Inhibition of Oroxyloside Against Two Sources of α-Amylase/α-Glucosidase: Spectral Analysis, Computer Simulation, and mm-PBSA Calculation.

In this work, the inhibition effects of oroxyloside on two α-amylase from porcine pancreas (PPA) and Bacillus subtilis (BSA), as well as two α-glucosidase from Aspergillus niger (ANG) and Saccharomyces cerevisiae (SCG), were systematically compared using spectral analysis, computer simulation, and mm-PBSA calculation. Oroxyloside displayed the most potent inhibitory activity on ANG, followed by PPA, BSA, and SCG. Meanwhile, oroxyloside exhibited a mixed-type inhibition against BSA, PPA, ANG, and SCG. Oroxyloside interacted with enzyme residues mainly by hydrogen bonds and van der Waals forces, leading to the changes in the microenvironment and the secondary structure changes of enzymes, and ultimately exerting inhibitory effects. The optimal binding modes and the stability of four complexes were predicted by computer simulation. The free energy decomposition of critical residues was calculated using mm-PBSA. Oroxyloside was identified as a potential inhibitor of four enzymes, exhibiting significantly stronger inhibitory activity than acarbose.