Tyrosinase inhibitory effect of benzoic acid derivatives and their structure-activity relationships

Abstract

A series of benzoic acid derivatives 1–10 have been synthesised by two different methods. Compounds 1–6 were synthesised by a facile procedure for esterification using N,N’-dicyclohexylcarbodiimide (DCC) as a coupling agent, methylene chloride as a solvent system and dimethylaminopyridine (DMAP). While 7–10 were synthesised by converting benzoic acid into benzoyl chloride by treating with thionyl chloride in the presence of benzene and performing a further reaction with amine in dried benzene. The structures of all the synthesised derivatives of benzoic acid (1–10) were assigned on the basis of extensive NMR studies. All of them showed inhibitory potential against tyrosinase. Among them, compound 7 was found to be the most potent (1.09 μM) when compared with the standard tyrosinase inhibitors of kojic acid (16.67 μM) and L-mimosine (3.68 μM). Finally in this paper, we have discussed the structure–activity relationships of the synthesised molecules.