Use of a phosphorylated spin trap to discriminate between the hydroxyl radical and other oxidising species

Abstract

The spin-trap 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide (DEPMPO) is shown to provide a simple method to distinguish free-radical reactions which lead to the production of ˙OH from those which proceed via one-electron transfer followed by hydration or nucleophilic substitution of another adduct. In the first case, only an ˙OH adduct is detected; in the latter, signals from the hydroxyl adduct (labelled with ¹⁷O when H₂¹⁷O is employed) are accompanied by a second signal believed to result via internal trapping of a radical formed from an intermediate radical cation. This provides a potentially useful mechanistic probe, for example for use in biochemical systems.