Inhibitory effect and mechanism on melanogenesis from fermented herbal composition for medical or food uses

Nowadays, herbal foods of skin-whitening cosmetics are popular with Asian women. To investigate the efficacy of Korean herbs having skin-whitening activity, we screened eight kinds of herbs exhibiting high inhibition activity of mushroom tyrosinase among traditional herbs selected based on the Korean herbal foods literature. The mixture of eight herbs was extracted with water (each at 2%) and then fermented with Phellinus linteus. The 9-day fermented product was potently anti-melanogenetic when tested against cultured B16F0 mouse melanoma cells and had a high phenolic content, and so was used in subsequent melanogenesis experiments. The whitening effect of the P. linteus complex culture broth (P. linteus culture broth with Glycyrrhiza glabra, Broussonetia kazinoki, Angelica gigas, Atractylodes macrocephala, Poria cocos, Morus alba (root bark), Paeonia albiflora, and Lithospermum officinale) was evaluated by measurement of melanin content, tyrosinase activity, and Western blot in melanoma cells. P. linteus complex culture broth dose-dependently inhibited melanin and tyrosinase activity, and reduced melanogenesis-related proteins including tyrosinase and microphthalmia-associated transcription factor in cells stimulated with 100 μM 3-isobutyl-1-methylxanthine (IBMX; which elevates cellular cAMP). However, P. linteus complex culture broth exhibited no inhibitory effects on tyrosinase related protein-1 and tyrosinase related protein-2. Additionally, we examined the involvement of P. linteus complex culture broth in the phosphatidylinositol-3-kinase pathway. P. linteus complex culture broth markedly inhibited the reduction of Akt and glycogen synthase kinase-3beta phosphorylation induced by LY294002, a selective inhibitor of phosphatidylinositol 3-kinase/Akt. These results suggest that P. linteus complex culture broth inhibits melanogenesis through the activation of the phosphatidylinositol 3-kinase/Akt/glycogen synthase kinase-3beta signaling pathway and down-regulation of microphthalmia-associated transcription factor, and also suggests that P. linteus complex culture broth may be an effective inhibitor of hyperpigmentation.