INFLUENCE OF INDOLES (MELATONIN, SEROTONIN AND TRYPTOPHAN) ON THE PORPHYRIN METABOLISM IN-VITRO

We examined the influence of melatonin, serotonin and tryptophan on th e basal and delta-aminolevulinic acid (ALA)-induced porphyrin content in HaCaT, SKMel-23 and HepG2 cells. ALA-preincubated and ALA-free cell s were fed with medium containing 1 mM melatonin, serotonin or tryptop han. After 24 h the porphyrin content in the cells and in the culture medium was measured. In the three cell lines the inbucation with 1 mM ALA over 24 h increased the porphyrin concentration in all cell lines in different degrees: HepG2 > SKMel-23 > HaCaT cells. In HepG2 cells, neither melatonin, serotonin nor tryptophan influenced ALA-induced por phyrin concentrations significantly, but all three indoles depressed t he porphyrin levels in SKMel-23 and HaCaT cells. The indoles may decre ase the ALA uptake in HaCaT or SKMel-23 cells. Another mechanism could be the inhibition of enzymes converting ALA into porphyrins.