Antiproliferative effect of the piperidine nitroxide TEMPOL on neoplastic and nonneoplastic mammalian cell lines

Free Radic Biol Med. 1998 Apr;24(6):913-23. doi: 10.1016/s0891-5849(97)00372-9.


The stable nitroxide 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL) is widely used as a probe in biophysical studies and as an antioxidant in several experimental models. The potential cytotoxic effects of TEMPOL were tested on a panel of human and rodent cell lines, and the nitroxide proved to be significantly more effective in inhibiting the growth of neoplastic than nonneoplastic cell lines after a 96-h exposure. More detailed studies on MCF-7/WT cells indicate that at least 24 h are necessary for TEMPOL to induce irreversible cell damage, which seems to be related to the reactivity of the nitroxyl group. This observation, together with the antagonistic effect of N-acetylcysteine, suggests an involvement of free radical-mediated processes. Cell cycle studies indicate a biphasic effect of TEMPOL, with a short-term accumulation of the cells in the G1 phase and a later increase in G2/M phase; the pattern of DNA fragmentation observed in TEMPOL-treated cells points to an apoptotic mode of cell death. In conclusion, our data suggest that, while the possible cytotoxic effects of TEMPOL should not be overlooked when using this compound as a biophysical probe or antioxidant, these same properties could be exploited as a novel approach to cancer chemotherapy, especially in tumor cells exhibiting unfavorable characteristics, such as a multidrug-resistant phenotype or loss of hormone receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcysteine / pharmacology
  • Animals
  • Antineoplastic Agents / pharmacology*
  • CHO Cells
  • Cell Cycle / drug effects
  • Cell Division / drug effects
  • Cell Line
  • Cricetinae
  • Cyclic N-Oxides / pharmacology*
  • DNA Fragmentation / drug effects
  • Drug Screening Assays, Antitumor
  • Electron Spin Resonance Spectroscopy
  • Female
  • Growth Inhibitors / pharmacology*
  • Humans
  • Rats
  • Spin Labels
  • Tumor Cells, Cultured


  • Antineoplastic Agents
  • Cyclic N-Oxides
  • Growth Inhibitors
  • Spin Labels
  • tempol
  • Acetylcysteine