Stimulation of melanin synthesis of B16-F10 mouse melanoma cells by bufalin.

Bufalin, which is one of prominent components of Chinese toad venom, was found to decrease the rate of cell proliferation of mouse melanoma clone B16-F10 cells and a concomitant stimulation of expression of its melanotic phenotype. The effect of bufalin on melanogenesis included stimulation of tyrosinase activity and increase of cellular melanin content. These effects became apparent after 48 hr exposure to 10(-4) M bufalin and increased thereafter. Other cardiotonic steroids, such as cinobufagin and ouabain, at the concentration of 10(-4) M for 6 days, also showed the stimulatory effect on melanin synthesis of B16-F10 cells, but not digitoxigenin.