Inonotus obliquus Extract as An Inhibitor of α-MSH-Induced Melanogenesis in B16F10 Mouse Melanoma Cells

Melanogenesis is a biosynthetic pathway that produces the pigment melanin in human skin. The catalyzation of the key enzyme tyrosinase is the first step in melanogenesis, and the downregulation of tyrosinase enzyme activity is the most reported method for inhibiting melanogenesis. Hyperpigmentation is an important issue in the cosmetic industry, and there is great demand for melanogenesis inhibitors. In the present study, we demonstrated the anti-melanogenic effect of Inonotus obliquus in alpha-melanocyte-stimulating hormone (α-MSH)-induced B16F10 mouse melanoma cells and identified it as a new melanogenesis inhibitor. Comparing the B16F10 cells treated with the control and the Inonotus obliquus extract, we identified the melanin contents, mRNA and protein expression of tyrosinase, tyrosinase activity, and microphthalmia-associated transcription factor (Mitf) activity using a constructed plasmid. Through these experiments, we confirmed that Inonotus obliquus extract inhibits melanin synthesis by downregulating the activity and expression of tyrosinase. Furthermore, we revealed that tyrosinase expression is regulated by Inonotus obliquus extract via the repression of Mitf transcriptional activity. Thus, in this study, we found that Inonotus obliquus extract has anti-melanogenic effects via the suppression of melanin synthesis. Taken together, we demonstrated that Inonotus obliquus extract is a good potential candidate for use as a natural source for the therapeutic treatment of hyperpigmentation and for applications in whitening cosmetic products.