Author(s)

Yang Wang, Yudong Du, Zhaoming Liu, Yafei Fu, Xiao Sheng and Shouxin Wang

Corresponding Author

Xiao Sheng

Abstract

In this study, 12 imine compounds were synthesized by the condensation reaction of tyramine and 4-hydroxybenzylamine with 6 aromatic aldehydes; their structures were confirmed by 1H NMR, 13C NMR and MS. Using L-DOPA as the substrate, the tyrosinase inhibition activity and mechanism of the target compounds were determined by measuring the rate of oxidation of DOPA in mushroom tyrosinase and the enzyme inhibition kinetic experiment. All compounds have different degrees of tyrosinase inhibition activity, among which the activity of aromatic aldehydes tyramine compound 4a - 4f is significantly higher than that of the corresponding aromatic aldehydes 4-hydroxy benzylamine 3a - 3f. The compound 4c has the strongest tyrosinase inhibition activity; the IC50 value is 19.30 μmol•L-1, which is significantly better than the control drug kojic acid (IC50 =77.58 μmol•L-1). The results of inhibition mechanism and inhibition kinetics show that the inhibitory effect of 4c on tyrosinase is reversible and competitive; the KI value is 14.61 μmol•L-1. The aromatic aldehydes tyramine compounds synthesized in this study have good tyrosinase inhibitory activity, which is worthy of further study.

Keywords

Tyrosinase inhibitors; polyphenol; imine; synthesis; kinetics