Effect of antiooxidants on phthalocyanine photosensitization of human erythrocytes

Ehud Ben-Hur; Ionel Rosenthal

doi:10.1117/12.146324

18 June 1993 Effect of antiooxidants on phthalocyanine photosensitization of human erythrocytes

Ehud Ben-Hur, Ionel Rosenthal

Proceedings Volume 1881, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy II; (1993) https://doi.org/10.1117/12.146324
Event: OE/LASE'93: Optics, Electro-Optics, and Laser Applications in Scienceand Engineering, 1993, Los Angeles, CA, United States

Abstract

Photohemolysis of human erythrocytes sensitized by sulfonated aluminum phthalocyanine was used as an endpoint to study possible chemical modifications of photodynamic therapy. Ascorbate, in concentrations up to 0.1 mM, had a small protective effect. In larger amounts it stimulated the rate of photohemolysis in a concentration dependent manner up to 1mM, by a factor of 2. Azide and D20 tests indicated some participation of singlet oxygen, although to a lesser extent than in the absence of ascorbate. Kinetic considerations augur for a reaction path initiated by an interaction of excited sensitizer-ascorbate, parallel to the singlet oxygen-mediated process. Because of the ubiquitous presence of ascorbate in human tissues in concentrations comparable to those of dissolved oxygen, it is a reasonable estimation that in photodynamic therapy, a fraction of the photodynamic damage proceeds via a Type I, ascorbate-assisted, mechanism. Tocopherol had an effect opposite to that of ascorbate, namely it inhibited the photohemolysis. Likewise, quercetin, a plant flavonoid, was protective against phthalocyanine-induced photohemolysis.

Citation Download Citation

Ehud Ben-Hur and Ionel Rosenthal "Effect of antiooxidants on phthalocyanine photosensitization of human erythrocytes", Proc. SPIE 1881, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy II, (18 June 1993); https://doi.org/10.1117/12.146324

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