Meanwhile, the anti-melanogenic activity of PTS (2) was examined in UVB-irradiated B164A5 mouse melanoma cells, and it was reported that 5 or 10 μM PTS (2) inhibited tyrosinase activity in a dose-dependent manner by 37% or 58%, respectively, and that PTS (2) had a 10-fold stronger anti-melanogenic activity than RES (1) [74]. This evidence concerns the gene TYR and melanoma.