Abstract
In this article, a method was established to screen compounds with enzyme activity inhibition in vitro using chromatographic analysis. The flower buds of Sophora japonica L. (FBSJ) were found to contain abundant flavonoids. And then these flavonoids were screened for the high inhibition activity against α-amylase and α-glucosidase using HPLC fingerprint and activity difference analysis. Consistent conclusions were drawn from multiple techniques, including the reported technique, IC50 data, and our method. The inhibitory mechanism was furtherly analyzed through enzyme inhibition kinetics, circular dichroism (CD), fluorescence spectrometry, molecular docking, and molecular dynamics. Among the six flavonoid components studied, quercetin acted as a competitive inhibitor against α-amylase, while kaempferol showed a mixed manner of inhibition against α-glucosidase. Molecular docking and molecular dynamics simulations demonstrated that quercetin and kaempferol had higher binding energy and bind more tightly. Generally, flavonols exhibited higher inhibitory activity than their corresponding flavonol glycosides against α-amylase and α-glucosidase. Quercetin and kaempferol in FBSJ showed potential as inhibitors of α-amylase and α-glucosidase. This study not only presented a novel method for screening compounds with high activity, but also provided a theoretical basis for studying the application and mechanism of flavonoids against α-amylase and α-glucosidase in FBSJ.