AN ENZYMATIC EVALUATION OF THIOL RADIOPROTECTORS

Abstract

A number of thiol and disulfide compounds have been tested for their ability to inhibit the oxidation of α-ketoglutarate by rat-liver homogenates. In general, a correlation exists between the degree of inhibition and the radioprotective ability of the compound. It is possible that a better correlation exists for the corresponding disulfides.The inhibition involves oxidation of the thiol, and the disulfides were found to be more potent inhibitors than the thiols.There is no change in the ATP level of normal tissues after the administration of aminoethylisothiouronium bromide hydrobromide in vivo, and the protective ability of this compound is not considered to be related to any interference with mitochondrial oxidative phosphorylation. Mitochondrial respiration is, however, inhibited. The results support the mixed disulfide protection theory of Eldjarn and Pihl, and provide a physiologically significant test system for this hypothesis.