The reaction between nitric oxide and alpha-tocopherol: a reappraisal.
Recently Gorbunov et al. reported that nitric oxide (.NO) can directly oxidize alpha-tocopherol to alpha-tocopheroxyl radical (Gorbunov et al., Biochem. Biophys. Res. Commun., 219, 835-841, 1996). We have reinvestigated this reaction and report that a direct reaction between .NO and alpha-tocopherol does not occur. However, the reaction between .NO and oxygen generates an oxidant which oxidizes alpha-tocopherol to alpha-tocopheryl quinone. Exposure of alpha-tocopherol to a low flux of .NO generated from spermine NONOate (100 microM) results in no consumption of alpha-tocopherol under either aerobic or anaerobic conditions. A higher flux of .NO, generated from 1 mM spermine NONOate, oxidizes alpha-tocopherol only under aerobic conditions. Artifactual oxidation of alpha-tocopherol can be observed when using commercial .NO that is contaminated with higher oxides of nitrogen, such as dinitrogen trioxide and dinitrogen tetraoxide.
Hogg
N
N
Biophysics Research Institute, Medical College of Wisconsin, Milwaukee 53226, USA.
Singh
R J
RJ
Goss
S P
SP
Kalyanaraman
B
B
D005609:Free Radicals; D009569:Nitric Oxide / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D014810:Vitamin E / Q000031:analogs & derivatives / Q000737:chemistry*
D005609:Free Radicals; D014810:Vitamin E; D009569:Nitric Oxide; C002421:tocopherylquinone; D010100:Oxygen