Effects of aloesin on melanogenesis in pigmented skin equivalents

Reconstituted 3-dimensional human skin equivalents in vitro are gaining popularity for studies of skin metabolism and depigmenting agents because they exhibit morphological and growth characteristics similar to human skin. The effects of aloesin on melanogenesis, however, have never been examined with the pigmented skin equivalent. The purpose of the study was to construct the skin equivalent and observe the effects of aloesin on melanogenesis in the model. We constructed an in vitro pigmented skin equivalent and examined the general structure and condition of the pigmented skin equivalent with H&E staining and Fontana Masson staining. Then, we examined the effects of aloesin on tyrosinase activity and formation of melanin in the model. Such a pigmented skin model demonstrated morphology similar to that seen in normal skin and can be used to assess the regulation of pigmentation by melanogenic compounds. The results suggested that aloesin had direct inhibitory effects on melanogenesis and showed dose-dependent reductions in tyrosinase activity (P < 0.05) and melanin content (P < 0.05). In conclusion, our study indicated that skin equivalents provided a convenient and cost-effective alternative to animal testing for evaluating the regulation of pigmentation. Aloesin showed promise as a pigmentation-altering agent for cosmetic or therapeutic applications.