Synergistic effects and antityrosinase mechanism of four plant polyphenols from Morus and Hulless Barley

Sanggenone C, oxyresveratrol, catechin and L-epicatechin exist in Morus and Hulless Barley as natural polyphenols with antityrosinase activity. Little research on their synergistic and structure-function relationships of them has been reported in recent years. In this paper, the inhibition mechanisms of these four plant polyphenols were investigated by enzyme kinetics, HPLC, fluorescence spectra, and molecular docking methods. The results showed that oxyresveratrol (IC50 = 1.096 +/- 0.048 mu g/mL), sanggenone C (IC50 = 13.360 +/- 1.029 mu g/mL), L-cepicatechin (IC50 = 55.730 +/- 1.762 mu g/mL), and catechin (IC50 = 148.500 +/- 3.355 mu g/mL) exhibited tyrosinase inhibition activity. When sangenone C (14 mu g/mL) was mixed with L-epicatechin (56 mu g/mL) at 4:1 (40 mu L + 10 mu L), the highest tyrosinase inhibition was achieved. Molecular docking showed that the number and position of phenolic hydroxyls of polyphenols were the key for tyrosinase inhibition activity. This study provided new ideas for the application of these four plant polyphenols from Hulless Barley and Morus as tyrosinase inhibitors in food preservation.

Automated summary

This study investigated the inhibition mechanisms and synergistic effects of four plant polyphenols from Hulless Barley and Morus on tyrosinase. The results showed that these polyphenols exhibited tyrosinase inhibition activity, and the mixture of sanggenone C and L-epicatechin had the highest inhibition. Molecular docking analysis revealed that the number and position of phenolic hydroxyls were crucial for the inhibition activity. This study provides new insights into the potential application of these plant polyphenols as tyrosinase inhibitors in food preservation.