Photodynamic aspects of some metal complexes.

The potential phototoxic capacity of some metal compounds of clinical significance in dermatology has been investigated by means of the photohemolysis technique. No photosensitized hemolysis of erythrocytes was observed with the chromium, nickel, copper and cobalt compounds studied. On the contrary, nickel and cobalt compounds proved to be efficient in quenching singlet oxygen mediated photo-oxidative membrane damage of red blood cells. Cadmium compounds showed a pronounced photohemolytic activity and the reaction was oxygen dependent. The deuterium test for singlet oxygen showed a significant increase in photohemolytic efficiency. The addition of histidine, a known quencher of singlet oxygen, resulted in a significant inhibition of the photohemolysis. Pronounced photo-oxidative damage to plasma membranes was also observed in vitro cultivated cells by means of scanning electron microscopy.