Radiation protection agents

Some of the commercial uses that pseudoureas have found are herbicides [27, 28] inhibitors for discoloration of color photographic layers [29] monomers for the preparation of some novel copolymers [30, 31] and dyes [32,33]. A survey of the recent decennial indexes of Chemical Abstracts should be made to see the large number of pseudoureas reported for varied uses. Pseudothioureas have also been found useful as radiation protective agents [34]. 

Anthocyanins also have functional potential to serve as radiation-protective agents, vasotonic agents, and chemoprotective agents [5]. 

Foye WO. Radiation-protective agents in mammals. J Pharm Sci 1969 58(3) 283-300. Vadas EB. Stability of pharmaceutical products. In Gennaro AR, ed. Remington s Pharmaceutical Sciences. Easton Pennsylvania Mack Publishing Company, 1990 1507. Cox N, Meakin BJ, Davies DJ. The influence of some antioxidants on the photochemical decomposition kinetics of promethazine hydrochloride. J Pharm Pharmacol 1976 28(suppl) 45. 

Fatome M., Poutrain R, Granger R., Orzalesi H., Robbe Y., Randon M., Valentin M., Chevallet R, Fernandez J.R, Radiation protective agents. Dithiolanes, Chim.Then, 1970,5,327. 

Compounds such as 2-(2-hydroxy-5-methylphenyl)benzotriazole 2 (tinuvin P) absorb UV light in the region of 300 - 400 nm and are used as radiation protection agents, e.g. for the prevention of sunburn, and also as photostabilizers for plastics, rubber and chemical fibres [155]. Tests have been carried out as to the suitability of polynitro-l-phenylbenzotriazoles as explosives [156]. 

Several other radiation protection agents are known. These compounds are typically amino thiols, similar to the natural amino acid cysteamine. They probably function as scavengers for the products of water radiolysis. Their effectiveness is evaluated by determination of the dose reduction factor (DRF), which is the ratio of LD5Q/3Q for protected and unprotected animals. Because of their chemical toxicity, many can o y be administered in small doses. 

Cysteamine, as radiation protecting agent 511 data on RSSR 491 hydrochloride, e.s.r. study 507, 508 radiolysis in solid state 507... 

Potassium iodine tablets can be used to reduce radioactive iodine exposure to the thyroid gland. According to the National Council of Radiation Protection and Measurement (NCRP), taking 130 milligrams of potassium iodine at or before exposure to radioactive iodine effectively blocks nearly 100% of radioactive iodine from reaching the thyroid (1977). See Table 3.3 for a summary of antidotes for various chemical and biological agents. 

The above-mentioned radical acceptors are not the only effective protective agents against radiation. Studies performed with benzene and nitrobenzene in natural rubber and styrene butadiene rubber (SBR) with N-phenyl-p-naphtylamine demonstrated radiation protection of the respective compounds. 

Reactions of the hydrated electron possibly may be somewhat relevant to the action of dose-modifying agents such as 02, NO, C02, and sulfhydryl compounds. It can safely be assumed that these exert their influence at the radiation-chemical level, and it is notable that many of them react rapidly with hydrated electrons. Table II, taken from a paper by Braams (6), compares the rate constant for reaction with the hydrated electron with the concentration at which certain compounds have been used as protective agents. It can be seen that, at the concentrations used in biological systems, those substances which are effective as protectors can compete favorably with oxygen for hydrated electrons. Penicillamine was not a good protector at the concentration used and did not compete as favorably as the other substances for hydrated electrons. Higher concentrations of penicillamine could not be... 

It seems appropriate here to mention some interesting aspects of damaging cells in aqueous solution that is not directly related to the interaction of ionizing radiation with the cellular DNA. For example, thiourea, generally considered as a protecting agent, sensitizes cells at low concentrations and this effect... 

Vascular Tone Immune Surveillance Cellular Adhesion Vascular Permeability Neurotransm ission Bronchodilation Platelet Adhesion Inhibition Renal Function Antioxidant Leukocyte Adhesion Inhibition Protection Against TNF Toxicity Enzyme Function Inhibition DNA Damage Induction Lipid Peroxidation Induction Increased Susceptibility to Radiation Alkylating Agents Toxic Metals Antioxidant Stores Depletion... 

The mechanisms of radiation damage and effects of hardeners were studied recently by pulse radiolysis [89], The epoxy resins require a relatively large amount of curing agents (hardeners), most of them are aromatic and aliphatic amines such as diamino diphenyl methane or triethylene tetramine. On the basis of the emission spectra and kinetic behavior of excited states observed, the radiation resistance of aromatic and aliphatic amine curing epoxy resin was explained by internal radiation protection effects due to energy transfer. 

The higher radiation protectiveness of polymeric compounds over low molecular weight compounds could be utilized in the design of radioprotective agents. A report dealing with the various polymeric antiradiation aibstances has been published ... 

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