α-Glucosidase inhibitory effect of Potentilla astracanica and some isoflavones: Inhibition kinetics and mechanistic insights through in vitro and in silico studies.

α-Glucosidase enzyme inhibitors are clinically used for the treatment of Type 2 diabetes mellitus. We tested α-glucosidase inhibitory effects of Potentilla astracanica Jacq. extracts (1, 2), two compounds isolated from these extracts, prunetin 5-O-β-glucopyranoside (3) and genistein 5-O-β-glucopyranoside (4), and their aglycon forms (5 and 6). All the tested materials possessed remarkable α-glucosidase inhibitor activity compared to the positive control, acarbose. Genistein (6) showed the highest activity with an IC50 value of 1.47 (±0.11) μg/ml. An enzyme kinetics analysis revealed that 3 and 6 were uncompetitive, 5 was noncompetitive, and 4 was competitive inhibitors. Using molecular modeling techniques we tried to provide insight into molecular mechanisms of their activity and how allosteric binding of 6 affected binding interactions between the agonist (maltose) and the enzyme.