Radioprotective Properties of Some Heterocyclic Nitrogenous Compounds Against X-radiation Injury to Serum Proteins in Mice

Abstract

The results obtained from this study suggest the following: The concentration of total serum proteins in mice is changed very little under the various treatments, while protein fractions showed significant alterations.The concentrations of various serum proteins remain almost constant under normal conditions. Intraperitoneal administration of imidazole or benzimidazle at the mentioned doses induces rapid quantitative changes in the serum which are recovered in about 3 days after injection.Whole-body X-irradiation at 750 r creates slow but progressive and persisting serious changes in concentration of serum protein fractions which end in death of animals 8 -10 days after ir radiation.Whole-body X-irradiation of imidazole or benzimidazole protected animals results in quantitative rapid changes in concentration of serum protein fractions for about four days. There after a slow but steady restoration begins. The concentration approaches the normal levels towards the 10th day after irradiation.Imidazole and benzimidazole proved to be good radioprotectants against the effects of X-radiation on serum protein fractions. Benzimidazole seems to surpass imidazole.Because of the potential practical importance of certatin chemical compounds that exhibit a protec tive character against lethal effects of ionizing ra diation, excessive work has been done to identify the most effective non-toxic ones. Since P a t t et a l . 1 reported that the amino acid, cysteine, signicantly increased the survival of irradiated rats, thousands of agents have been tested, T h o m s o n 2. Repeated investigations have been also carried out to study the mechanism through which such compounds m ani fest their protective effects. It seems likely, however, that all those compounds exert their effects by in fluencing the production of reactive radicals by radiation. The protection of the vital cellular func tions is thus achieved either by production of hy poxia, i. e. reduction of oxygenation in tissues, or through reaction with the free radicals released by radiation to inactivate them. The biological diffi culty with the application of these compounds in general is that they appear to be effective only at close to toxic levels. Moreover, almost none of these agents has been shown to be of benefit when given after radiation exposure. Most of the experiments were carried out on mice. The increase in 30 day survival has been usually taken as a parameter to assume that the protectant is effective in changing