Advances in the Tyrosinase Inhibitors from Plant Source.

Tyrosinase is a multifunctional copper-containing oxidase which catalyses the oxidation of tyrosine to produce melanin. The alteration in melanin biosynthesis occurs in many diseases. The pigment has a protecting role against skin photo-carcinogenesis, but anomalous melanin pigmentation is an aesthetic problem in human beings. Moreover, the formation of neuromelanin in human brain could contribute to the neurodegeneration associated with Parkinson's disease. Finally, tyrosinase is also responsible for undesired browning in fruits and vegetables. These topics encouraged the search for new inhibitors of this enzyme for pharmaceutical, cosmetic and foods industries. This review is to report recent trends in the discovery of tyrosinase inhibitors from plant sources, to provide a rationale for the continued study of natural tyrosinase inhibitors, and to recognise the potential therapeutic rewards associated with the identification of these agents.