α-Glucosidase inhibition and antihyperglycemic activity of flavonoids from Ampelopsis grossedentata and the flavonoid derivatives.

The dried leaves and stems of Ampelopsis grossedentata have been used as a health tea and herbal medicine for hundreds of years in China. The study was aimed at searching for novel α-glucosidase inhibitors among the richest components of A. grossedentata and their derivatives. Three known major components (1-3) were isolated by recrystallization process and six new derivatives (4-9) were obtained by etherification of the bioactive flavonoid. All compounds were evaluated for their inhibitory activities against α-glucosidase (from Saccharomyces cerevisiae). As a result, compound 9 showed a significant α-glucosidase inhibitory activity with IC50 value of 9.3 μM and acted as a competitive inhibitor with the value of the inhibition constant (Ki) being 10.3 μM. The oral administration of compound 9 at a dose of 50mg/kg significantly reduced the post prandial blood glucose levels of normal and streptozotocin (STZ)-induced diabetic mice. Furthermore, compound 9 significantly decreased the fasting blood glucose levels in STZ-induced diabetic mice.