=0, TZD), 167.09 (-C=0, TZD), 13 1.24 (- H=C-), 122.31 (-C-CO-), 70.55 (-CH2O-), 30.48 (-NCH3), 159.85, 142.32, 135. 12, 132.61, 129.60, 129.25, 128.49, 127.31, 127.10, 125.33, 122.81 and 1 15.54 ppm (C, arom)

Mass (APCI): 430 (M ⁺ +l). Example 6: Synthesis of (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]- 3-ethyl-thiazolidine-2,4-dione (I _c )

A mixture of (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazol idine- 2,4-dione (I _a ) (0.83 g, 2.0 mmol), ethyl bromide (Rs-Br) (0.22 mL, 3.0 mmol) and dry potassium carbonate (1.38 g, 10.0 mmol) in acetone (50.0 mL) was refluxed for 24 hr. The solvent was evaporated under reduced pressure to obtain the residue. To this was added crushed ice and stirred for 30 min. The separated product obtained was filtered, washed with water dried. It was crystallised using methanol to yield (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-ethyl -thiazolidine-2, 4- dione (I _c ) (0.73 g, 82.5%) m. p. 155-158°C.

Analysis:

R _f : 0.54 (CHCh : MeOH : : 9: 1)

IR (KBr): 3031, 2931, 1737, 1682, 1597 and 1230 cm ^"1

¾ NMR (CDCb): δ 1.23 (t, 3H, -NCH2CH3), 3.76 (q, 3Η, -NCH2CH3), 5.59 (s, 2H, -CH ₂ O),7.08 (d, 2Η, -CH arom), 7.42(t, 1Η, -CH arom), 7.47 (t, 2Η, -CH arom), 7.51 (t, 2Η, -CH arom), 7.67 (d, 2Η, -CH arom), 7.71 (s, 1Η, -CH=), 7.77 (d, 2Η, - CH arom) and 8.10 ppm (d, 2Η, -CH arom)

¹³ C NMR (CDCI3): δ 192.88 (-C=0), 167.66 (-C=0, TZD), 167.00 (-C=0, TZD), 13 1.59 (-CH=C-), 121. 19 (-C-C=0-), 70.05 (-CH2O-), 38.16 (-NCH2CH3), 13.16 (-NCH2 H3), 159.35, 145.67, 139.87, 132.61, 131.48, 129.16, 128.70, 128.31, 126.87, 126.77, 126.94 and 1 15.17 ppm (C, arom)

Mass (ESI): 444 (M ⁺ +l).

Example 7: Synthesis of (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]- 3-(2-chloroethyl) thiazolidine-2,4-dione (I _d )

A mixture of (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazol idine- 2,4-dione (I _a ) (0.83 g, 2.0 mmol), l-bromo-2-chloroethane (Rt-Br) (0.25 mL, 3.0 mmol) and anhydrous potassium carbonate (1.38 g, 10.0 mmol) in acetone (50.0 mL) was refluxed for 24 hr. The solvent was removed under reduced pressure to obtain the residue. The residue was poured onto crushed ice with stirring. The precipitated product was filtered, washed with water, dried and crystallised with methanol to yield (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-(2- chloroethyl)-thiazolidine-2,4-dione (I _d ) (0.77 g, 80.1 %) m. p. 121-124°C.

Analysis:

R _f : 0.51 (CHCh : MeOH : : 9: 1)

IR (KBr): 3031, 2931, 1757, 1685, 1599, 1230 and 763 cm ^"1

¾ NMR (CDCb): δ 3.47 (t, 3H, -NCH2CH2-), 4.10 (t, 3Η, -NCH2CH2-), 5.40 (s, 2H, -CH2O), 7.03 (d, 2Η, -CH arom), 7.41 (t, 1Η, -CH arom), 7.44 (t, 2Η, -CH arom), 7.47 (t, 2Η, -CH arom), 7.60 (d, 2Η, -CH arom), 7.74 (d, 2Η, -CH arom), 7.87 (s, 1Η, -CH=) and 8.06 (d, 2Η, -CH arom)

¹³ C NMR (CDCI3): δ 193.10 (-00), 167.77 (-00, TZD), 166.02 (-OO, TZD), 132.82 (-CH=C-), 1 18.45 (-C-C=0-), 70.54 (-CH2O-), 42.60 (-NCH2CH2-), 25.81 (-NCH2CH2), 159.94, 146.93, 139.51 , 134.16, 132.37, 129.06, 128.69, 128.57, 127.58, 127.30, 126.58 and 1 15.56 ppm (C, arom)

Mass (ESI): 477(M ⁺ ) and 479 (M ⁺ +2).

Example 8: Synthesis of (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]- 3-(2-bromoethyl)-thiazolidine-2,4-dione (I _e )

A mixture of (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazol idine- 2,4-dione (I _a ) (0.83 g, 2.0 mmol), 1,2-dibromoethane (R ₅ -Br) (0.26 mL, 3.0 mmol) and dry potassium carbonate (1.38 g, 10.0 mmol) in acetone (50.0 mL) was refluxed for 24 hr. The solvent was evaporated under reduced pressure to obtain residue which was poured onto crushed ice with stirring. The product obtained was filtered, washed with water, dried, crystallized using methanol to get (Z)-5-[4-(2- biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-(2-bromoethyl)-th iazolidine-2,4- dione (I _e ) (0.82 g, 78.2 %) m. p. 136-138°C.

Analysis:

R _f : 0.51 (CHCh : MeOH : : 9: 1)

IR (KBr): 3031, 2892, 1743, 1685, 1595, 1228 and 760 cm ^"1

¾ NMR (CDCb): δ 3.58 (t, 3H, -NCH2CH2-), 4.14 (t, 3Η, -NCH2CH2-), 5.39 (s,

2H, -CH2O), 7.03 (d, 2Η, -CH arom), 7.41 (t, 1Η, -CH arom), 7.44 (t, 2Η, -CH arom), 7.47 (t, 2H, -CH arom), 7.60 (d, 2Η, -CH arom), 7.74 (d, 2Η, -CH arom), 7.87 (s, 1Η, -CH=) and 8.06 (d, 2Η, -CH arom)

¹³ C NMR (CDC1 ₃ ): δ 193.10 (-00), 167.77 (-00, TZD), 166.02 (-00, TZD), 132.82 (-CH=C-), 1 18.45 (-C-C=0-), 70.54 (-CH2O-), 42.60 (-NCH2CH2-), 26.90 (-NCH2CH2), 159.94, 146.93, 139.51 , 134.16, 132.37, 129.06, 128.69, 128.57, 127.58, 127.30, 126.58 and 1 15.56 ppm (C, arom)

Mass (MALDI): 521 (M ⁺ ) and 523 (M ⁺ +2).

Example 9: Synthesis of (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]- 3-propyl-thiazolidine-2,4-dione (If)

A mixture of (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazol idine- 2,4-dione (I _a ) (0.83 g, 2.0 mmol), propyl bromide (Re-Br) (0.27 mL, 3.0 mmol) and anhydrous potassium carbonate (1.38 g, 10.0 mmol) in acetone (50.0 mL) was refluxed for 24 hr. The solvent was evaporated under reduced pressure to obtain residue. The residue was poured onto crushed ice with stirring. The precipitated product was filtered, washed with water and dried. It was crystallised using methanol to yield (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-propy l- thiazolidine-2,4-dione (If) (0.72 g, 79.0 %) m. p. 133-135°C.

Analysis:

R _f : 0.55 (CHCh : MeOH : : 9: 1)

IR (KBr): 3035, 2917, 1736, 1683, 1598 and 1231cm ^"1

¾ NMR (CDC ): δ 0.92 (t, 3H, -NCH2CH2CH3), 1.66 (m, 3Η, -NCH2CH2CH3), 3.69 (t, 3H, -NCH2CH2CH3), 5.38 (s, 2H, -CH2O), 7.07 (d, 2Η, -CH arom), 7.40 (t, 1Η, -CH arom), 7.46 (t, 2Η, -CH arom), 7.50 (t, 2Η, -CH arom), 7.66(d, 2Η, -CH arom), 7.76 (d, 2Η, -CH arom), 7.83 (s, 1Η, -CH=) and 8.06 ppm (d, 2Η, -CH arom) ¹³ C NMR (CDCb): δ 193.14 (-00), 167.99 (-00, TZD), 166.41 (-OO, TZD), 132.84 (-CH=C-), 1 18.77 (-C-O0-), 70.56 (- H2O-), 42.62 (-N H2CH2CH3), 20.52 (-NCH2 H2CH3), 12.25 (-NCH2CH2CH3), 159.87, 146.93, 139.52, 133.77, 132.32, 129.08, 128.71, 128.58, 127.60, 127.31, 126.68 and 1 15.62 ppm (C, arom) Mass (MALDI): 456 (M ⁺ -l). Example 10: Synthesis of (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)- benzylidene]-3-(3-chloropropyl)- thiazolidine-2,4-dione (I )

A mixture of (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazol idine- 2,4-dione (I _a ) (0.83 g, 2.0 mmol), l-bromo-3-chloropropane (R ₇ -Br) (0.32 mL, 3.0 mmol) and dry potassium carbonate (1.38 g, 10.0 mmol) in acetone (50.0 mL) was refluxed for 24 hr. The solvent was removed under reduced pressure to obtain residue which was poured onto crushed ice with stirring. The product obtained was filtered, washed with water, dried and crystallised using methanol to yield (Z)-5-[4- (2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-(3-chloropropy l)-thiazolidine-2,4- dione (I _g ) (0.78 g, 79.7 %) m. p. 130-132°C.

Analysis:

R _f : 0.52 (CHCh : MeOH : : 9: 1)

IR (KBr): 3035, 2917, 1734, 1684, 1598, 1229 and 761cm ^"1

¾ NMR (DMSO-rf ₆ ): δ 2.07 (m, 2H, -NCH2CH2CH2-), 3.48 (t, 2H, - NCH2CH2CH2-), 3.82 (t, 2Η, -NCH2CH2CH2-), 5.32 (s, 2H, -CH2O-), 6.95 (d, 2Η, -CH arom), 7.35 (t, 1Η, -CH arom), 7.40 (t, 2Η, -CH arom), 7.42 (t, 2Η, -CH arom), 7.55 (d, 2Η, -CH arom), 7.67 (d, 2Η, -CH arom), 7.78(s, 1Η, -CH=) and 7.99 ppm (d, 2Η, -CH arom)

¹³ C NMR (DMSO-rf ₆ ): δ 193.14 (-C=0), 168.00 (-C=0, TZD), 166.41 (-C=0, TZD), 132.83 (- H=C-), 1 18.76 (-C-C=0-), 70.55 (-CH2O-), 41.87 (- NCH2CH2CH2-), 39.59 (-NCH2CH2 H2-), 30.68 (-NCH2CH2CH2-), 159.85, 146.93, 139.52, 133.74, 132.32, 129.08, 128.71, 128.59, 127.60, 127.31, 126.67 and 1 15.55 ppm (C, arom)

Mass (MALDI): 491 (M ⁺ ) and 493 (M ⁺ +2).

Example 11: Synthesis of (Z)-5-[4-(2-Biphenyl-4-yl-2-oxo-ethoxy)- benzylidene]-3-(3-bromopropyl)-thiazolidine-2,4-dione (Ih)

A mixture of (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazol idine- 2,4-dione (I _a ) (0.83 g, 2.0 mmol), 1,3-dibromopropane (Rs-Br) (0.32 mL, 3.0 mmol) and anhydrous potassium carbonate (1.38 g, 10.0 mmol) in acetone (50.0 mL) was refluxed for 24 hr. The solvent was evaporated under reduced pressure to obtain the residue. The residue was mixed stirred with crushed ice. The precipitated product was filtered, washed with water, dried crystallised using methanol to yield (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-(3-br omopropyl)- thiazolidine-2, 4-dione (I _h ) (0.84 g, 78.5 %) m. p. 1 10-1 12°C.

Analysis:

R _f : 0.53 (CHCh : MeOH : : 9: 1)

IR (KBr): 3030, 2946, 1741, 1682, 1597, 1232 and 760 cm ^"1

¾ NMR (CDCb): δ 2.16 (m, 2H, -NCH2CH2CH2-), 3.32 (t, 2H, -NCH2CH2CH2-

), 3.81 (t, 2Η, -NCH2CH2CH2-), 5.33 (s, 2H, -CH2O-), 6.96 (d, 2Η, -CH arom), 7.33

(t, 1Η, -CH arom), 7.40 (t, 2Η, -CH arom), 7.43 (t, 2Η, -CH arom), 7.55 (d, 2Η, -

CH arom), 7.68 (d, 2Η, -CH arom), 7.78 (s, 1Η, -CH=) and 7.99 ppm (d, 2Η, -CH arom)

¹³ C NMR (CDCb): δ 193.14 (-C=0), 166.41 (-C=0, TZD), 166.10 (-C=0, TZD), 132.83 (- H=C-), 1 18.76 (-C-CO-), 70.55 (- H2O-), 40.62 (-N H2CH2CH2-), 30.16 (-N CH2CH2CH2-), 29.54 (-NCH2CH2CH2-), 159.86, 146.29, 139.52, 133.78, 132.33, 129.08, 128.71, 128.59, 127.60, 127.31, 126.67 and 1 15.55 ppm (C, arom)

Mass (MALDI): 536 (M ⁺ ) and 538 (M ⁺ +2).

Example 12: Synthesis of (Z)-5-[4-(2-Biphenyl-4yl-2-oxo-ethoxy)- benzylidene]-3-butyl-thiazolidine-2, 4-dione (Ii)

A mixture of (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazol idine- 2,4-dione (I _a ) (0.83 g, 2.0 mmol), butyl bromide (R ₉ -Br) (0.32 mL, 3.0 mmol) and anhydrous potassium carbonate (1.38 g, 10.0 mmol) in acetone (60.0 mL) was refluxed for 24 hr. The solvent was evaporated under reduced pressure to obtain the residue which was poured onto crushed ice with stirring. The product obtained was filtered, washed with water and dried. It was crystallised using methanol to yield (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-3-butyl -thiazolidine-2, 4- dione (¾) (0.79 g, 79.2 %) m. p. 92-95°C.

Analysis:

R _f : 0.58 (CHCh : MeOH : : 9: 1) IR (KBr): 3031, 2925, 1748, 1686, 1600 and 1229 cm ^"1

¾ NMR (CDCb): δ 0.92 (t, 3H, -NCH2CH2CH2CH3), 1.33 (m, 2Η, - NCH2CH2CH2CH3), 1.60 (m, 2H, -NCH2CH2CH2CH3), 3.72 (t, 2H, - NCH2CH2CH2CH3), 5.38 (s, 2H, -CH2O), 7.02 (d, 2Η, -CH arom), 7.35 (t, 1Η, -CH arom), 7.45 (t, 2Η, -CH arom), 7.50 (t, 2Η, -CH arom), 7.59(d, 2Η, -CH arom), 7.71 (d, 2Η, -CH arom), 7.83 (s, 1Η, -CH=) and 8.06 ppm (d, 2Η, -CH arom)

1 ³ C NMR (CDCb): δ 193.18 (-C=0), 168.03 (-C=0, TZD), 166.57 (-C=0, TZD), 132.86 (-CH=C-), 1 19.24 (-C-C=0-), 70.56 (- H2O-), 41.80 (- NCH2CH2CH2CH3), 29.82 (-NCH2CH2CH2CH3), 19.97 (-NCH2CH2CH2CH3), 13.62 (-NCH2CH2CH2CH3), 159.70, 146.89, 139.52, 133.17, 132.20, 129.05, 128.69, 128.55, 127.56, 127.29, 126.84 and 1 15.49 ppm (C, arom)

Mass (ESI): 472 (M ⁺ +l).

Example 13: Synthesis of 4-[(Z)-5-{4-(2-Biphenyl-4yl-2-oxo-ethoxy)- benzylidene}-thiazolidine-2,4-dione-3-yl- methylj-benzoic acid (I _j )

A mixture of (Z)-5-[4-(2-biphenyl-4yl-2-oxo-ethoxy)-benzylidene]-thiazoli dine- 2,4-dione (I _a ) (0.83 g, 2.0 mmol), 4-(bromomethyl)benzoic acid (Rio-Br) (0.43 g, 2.0 mmol) and anhydrous potassium carbonate (1.38 g, 10.0 mmol) in acetone (50.0 mL) was refluxed for 24 h. The solvent was evaporated under reduced pressure to obtain residue. The residue was poured onto crushed ice with stirring. The precipitated product was filtered, washed with water and dried. It was crystallised from methanol to yield 4-[(Z)-5-{4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene}- thiazolidine-2,4-dione-3-yl-methyl]-benzoic acid (Ij) (0.86 g, 78.5 %) m. p. 235- 238°C.

Analysis:

R _f : 0.42 (CHCh : MeOH : : 9: 1)

IR (KBr): 3396, 3058, 2955, 1717, 1684, 1598 and 1270 cm ^"1

¾ NMR (DMSO-rf ₆ ): δ 4.66 (s, 2H, -NCH2-), 5.66 (s, 2Η, -CH2O-), 6.94(d, 2Η, - CH arom), 7.16 (d, 2Η, -CH arom), 7.40 (t, 1Η, -CH arom), 7.42 (t, 2Η, -CH arom), 7.47 (t, 2Η, -CH arom), 7.66 (d, 2Η, -CH arom), 7.75 (d, 2Η, -CH arom), 7.86 (s, 1H, -CH=), 7.98 (d, 2Η, -CH arom), 8.10 (d, 2Η, -CH arom) and 12.41 (br s, 1Η, - COOH exchangeable with D ₂ 0)

¹³ C NMR (DMSO-rf ₆ ): δ 194.79 (-C=0), 167.68 (-COOH), 167.27 (-C=0, TZD), 166.79 (-C=0, TZD), 132.23 (-CH=C-), 121.38 (-C-CO-), 70.50 (-CH2O- ), 32.75 (-NCH2-), 159.71 , 151.36, 144.06, 139.53, 137.60, 137.42, 133.89, 133.66, 133.37, 132.01, 128.89, 121.43 and 1 15.55 ppm (C, arom)

Mass (ESI): 550 (M ⁺ +l).

Example 14: Synthesis of 3-Acetyl-(Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)- benzylidene]-thiazolidine-2,4-dione (IK)

A mixture of (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazol idine- 2,4-dione (I _a ) (0.83 g, 2.0 mmol), acetic anhydride (R11-OCOCH3) (0.38 mL, 4.0 mmol) and pyridine (0.25 mL) in glacial acetic acid (60.0 mL) was refluxed for 4 hr. The mixture was poured on to the crushed ice with stirring. The precipitated product was filtered, washed with solution of hydrochloric acid (5%), water and dried. The residue was crystallised from methanol to yield 3-acetyl-(Z)-5-[4-(2- biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazolidine-2,4-di one (IK) (0.76 g, 83.1 %) m. p. 216-220°C.

Analysis:

R _f : 0.47 (CHCh : MeOH : : 9: 1)

IR (KBr): 3030, 2921, 1742, 1684, 1594 and 1227 cm ^"1

¾ NMR (DMSO-rf ₆ ): δ 2.08 (s, 3H, -COCH3), 5.42 (s, 2Η, -CH2O-), 6.95 (d, 2Η, -CH arom), 7.33 (t, 1Η, -CH arom), 7.39 (t, 2Η, -CH arom), 7.42 (t, 2Η, -CH arom), 7.58 (d, 2Η, -CH arom), 7.68 (d, 2Η, -CH arom), 7.70 (s, 1Η, -CH=) and 8.02 ppm (d, 2Η, -CH arom)

¹³ C NMR (DMSO-rf ₆ ): δ 193.49 (-C=0), 175.39 (-COCH3), 166.49 (-C=0, TZD), 164.72 (-C=0, TZD), 13 1.49 (-CH=C-), 1 18.76 (-C-CO-), 70.53 (-CH2O- ), 30.97 (-CO CH3), 159.85, 146.93, 139.52, 133.74, 132.32, 129.12, 128.72, 128.55, 127.39, 127.22, 126.67 and 1 15.55 ppm (C, arom)

Mass (ESI): 458 (M ⁺ +l). Example 15: Synthesis of Methyl 2-[(Z)-5-{4-(2-biphenyl-4-yl-2-oxo-ethoxy)- benzylidene}-thiazolidine-2,4-dione-3-yl] acetate (Ii)

A mixture of (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]- thiazolidine-2,4-dione (I _a ) (0.83 g, 2.0 mmol), methyl chloroacetate (R12-CI) (0.26 mL, 3.0 mmol) and anhydrous potassium carbonate (1.38 g, 10.0 mmol) in acetone (50.0 mL) was refluxed for 24 hr. The solvent was evaporated under reduced pressure to obtain the residue. It was poured onto crushed ice with stirring. The product obtained was filtered, washed with water, dried and crystallized from methanol to yield methyl 2-[(Z)-5-{4-(2-biphenyl-4-yl-2-oxo- ethoxy)-benzylidene}-thiazolidine-2,4-dione-3-yl]acetate (Ii) (0.80 g, 82.0 %) m. p. 155-159°C.

Analysis:

R _f : 0.52 (CHCh : MeOH : : 9.5 :0.5)

IR (KBr): 3032, 2941 , 1743, 1677, 1597 and 1215 cm ^"1

¾ NMR (DMSO-rf ₆ ): δ 3.78 (s, 3H, -CH2COOCH3), 4.45 (s, 2Η, -CH2COO-), 5.56 (s, 2Η, -CH2O), 7.06 (d, 2Η, -CH arom), 7.40 (t, 1Η, -CH arom), 7.47 (t, 2Η, -CH arom), 7.50 (t, 2Η, -CH arom), 7.62 (d, 2Η, -CH arom), 7.70 (s, 1Η, - CH=), 7.78 ppm (d, 2Η, -CH arom) and 8.06 ppm (d, 2Η, -CH arom)

1 ³ C NMR (DMSO-rf ₆ ): δ 193. 14 (-C=0), 167.58 (-CH2COO-), 166.34 (-C=0, TZD), 165.73 (-C=0, TZD), 132.87 (-CH=C-), 1 18.57 (-C-C=0-), 70.57 (- CH2O-), 60.15 (-CH2COO-), 40.82 (-CH2COOCH3), 159.96, 146.89, 139.52, 134.26, 132.37, 129.08, 128.71 , 128.57, 127.58, 127.3 1 , 126.59 and 1 15.58 ppm (C, arom)

Mass (ESI): 488 (M ⁺ +l).

Example 16: Synthesis of Ethyl 2-[(Z)-5-{4-(2-biphenyl-4-yl-2-oxo-ethoxy)- benzylidene}-thiazolidine-2,4-dione-3-yl] acetate (I _m )

A mixture of (Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]-thiazol idine- 2,4-dione (I _a ) (0.83 g, 2.0 mmol), ethyl chloroacetate (R13-CI) (0.32 mL, 3.0 mmol) and anhydrous potassium carbonate (1.38 g, 10.0 mmol) in acetone (50.0 mL) was refluxed for 12 hr. The solvent was removed under reduced pressure to obtain the residue. The residue was poured onto crushed ice with stirring. The product obtained was filtered, washed with water and dried. It was crystallised from methanol to yield ethyl 2-[(Z)-5-{4-(2-biphenyl-4yl-2-oxo-ethoxy)- benzylidene}-thiazolidine-2,4-dione-3-yl] acetate (I _m ) (0.83 g, 83.2 %) m. p. 126-130°C.

Analysis:

R _f : 0.54 (CHCh : MeOH = 9.5 : : 0.5)

IR (KBr): 3032, 2919, 1736, 1685, 1599 and 1229 cm ^"1

¾ NMR (CDCb): δ 1.27 (t, 3H, -COOCH2CH3), 4.21 (q, 2Η, -COOCH2CH3), 4.47 (s, 2H, -CH2COO-), 5.39 (s, 2Η, -CH2O), 7.03 (d, 2Η, -CH arom), 7.40 (t, 1Η, -CH arom), 7.47 (t, 2Η, -CH arom), 7.50 (t, 2Η, -CH arom), 7.63 (d, 2Η, -CH arom), 7.69 (s, 1Η, -CH=), 7.88 (d, 2Η, -CH arom) and 8.06 ppm (d, 2Η, -CH arom)

¹³ C NMR (CDCb): δ 193.14 (-C=0), 167.59 (-CH2COO-), 166.33 (-C=0, TZD), 165.73 (-C=0, TZD), 132.85 - H=C-), 1 18.58 (-C-CO-), 70.57 (-CH2O-), 62.15 (- H2COO-), 42.12 (-COO H2-), 14. 10 (-COOCH2CH3), 159.96, 146.89, 139.53, 134.26, 132.37, 129.07, 128.71, 128.57, 127.59, 127.31, 126.60 and 1 15.58 ppm (C, arom)

Mass (ESI): 502 (M ⁺ +l).

Example 17: Synthesis of [(Z)-5-{4-(2-Biphenyl-4-yl-2-oxo-ethoxy)- benzylidene}-thiazolidine-2,4-dione]-acetic acid (I _n )

A mixture of ethyl 2-{(Z)-5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)-benzylidene]- thiazolidine-2,4-dione-3-yl } -acetate (I _m ) (1.0 g, 2.4 mmol), glacial acetic acid (R14-H) (25.0 mL) and hydrochloric acid (12N, 5.0 mL) was refluxed for 2 hr. The solvent was removed under reduced pressure to obtain the residue. The residue was poured onto crushed ice with stirring. The product obtained was filtered, washed with water, dried and crystallised from methanol to yield [(Z)-5-{4-(2-biphenyl-4- yl-2-oxo-ethoxy)-benzylidene}-thiazolidine-2,4-dione]-acetic acid (I _n ) (3.31 g, 70.0 %) m. p. 228-232°C. Analysis:

R _f : 0.39 (CHCh : MeOH : : 9: 1)

IR (KBr): 3421, 3032, 2980, 1736, 1686, 1599 and 1218 cm ^"1

¾ NMR (DMSO-rf ₆ ): δ 4.44 (s, 2H, -CH2COOH), 5.51 (s, 2H, -CH2O-), 7.05 (d, 2Η, -CH arom), 7.40 (t, 1Η, -CH arom), 7.43 (t, 2Η, -CH arom), 7.47 (t, 2Η, -CH arom), 7.65 (d, 2Η, -CH arom), 7.70 (s, 1Η, -CH=), 7.75 (d, 2Η, -CH arom), 8.09 (d, 2Η, -CH arom) and 12.21 ppm (br s, 1Η, -CH2COOH exchangeable with D2O) ¹³ C NMR (DMSO-rf ₆ ): δ 193.30 (-C=0), 176.30 (-CH2COOH), 168.27 (-C=0, TZD), 167.87 (-C=0, TZD), 132.97 (-CH=C-), 121.21 (-C-C=0-), 70.50 (-CH2O- ), 47.28 (-CH2COOH), 159.71 , 146.41 , 132.03, 129.10, 128.70, 128.55, 127.40, 127.22, 126.56 and 1 15.55 ppm (C, arom)

Mass (ESI): 496 (M ⁺ +Na).

BIOLOGICAL EVALUATION

1. Measurement of In Vitro Protein Tyrosine Phosphatase IB (PTP IB) Inhibitory Activity:

The PTP IB drug discovery assay kit was purchased from Enzo Life Sciences, which is a colorimetric, non-radioactive assay designed to measure the phosphatase activity of purified PTP IB. The kit composed of human, recombinant PTP IB (residues 1 -322; MW=37.4 kDa), expressed in E. coli. The detection of free phosphate released was based on the classic Malachite green assay and offers the advantages of convenient, single step detection and excellent sensitivity, without radioactivity. The [pTyrl l46] phosphorylated- peptide, corresponding to the sequence 1 142-1 153 of the insulin receptor β- subunit domain that must be auto phosphorylated to achieve full receptor kinase activation, was used as substrate for the inhibition assays. This "activation loop" was the target for regulators of PTP IB. All assays were performed at 30°C in a 96-well microtitre plate [PTP1B Tyrosine Phosphatase Drug Discovery Kit Manual. Available from URL: http://www.enzolifesciences.com/fileadmin/enzo/BML/ak822.pdf l.

Assay procedure: Assay buffer (35.0 μΐ) was added to each well in microtitre plate and warmed to assay temperature i. e. 30°C. Test sample/inhibitors (10.0 μΐ) at various concentrations were added to appropriate well. PTP IB enzyme solution (5.0 μΐ) was added to each well and enzymatic reaction was initiated by adding warmed substrate (50.0 μΐ) followed by incubation at 30°C for 30 min. After incubating wells for desired duration, reaction was terminated by addition of BIOMOL RED™ Reagent (BML-KI468) (25.0 μΐ). Mixing was carried out thoroughly by repeated pipetting with care to avoid producing bubbles. Color was allowed to develop at 30°C for 20 min. The amount of inorganic phosphate released from the peptide was determined by measuring the absorbance at 620 nm on a micro plate-reading spectrophotometer and the ICso values were calculated by a regression analysis of the linear portion of the inhibition curves [PTP IB Tyrosine Phosphatase Drug Discovery Kit Manual. Available from URL: http://www.enzolifesciences.com/fileadmin/enzo/BML/ak822.pdf 1.

The results of PTP IB inhibitory activities of biphenyl derivatives (I _a -n) are presented in Table 2. Among the series, compound Ij emerged as the most potent with ICso -5.90 μΜ as compared to reference standard Suramin having IC50—11.10 μΜ. In addition to biphenyl moiety, Ij also bears a phosphotyrosine mimic domain at 'N-3 ' of TZD ring. Compound I _n bearing acetic acid at 'N-3 ' of TZD also exhibited potent inhibitory activity (ICso-17.47 μΜ). Compound I _a bearing structural features of glitazones also exhibited moderate inhibitory activity. Substitution at 'N-3 ' with methyl resulted in compound (lb) with slight improvement of potency. Further increase in chain length from ethyl (I _c ) to butyl (Ii) resulted in compounds with decrease in potency. Compounds having electronegative halogen substituents exhibited better PTP IB inhibitory activity as compared with unsubstituted alkyl chain. Compound (Ik) bearing acetyl substitution also exhibited potent inhibitory activity. Ethyl and methyl esters (Ii, Im) were less active as compared to acid derivative (I _n ).

Table 2: In vitro PTP IB inhibitory activities of 5-[4-(2-biphenyl-4-yl-2-oxo- ethoxy)-benzylidene]-thiazolidine-2,4-dione derivatives (I _a -n

Compound ICso (μΜ)

I, 22.515 lb 19.397 Ic 28.204

Id 31.627

Ie 30.967

If 42.659

Ig 33.236

Ih 28.204

Ii 48.150

Ij 5.897

Ik 25.263

Ii 42.320

Im 30.495

In 17.471

Suramin 11.104

2. In Vivo Anti-Hyperglycemic Activity:

The anti-hyperglycemic activity testing of compounds was determined using Streptozotocin-Nicotinamide (STZ-NA) induced diabetic mice model [Badole, S. L.; Bodhankar, S. L. Antidiabetic activity of cycloart-23-ene-3beta, 25-diol (B2) isolated from Pongamia pinnata (L. Pierre) in streptozotocin- nicotinamide induced diabetic mice. Eur. J. Pharmacol. 2010, 632, 103-109]. Pioglitazone was taken as reference standard.

Animals: Mice

Species: Albino mice of Laca strain bred

Sex: Male

Body weight: 25±5 g

Age: 8-10 weeks

Animal feed and housing: Animals were housed in polypropylene cages. They were housed (six mice per cage) under standard (25 ± 2°C, 60-70% humidity) laboratory conditions, maintained on a 12 hr natural day-night cycle, had ad libitum access to standard food and water. The bedding material of cages was changed regularly.

Selection of animals: Only animals satisfying the conditions for body weight, age, non- infected/ non-wounded, and showing no abnormal behaviour were included in the study. Animals were acclimatized to laboratory conditions before the experiment. Animal handling was performed as per Good Laboratory Practice (GLP) and as per applicable National/International guidelines.

Drugs and reagents: Streptozotocin (Sigma Chemical Co., USA), Nicotinamide (Hi -Media), Tween-80 (Research-Lab, India) and D-Glucose (S. D. Fine-Chem. Ltd., India) were procured from respective vendors. A glucose oxidase peroxidase diagnostic enzyme kit was purchased from Span Diagnostic Chemicals, India. Streptozotocin was dissolved in citrate buffer (pH 4.5) and nicotinamide was dissolved in normal physiological saline.

Preparation of drug and dose: All the compounds as well as reference standard were administered at a fixed dose of 30 mg/kg body weight orally as suspension in carboxy methyl cellulose (CMC).

Duration of study: 7 days from the 0 hr serum glucose level of diabetic mice.

Induction of diabetes and determination of serum glucose: T2DM was induced in overnight fasted mice by a single intraperitoneal injection (i.p.) of STZ (45 mg/kg body weight) 15 min. after the i.p. administration of 1 10 mg/kg body weight of nicotinamide. Animals were fed with glucose solution (5%) for 12 hr to avoid hypoglycemia. The collected blood samples were placed in Eppendorffs tube (1.5 mL). The serum was separated by centrifugation maintained at 4 ^° C and run at speed of 7000 rpm for 15 min. Serum (10.0 μ ,) and working reagent (GOD-POD) (1.0 mL) were mixed and incubated for 15 min. at 37 ^° C [Badole, S. L.; Bodhankar, S. L. Antidiabetic activity of cycloart- 23-ene-3beta, 25-diol (B2) isolated from Pongamia pinnata (L. Pierre) in streptozotocin-nicotinamide induced diabetic mice. Eur. J. Pharmacol. 2010, 632, 103-109]. The absorbance of Sample (A _s ) and Standard (Astd) provided by manufacturer were measured against blank at 505 nm. Glucose was estimated by using the formula:

Glucose (mg/dl) = A _s /A _std x 100

Whereas A _s = Sample reading; Astd = Standard reading

The elevated glucose levels in serum determined at 72 hr confirmed hyperglycemia. Animals with blood glucose concentration more than 250 mg/dl were selected for the anti-hyperglycemic activity.

Acute study: In acute study, animals were fasted overnight and the fasting SG, 0 hr, levels were determined. All the compounds were administered at a fixed dose of 30 mg/kg body weight orally (homogenized suspension in 0.5% carboxy methyl cellulose (CMC) and permissible amounts of Tween 80). Animals of vehicle treated group were given an equal amount of 0.5% CMC and those of control group were kept as such. Blood samples were removed from all animals at 2, 4, 6 and 24 hr by retro orbital puncture method and percentage reduction in serum glucose was calculated with respect to control group. A 10% reduction in serum glucose level versus control group was considered as a positive screening result [PTP IB Tyrosine Phosphatase Drug Discovery Kit Manual. Available from URL: http://www.enzolifesciences.com/fileadmin/enzo/BML/ak822.pdf 1. Sub-acute study: In sub-acute study, animals were fasted overnight and the fasting SG, 0 day, levels were determined. Now the compounds were administered at a fixed dose of 30 mg/kg orally (homogenized suspension in 0.5% CMC and permissible amounts of Tween 80 for 7 days at a fixed time. After 7 ^th day, blood samples were collected from all animals and percentage change in SG was calculated. The data obtained were analyzed by one-way ANOVA followed by Dunnett test. The results were expressed as mean, ± standard error of mean (SEM) for each group, p < 0.001 was considered as statistically significant. Administration of I _a -n reduced serum glucose level (SGL) (except ) significantly (P < 0.001) in diabetic mice as compared to control group (Table 3 and Fig 1).

Table 3: Anti-hyperglycemic activity of 5-[4-(2-biphenyl-4-yl-2-oxo-ethoxy)- benzylidene]-thiazolidine-2,4-dione derivatives (I _a -n) in streptozotocin- nicotinamide (STZ-NA) induced diabetic mice.

Effect of Ia-n (30 mg/kg) on SGL in diabetic mice

Compounds

2 hr 4 hr 6 hr 24 hr 7 ^th day

Control 1.37±0.31 2.84±0.09 2.26±2.16 5.24±1.49 13.08±1.08 Pioglitazone -35.60±1.88 -39.17±2.35 -28.60±0.63 -16.66±2.41

34.81±0.71 la -30.49±1.59 -29.09±2.74 -26.72±3.65 -24.62±2.50

29.93±1.68 lb -26.87±0.37 -26.75±4.09 -15.65±4.27 5.97±4.51

25.08±1.88

Ic -19.61±2.45 -22.53±3.35 -24.82±2.49 1.34±0.64

20.01±1.39

Id -27.73±2.08 -22.85±2.99 -26.86±5.80 -20.16±1.25

26.32±2.92

Ie -29.51±1.80 -26.12±5.96 -23.79±4.49 -25.76±4.66

27.33±2.87

If -22.07±5.07 -36.48±1.10 -30.63±1.83 -12.94±1.56

28.19±3.30

Ig -20.75±4.58 -27.71±4.66 -18.79±2.92 -16.31±4.63

27.65±3.79 Ih -28.81±3.08 -34.30±0.89 -35.38±3.13 -22.97±3.64

31.05±1.33 Ii -12.31±0.93 -12.37±3.28 -12.66±2.88 -8.76±1.51

1 1.82±2.83

Ij -38.63±1.15 -38.86±1.22 -38.19±3.63 -34.84±2.17

37.54±3.28

Ik -27.69±3.50 -30.01±1.61 -30.57±2.43 -26.54±4.76

31.90±2.33

Ii -27.61±2.23 -28.84±2.39 -30.80±3.74 -26.74±2.50

28.01±2.69

Im -29.13±2.55 -29.57±0.62 -31.10±3.37 -25.81±2.47

26.71±3.92

In -26.22±4.1 1 -25.22±3.33 -29.86±4.46 -25.56±3.92

26.20±3.50

Compound Ij exhibited potent glucose lowering activity as compared to reference standard Pioglitazone at all thetime intervals. I _a bearing free acidic proton with TZD also exhibited potent activity which can be attributed due to structural features of glitazones. Introducing alkyl substituent resulted in compounds (lb, I _c and Ii) with decreased activity while alkyl chain bearing electronegative substituent resulted in compounds with better activity. Introduction of acetyl (Ik) also resulted in compound with potent anti- hyperglycemic activity. Compound (I _n ) bearing acetic acid substituent also exhibited very potent anti-hyperglycemic activity. Methyl and ethyl esters (Ii, Im) of acetic acid derivative (I _n ) also exhibited maximal activity at 6 hr.

3. Effect on body weight in diabetic mice:

During the study period of 7 days, the mice were weighed and their body weights were recorded. From this data, mean change in body weight and S.E.M. were calculated. In control mice, a trend of decrease in body weight was observed during the 7 days treatment period which can be attributed to diabetes. Pioglitazone treatment resulted in increase in body weight. Table 4: Effect on body weight after treatment with 5-[4-(2-biphenyl-4-yl-2-oxo- ethoxy)-benzylidene]-thiazolidine-2,4-dione derivatives (I _a -n) in diabetic mice

Body Weight (g)

S. No.

O Day 7 ^th Day

Control 29.33±0.47 26.33±0.24

Pioglitazone 24.33±2.09 26.67±1.93

la 27.33±2.05 28.00±1.47 lb 28.00±1.08 29.33±0.94

Ic 28.00±0.41 28.67±0.24

Id 27.33±2.72 28.67±2.90

Ie 26.67±1.89 28.00±2.12

If 25.67±0.85 26.00±1.22

Ig 25.00±2.86 25.67±2.36

Ih 26.00±0.41 27.67±0.47

Ii 29.33±0.24 29.22±0.41

Ij 26.00±1.87 26.67±1.93

Ik 28.33±1.70 28.67±1.25

Ii 26.33±1.03 25.00±1.78

Im 28.33±1.89 27.67±2.01

In 25.33±1.25 26.00±1.22

The most potent anti-hyperglyemic compound Ij, showed marginal increase in the body weight which indicated a beneficial effect of the ij administration (Fig 2).

4. Histopathology of mouse pancreas:

The isolated pancreas were trimmed into small pieces and preserved in 10.0% formalin for 24 hr. Specimens were cut in section of 3-5 μπι in thickness and stained by hematoxyline-eosin stain. The specimen was mounted by disterene phthalate xylene (DPX). The photomicrographs of each tissue section were observed using cell imaging software for life science microscopy (Olympus soft imaging solution GmbH, Munster, Germany). Pancreatic tissue was processed for Gomori staining for morphology of pancreatic β cells [Gomori, G. L. Gomori's aldehyde fuschin stain (special stain for β cells). Am. J. Clin. Pathol. 1950, 20, 665-666].

Histological analysis by Gomori staining of non-diabetic mouse pancreas showed normal histological structure, depicted average sized islets and normal sized β cells (Fig 3A). Enlarged and inflamed cells of islets, destruction of the β cells, damaged cell membrane, along with necrotic cells were seen in diabetic control animals (Fig 3B). However, intact cell membrane and normal sized cells were observed in Pioglitazone treatment group which indicated a significant protection against diabetes induced histopathological changes (Fig 3C).

In histopatological analysis, the most potent compounds (Ij) showed patterns similar to that of Pioglitazone i.e. intact cell membrane and nucleus were clearly visible (Fig 3D) indicated similar behavior in terms of protection against diabetes induced histopathological changes.