Kinetic of Mushroom Tyrosinase Inhibition by Benzaldehyde Derivatives

Polyphenol oxidase (PPO), known as tyrosinase (EC 1.14.18.1), is a multifunctional copper-containing oxidase which catalyzes the rate-limiting step in the formation of melanin from tyrosine. This enzyme is responsible not only for enzymatic browning in plants but also for melanogenesis in mammals. Thus, tyrosinase inhibitors have a huge impact on industry and the economy. In the current study, at first the enzyme was purified and then we evaluated inhibitory potency of three benzaldehyde derivatives: 2,4-dihydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde and 4-dimethylamino- benzaldehyde on diphenolase activity of the purified mushroom tyrosinase, compared to kojic acid. Despite their close structural similarity, 2,4-dihydroxybenzaldehyde was found as a potent and competitive inhibitor while a weak uncompetitive inhibition was observed for 4-dimethylaminobenzaldehyde. Further complementary studies on these types of inhibitors, as potential drug candidates for treating abnormal melanin pigmentation, are needed.