A reinvestigation of the reaction of desferrioxamine with superoxide radicals. A pulse radiolysis study

The reaction of desferrioxamine with superoxide has been studied using the pulse radiolysis technique. The decay of O₂^- was not accelerated in the presence of up to 4 × 10^-4 M desferrioxamine at physiological pH. The rate constant was found to be lower than 2 × 10⁴ M^-1 S^-1. In acid solutions the rate constant of the reaction between desferrioxamine and HO₂ was found to be lower than 10₅ M^-1 S^-1. The reaction was not studied in alkaline solutions due to the high absorbance of desferrioxamine in the U. V. region. The pK of desferrioxamine was determined to be 9.2 ± 0.05.