Mechanistic Insights into the Inhibitory Activities of Chemical Constituents from the Fruits ofTerminalia boiviniion α‐Glucosidase

Abstract Regulation of key digestive enzymes is currently considered an effective remedy for diabetes mellitus. In this study, bioactive constituents were purified fromTerminalia boiviniifruits and identified by1H‐NMR,13C‐NMR and EI‐MS.In vitroandin silicomethods were used to evaluate α‐glucosidase, α‐amylase, and lipase inhibition activities. Compounds1,2, and4–7with IC50values between 89 and 445 μM showed stronger α‐glucosidase inhibitory activities than the antihyperglycemic drug acarbose (IC50=1463.0±29.5 μM). However, the compounds showed lower inhibitory effects against α‐amylase and lipase with IC50values above 500 μM than acarbose (IC50=16.7±3.5 μM) and ursolic acid (IC50=89.5±5.6 μM), respectively. Lineweaver‐Burk plots showed that compounds1,2, and7were non‐competitive inhibitors, compounds4and5were competitive inhibitors and compound6was a mixed‐type inhibitor. Fluorescence spectroscopic data showed that the compounds altered the microenvironment and conformation of α‐glucosidase. Computer simulations indicated that the compounds and enzyme interacted primarily through hydrogen bonding. The findings indicated that the compounds were inhibitors of α‐glucosidase and provided significant structural basis for understanding the binding activity of the compounds with α‐glucosidase.