Inhibitory effect of phloretin on α-glucosidase: Kinetics, interaction mechanism and molecular docking

As the aglycone of phloridzin, phloretin belongs to dihydrochalcone with antioxidant, anti-inflammatory and antimicrobial activities. In this study, multispectroscopic techniques and molecular docking analysis were used to investigate the inhibitory activity and mechanisms of phloretin on alpha-glucosidase. The results showed that phloretin reversibly inhibited alpha-glucosidase in a mixed-type manner and the value of IC50 was 31.26 mu g L-1. The intrinsic fluorescence of alpha-glucosidase was quenched by the interactions with phloretin through a static quenching mechanism and spontaneously formed phloretin-alpha-glucosidase complex by the driving forces of van der Waals force and hydrogen bond. Atomic force microscope (AFM) studies and FT-IR measurements suggested that the interactions could change the micro-environments and conformation of the enzymes and the molecular docking analysis displayed the exact binding site of phloretin on alpha-glucosidase. These results indicated that phloretin is a strong alpha-glucosidase inhibitor, thus could be contribute to the improvement of diabetes mellitus. (C) 2016 Elsevier B.V. All rights reserved.