Photodynamic effects of two water soluble porphyrins evaluated on human malignant melanoma cells in vitro

Abstract

Two water soluble porphyrins: meso-tetra-4-N-methylpyridyl-porphyrin iodide (P1) and 5,10-di-(4-acetamidophenyl)-15,20-di-(4-N-methylpyridyl) porphyrin (P2) were synthesised and evaluated in respect to their photochemical and photophysical prop-erties as well as biological activity. Cytotoxic and phototoxic effects were evaluated in human malignant melanoma Me45 line using clonogenic assay, cytological study of micronuclei, apoptosis and necrosis frequency and inhibition of growth of megacolonies. Both porphyrins were characterised by high UV and low visible light absorptions. Dark toxicity measured on the basis of the clonogenic assay and inhibi- tion of megacolony growth area indicated that P1 was non-toxic at concentrations up to 50 g/ml (42.14 M) and P2 at concentrations up to 20 g/ml (16.86 M). The photodynamic effect induced by red light above 630 nm indicated that both porphy-rins were able to inhibit growth of melanoma megacolonies at non-toxic concentra-tions. Cytologic examination showed that the predominant mode of cell death was ne-crosis.