Figure 4: Effect of tanshinone IIA and salvianolic acid B on melanogenesis and tyrosinase activity. Melanin content and tyrosinase activity in B16F10 melanoma cells was determined after exposure to drugs at various concentrations for 72 h. (a) Effect of tanshinone IIA on melanogenesis in B16F10 cells. (b) Morphological observation of B16F10 cells treated with tanshinone IIA. (c) Effect of salvianolic acid B on melanin production and there was no significant promotion on melanin synthesis. (d) Effect of tanshinone IIA on tyrosinase activity. The result shown are expressed as a mean value ± standard error of the mean of three independent experiments and the data were analyzed by one-way analysis of variance followed by post hoc Tukey's test. (*P < 0.05 vs. control group).