Enhancement of hydroxyl radical generation in the Fenton reaction by alpha-hydroxy acid.
The effect of various organic acids on hydroxyl radical (.OH) generation in the Fenton reaction were examined by the ESR spin trapping technique, where 5,5-dimethyl-1-pyroline-N-nitroxide (DMPO) and alpha-phenyl-tert-butyl nitrone (PBN) were used as the spin trapping reagents. alpha-Hydroxy acids such as lactic acid, glycolic acid and 2-hydroxy isobutyric acid were found to markedly enhance .OH generation in the reaction. In contrast, beta-hydroxy acid, alpha-keto acid, esters of alpha-hydroxy acids, aldehydes and other straight chain organic acids had no such enhancing activity. alpha-Amino acids had also no enhancing effect. The results suggest that the alpha-hydroxy acid moiety is prerequisite for the enhancement of .OH generation in the Fenton reaction. Superoxide dismutase did not inhibit the enhancing effect of alpha-hydroxy acids whereas catalase completely inhibited the .OH generation. Thus, alpha-hydroxy acids directly enhanced the .OH generation via the Fenton reaction but not the Haber-Weiss reaction. Possible role of lactic acid manipulating .OH generation is discussed in relation to the ischemia-reperfusion cell damage.
Department of Radiochemistry-Biophysics, Niigata College of Pharmacy, Japan.
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Ali
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Konishi
D002374:Catalase / Q000494:pharmacology; D003497:Cyclic N-Oxides; D004578:Electron Spin Resonance Spectroscopy; D000431:Ethanol / Q000494:pharmacology; D006016:Glycolates / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D006880:Hydroxy Acids / Q000494:pharmacology*; D006885:Hydroxybutyrates / Q000494:pharmacology; D017665:Hydroxyl Radical / Q000378:metabolism*; D019344:Lactic Acid / Q000494:pharmacology; D009589:Nitrogen Oxides; D013113:Spin Labels; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism
D003497:Cyclic N-Oxides; D006016:Glycolates; D006880:Hydroxy Acids; D006885:Hydroxybutyrates; D009589:Nitrogen Oxides; D013113:Spin Labels; C031149:glycolic acid; D013481:Superoxides; D017665:Hydroxyl Radical; D019344:Lactic Acid; C029217:phenyl-N-tert-butylnitrone; D000431:Ethanol; C017245:5,5-dimethyl-1-pyrroline-1-oxide; C008039:2-hydroxyisobutyric acid; D002374:Catalase; D013482:Superoxide Dismutase