Formation of reactive oxygen species following bioactivation of gentamicin

Free Radic Biol Med. 1999 Feb;26(3-4):341-7. doi: 10.1016/s0891-5849(98)00207-x.


The present study investigated the ability of gentamicin to catalyze free radical reactions and probed the underlying mechanisms by hydroethidine imaging, oxygen consumption, and reduction of cytochrome c. In Epstein-Barr virus-transformed lymphoblastoid cells, a respiratory burst was induced by phorbol ester and detected by hydroethidine, a fluorescent indicator of superoxide radical. The addition of gentamicin increased the fluorescence two-fold while gentamicin did not produce fluorescence in the absence of phorbol ester. In membrane preparations, gentamicin did not enhance NADPH consumption ruling out a direct activation of NADPH oxidase. The formation of reactive oxygen species by gentamicin was additionally supported by experiments that showed gentamicin increased oxygen consumption two-fold in intact cells and a cell-free system. In addition, generation of superoxide was indicated by the gentamicin-stimulated reduction of cytochrome c. The stimulation by gentamicin depended upon the presence of iron (FeII/FeIII) and of arachidonic acid as an electron donor. These results support the hypothesis that an iron-gentamicin complex can increase reactive oxygen species in nonenzymatic and in biological systems. The requirement for a reductive activation in intact cells (e.g., by a respiratory burst) is interpreted as the conversion of an inactive FeIII-gentamicin to a redox-active FeII-gentamicin complex.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Analysis of Variance
  • Biotransformation
  • Catalysis
  • Cell Line, Transformed
  • Cell-Free System
  • Cytochrome c Group / metabolism
  • Fluorescent Dyes
  • Free Radicals
  • Gentamicins / pharmacokinetics*
  • NADP / metabolism
  • Oxidation-Reduction
  • Oxygen Consumption / drug effects*
  • Phenanthridines
  • Reactive Oxygen Species / metabolism*


  • Cytochrome c Group
  • Fluorescent Dyes
  • Free Radicals
  • Gentamicins
  • Phenanthridines
  • Reactive Oxygen Species
  • hydroethidine
  • NADP