EVIDENCE AGAINST THE PRODUCTION OF SUPEROXIDE BY PHOTOIRRADIATION OF HEMATOPORPHYRIN DERIVATIVE |
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| Authors: | Scott L. Gibson Harvey J. Cohen Russell Hilf |
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| Affiliation: | 1Departments of Biochemistry and University of Rochester Cancer Center, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, USA;2Departments of Pediatrics and University of Rochester Cancer Center, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, USA |
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| Abstract: | ![]()
Abstract Experiments were performed to ascertain whether superoxide anion (O2−) was produced by the photodynamic activation of hematoporphyrin derivative (HPD). Three different systems were utilized to detect formation of O2−, oxidation of epinephrine to adrenochrome, reduction of cytochrome c and reduction of nitro blue tetrazolium (NBT). The effects on these detectors under identical conditions for HPD + h ν were compared to those obtained with two O2− generating systems, riboflavin + by and xanthine-xanthine oxidase, and to a singlet oxygen generating system, photoradiation of methylene blue. The results indicated that HPD + hv differed from the two O2− generating systems in failing to reduce cytochrome c or NET, and that HPD + h ν was similar to the behavior of methylene blue + h ν . In addition, HPD + h ν but not the O2− generating systems could inhibit mitochondrial cytochrome c oxidase activity. We conclude that the photodynamic activation of HPD does not produce O2− as a major oxygen radical and that the effects of HPD + h ν on mitochondrial cytochrome c oxidase are not caused by O2−. |
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