Studies on the inhibition of a-glucosidase by biflavonoids and their interaction mechanisms

Biflavonoids are a kind of polyphenol compounds with numerous biological functions. However, the potential inhibitory activities of biflavonoids on a-glucosidase are yet unknown. Here, the inhibitory effects of two biflavonoids (amentoflavone and hinokiflavone) on a-glucosidase and their interaction mechanisms were explored using multispectral approaches and molecular docking. The results showed that the inhibitory activities of biflavonoids were much better compared with monoflavonoid (apigenin) and acarbose, and the order of inhibition ability was hinokiflavone > amentoflavone > apigenin > acarbose. These flavonoids were noncompetitive inhibitors of a-glucosidase and showed synergistic inhibition effects with acarbose. Additionally, they could statically quench the intrinsic fluorescence of a-glucosidase, and form the non-covalent complexes with enzyme primarily through hydrogen bonds and van der Waals forces. The binding of flavonoids changed the conformational structure of a-glucosidase, therefore impairing the enzyme activity. The findings suggested that biflavonoids could be considered as potential hypoglycemic functional foods in diabetes therapy.