Acetoside inhibits α-MSH-induced melanin production in B16 melanoma cells by inactivation of adenyl cyclase

Abstract Objectives The aim of the study was to determine the mechanism of the whitening effect of acteoside. Methods We used tyrosinase activity and melanin production stimulated in B16 melanoma cells by α-melanocyte stimulating hormone (α-MSH) or forskolin to measure the whitening effect of acteoside. Key findings Acteoside did not directly inhibit mushroom tyrosinase activity, but dose-dependently inhibited tyrosinase activity and melanin production in B16 melanoma cells stimulated by 1 μmol/l α-MSH. Acteoside also reduced cyclic AMP levels in cells stimulated by 1 μmol/l α-MSH, suggesting direct inhibition of adenyl cyclase. Acteoside also inhibited productionofbothmelanin and cyclic AMP in cells stimulated by 1 μmol/l forskolin, an adenyl cyclase activator. Acteoside showed antioxidant activity in a cell-free DPPH (1-diphenyl-2-picrylhydroazyl) assay and inhibited generation of intracellular reactive oxygen species. Conclusions These results suggest that the whitening activity of acteoside results from inhibition of adenyl cyclase and α-MSH signalling.