(A) Cell viability (%) of B16BL6 cells exposed to ginsenoside Ia and ginsenoside F1. Cell viability was determined by the MTT assay. Cells (1 × 105 cells/well) were incubated with various concentrations of ginsenoside Ia or F1 for 5 d. Data are expressed as a percentage of untreated control and reflect the mean ± standard deviation of two separate experiments. *** p < 0.0001 versus control. (B) Effect of ginsenoside Ia on melanin content. Cells (2 × 105 cells/well) were incubated with 100 μM of G-Ia, G-F1, or arbutin in the presence of 1μM of α-melanocyte-stimulating hormone (MSH) for 5 d. Melanin and protein content were determined as described in the Materials and methods section. Data are expressed as a percentage of α-MSH treated control and presented as mean ± SDM of two separate experiments. * p < 0.05, ** p < 0.01, *** p < 0.001 versus α-MSH-treated control. (C) Effect of ginsenoside Ia on tyrosinase activity. Cells (4 × 105 cells/well) were incubated with 100μM of G-Ia, G-F1, or arbutin in the presence of 1μM α-MSH for 5 d. Tyrosinase activity in cellular lysates was determined as described in the Materials and methods section. Data are expressed as a percentage of α-MSH-treated control and presented as mean ± standard deviation of two separate experiments. * p < 0.05, ** p < 0.01, *** p < 0.001 versus α-MSH-treated control.