Synthesis and biological evaluation of novel 4-hydroxybenzaldehyde derivatives as tyrosinase inhibitors.

A series of novel 4-hydroxybenzaldehyde derivatives were synthesized and their inhibitory effects on the diphenolase activity of mushroom tyrosinase were investigated. Most of target compounds had more potent inhibitory activities than the parent compound 4-hydroxybenzaldehyde (IC(50)=1.22 mM). Interestingly, compound 3c bearing a dimethoxyl phosphate was found to be the most potent inhibitor with IC(50) value of 0.059 mM. The inhibition kinetics analyzed by Lineweaver-Burk plots revealed that compound 3c was a non-competitive inhibitor (K(I)=0.0368 mM). In particular, compound 3c showed no side effects at dose of 1600 mg/kg in mice. These results suggested that such compounds might be served as lead compounds for further designing new potential tyrosinase inhibitors.