Proanthocyanidin B-2 attenuates postprandial blood glucose and its inhibitory effect on alpha-glucosidase: analysis by kinetics, fluorescence spectroscopy, atomic force microscopy and molecular docking

As a dimer of proanthocyanidin, proanthocyanidin B-2 (PB2) was found to effectively attenuate postprandial blood glucose in mice after sucrose loading. Further studies showed that PB2 revealed strong inhibitory activity against -glucosidase with an IC50 value of (0.23 +/- 0.01) g mL(-1), and this process was reversible with a mixed-type inhibitory manner. PB2 quenched the intrinsic fluorescence of -glucosidase through a static quenching mechanism and changed the micro-environments and conformations of -glucosidase that led to an aggregation phenomenon. A further molecular docking study provided more information about the interactions of PB2 with the amino acid residues of -glucosidase. Our results suggest that PB2 is useful for protection against hyperglycemia through inhibiting the activity of -glucosidase.