Carthamus yellow (CY) is the major component of the yellow pigments of Carthamus tinctorius L CY has been extensively used as a natural color additive for food and cosmetics. Here, our results demonstrate that carthamus yellow reduced the activity of mushroom tyrosinase in a dose-dependent manner with a half maximal inhibitory concentration (IC50) value of approximately 1.01 +/- 0.03 mg/mL. A kinetic study of carthamus yellow on tyrosinase exhibited a mode of competitive inhibition with a Ki of 0.607 mg/mL. Moreover, cell viability analysis indicated that carthamus yellow used at concentrations of 1.0-4.0 mg/mL had no cytotoxicity in B16F10 melanoma cells. Melanin content analysis showed that melanin production in B16F10 melanoma cells treated with 4 mg/mL carthamus yellow can decrease to 82.3 +/- 0.4% of the levels of melanin production of untreated cells. Thus, carthamus yellow has the potential to become a useful skin-whitening agent in the future. (C) 2012, The Society for Biotechnology, Japan. All rights reserved.