Investigation the interaction between procyanidin dimer and α-amylase: Spectroscopic analyses and molecular docking simulation.

Procyanidins were reported to have an inhibitory effect on α-amylase, but the interaction mechanism between procyanidins and α-amylase was rarely reported. Spectroscopic and molecular docking techniques were utilized to explore the interaction between porcine pancreatic α-amylase (PPA) and B-type procyanidin dimer (PB2). PB2 decreased the intrinsic fluorescence and surface hydrophobicity of PPA, indicating that an interaction occurred and complex formed. The binding process of complex was spontaneous and the main interaction was hydrophobic force. Circular dichroism showed conformational changes of PPA with an increasing of α-helix and β-sheet structure. Molecular docking speculated that PB2 could form hydrophobic force with PPA by bind to the active sit (Asp 167, Asn 100, Arg 158, His 201). This research can offer new insights into the mechanism of PB2 in inhibiting PPA catalysis and provide useful information on dietary recommendation of PB2 for the treatment of type 2 diabetes.