Radiation-protection by Some Sulphydryl Derivatives of Pyridoxine and a New BAL Preparation

Abstract
5-Mercaptopyridoxine was shown to be a protective agent against ionizing radiation for mice and Escherichia coli strain B/r, while pyridoxine was inactive. 4, 5-Dimercaptopyridoxine protected bacteria but not mice. The lack of effect with mice might be due to the greater toxicity of the disulphydryl compound, which prevents the administration of an adequate dose for protection. The protective effect of both sulphydryl derivatives on E. coli was abolished by irradiating under aerated conditions, suggesting that the mechanism involves the production of anoxia. BAL-sulphonic acid showed a protective effect with mice in contrast to other experiments with normal BAL. The cysteine-cysteamine configuration is therefore shown to be unnecessary for the protective action of sulphydryl compounds.