α-Glycosidase inhibitory activity of hexagalloylglucose from the galls of Quercus infectoria

Hexagalloylglucose (3-O-digalloyl-1,2,4,6-tetra-O-galloyl-β-D-glucose), which was isolated from the methanol extract of the galls of Quercus infectoria, significantly inhibited α-glycosidases such as sucrase, maltase and isomaltase. Its inhibitory activity was comparable to acarbose being used as a hypoglycemic agent, while the inhibitory activity on α-amylase was approximately 10 times lower than that of acarbose. The results indicate that, when compared to acarbose, hexagalloylglucose might reduce the side effects by reducing inhibition of α-amylase.