Chromate-mediated free radical generation from cysteine, penicillamine, hydrogen peroxide, and lipid hydroperoxides

Xianglin Shi, Zigang Dong, Nar S. Dalal, Peter M. Gannett

Research output: Contribution to journalArticlepeer-review

65 Scopus citations


The Cr(VI)-mediated free radical generation from cystein, penicillamine, hydrogen peroxide, and model lipid hydroperoxides was investigated utilizing the electron spin resonance (ESR) spin trapping technique. Incubation of Cr(VI) with cysteine (Cys) generated cysteinyl radical. Radical yield depended on the relative concentrations of Cr(VI) and Cys. The radical generation became detectable at a cysteine: Cr(VI) ration of about 5, reached its highest level at a ratio of 30, and declined thereafter. Cr(VI) or Cys alone did not generate a detectable amount of free radicals. Similar results were obtained with penicillamine. Incubation of Cr(VI), Cys or penicillamine adn H2O2 led to hydroxyl (·OH) radical generation, which was verified by quantitative competition experiments utilizing ethanol. The mechanism for ·OH radical generation is considered to be a Cr(VI)-mediated Fenton-like reaction. When model lipid hydroperoxides such as t-butylhydroperoxide and cumene hydroperoxide were used in place of H2O2, hydroperoxide-derived free radicals were produced. Since thiols, such as Cys, exist in cellular systems at relatively high concentrations, Cr(VI)-mediated free radical generation in the presence of thiols may participate in the mechanisms of Cr(VI)-induced toxicity and carcinogenesis.

Original languageEnglish
Pages (from-to)65-72
Number of pages8
JournalBiochimica et Biophysica Acta - Molecular Basis of Disease
Issue number1
StatePublished - Apr 12 1994


  • Chromium(V)
  • Hydrogen peroxide
  • Hydroxyl radical
  • Lipid hydroperoxide
  • Spin trapping
  • Thiyl radical

ASJC Scopus subject areas

  • Molecular Medicine
  • Molecular Biology


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