Insight into the alpha-glucosidase-inhibiting mechanism of beta-PGG, a commonly occurring polyphenol in diets

1,2,3,4,6-Penta-O-galloyl-beta-D-glucopyranose (beta-PGG) is a compound commonly available in vegetables and fruits. It exhibited potential inhibition of alpha-glucosidase and hypoglycemic effect in vivo. This study explored its dynamics properties inhibiting alpha-glucosidase by Lineweaver - Burk plots, spectral analysis, docking analysis, and molecular dynamics simulations. beta-PGG showed a mix-type inhibition when it was interacting with alpha-glucosidase. The fluorescence quenching indicated that the PGG-glucosidase complex formed in a spontaneous exothermic process and was driven by enthalpy. The synchronous fluorescence and ECD spectra indicate that beta-PGG induced and changed the enzyme conformation in the complex formation. Docking results revealed multiple hydrogen bonds between the phenols and the amino acid residues. Further dynamic simulations indicated that the residues Asp345, Phe153, Arg435, Glu300, Pro305, and Phe296 played a more critical role in the interactions between beta-PGG and alpha-glucosidase.