Glycosidase Inhibitory Polyphenols From Roots Of Sophora Flavescens Aiton

Sophora flaveseens Aiton. (Leguminosae) is a perennial shrub occurring wild as well as being cultivated in Northeast Asia. The plant, known as 'kushen' (which literally means 'the bitter root,') is used to make a crude extract that is applied in traditional Chinese medicine as an antipyretic, analgesic, anthelmintic, and stomachic drug. Previous studies have demonstrated that this species contains biologically active flavonoids and alkaloids, but their glycosidase inhibitory activity has not previously been evaluated. Therefore, this study was a phytochernical investigation of MeOH extracts from roots of S. flavescens. A total of five compounds were isolated and then identified as lavandulylated flavanones when analyzed by NMR spectroscopic analysis. These five isolated compounds were investigated for glycosidase inhibitory activity against a-glucosidase, beta-galactosidase, alpha-amylase, beta-amylase and invertase. All of the compounds showed potent inhibition of a-glucosidase with IC50 values of 45.3, 124.4, 34.0, 74.6 and 155.3 mu M respectively. All compounds except no. 1 also inhibited beta-amylase, with IC50 values ranging between 44.9 and 156.3 mu M. By contrast, they were inactive in the case of beta-galactosidase, a-amylase and invertase at the same concentrations. The enzyme inhibition properties of the five compounds were modeled using a double reciprocal plot (Lineweaver-Burk plot), demonstrating a noncompetitive inhibition model for a-glucosidase, whereas compounds 2-3 displayed a mixed-type inhibition for beta-amylase.