The Effects of Ionizing Radiation on Aqueous Solutions of Cysteamine and Cystamine

Abstract

Aqueous solutions of S35-labeled cysteamine and cystamine were irradiated with a C060 source or a 175-kv X-ray machine. The products formed by irradiation were resolved by paper chromatography and identified. Irradiation of cysteamine solutions resulted in oxidation to cystamine at pH 3 and 5 with G values of 3.6 to 5 and 11 to 20, respectively. Three products were isolated from irradiated solutions of cystamine and identified as cysteamine, 2-aminoethane sulfinic acid, and taurine. The G values for the latter 2 were 0.8 to 1.2 and 0.4 to 1.1, respectively, varying inversely with dosage. The yields of the products were measured under different conditions of dose, dose rate, concentration and pH of the solutions, temperature, and source of radiation. The findings are discussed in relation to the X-ray protective activity of the compounds and to the mechanism of radiation damage.