Tea contains polyphenols and is one of the most popular beverages consumed worldwide. Because most tyrosinase inhibitors that regulate melanogenesis are phenol/catechol derivatives, this study investigated the inhibitory effects of Camellia sinensis water extracts (CSWEs), including black tea, green tea, and white tea extracts, on melanogenesis using immortalized melanocytes. CSWEs inhibited melanin accumulation and melanin synthesis along with tyrosinase activity in a concentration-dependent manner. These inhibitory effects were superior to those of arbutin, a well-known depigmenting agent. The anti-melanogenic activity of black (fermented) tea was higher than that of a predominant tea catecholamine, epigallocatechin gallate. CSWEs, especially black tea extract, decreased tyrosinase protein levels in a concentration-dependent manner. These results suggest that the anti-melanogenic effect of CSWEs is mediated by a decrease in both tyrosinase activity and protein expression, and may be augmented by fermentation. Thus, CSWEs could be useful skin-whitening agents in the cosmetic industry.
Animals ; Catechin/analogs & derivatives/metabolism ; Cell Line ; Melanins/*metabolism ; Melanocytes/enzymology/*metabolism ; Mice ; Monophenol Monooxygenase/*metabolism ; Plant Extracts/*pharmacology ; Plant Leaves/chemistry ; Tea/*chemistry

Increasing evidence suggests that stress may induce changes in hair color, with the underlying mechanism incompletely understood. In this study, female C57BL/6 mice subjected to electric foot shock combined with restraint stress were used to build chronic stress mouse model. The melanin contents and tyrosinase activity were measured in mouse skin and B16F10 melanoma cells. The enzyme-linked immunosorbent assay (ELISA) was used to determine the content of tumor necrosis factor α (TNF-α), interleukin- 1β (IL-1β) and interleukin-6 (IL-6) in the mouse skin. The content of nuclear factor κB (NFκB)/p65 subunit in mouse skins was valued by immunofluorescence staining. The results demonstrated that under chronic stress, the fur color turned from dark to brown in C57BL/6 mice due to the decrease of follicle melanocytes and tyrosinase activity in C57BL/6 mouse skin. Simultaneously, inflammatory responses in skins were detected as shown by increased NFκB activity and TNF-α expression in stressed mouse skin. In cultured B16F10 melanoma cells, TNF-α reduced the melanogenesis and tyrosinase activity in a dose-dependent manner. These findings indicate that chronic stress induces fur color change by decreasing follicle melanocytes and tyrosinase activity in female C57BL/6 mice, and TNF-α may play an important role in stress-induced hair color change.
Animal Fur ; Animals ; Color ; Female ; Melanins ; Melanocytes ; enzymology ; Melanoma, Experimental ; Mice ; Mice, Inbred C57BL ; Monophenol Monooxygenase ; metabolism ; Pigmentation ; Skin ; physiopathology ; Stress, Physiological