Inhibitory Kinetics of Azachalcones and their Oximes on Mushroom Tyrosinase: A Facile Solid-state Synthesis

A solid-state-based mechanochemical process was used to synthesize novel azachalcones and their oximes as tyrosinase inhibitors. Their inhibitory activities on mushroom tyrosinase using l-3,4-dihydroxyphenylalanine as a substrate were investigated. Two of the novel oxime derivatives synthesized were seen to be more potent than the positive control, kojic acid. Both the compounds 1b and 2b inhibited the diphenolase activity of tyrosinase in a dose-dependent manner with their IC50 values of 15.3 and 12.7 μm, respectively. The kinetic analysis showed that their inhibition mechanism was reversible. Both the novel oxime compounds displayed competitive inhibition with their Ki values of 5.1 and 2.5 μm, respectively. This method minimizes waste disposal problems and provides a simple, efficient, and benign method for the synthesis of novel tyrosinase inhibitors for use as skin-whitening agents or as anti-browning food additives.