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    National Tsing Hua University Institutional Repository > 生命科學院  > 生命科學系 > 期刊論文 >  Formation of reactive oxygen species and DNA strand breakage during interaction of chromium(III) and hydrogen peroxide in vitro: Evidence for a chromium(III)-mediated Fenton-like reaction


    Please use this identifier to cite or link to this item: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/49255


    Title: Formation of reactive oxygen species and DNA strand breakage during interaction of chromium(III) and hydrogen peroxide in vitro: Evidence for a chromium(III)-mediated Fenton-like reaction
    Authors: Tsu, TC;Yang, JL
    教師: 楊嘉鈴
    Date: 1996
    Publisher: Elsevier
    Relation: Chemico-Biological Interactions,Elsevier,Volume 102,Issue 3,20 December 1996,Pages 133-153
    Keywords: antioxidant
    DNA strand breakage
    EPR
    radical scavenger
    reactive oxygen species
    Abstract: The role of reactive oxygen species in causing DNA damage through interaction of chromium(III) and hydrogen peroxide was examined using plasmid relaxation assay and EPR spectroscopy. Marked DNA strand breakage was induced by CrCl3 plus H2O2 in a phosphate buffer at pH 6-8.9; whereas, only slight DNA strand breakage was observed during similar treatment at pH less than 4. DNA breakage also increased as the reaction temperature and Cr(III)/H2O2 concentrations increased. Control experiments with Cr(III) or H2O2 alone did not cause DNA breakage. Sodium azide, D-mannitol, Tris-HCl, or catalase completely inhibited Cr(III)/H2O2-induced DNA breakage, but superoxide dismutase did not. The D2O enhancing effect on DNA breaks was not observed. Cr(III) pre-incubated with a 30-foId molar excess of EDTA did not cause any significant DNA breakage in the presence of H2O2. In a phosphate buffer containing Cr(III) and H2O2, singlet oxygen and hydroxyl radicals were detected using EPR spectrometry with the spin traps 2,2,6,6-tetramethyl-4-piperidone and 5,5-dimethyl-1-pyrroline 1-oxide (DMPO), respectively. DMPO/(OH)-O-. adducts and DNA breakage induced by Cr(III)/H2O2 were markedly higher than those induced by Cr(VI)/H2O2. Furthermore, ascorbate decreased Cr(III)/H2O2-induced DNA breakage. EPR studies revealed that ascorbate (mole ratio to Cr(III)=0.5:1) attenuated the DMPO/(OH)-O-. signal generated by Cr(III)/H2O2/DMPO, but a Cr(V) signal and ascorbate radicals were detected. NADPH, GSH, and GSSG also decreased DMPO/(OH)-O-. generated by Cr(III)/H2O2/ DMPO; however, they were less efficient than ascorbate and no Cr(V) signals were detected. This study shows that Cr(III)/H2O2 generates oxidative damage to DNA through a Fenton-like reaction: Cr(III) + H2O2 --> Cr(IV) + (OH)-O-. + OH.
    URI: http://www.elsevier.com/
    http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/49255
    Appears in Collections:[生命科學系] 期刊論文

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