Effect of heterocyclic pyrimidine compounds on UVB-induced cell damage in human keratinocytes and on melanogenesis in mouse B16 cells.

We investigated the protective effect of several heterocyclic pyrimidine compounds against ultraviolet B (UVB)-induced damage in human keratinocyte HaCaT cells, as well as the inhibitory effect on melanogenesis in B16 melanoma cells. One of the compounds examined, 2-piperadino-6-methyl-5-oxo-5,6-dihydro(7H)pyrrolo[3,4d]pyrimidine maleate (MS-818), showed low cytotoxicity even at 500 microM. At 50-500 microM, MS-818 dose-dependently suppressed the UVB (100 mJ/cm(2))-induced elevation of tumor necrosis factor alpha (TNF-alpha), one of the trigger cytokines for cell death, in HaCaT cells. In addition, MS-818 (100 microM) markedly inhibited melanogenesis in B16 melanoma cells via downregulation of tyrosinase expression mediated by microphthalmia-associated transcription factor (MITF) and extracellular signal-regulated kinase (ERK). In conclusion, MS-818 protected epidermal cells from UVB-induced damage and also suppressed melanogenesis in melanoma cells. It appears to be a good candidate for a new UVB-protective and whitening agent for application in cosmetics.