PHOTODYNAMIC TREATMENT OF YEAST WITH CHLOROALUMINUM-PHTHALOCYANINE - ROLE OF THE MONOMERIC FORM OF THE DYE

The effect of photodynamic treatment on the yeast Kluyveromyces marxianus with aluminum-phthalocyanines has been studied. It was found that the nonsulfonated sensitizer caused light-dependent loss of colony-forming capacity, whereas the mono- and tetrasulfonated forms did not induce loss of clonogenicity. The effect of the nonsulfonated sensitizer increased with longer preincubation periods of cells with the dye. Formation of cell-attached, mostly intracellularly localized monomeric sensitizer also increased with time. The amount of cell-bound multimeric nonsulfonated phthalocyanine did not vary with time. Experiments designed to specifically increase the amount of cell-attached monomers led also to an increased photoinactivation of the cells. It is therefore concluded that the photodynamic effect of the nonsulfonated Al-phthalocyanine is mediated by the monomeric form of the dye.