Reduction kinetics and electrochemistry of tetracarboxylate nitroxides

Shengdian Huang, Hui Zhang, Joseph T. Paletta, Suchada Rajca, Andrzej Rajca

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Tetracarboxylate pyrroline nitroxides undergo very fast reduction with ascorbate/glutathione (GSH), with second-order rate constants that are five orders of magnitude greater than those for gem-diethyl pyrroline nitroxides. For tetracarboxylate nitroxides, the electrochemical reduction potentials, measured by square wave voltammetry, are much less negative (by about 0.8 V), compared with the corresponding gem-diethyl nitroxides, while the oxidation potentials become more positive (by about 0.7 V). Electrochemical potentials correlate well via simple regressions with field/inductive parameters such as Swain/Lupton F-parameters (and/or Charton σI-parameters). Rates of reduction with ascorbate/GSH similarly correlate well for four pyrroline nitroxides, except for the slowest reducing gem-diethyl nitroxide. These results suggest that the electron withdrawing groups adjacent to the nitroxide moiety have a strong accelerating impact on the reduction rates, and thus they are not suitable for the design of hydrophilic nitroxides for in vivo applications.

Original languageEnglish (US)
Pages (from-to)327-334
Number of pages8
JournalFree Radical Research
Issue number3
StatePublished - Mar 4 2018


  • Electrochemistry
  • Hammett correlation
  • electron paramagnetic resonance
  • nitroxide
  • voltammetry

ASJC Scopus subject areas

  • Biochemistry

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