Determination of hydroxyl radical production in aqueous solutions irradiated to clinically significant doses

Decarboxylation of 14C-carboxylbenzoic acid in aqueous solutions after low-dose irradiation has been used to determine the relative magnitude of oxidation reactions and estimate the hydroxyl radicals produced. The G CO2 values determined from these measurements of 0.4 to 1.0 mM solutions of benzoic acid after x-ray doses of 1000 rads ranged from 0.72 to 0.77, in excellent agreement with values reported by authors using much higher doses of radiation. Superoxide dismutase and catalase, known scavengers of superoxide and hydrogen peroxide, respectively, did not show impairment of the oxidation of benzoic acid. On the other hand, biologically significant concentrations of phenol and mannitol appear to impair the radiation-induced oxidation of benzoic acid, indicating that the process is secondary to a reaction with OH . . We found that serum and glucose, common cell media contents, are potent OH . scavengers. These observations indicate that the oxidation of benzoic acid can be as a reliable method to estimate OH . with radiation doses of clinically significant magnitudes. In addition, these results suggest that the radiation induced by OH . in cell systems can be significantly modified by the type of buffer used.