Gamma and pulse radiolysis investigation of the reaction of desferrioxamine with superoxide anions.
The kinetic scheme of the reaction of desferrioxamine (DFO) with O2-. was studied using pulse and gamma-radiolysis. The rate constant k(O2-. + DFO) is equal to 1.3 +/- 0.1 x 10(6) dm3 mol-1s-1 at pH 7.4. Studying the competition between DFO and ferricytochrome-c for O2-. generated by gamma-radiolysis, we observed that the nitroxide free radical resulting from the reaction of O2-. with DFO and the product(s) resulting from the decay of this nitroxide radical act inversely towards the cytochrome-c-Fe3+/cytochrome-c-Fe2+ redox couple. This explains the discrepancy between our value of k(O2-. + DFO) and the one measured previously using ferricytochrome-c for the detection of O2-. The reported results show that DFO acts as a powerful O2-. scavenger, and that the products resulting from the reaction of DFO with O2-. can initiate oxidative and/or reductive reactions that should be taken into account in interpreting the effects of DFO in vitro and in vivo.
Sabourault
D
D
Department of Biomedical Research on Alcoholism, Faculté de Médecine, Université René Descartes, Paris, France.
Ribiere
C
C
Nordmann
R
R
Houee-Levin
C
C
Ferradini
C
C
D000838:Anions; D003037:Cobalt Radioisotopes; D003676:Deferoxamine / Q000528:radiation effects; D005609:Free Radicals; D005720:Gamma Rays; D011675:Pulse Radiolysis; D012996:Solutions; D013481:Superoxides; D014867:Water
D000838:Anions; D003037:Cobalt Radioisotopes; D005609:Free Radicals; D012996:Solutions; D014867:Water; D013481:Superoxides; D003676:Deferoxamine