Figure 1.
Tyrosinase activity decreased in melanoma cells in presence of melatonin and its metabolites. Amelanotic (A375 and Sk-Mel-28) and melanotic (MNT-1) human melanoma cell lines were incubated with MEL, AFMK, 5-MT and 6(OH)MEL for 72 h with 10−6 M (A,C,E) or 10−3 M (B,D,F) in comparison to melanogenic inhibitor, that is, 10−3 M N-phenylthiourea (PTU, positive control) and assessed as described in Materials and Methods. Data are presented as the mean + S.E.M. (n = 5) and values are normalized and expressed as percentage of the control value. Statistically significant differences are indicated as * p < 0.05, ** p < 0.01, *** p < 0.001.