Abstract: Using the drug substitution method,the two stages in the process of melanin formation (i.e.enzyme catalysis and nonenzymatic catalysis) were blocked,in order to explore the mechanism of inhibition of melanin formation by phenethyl resorcinol.Using L-tyrosine and L-DOPA as substrates,after the reaction at 37 ℃ in the phosphate buffer solution of pH=6.8,the absorbance was measured at 475 nm.The effect of phenethyl resorcinol on the catalytic reaction of tyrosinase was studied,and the inhibition kinetic parameters were calculated;The mechanism of inhibition of tyrosinase by phenethyl resorcinol was explored by molecular docking analysis.Results show that phenethyl resorcinol is a tyrosinase inhibitor which can inhibit the enzymic catalytic reaction in the process of melanin formation,while it has no effect on nonenzymatic catalysis;phenethyl resorcinol can efficiently inhibit the activities of monophenolase and diphenolase of tyrosinase,with 50% inhibiting concentrations being 0.28 and 31 μmol/L,respectively;it is found that the inhibition of diphenolase is noncompetitive,and the inhibition constant is K_m=1.1;molecular docking results show that phenethyl resorcinol forms hydrogen bonds with tyrosinase MET A:280,accompanied by hydrophobic interaction.

Key words: whitening cosmetic additive, phenethyl resorcinol, tyrosinase, kinetics, molecular docking