The Modulation Effects of Chitosan on Melanin Synthesis and Melanosomes Uptake

Decreasing skin pigmentation is an unmet need encountered in various medical or cosmetic conditions. Although some pharmaceutical agents are available for inhibiting melanogenesis, their effects are not ideal. Chitosan, a natural compound extracted from shell fish sources, is a well-known biocompatible and anti-bacterial material. The present research aimed to investigate the skin whitening effects of chitosan on three related processes—melanin synthesis, melanosomes release and melanosomes uptake; and evaluate the possible mechanisms involved. To clarify how the characteristic of chitosan inhibited the melanin synthesis, different molecular weight and different degree of deacetylation (D.D.) of chitosan were added into the culture medium with B16F10 melanoma cells in the basal or αMSH-stimulated condition. Also, our co-culture system is able to study the melanosomes release and uptake between human melanocytes and human keratinocytes HaCaT cell line under the presence of chitosan. Our results have revealed that molecular weight of chitosan would not affect melanogenesis while increasing D.D. of chitosan would enhance the depigmentation effect. Moreover, chitosan can significantly inhibit melanin synthesis and melanosomes release on pigment cells; and lessen melanosomes uptake on keratinocytes. Given the inhibition effect of chitosan on these three processes, we suggest that chitosan is a potential candidate as the treatment of hyperpigmentation disorders.