Mn porphyrin-based superoxide dismutase (SOD) mimic, MnIIITE-2-PyP5+, targets mouse heart mitochondria

The Mm(HI) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin, (MnTE)-T-III-2-pyp(5+) (AEOL-10113) has proven effective in treating oxidative stress-induced conditions including cancer, radiation damage, diabetes, and central nervous system trauma. The ortho cationic pyridyl nitrogens of MnTE-2-PYP5+ are essential for its high antioxidant potency. The exceptional ability of (MnTE)-T-III-2-PyP5+ to dismute O-2(.-) parallels its ability to reduce ONOO- and CO3-. Decreasing levels of these species are considered its predominant mode of action, which may also involve redox regulation of signaling pathways. Recently, Ferrer-Sueta at al. (Free Radic. BioL Med. 41:503-512; 2006) showed, with subillitochondrial particles, that >= 3 mu M (MnTE)-T-III-2-pyp(5+) was able to protect components of the mitochondrial electron transport chain frorn peroxynitrite-mediated damage. Our study complements their data in showing, for the first time that microiriolar mitochondrial concentrations of (MnTE)-T-III-2-PyP5+ are obtainable in vivo. For this study we have developed a new and sensitive method for (MnTE)-T-III-2-pyp(5+) determination in tissues. The method is based on the exchange of porphyrin Mn2+ with Zn2+ followed by the HPLC/fluorescence detection of (ZnTE)-T-II-2-Pyp(4+). At 4 and 7 h after a single 10 mg/kg intraperitoneal administration of (MnTE)-T-III-2-PyP5+, the mice (8 in total) were anesthetized and perfused with saline. Mitochondria were then isolated by the method of Mela and Seitz (Methods Enzymol. 55:39-46; 1979). We found (MnTE)-T-III-2-pyp(5+) localized in heart rnitochondria to 2.95 ng/mg protein. Given the average value of mitochondrial volume of 0.6 mu L/mg protein, the calculated (MnTE)-T-III-2-PyP5+ concentration is 5.1 mu M, which is sufficient to protect mitochondria from oxidative damage. This study establishes, for the first time, that (MnTE)-T-III-2-pyp(5+), a highly charged metalloporphyrin, is capable of entering mitochondria in vivo at levels sufficient to exert there its antioxidant action; such a result encourages its development as a prospective therapeutic agent. (c) 2007 Elsevier Tnc. All rights reserved.