Effect of pH on superoxide/ hydroperoxyl radical trapping by nitrones: an EPR/kinetic study

Beatrice Tuccio (1) , Robert Paul Lauricella (1)

1 AMU - Aix Marseille Université

The pH dependence of the apparent rate constant kTap for O2-./HO2. trapping by four nitrones was examined. In each case, kinetic curves were obtained after treatment of EPR spectra of the spin adduct formed using both singular value decomposition and pseudo-inverse deconvolution methods. Modelling these curves led to evaluate kTap at various pH values. Analysis of the pH dependence of kTap permitted the determination of the rate constants for the spin trapping of O2-. and of HO2. separately. Whatever the nitrone, our results clearly show that the EPR signals of the nitrone/superoxide spin adducts observed in aqueous media were essentially due to the trapping of the protonated species HO2.

Mots clés: Physical Sciences

Beatrice Tuccio, Robert Paul Lauricella. Effect of pH on superoxide/ hydroperoxyl radical trapping by nitrones: an EPR/kinetic study. Molecular Physics, 2008, 105 (15-16), pp.2017-2024. ⟨10.1080/00268970701494024⟩. ⟨hal-00513116⟩