Comparative analysis of the interaction of oroxylin A with two sources of α -glucosidase and α -amylase

Background: Oroxylin A exhibits various biological activities. Alpha-amylase and a-glucosidase can hydrolyze carbohydrates, leading to an increase in postprandial blood glucose, thus, they have become important targets for screening enzyme inhibitors in vitro and studying the interaction mechanisms. Multi-spectral analysis and molecular docking are better to understand the interaction of oroxylin A with a-amylase and a-glucosidase at the molecular level. Method: Interaction mechanisms of oroxylin A with a-glucosidase from S. cerevisiae (ANG) and A. niger (SCG), a-amylase from porcine pancreas (PPA) and B. subtilis (BSA) are explored by fluorescence quenching, timeresolved fluorescence, synchronous fluorescence, three-dimensional fluorescence, UV-Vis, FT-IR and molecular docking.Results: The quenching mechanisms of ANG, SCG, PPA and BSA are principally by static quenching, and auxiliary by dynamic quenching. Hydrophobic force, hydrogen bonds and electrostatic force exhibit in binding of oroxylin A to ANG and SCG, while hydrogen bonds and van der Waals force exhibit in the binding of oroxylin A to BSA and PPA. At the same temperature, oroxylin A exhibits strongest binding force on ANG, followed by BSA, SCG and PPA. Besides, the conformations of four proteins are significantly altered by oroxylin A based on multispectral analysis. The interaction forces between oroxylin A and four proteins obtained by molecular docking are consistent with the fluorescence analysis. Their possible binding patterns are further revealed by molecular docking.