Proanthocyanidin B2 attenuates postprandial blood glucose and its inhibitory effect on alpha-glucosidase: analysis by kinetics, fluorescence spectroscopy, atomic force microscopy and molecular docking

Abstract

As a dimer of proanthocyanidin, proanthocyanidin B₂ (PB₂) was found to effectively attenuate postprandial blood glucose in mice after sucrose loading. Further studies showed that PB₂ revealed strong inhibitory activity against α-glucosidase with an IC₅₀ value of (0.23 ± 0.01) μg mL⁻¹, and this process was reversible with a mixed-type inhibitory manner. PB₂ quenched the intrinsic fluorescence of α-glucosidase through a static quenching mechanism and changed the micro-environments and conformations of α-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 α-glucosidase. Our results suggest that PB₂ is useful for protection against hyperglycemia through inhibiting the activity of α-glucosidase.