MODE OF CYTOTOXIC ACTION OF PHOTO-ACTIVATED PORPHYRINS

Upon photo-activation, certain porphyrins can exert a substantial cytotoxic action on mammalian cells. A study of the interaction between a group of porphyrins and some transplantable murine ascitic tumors has suggested several major determinants of porphyrin toxicity. Optimally effective porphyrins are water soluble; however, they can be extracted from aqueous solution by octanol, but not by decane. Upon photoactivation, porphyrins accumulated by tumor cells catalyze cross-linking of membrane protein but not of glycoprotein. This cross-linking is associated with a decrease in cell-surface hydrophobicity and with other alterations in vital membrane propeprties. © 1979.