ABSTRACT

Melanin pigments are responsible for skin and hair colors. They play an important role in the defense against harmful ultraviolet radiation (Fitzpatrick et al. 1949; Tomita et al. 1984). In the body, the formation of pigment melanin occurs within the melanosome of skin melanocytes (Mason 1949; Fitzpatrick et al. 1950). This process is regulated by melanogenic enzymes such as tyrosinase and tyrosinase-related protein 1/2 (TRP1/2) (Chen and Chavin 1966). Speci•cally, these proteins catalyze the rate-limiting, two-part reaction in melanin biosynthesis: the hydroxylation of l-tyrosine to 3,4-dihydroxyphenylalanine (DOPA) and its subsequent oxidation to dopaquinone (Korner and Pawelek 1982). Modulation of tyrosinase activities therefore represents a key process for the regulation of cutaneous melanogenesis (Korner and Pawelek 1982). In addition, because increased levels of epidermal pigmentation (melanogenesis process) is a hallmark of cosmetic problems (e.g., skin blemishes, melasma) and malignant skin diseases (e.g., melanoma), the control of tyrosinase activity may provide a basis for treating patients with this type of malignancies.