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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| Institution: | 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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