Screening of alpha-Glucosidase Inhibitors from Houttuynia cordata and Evaluation of the Binding Mechanisms

摘要

abstract_textpalpha-glucosidase inhibitors have been used to treat diabetes for many years. Recently, natural products have attracted much attention, because they are kinds of safety source to screen alpha-glucosidase inhibitor. In this study, we separated two monomers (quercitrin and afzelin) fromHouttuynia cordatawith notable inhibitory activity against alpha-glucosidase, and evaluated inhibitory kinetics and the binding mechanisms. The 50 inhibitory concentration (IC50) of the quercitrin and afzelin were 0.231 +/- 0.033 mg/mL and 0.215 +/- 0.004 mg/mL, which were lower than the IC(50)of acarbose. The inhibitory type between alpha-glucosidase and the two monomers was a competitive inhibition, which is similar to acarbose and could compete binding sites. The fluorescence spectroscopy showed that quercitrin and afzelin statically quenched the fluorescence of alpha-glucosidase. Circular dichroism and molecular docking analyses indicated that quercitrin and afzelin changed the alpha-helix structure of alpha-glucosidase and bound with the key amino acids through hydrophobic interactions, hydrogen bonds and salt bridge interaction. This study is the first time to clarify the inhibitory kinetics and binding mechanisms of quercitrin and afzelin on alpha-glucosidase./p/abstract_text