Inhibitory Effects on L-Dopa Oxidation of Tyrosinase by Skin-whitening Agents

Tyrosinase (EC 1.14.18.1) is a copper-containing monooxygenase catalyzing the o-hydroxylation of monophenols to the corresponding catechols (monophenolase or cresolase activity), and the oxidation of monophenols to the corresponding o-quinones (diphenolase or catecholase activity). 1These functions of tyrosinase play an important role in the formation of melanin pigments during melanogenesis. 2 Melanin production is principally responsible for skin color and plays an important role in prevention of sun-induced skin injury.However, abnormal accumulation of melanin products is responsible for hyperpigmentations including melasma, freckles, and senile lentigines, which could be a serious aesthetic problem.Recently, a global market demand has developed for skinwhitening agents because some dark-skinned individuals in many countries and races are prefer lighter skin color. 3