Fatty acid radical formation in rats administered oxidized fatty acids: in vivo spin trapping investigation.
We report in vivo evidence for fatty acid-derived free radical metabolite formation in bile of rats dosed with spin traps and oxidized polyunsaturated fatty acids (PUFA). When rats were dosed with the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) and oxidized PUFA, the DMPO thiyl radical adduct was formed due to a reaction between oxidized PUFA and/or its metabolites with biliary glutathione. In vitro experiments were performed to determine the conditions necessary for the elimination of radical adduct formation by ex vivo reactions. Fatty acid-derived radical adducts of alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) were detected in vivo in bile samples collected into a mixture of iodoacetamide, desferrioxamine, and glutathione peroxidase. Upon the administration of oxidized 13C-algal fatty acids and 4-POBN, the EPR spectrum of the radical adducts present in the bile exhibited hyperfine couplings due to 13C. Our data demonstrate that the carbon-centered radical adducts observed in in vivo experiments are unequivocally derived from oxidized PUFA. This in vivo evidence for PUFA-derived free radical formation supports the proposal that processes involving free radicals may be the molecular basis for the previously described cytotoxicity of dietary oxidized PUFA.
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Laboratory of Molecular Biophysics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709.
Jordan
S J
SJ
Mason
R P
RP
D000818:Animals; D001646:Bile / Q000737:chemistry; D003497:Cyclic N-Oxides / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D005231:Fatty Acids, Unsaturated / Q000737:chemistry*; D005609:Free Radicals; D010084:Oxidation-Reduction; D051381:Rats
D003497:Cyclic N-Oxides; D005231:Fatty Acids, Unsaturated; D005609:Free Radicals; C017245:5,5-dimethyl-1-pyrroline-1-oxide