Abstract
The present study was conducted for the isolation and characterization of gymnemic acid from indigenous Gymnema sylvestre leaves. Four different methods of extraction were employed to obtain the maximum yield. The method where the defatted leaves were extracted under continuous hot extraction in Soxhlet apparatus with 95% ethanol gave the maximum yield of gymnemic acid (6.15% m.f.b.). The yield was minimum in aqueous extraction method (1.66% m.f.b.) Gymnemic acid was purified by preparative chromatographic method in two solvent systems. Its circular Thin Layer Chromatography (TLC) also resulted in to a single concentric ring. Gymnemic acid was hydrolyzed by two methods to confirm its glycosidic nature. The glycon portion thus obtained gave a positive test with Fehling’s solution showing the presence of reducing sugars and indicating that gymnemic acid was a glycoside. The aglycone portion on thin layer chromatographic examination in two systems showed the presence of four genins. Therefore the gymnemic acid was a glycoside and was triterpenoid saponins in character. The resinous extract obtained on defatting the leaves with the petroleum ether in first method of extraction separated out in to four spots on TLC. The presence of stigmasterol, -amyrin, -amyrin acetate and lupeol was indicated when the reference samples of these compounds were run on the same chromatoplate.
