title: Generation of free radicals by Cr(IV) from lipid hydroperoxides and its inhibition by chelators.
abstract: The generation of free radicals by Cr(IV) from lipid hydroperoxides was investigated by ESR spin trapping. The spin trap used was 5,5-dimethyl-1-pyrroline N-oxide (DMPO). Reaction of Cr(VI) with ascorbate was used as a source of Cr(IV). Incubation of Cr(VI) with ascorbate generated Cr(IV) and Cr(V). Addition of cumene hydroperoxide generated DMPO/R adduct with an enhancement of Cr(V) signal. Addition of Mn(II), whose function is to remove Cr(IV), caused dose-dependent inhibition of DMPO/R formation. Similar results were obtained using t-butyl hydroperoxide. Metal ion chelators, deferoxamine, 1,10-phenanthroline and diethylenetriaminepentaacetic acid inhibited DMPO/R formation in the order of deferoxamine > 1,10-phenanthroline > diethylenetriaminepentaacetic acid. The results suggest the possible role of Cr(IV) and its mediated free radical generation from lipid hydroperoxides in the mechanism of Cr(VI) carcinogenesis.
authors.affiliation: Laboratory of Experimental Pathology, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Mao
authors.forename: L
authors.initials: L
authors.lastname: Zang
authors.forename: X
authors.initials: X
authors.lastname: Shi
mesh_terms: D001205:Ascorbic Acid / Q000378:metabolism; D001555:Benzene Derivatives / Q000378:metabolism*; D002614:Chelating Agents / Q000494:pharmacology*; D002857:Chromium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003497:Cyclic N-Oxides / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000378:metabolism; D008054:Lipid Peroxides / Q000378:metabolism*; D008345:Manganese / Q000494:pharmacology; D010545:Peroxides / Q000378:metabolism*; D013113:Spin Labels; D020122:tert-Butylhydroperoxide
chemical_list: D001555:Benzene Derivatives; D002614:Chelating Agents; D003497:Cyclic N-Oxides; D005609:Free Radicals; D008054:Lipid Peroxides; D010545:Peroxides; D013113:Spin Labels; D002857:Chromium; D008345:Manganese; C017245:5,5-dimethyl-1-pyrroline-1-oxide; D020122:tert-Butylhydroperoxide; C007164:cumene hydroperoxide; D001205:Ascorbic Acid