EPR Imaging Spin Probe Trityl Radical OX063: A Method for Its Isolation from Animal Effluent, Redox Chemistry of Its Quinone Methide Oxidation Product, and in Vivo Application in a Mouse

Chem Res Toxicol. 2016 Dec 19;29(12):2153-2156. doi: 10.1021/acs.chemrestox.6b00277. Epub 2016 Nov 22.


We report herein a method for the recovery, purification, and application of OX063, a costly, commercially available nontoxic spin probe widely used for electron paramagnetic resonance (EPR) imaging, as well as its corresponding quinone methide (QM) form. This precious probe can be successfully recovered after use in animal model experiments (25-47% recovery from crude lyophilizate with 98.5% purity), even from samples that are >2 years old. Significantly, the recovered trityl can be reused in further animal model EPR imaging experiments. The work also describes support for the observed formation of an air-sensitive radical derived from the QM under reducing conditions.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Electron Spin Resonance Spectroscopy
  • Indolequinones / chemistry*
  • Mice
  • Oxidation-Reduction
  • Spin Labels*
  • Tritium / chemistry*


  • Indolequinones
  • Spin Labels
  • Tritium
  • quinone methide