Pregnane glycosides from Gymnema inodorum and their α-glucosidase inhibitory activity

Two new pregnane glycosides, gyminosides A and B (1 and 2) and three known, tinctoroside B (3), tinctoroside C (4), and gymnepregoside F (5) were isolated from the leaves of Gymnema inodorum (Lour.) Decne. Their structures were elucidated by physical and chemical methods and comparing with those reported in the literature. All these compounds were evaluated for α-glucosidase assay. Compound 5 exhibited the most anti α-glucosidase activity with inhibitory percentage of 63.7 ± 3.9% at the concentration of 200 μM. Compounds 1–4 showed moderate anti α-glucosidase activity with inhibitory percentage ranging from 40.0 to 52.1%.