title: The roles of ascorbic acid and other antioxidants in the erythrocyte in reducing membrane nitroxide radicals.
abstract: Fatty acid nitroxide radicals in CO-gassed erythrocytes are reduced by intracellular components with a half-life of about 160 min. In this study, using reduction rate constants of fatty acid spin labels to determine the reduction quantitatively, we found that catalase, glutathione, glutathione peroxidase, superoxide dismutase, and vitamin E--as well as hemoglobin, individually or in concerted manner, contributed little in reducing membrane nitroxides. Ascorbic acid appeared to be the predominant component in the erythrocyte to reduce membrane nitroxides. However, ascorbic acid solutions at 0.1 mM or less, concentrations similar to those found in the erythrocyte, produced no observable reduction in spin labeled membranes during the 2 h monitoring period. Ascorbic acid solutions at about 1 mM were needed to exhibit rate constants similar to those observed in labeled erythrocyte samples. It was also found that beta-nicotinamide adenine dinucleotide, beta-nicotinamide adenine dinucleotide phosphate, and heat-sensitive components in the erythrocyte enhanced the ability of ascorbic acid to scavenge nitroxide radicals in the erythrocyte membrane near the membrane surface.
authors.affiliation: Department of Chemistry, Loyola University of Chicago, IL 60626.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: L W
authors.initials: LW
authors.lastname: Fung
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000378:metabolism* / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000097:blood*; D002263:Carboxyhemoglobin / Q000494:pharmacology; D002374:Catalase / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D004910:Erythrocyte Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D005609:Free Radicals / Q000097:blood; D005978:Glutathione / Q000494:pharmacology; D005979:Glutathione Peroxidase / Q000494:pharmacology; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D009589:Nitrogen Oxides / Q000097:blood*; D013482:Superoxide Dismutase / Q000494:pharmacology; D014810:Vitamin E / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D005609:Free Radicals; D006454:Hemoglobins; D009589:Nitrogen Oxides; D014810:Vitamin E; D002263:Carboxyhemoglobin; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005978:Glutathione; C039900:nitroxyl; D001205:Ascorbic Acid