Production of activated species of oxygen during the chromate(VI)-ascorbate reaction: implication in carcinogenesis.
The reaction of chromate and ascorbate in a 1:1 molar ratio at pH 7.4 and 37 degrees C produces a Cr(V) signal observable by EPR at g = 1.980. When this reaction is carried out in aerated media and in the presence of formate, carboxylate radicals (COO.-) can be trapped as DMPO-COO.- spin adducts (DMPO, 5,5-dimethyl-1-pyrroline N-oxide). The use of a known complexant of Cr(V), 2-ethyl-2-hydroxybutyric acid, produces a different Cr(V) signal at g = 1.978 and a decrease of the DMPO-COO.- signal. Hydroxyl radicals are not detected in the media. The oxidizing behavior is suggested to be produced by activation of molecular oxygen present in the reaction mixture.
Lefebvre
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Laboratoire de réactivité de surface et structure, Université Pierre et Marie Curie, Paris, France.
Pézerat
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H
D001205:Ascorbic Acid / Q000737:chemistry*; D002273:Carcinogens / Q000737:chemistry*; D002840:Chromates / Q000737:chemistry*; D003497:Cyclic N-Oxides / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry
D002273:Carcinogens; D002840:Chromates; D003497:Cyclic N-Oxides; D005609:Free Radicals; C017245:5,5-dimethyl-1-pyrroline-1-oxide; D001205:Ascorbic Acid; D010100:Oxygen