Gymnemic Acid-Rich Fraction from Gymnema Sylvestre Leaves Ameliorates Post Prandial Hyperglycaemia in In-vitro and In-vivo Studies

Abstract

Gymnemic acids are triterpenoid glycosides with gymnemagenin as common aglycone found in Gymnema sylvestre (Gurmar). G. sylvestre is often used in herbal formulations because of its beneficial actions in diabetes, hyperlipidemia, and gastric problems. The purpose of the present study is to evaluate gymnemic acid-rich fraction of G. sylvestre in in-vitro and in-vivo model to control postprandial hyperglycemia. The gymnemic acid-rich fraction of G. sylvestre (GARF) was prepared by ultrasonic-assisted extraction using methanol-water (81:19 v/v) at a temperature of 49°C for 50 min using a solid-to-solvent ratio of 1:12.5 g/ml and gymnemic acid content was determined by validated High-performance thin-layer chromatography (HPTLC) densitometric method. The GARF effect was evaluated in the in-vitro model on α-amylase and α-glucosidase enzymes, while the antihyperglycemic effect was studied in carbohydrate-challenged and diabetic rats induced by Streptozotocin (STZ). In vitro studies show that GARF produces dose-dependent enzyme inhibition with IC₅₀ values of 4.34 ± 0.81 mg/ml and 8.78 ± 1.22 mg/ml, respectively. In-vivo studies of normal and diabetic rats showed that GARF treatment (200 mg/kg b.w., p.o.), causes a significant (p < 0.01) blood glucose reduction effect in both models. The current study provides a scientific basis for the use of G. sylvestre in the management of diabetes mellitus.

Keywords:

• Gymnema sylvestre
• Apocynaceae
• gymnemic acids
• diabetes mellitus
• α-amylase
• α-glucosidase PPHG