INTRODUCTION:

Diabetes mellitus¹is a heterogeneous group of diseases, characterized by a state of chronic hyperglycemia², resulting from a diversity of etiologies, environmental and genetic, acting jointly. The underlying causes of diabetes are the defective production or action of insulin, a hormone that controls carbohydrate, fat and protein metabolism. Characteristically diabetes is a long-term disease with variable clinical manifestations and progression, chronic hyperglycemia from whatever cause, leads to a number of complications including cardiovascular such as hypertension, renal, neurological such as anxiety, stress, ocular and other such inter-current infections³.Thiazolidones and thiazolidinediones were the first parent compounds in which thiazole ring was recognized. The thiazolidinediones⁴used in oral combination therapy in management of patients with type II diabetes who have insufficient glycaemic control despite maximal tolerated dose of oral mono-therapy with either metformin or sulphonylurea. These observations promoted us to synthesis the title compound with presumption that incorporation of aromatic amines and thiazolidinediones nuclei would produce new compounds with significant antidiabetic properties.

MATERIAL AND METHODS:

Antidiabetic activity⁵:

The acclimatized animals were kept fasting for 24 hrs with water ad libitm and Alloxan Monohydrate (120 mg/Kg i.p) in normal saline was administered. After one hour of alloxan administration the animals were given adlibitm.

A 5% dextrose solution was given in feeding bottle for a day to overcome the early hypoglycemic phase. The blood glucose regulator was monitored after alloxination by withdrawing a drop of blood from the tail vein by Tail tipping method. The blood was dropped on the dextrostrix reagent Pad. The strip was inserted into microprocessor digital Blood Gluco Meter and readings were noted.

After 72 hrs rats having blood glucose level beyond 150-mg/dl of blood were selected for the study and divided into 6 groups. The quantity of 2,4-thiazolidinedione derivatives equivalent to average human intake 200-mg/ kg at a time was calculated for single dose 36 mg/kg (for acute study). The test compounds were administered orally by mixing with CMC (0.25 %) solution. The blood glucose level was monitored at different times 0 hr, 1hr, 3hr, and 6hr respectively. The antidiabetic activities of the synthesized compounds are shown in Table 1.

Table No: 1 Antidiabetic activities of synthesized compounds

Compound.	Blood glucose level mg/dl (Mean ± SE)
Compound.	0 hour	1 hour	3 hour	6 hour
B₁	296.7±4.05	292.7± 4.25	187.7±15.6**	148.0± 7.8**
B₂	300.5±0.12**	134.5± 2.72	123.5± 5.23	116.5±5.90**
B₃	320.5±15.81**	145.5± 2.26	137.0± 3.80	123.5± 1.10*
B₄	213.5±8.78	140.7± 3.30*	106.3± 6.91	95.75±6.06**
B₅	283.5±43.76	205.75±49.7	166.3± 38.92	124.5±13.16*
B₆	295.3±7.42*	233.3±23.8	193.0±13.86	159.3±12.12
B₇	289.2±9.98	280.6±9.29*	244.2±9.04**	180.4±1.99**
B₈	203.7±13.79	156.2±13.5	123.3±4.3*	101.5±4.5**
B₉	217.0±3.01	213.0± 2.53	164.3± 4.74*	146.0±2.19**
Control	123.3± 6.00	120.7± 5.54	122.3± 5.81	123.0± 6.4
Standard	385.8±21.37	230.8±12.35**	156.8±10.87**	93.4±4.98**

Statistical analysis is done by One-way ANOVA followed by Dunnet’s‘t’ test. Standard Drug: Glibenclamide. ** P<0.01 (considered as significant), *P<0.05

Table No: 2Physical data of synthesized compounds

Comp.	Molecular formula	Mol. Wt.	m.p. (⁰C)	Yield (%)	Elemental analysis Calculated(found)
Comp.	Molecular formula	Mol. Wt.	m.p. (⁰C)	Yield (%)	C	H	N
B₁	C₁₈H₁₃N₅O₄S₃	459.53	174-176	68%	47.05 (46.68 )	2.85 ( 2.57 )	15.24 (14.96)
B₂	C₁₈H₁₁N₅O₆S₃	489.51	180-182	54%	44.17 (43.89 )	2.27 (1.97 )	14.31 (13.94 )
B₃	C₂₀H₁₄N₄O₄S₃	470.55	118-120	62%	51.05 ( 50.76)	3.00 (2.80 )	11.91 (11.75 )
B₄	C₁₃H₁₃N₆O₄S₂	381.41	199-200	64%	40.94 ( 40.77)	3.44 (3.14 )	22.03 ( 21.56)
B₅	C₁₅H₁₃N₃O₄S₂	363.42	241-243	56%	49.58 (49.18 )	3.61 ( 3.33)	11.56 ( 11.26)
B₆	C₁₅H₁₇N₃O₅S₂	383.43	234-237	52%	46.99 (46.63 )	4.47 (4.31 )	10.96 (10.78 )
B₇	C₁₆H₁₁N₂O₄S₂Cl	394.86	222-223	56%	48.67 (48.37 )	2.81 ( 2.56)	7.09 (6.88 )
B₈	C₁₄H₁₀N₄O₄S₂	362.39	180-182	55%	46.40 ( 46.32)	2.78 (2.48 )	15.46 ( 15.21)
B₉	C₁₂H₁₀N₄O₄S₃	370.43	192-193	63%	38.91 ( 38.55)	2.72 (2.38 )	15.12 ( 14.96)

All the compounds gave satisfactory elemental analysis. ± 0. 4

Table No: 3 Infra Red/ ¹H-NMR spectral study of the synthesized compounds.

Compd.	IR (cm^-1)	¹H-NMR (δ, ppm)
B₁	3096.6 (Ar-CH-str.), 1691.5 (C=O-str.), 1286.4 (C-N-str.), 3452.6 (N -H–str.), 620.8 (C-S-str.)	---
B₂	3098.2 (Ar-CH-str.), 1694.5 (C=O-str.), 1286.4 (C-N-str.), 1377.1 (N0₂–str.),628.8 (C-S-str.)	---
B₃	3094.6 (Ar-CH-str.), 1694.5 (C=O-str.), 1286.4 (C-N-str.), 1639.4 (C= C–str.),628.8 (C-S-str.)	---
B₄	3095.4 (Ar-CH-str.),1694.5 (C=O-str.), 1298.0 (C-N-str.),3394.6 (N -H–str.), 612.7 (C-S-str.)	7.42-7.75(4H,Ar-CH ) 6.13(1H, NH) 7.41(1H, tetrazole) 3.46(1H-Benzylidine )
B₅	3069.5 (Ar-CH-str.),1693.4 (C=O-str.), 1299.4 (C-N-str.), 3408.2 (N -H–str.), 612.8 (C-S-str.)	7.34-7.7 (4H,Ar-CH ) 5.16(1H, NH) 3.4-3.6(10H,Piperidine) 2.9(1H-Benzylidine)
B₆	3084.5(Ar-CH-str.),1695.2 (C=O-str.), 1299.6 (C-N-str.), 3408.2 (N -H–str.), 617.4 (C-S-str.)	7.34-7.6(4H,Ar-CH ) 5.15(1H, NH) 3.06-3.08(8H,Morpholine.) 3.8(1H-Benzylidine)
B₇	3041.5 (Ar-CH-str.), 1698.2 (C=O-str.), 1301.3 (C-N-str.), 3408.2 (N -H–str.), 619.8 (C-S-str.)	---
B₈	3041.5 (Ar-CH-str.), 1696.2 (C=O-str.), 1300.8 (C-N-str.), 3406.4 (N -H–str.), 619.8 (C-S-str.)	---
B₉	3041.5 (Ar-CH-str.), 1698.4 (C=O-str.), 1300.8 (C-N-str.), 3409.2 (N -H–str.), 619.8 (C-S-str.)	---

The mixture was stirred for 15 min to form a white precipitate, accompanied by considerable cooling. To the contents of the flask was then added slowly 60 mL of concentrated hydrochloric acid from a dropping funnel, the flask was then connected with a reflux condenser and gentle heat applied to effect complete solution, after which the reaction mixture was stirred and refluxed for 8-10 hrs at 100-110°C. On cooling the contents of the flask solidified to a cluster of white needles. The product was filtered and washed with water to remove traces of hydrochloric acid and dried. It was purified by recrystallization from ethyl alcohol. Yield 85%, m.p.123-125 °C.

Synthesis of 5-benzylidine 2,4-thiazolidinedione: (II)

In a 250 mL three necked round-bottomed flask provided with a Dean-Stark apparatus, benzaldehyde (20 gm, 0.188 mol) and 2,4-thiazolidinedione (22 gm, 0.188 mol) were together suspended in ethanol. To

this a catalytic amount of piperidine (1mL) was added. The mixture was stirred and refluxed. After the complete removal of water and when the temperature reached above 110°C the reaction mixture was stirred for a further 1 hr. On cooling the product precipitated out from ethanol. The compound was filtered and washed with cold dry toluene and dry ethanol. Yield 93%, m.p. 240-242 °C.

Synthesis of 4'-chlorosulphonyl-benzylidene 2, 4-thiazolidinedione:(III)

Benzylidine-2, 4-thiazolidinedione (8 gm, 0.0388 mol) was placed in a 100mL round-bottomed flask equipped with a condenser and a dropping-funnel. Chlorosulphonic acid (18.08 gm, 0.155 mol) was added at room temperature using the dropping funnel. The reaction was found to be exothermic. After addition of Chlorosulphonic acid was over the reaction mass was refluxed for 1 hr on a water bath. The reaction was cooled and poured in a thin stream with stirring into crushed ice contained in a one litre beaker. The product was filtered and dried^6,7. The product was purified by recrystallization from ethanol. Yield 68%, m.p. 180-181°C.

Synthesis of (Z)-N-(5-(4-aminophenyl)-1,3,4-thiadiazole-4-((2,4-dioxothiazolidin-5-ylidene) benzenesulfonamide. (B₁):

A mixture of 5-(4-Chlorosulfonyl benzylidene)-2,4- thiazolidenedione (0.01 mole) and 5-(4-aminophenyl)-N-ethyl-1,3,4-thiadiazole-2mine were taken in a beaker and made a homogenous paste. The paste was exposed to microwave irradiation for 1-2 min, at intervals of 30 seconds. After the completion of reaction, ice-cold water was added to the reaction mixture and precipitated solid was separated by filtration, dried and recrystallized from ethanol to get (Z)-N-(5-(4-aminophenyl)-1,3,4-thiadiazole-4-((2,4-dioxothiazolidin-5 ylidene) benzenesulfonamide (B₁).Yield68%, m.p. 174-176°C. The compounds B₂-B₉were synthesized following a similar procedure. The physical data of the synthesized compounds are shown in Table 2.

RESULT AND DISCUSSION:

A series of thiazolidinedione derivatives were synthesized. The structures of these compounds were established by means of IR,¹H-NMR and elemental analysis. Infra Red/ ¹H-NMR spectral study of the synthesised compounds are shown in Table 3.

The title compounds were screened for their antidiabetic activity by Alloxan induced tail tipping method. The Albino rats of either sex weighing between 150-200 g were selected. The blood glucose level was induced and the study was carried out in six difference groups.

Out of Nine compounds synthesized (B₁-B₉). The compounds B₁, B₂, B₄, B₇, B₈, and B₉ have shown significant antidiabetic activity. B₃, B₅and B₆ have shown moderate antidiabetic activity on oral administration. The results were calculated by measuring the mean SE ± and ‘p’ value with the suitable molecular manipulations of the synthesized compounds, and the attracting significance of thiazolidinediones can be better explored in future as a potent candidate for diabetus mellitus. It is also note worthy that the toxicity studies have been carried out for these compounds and least toxicity is being found in all these compounds.

ACKNOWLEDGEMENT:

Authors wish to thank Honorable Shri.Radhakrishna Vikhe Patil, Minister for Education, Law and Justice govt. of maharashtra for his constant encouragement and support. Sincere thanks to Mr. Sanjay Bhawar for his help in carrying out antidiabetic activity.

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6. Pattan S.R., Khade A.B., Pawar P.D., Tarnalli A.D., Kittur B.S.and Borkar S.D, Synthesis of 2-amino [5’-(4-sulphonyl benzylidene)-2,4-thiazolidinedione]-6-fluro benzothiazoles as antiinflammatory agents. Indian Journal of Heterocyclic Chemistry, 2007; 16: 299-300.

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Received on 24.04.2009 Modified on 13.05.2009

Asian J. Research Chem. 2(2): April.-June, 2009, Page 123-126