Synthesis and Biological Evaluation of Kojic acid Derivatives as Tyrosinase Inhibitors

Abstract

Tyrosinase1 is a copper-containing enzyme which is wide-ly distributed in nature. This enzyme is associated with the production of melanin for the protection of the skin from solar irradiation. However, overproduction of melanin in the skin is of particular concern to woman, for example, in the conditions melasma and lentigo.2 Tyrosinase catalyzes the first two steps of melanin biosynthesis, namely the hydrox-ylation of L-tyrosine to L-dopa and the subsequent oxidation of L-dopa to dopaquinone. Tyrosinase is contained in veget-ables and fruits and is responsible for the undesirable enzy-matic browning that occurs upon long term storage of these.3 Therefore, tyrosinase inhibitors have attracted attention as important depigmenting agents for the treatment of hyper-pigmentation and as anti-browning agents in vegetables and fruits. Kojic acid4 (1) is a well known tyrosinase inhibitor