Abnormal pigmentation owing to excessive
melanin synthesis can result in serious problems such as
freckles, age-spots, and
melanoma.
Tyrosinase inhibitors have been an interesting target for the treatment of
hyperpigmentation because
tyrosinase is the rate-limiting
enzyme in
melanin synthesis. The screening for strong
tyrosinase inhibitors led to the finding of the
flavonoid galangin, which showed notable inhibitory effects on mushroom
tyrosinase. The IC50 value of
galangin (3.55±0.39 µM) was lower than that of
kojic acid (48.55±1.79 µM), which was used as a positive control. In silico docking simulation and mechanistic studies demonstrated that
galangin interacted with the catalytic sites of
tyrosinase and competed with
tyrosine. In B16F10
melanoma cells stimulated with α-
melanocyte stimulating hormone,
galangin inhibited
tyrosinase activity as well as
melanin production. Although high doses of
galangin were cytotoxic, no cytotoxic effects were observed at low doses. In addition, the in vivo efficacy of
galangin was evaluated in HRM2
melanin-possessing hairless mice. As measured by the skin-whitening index and
melanin staining, repeated UVB exposure increased skin
melanin synthesis.
Galangin application significantly reduced melanogenesis induced by UVB exposure. Collectively, our data indicates that
galangin shows strong
tyrosinase inhibition activity, which suggests that it may be an effective
skin-whitening agent.