Figure 1

Spermidine (SPD) treatment increases melanin production. (a) Scheme of the chemical structure of SPD. (b) Cell viability of MNT-1 cells was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays after 24 h of SPD treatment. (c) Melanin levels in MNT-1 cells treated with 0, 0.25, 0.5, 1, and 2 μM of SPD for 10 days were measured at 450 nm. The data are representative of two independent experiments. (d,e) Melanin levels in young and aged primary human melanocyte cells treated with 1 μM of SPD for 10 days were measured at 450 nm. The data are representative of three independent experiments. CTL: control, *P < 0.05, **P < 0.01, ***P < 0.005.