α-Glucosidase inhibition by prenylated and lavandulyl compounds from Sophora flavescens roots and in silico analysis

The enzyme α-glucosidase is a good drug target for the treatment of diabetes mellitus. Four minor flavonoids (1–4) from roots of Sophora flavescens showed the inhibitory activity, with IC₅₀ values ranging from 11.0 ± 0.3 to 50.6 ± 1.3 μM, toward α-glucosidase. An enzyme kinetics analysis of them revealed that the compounds 1 and 4 were non-competitive, and compounds 2 and 3 were un-competitive inhibitors. For molecular docking, 3-dimensional structure of α-glucosidase was built by homology modeling. As the result, four compounds 1–4 were confirmed to interact into common binding site of α-glucosidase. In addition, all of the four prenylated and lavandulyl compounds (1–4) were abundant in an ethyl acetate fraction separated from a methanol extract, and the potential inhibitor (3) was extracted best using tetrahydrofuran.