title: Real-time quantification of oxidative stress and the protective effect of nitroxide antioxidants.
abstract: Nitroxides have been exploited as profluorescent probes for the detection of oxidative stress. In addition, they deliver potent antioxidant action and attenuate reactive oxygen species (ROS) in various models of oxidative stress, with these results ascribed to superoxide dismutase or redox and radical-scavenging actions. Our laboratory has developed a range of novel, biostable, isoindoline nitroxide-based antioxidants, DCTEIO and CTMIO. In this study we compared the efficiency of these novel compounds as antioxidant therapies in reducing ROS both in vivo (rat model) and in vitro (661W photoreceptor cells), with the established antioxidant resveratrol. By assessing changes in fluorescence intensity of a unique redox-responsive probe in the rat retina in vivo, we evaluated the ability of antioxidant therapy to (1) ameliorate ROS production and (2) reverse the accumulation of ROS after complete, acute ischemia followed by reperfusion (I/R). I/R injury induced a marked decrease in fluorescence intensity over 60 min of reperfusion, which was successfully ameliorated with each of the antioxidants. DCTEIO and CTMIO reversed the accumulation of ROS when administered intraocularly post ischemic insult, whereas, the effect of resveratrol was not significant. We also investigated our novel agents' capacity to prevent ROS-mediated metabolic dysfunction in the 661W photoreceptor cell line. Cellular stress induced by the oxidant, tert-butyl hydroperoxide, resulted in a loss of spare mitochondrial respiratory capacity (SMRC) and in the extracellular acidification rate in 661W cells. DCTEIO antioxidant administration successfully reduced the loss of SMRC. Together, these findings show we can quantify dynamic changes in cellular oxidative status in vivo and suggest that nitroxide-based antioxidants may provide greater protection against oxidative stress than the current state-of-the-art antioxidant treatments for ROS-mediated diseases.
authors.affiliation: Queensland Eye Institute, South Brisbane, Queensland, Australia. Electronic address: cassie.rayner@qei.org.au.
authors.forename: Cassie L
authors.initials: CL
authors.lastname: Rayner
authors.affiliation: ARC Centre of Excellence for Free Radical Chemistry, School of Physical and Chemical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia. Electronic address: s.bottle@qut.edu.au.
authors.forename: Steven E
authors.initials: SE
authors.lastname: Bottle
authors.affiliation: Department of Paediatrics & Child Health, University of Queensland, Brisbane, Queensland, Australia. Electronic address: g.gole@uq.edu.au.
authors.forename: Glen A
authors.initials: GA
authors.lastname: Gole
authors.affiliation: Glycation and Diabetes, Mater Research Institute, Translational Research Institute, University of Queensland, Brisbane, Queensland, Australia; School of Medicine, University of Queensland, Brisbane, Queensland, Australia. Electronic address: micheal.ward@mater.uq.edu.au.
authors.forename: Micheal S
authors.initials: MS
authors.lastname: Ward
authors.affiliation: Queensland Eye Institute, South Brisbane, Queensland, Australia; The University of Queensland, UQ Centre for Clinical Research, Herston, Queensland, Australia; School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia. Electronic address: nigel.barnett@qei.org.au.
authors.forename: Nigel L
authors.initials: NL
authors.lastname: Barnett
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002460:Cell Line; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009589:Nitrogen Oxides / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects*; D020419:Photoreceptor Cells, Vertebrate / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D015427:Reperfusion Injury / Q000188:drug therapy; D000077185:Resveratrol; D012171:Retinal Vessels / Q000187:drug effects; D013267:Stilbenes / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D018696:Neuroprotective Agents; D009589:Nitrogen Oxides; D017382:Reactive Oxygen Species; D013267:Stilbenes; D000077185:Resveratrol
keywords: Antioxidant; Ischemia; Neuroprotection; Nitroxide; Radical; Retina