title: A manganese porphyrin complex is a novel radiation protector.
abstract: Exposure of cells to ionizing radiation leads to formation of reactive oxygen species, which are associated with radiation-induced cytotoxicity. Therefore, compounds that scavenge reactive oxygen species may confer radioprotective effects. Superoxide dismutase (SOD) mimetics have been shown to be protective against cell injury caused by reactive oxygen species. The objective of this study was to investigate the effects of manganese(III) tetrakis(N-methyl-2-pyridyl)porphyrin (MnTMPyP), a cell-permeable SOD mimetic, on radiation-dependent toxicity. We investigated the protective role of MnTMPyP against ionizing radiation in U937 cells and mice. On exposure to ionizing radiation, there was a distinct difference between control cells and cells pretreated with MnTMPyP with respect to viability, cellular redox status, and oxidative damage to cells. Lipid peroxidation, oxidative DNA damage, and protein oxidation were significantly lower in the cells treated with MnTMPyP when the cells were exposed to ionizing radiation. The [GSSG]/[GSH + GSSG] ratio and the generation of intracellular reactive oxygen species were higher and the [NADPH]/[NADP+ + NADPH] ratio was lower in control cells compared with MnTMPyP-treated cells. Ionizing radiation-induced mitochondrial damage, as reflected by the altered mitochondrial permeability transition, increase in accumulation of reactive oxygen species, reduction of ATP production, and morphological change, was significantly higher in control cells than in MnTMPyP-treated cells. MnTMPyP administration for 14 days at a daily dosage of 5 mg/kg provided substantial protection against killing and oxidative damage in mice exposed to whole-body irradiation. These data indicate that MnTMPyP may have great application potential as a new class of in vivo, non-sulfur-containing radiation protectors.
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Kyungpook National University, Taegu 702-701, South Korea.
authors.forename: Jin Hyup
authors.initials: JH
authors.lastname: Lee
authors.forename: Jeen-Woo
authors.initials: JW
authors.lastname: Park
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D004307:Dose-Response Relationship, Radiation; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D015227:Lipid Peroxidation; D008297:Male; D008345:Manganese / Q000494:pharmacology*; D008665:Metalloporphyrins / Q000494:pharmacology; D051379:Mice; D008813:Mice, Inbred ICR; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000473:pathology; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism; D011166:Porphyrins / Q000378:metabolism*; D011839:Radiation, Ionizing; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors; D020298:U937 Cells
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D008665:Metalloporphyrins; D011166:Porphyrins; D011837:Radiation-Protective Agents; D017382:Reactive Oxygen Species; D008345:Manganese; C050950:tetrakis(N-methyl-4-pyridiniumyl)porphine manganese(III) complex; D013482:Superoxide Dismutase; D010100:Oxygen