Quercetin-induced melanogenesis in a reconstituted three-dimensional human epidermal model.

Quercetin (3,5,7,3',4'-pentahydroxyflavone) is one of the most abundant natural flavonoids. It is present in various common vegetables and fruits. In this report, we examined the effect of quercetin on melanogenesis using a three-dimensional reconstituted human epidermal culture model, MelanoDerm, which is a new commercially-available cultured human epidermis containing functional melanocytes. Treatment with 10 microM quercetin induced an increase of tyrosinase activity in cultured epidermis after 3-5 days in time-dependent manner. In the quercetin-treated epidermis, furthermore, melanin content and tyrosinase expression were markedly increased, as shown by immunohistochemistry after a 7-day culture period. Ultrastructural studies clearly indicated an accumulation of mature melanosomes (stages III and IV) inside the basal layer of the cultured epidermis after the quercetin treatment. In addition, the dendrites of melanocytes extended further towards the adjacent keratinocytes after quercetin treatment. These results suggest that quercetin has an effect on maturation of melanosomes and that quercetin has the potential to induced melanogenesis in human epidermis.