Inhibitory effects of Korean indigenous plants on tyrosinase and melanogenesis.

To search for new depigmenting cosmetic ingredients from Korean herbal extracts of traditional Korean medicines (TKMs), we screened about 17 TKM extracts collected in the Republic of Korea. Samples were prepared from the natural plants, including medicinal plants such as Chrysanthemum indicum (flower), using methanol, methylene chloride, ethyl acetate (EtOAc), n-butyl alcohol, and water as the extraction and/or the partitioning solvents. We then tested their inhibitory effects on melanogenesis by using in vitro tyrosinase inhibition assay, in vitro L-3,4-dihydroxy-indole-2-carboxylic acid (L-DOPA) auto-oxidation assay, and B16 melanoma cells. In addition, cytotoxicity testing (NR50 and MTT50) was conducted to evaluate safety. From the results of these assays, four fractions with good efficacy and low toxicity were selected among them, including EtOAc fraction of Smilax china (rhizome), Paeonia lactiflora (root), and Polyporus umbellatus (sclerotium), and BuOH fraction of Evodia officinalis (fruit). In the inhibition assay of intracellular tyrosinase activity and melanogenesis in B16 melanoma cell line, the four plant fractions showed dose-dependent inhibitory effects, and the EtOAc fraction of P. lactiflora showed the highest activity among the four fractions. The EtOAc fraction of P. lactiflora was found to be the most effective substrate.