PHOTOSENSITIZED INACTIVATION OF CHINESE HAMSTER CELLS BY PHTHALOCYANINES

Abstract

Chloroaluminum phthalocyanine was found to sensitize cultured Chinese hamster cells upon exposure to white fluorescent light. Elimination of wavelengths below 370 nm did not reduce the effect significantly, indicating that the effective wavelengths were those absorbed by the Q band (600–700 nm) of phthalocyanine. The magnitude of the photosensitizing effect increased with the dye concentration and the time of its contact with the cells prior to light exposure. Although photosensitization was drastically reduced in the absence of oxygen, the lack of effect of glycerol and D 2 0 during exposure suggests that neither hydroxyl radicals nor 1 O 2 are responsible for the cytotoxic response. The efficiency of the photosensitized induced cell killing did not vary with the position of the cells in the cell cycle, in contrast to exposure to X‐rays. The improved spectral properties, the reported low toxicity and the selective retention by neoplasms, make phthalocyanines promising candidates for use in photodynamic therapy of cancer.