| Background and objectivesVitiligo is a kind of common diseases manifesting by skin depigmentation, which affects life quality of the patients by influencing appearance. The problem of treatment has not been satisfactorily solved and remains a focus of investigation in the field of dermatology. The mechanism of depigmentation in vitiligo has not been clarified and there are different points of view concerning the strategy of treatment. In 2003, Garlie put forward that in vitiligo, interfollicular melanocytes die, ultimately resulting in a depigmented epidermis. Perifollicular melanocytes are thought to survive, and in successful treatment modalities, it is postulated that it is this reservoir of melanocytes that is stimulated to proliferate and migrate back into the epidermis. Also, at some stage, the melanocytes must reactivate their melanogenic pathway, synthesize melanin and transfer this to the surrounding keratinocytes, resulting in the repigmentation of the skin. For a vitiligo treatment to be effective, it must enhance or activate one or more of these processes.In the complex biochemical process of melanogenesis. at least three enzymes related to melanin-production, namely, the velocity limiting enzyme tyrosinase (with activities of tyrosine hydroxylase and Dopa oxidase), TRP-1 and TRP-2 (DCT) are involved. The latter two enzymes are important in the maintanance of tyronase stability on the membrane of melanosome. TRP-1 protein might regulate tyrosinase activity in early stage of melanogenesis. TRP-2 functions to accelarate melanin production. Both of them join the enzymatic procedure of melanin production.
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