Inhibitory Effects of Myricetrin and Dihydromyricetin toward α-Glucosidase and Pancreatic Lipase with Molecular Docking Analyses and Their Interaction

The aim of the current study was to evaluate the interaction effects of myricetrin and dihydromyricetin in inhibiting α-glucosidase and pancreatic lipase at different combination ratios and concentrations and to illuminate the underlying mechanisms of their inhibitions by molecular docking analyses. Results showed that both phenolic compounds possessed good inhibitory effects toward two enzymes in a dose-dependent manner. Myricetrin demonstrated a stronger inhibition against α-glucosidase (IC50, 41.14 ± 2.52 and more than 200 μg/mL, respectively), while dihydromyricetin had a better pancreatic lipase inhibition (IC50, 244.96 ± 4.24 and 373.26 ± 21.36 μg/mL, respectively). Different interaction types were observed when myricetrin and dihydromyricetin inhibited α-glucosidase and pancreatic lipase in combination, which were closely related to the combination ratio and concentration. For α-glucosidase inhibition, synergistic effects were observed at relative low concentrations when the combination ratio of myricetrin to dihydromyricetin was set as 1 : 2, while strong synergistic effects existed at relative high concentrations for pancreatic lipase inhibition. In other combination ratios (1 : 1 or 2 : 1), additive and/or antagonistic effects occurred. Molecular docking analyses showed that myricetrin formed nine hydrogen bonds with α-glucosidase, while only three hydrogen bonds were formed between dihydromyricetin and α-glucosidase. However, these two phenolic compounds had similar hydrogen bonds and hydrophobic interactions with pancreatic lipase. The present study suggested that myricetrin and dihydromyricetin or food materials rich in these two phenolic compounds could be exploited as α-glucosidase and/or pancreatic lipase inhibitors to deal with health problems caused by excessive energy intake, and the combination ratio and concentration of these two phenolic compounds should be considered when producing new functional foods.