Anti-melanogenic Effects of Kojic Acid and Hydroxycinnamic Acid Derivatives

Melanin provides photoprotection against UV irradiation, but excessive melanin accumulation can cause several problems such as darkened skin, melasma, and freckles. Although many anti-melanogenic agents have been developed for skin-whitening cosmetics, safety issues have been raised regarding these products. As natural substances are often non-toxic and are considered by some to be safer than synthetic compounds, various attempts have been made to synthesize active derivatives from natural substances. In this study, we evaluated the anti-melanogenic effects of four synthesized derivatives (compound 2a, 2b, 2c, and 2d) of kojic and hydroxycinnamic acids which are natural anti-melanogenic substances. Three of these derivatives (2a, 2b, and 2c) inhibited tyrosinase, which catalyzes a rate-limiting step of melanogenesis. Additionally, cell viability and melanin formation were investigated using B16F10 melanoma cells. Compounds 2b and 2c exhibited cytotoxicity towards B16F10 melanoma cells, while compound 2a caused a significant decrease in melanin formation without cytotoxicity. Thus, compound 2a may be viable as a potent skin-whitening agent derived from natural compounds.