Potential of Fairy Chemicals as Functional Cosmetic Ingredients: Effect of 2-Aza-8-Oxohypoxanthine on Skin Lightness

Among the "fairy chemicals" involved in forming the natural phenomenon of "fairy rings," we focused on 2-aza-8-oxohypoxanthine (AOH) as a candidate functional cosmetic ingredient. In previous studies, AOH was confirmed to be safe for use on human skin, and no adverse reactions were observed in any of the safety studies. In this study, we report the results of a clinical trial using a lotion containing AOH. Our analysis using the L* value for indices of skin lightness indicated that the AOH application significantly increased the L* value after 8 weeks. Since a previous DNA microarray study using normal human epidermal cells showed that AOH suppressed the expression of a group of genes that induce inflammatory cytokines (prostaglandin E synthase, prostaglandin-endoperoxide synthase 2 [cyclooxygenase-2], and interleukin-18), our results suggest that the AOH-induced suppression of inflammatory factors results in skin lightening.