To evaluate the effect of persimmon(Diospyros kaki Thunb.) leaves(PL) extract on the cytotoxicity and melanogenesis of nickel sulfate(NiSO4), an environmental pollutant or an allergic contact dermatitis inducer, the colorimetric assay was performed to measure the cell viability and lactate dehydrogenase(LDH) activity as well as the tyrosinase activity and total amount of melanin in cultured B16/F10 melanoma cells. In this study, NiSO4 significantly decreased cell viability in dose-dependent

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... er, and XTT50 value was calculated at 106.7μM of NiSO4. The cytotoxicity of NiSO4 was revealed to be mid-toxic in these cultures by Borenfreund and Puerner's toxic criteria. And also, vitamin E effectively prevented NiSO4-induced cytotoxicity by the significant increase of cell viability. PL extract showed the antioxidative activity by the significant increase of cell viability and the decrease of LDH activity compared to positive control(NiSO4). In the melanogenesis, PL extract significantly decreased both tyrosinase activity and total amount of melanin which were increased by NiSO4-induced cytotoxicity. From these findings, it is suggested that the cytotoxicity of NiSO4 is involved in oxidative stress, and PL extract effectively prevented the cytotoxicity and the melanogenesis induced by NiSO4. Conclusively, natural component such as PL extract may be a putative resources for beauty or detoxification by the prevention of the toxicity and the melanogenesis of heavy metals related with oxidative stress such as NiSO4.