The reduction of nitroxide spin label as a probe of human blood antioxidant properties

O. Saphier, T. Silberstein, A. I. Shames, G. I. Likhtenshtein, E. Maimon, D. Mankuta, M. Mazor, M. Katz, D. Meyerstein, Naomi Meyerstein

Research output: Contribution to journalReview articlepeer-review

28 Scopus citations


The kinetics of reduction of the radical R, 5-dimethyla minonaphthalene-1-sulfonyl-4-amino-2,2,6,6-tetramethyl- 1-piperidine-oxyl, by blood and its components were studied using the EPR technique. The results demonstrate that R is adsorbed to the outer surface of the membrane and does not penetrate into the erythrocytes. A series of control experiments in PBS demonstrate that ascorbate is the only natural reducing agent that reacts with R. The observed first order rate of disappearance of the nitroxide radical, κ, is: κblood > κeryth > κplasma and κblood ≅ κeryth + κplasma. The results demonstrate that: a. The erythrocytes catalyze the reduction of R by ascorbate. b. The rate of reduction of the radical is high though it does not penetrate the cells. c. In human erythrocytes there is an efficient electron transfer route through the cell membrane. d. The study points out that R is a suitable spin label for measuring the reduction kinetics and antioxidant capacity in blood as expressed by reduction by ascorbate.

Original languageEnglish
Pages (from-to)301-308
Number of pages8
JournalFree Radical Research
Issue number3
StatePublished - 1 Mar 2003


  • Antioxidant capacity
  • Ascorbic acid
  • EPR
  • Erythrocyte
  • Nitroxide

ASJC Scopus subject areas

  • Biochemistry


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