Phytochemical and antidiabetic activity investigations of tetracera indica merr.

Abstract

The work embodied in the present thesis relates to the studies on the biological activity and chemical constituents of the leaves of Tetracera indica Merr. (Dilleniaceae) (mempelas paya) and is presented in two parts. Part A involves studies on the antidiabetic activity of aqueous (AQ) and methanol (MeOH) extracts of the leaves of T. indica Merr. in vivo and isolation of the active principle (wogonin). Part B describes the isolation and characterization of chemical constituents from MeOH extracts of the leaves of T. indica Merr. Part A comprises of investigation of antidiabetic activity of the aqueous (AQ) and methanol (MeOH) extracts of the leaves of T. indica along with the active principle isolated from MeOH extract in vivo in alloxan induced diabetic and normal male albino rats (Sprague Dawley strain (SD)). Two doses of each extract 250 and 500 mg/kg b.w. and 0.5 and 1mg/kg b.w in the case of active principle (wogonin) were evaluated. Both AQ and MeOH extracts exhibited significant anti-hyperglycemic activity in alloxan induced diabetic rats, however in normal rats, no hypoglycemic activity was observed, when compared with both +ve and –ve controlled groups except that of AQ extract which exhibited hypoglycemic activity in normal rats at 250 mg/kg b.w. The antidiabetic activity was also found to be comparable to that of the effect produced by glibenclamide (GLBC) (0.25 mg/kg b.w.). The LD50 of both AQ and MeOH extracts was found to be more than 5000 mg/kg body weight and no lethal toxicity was observed within this range. Wogonin was isolated as an active principle from MeOH extract which revealed antihyperglycemic activity in vivo comparable to GLBC. Part B deals with the isolation and structure elucidation of the active principle (wogonin) along with other chemical constituents from MeOH extract of the leaves of T. indica Merr. MeOH extract upon repeated silica gel and sephadex LH-20 column chromatography afforded two terpenoids and six flavonoids viz., mixture of glycosides of ?-sitosterol and stigmasterol, betulinic acid; 5,7-dihydroxy-8-methoxyflavone (wogonin); 5,7,8- trihydroxyflavone (norwogonin); 4’,5,7-trihydroxy-8-methoxyflavone (isoscutellarein methyl ether); 4’3,5,7,-tetrahydroxyflavone (kaempferol); 3’,4’3,5,7- pentahydroxyflavone (quercetin) and 5-hydroxy-7-methoxyflavone (techtochrysin). Occurrence of norwogonin, isoscutellarein methyl ether, kaempferol, quercetin, techtochrysin and isomeric mixture of ?-sitosterol and stigmasterol is being reported for the first time from the leaves of T. indica Merr. Keywords: Tetracera indica Merr., Dillineceae, Antidiabetic activity in vivo, active principle, other phytoconstituents.