Oxidative Polymerization of Dihydromyricetin Catalyzed by Laccase

The effects of laccase catalysis conditions on the color, α-glucosidase inhibitory activity and antioxidant activity of dihydromyricetin derivatives were systematically investigated, and the structures of the derivatives were also characterized.It was found that the oxidative polymerization of dihydromyricetin was achieved by using laccase. Laccase concentration, pH, reaction time and temperature had regular effects on the color of the derivatives. The α-glucosidase inhibitory activity of the derivatives was significantly higher than that of dihydromyricetin, with half-maximal inhibitory concentration (IC₅₀)of 6.2 versus 85.95 μg/mL, but the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical cation scavenging capacities were inferior to those of dihydromyricetin.Spectral analysis indicated that laccase catalyzed the oxidation of the phenolic hydroxyl groups of dihydromyricetin, consequently leading to the polymerization of dihydromyricetin by ether bonding. These results can promote the application of dihydromyricetin in foods, and the development of new functional foods.