Mechanism of photosensitization in photodynamic therapy of tumor: interaction of metal phthalocyanine-excited states with molecular oxygen

Huijun Xu; Xian-Fu Zhang; J. X. Ran; J. H. Song; Q. Yu; Q. F. Zhou; Jinshi Ma; D. W. Chen

doi:10.1117/12.137026

5 March 1993 Mechanism of photosensitization in photodynamic therapy of tumor: interaction of metal phthalocyanine-excited states with molecular oxygen

Huijun Xu, Xian-Fu Zhang, J. X. Ran, J. H. Song, Q. Yu, Q. F. Zhou, Jinshi Ma, D. W. Chen

Author Affiliations +

Proceedings Volume 1616, International Conference on Photodynamic Therapy and Laser Medicine; (1993) https://doi.org/10.1117/12.137026
Event: International Conference on Photodynamic Therapy and Laser Medicine, 1991, Beijing, China

Abstract

The ability of photosensitized generation of singlet oxygen by phthalocyanines has been evaluated using diphenylisobenzofuran as a chemical trap and arranged in the following decreasing order: ZnDSPC > ClGaTSPC > H₂TSPC > ClAlTSPC. The efficiency of photogeneration of superoxide anion radical has also been estimated using 5,5-dimethyl-1-pyrroline-1-oxide DMPO as a spin trap and identified by ESR. The ability of photochemical generation of O₂^- is arranged in the decreasing order: ClGaTSPC > ClAlTSPC > CuDSPC > ZnDSPC. The interaction of phthalocyanines with amino acids has been studied by laser flash photolysis. The results show that the excited states of phthalocyanines interact with tyrosine and tryptophan via electron transfer but not with cysteine. It is thus concluded that photo-oxidation of cysteine sensitized by phthalocyanines is mediated solely by Type II (O₂^- involving) mechanism while photo-oxidation of tyrosine and tryptophan proceeds via Type I (electron transfer) and Type II mechanism depending on the structure of the sensitizer and substrate as well as the environment.

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Huijun Xu, Xian-Fu Zhang, J. X. Ran, J. H. Song, Q. Yu, Q. F. Zhou, Jinshi Ma, and D. W. Chen "Mechanism of photosensitization in photodynamic therapy of tumor: interaction of metal phthalocyanine-excited states with molecular oxygen", Proc. SPIE 1616, International Conference on Photodynamic Therapy and Laser Medicine, (5 March 1993); https://doi.org/10.1117/12.137026

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