title: In vitro electron paramagnetic resonance characterization of free radicals: relevance to exercise-induced lipid peroxidation and implications of ascorbate prophylaxis.
abstract: This study tested the hypothesis that exercise-induced oxidative stress is caused by free radical-mediated damage to polyunsaturated fatty acids (PUFA) which can be prevented following ascorbate prophylaxis. Hyperfine coupling constants (HCC) of alpha-phenyl-tert-butylnitrone (PBN)-adducts were measured via room temperature electron paramagnetic resonance (EPR) spectroscopy in the venous blood of 12 subjects at rest and following maximal exercise during a randomized double-blind placebo-controlled trial and compared to those observed following room-air incubation (2 h at 37 degrees C) of L-alpha-phosphatidycholine, linoleic acid, alpha-linolenic acid and arachidonic acid. All adducts exhibited similar HCC [a(N) 13.6 Gauss (G) and a beta(H) 1.8 G] with the exception of L-alpha-phosphatidycholine [a(N1)=13.4 G, a beta(H1)=1.6 G (37%) and a(N2)=14.9 G, a beta(H2)=0.3 G (63%)] consistent with the trapping of lipid-derived alkoxyl and oleate radicals, respectively. Ascorbate pre-treatment ablated radical formation in both systems. These findings identify circulating PUFA as a potential source of secondary radicals that are capable of initiating oxidative stress in the exercising human.
authors.affiliation: Sport and Exercise Sciences Research Institute, University of Ulster Jordanstown, Newtownabbey, UK. gw.davison@ulster.ac.uk
authors.forename: Gareth W
authors.initials: GW
authors.lastname: Davison
authors.forename: Tony
authors.initials: T
authors.lastname: Ashton
authors.forename: Bruce
authors.initials: B
authors.lastname: Davies
authors.forename: Damian M
authors.initials: DM
authors.lastname: Bailey
mesh_terms: D016718:Arachidonic Acid / Q000494:pharmacology; D001205:Ascorbic Acid / Q000737:chemistry / Q000494:pharmacology*; D003497:Cyclic N-Oxides / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D015444:Exercise; D005609:Free Radicals; D006801:Humans; D007700:Kinetics; D019787:Linoleic Acid / Q000494:pharmacology; D015227:Lipid Peroxidation; D008297:Male; D008315:Malondialdehyde / Q000737:chemistry; D018384:Oxidative Stress; D010713:Phosphatidylcholines / Q000494:pharmacology; D017962:alpha-Linolenic Acid / Q000494:pharmacology
chemical_list: D003497:Cyclic N-Oxides; D005609:Free Radicals; D010713:Phosphatidylcholines; D017962:alpha-Linolenic Acid; D016718:Arachidonic Acid; C029217:phenyl-N-tert-butylnitrone; D008315:Malondialdehyde; D019787:Linoleic Acid; D001205:Ascorbic Acid