Radioprotectors: Nature’s Boon

Objective: To reduce the chances of toxicity, reduction in radiation dose or reducing the frequency of the therapy is done which usually leads to a therapeutically poor outcome. The most feasible method is to protect the normal cells by administration of radioprotective agents either before or after the exposure. These agents have been tested on animals and human cellmodels for evaluating theirsafety window and toxicityprofile at the cellular level. The study aims to compile the effective natural radioprotective agents available which can be further exploited by using certain QSAR studies to increase their potency. Method: Structured literature search from EMBASE, PubMed, Bentham Science, Scopus, and ScienceDirect was done and appropriate peer-reviewed review articles, as well as certain research articles, were included and compiled in this review paper. Conclusion: As various studies have indicated the harmful effects of ionizing radiations on normal cells, to reduce these effects radioprotective agents are used before or after exposure to radiations. Compounds derived from natural sources are proved to have few side effects and they possess radioprotective property due to the presence of alkaloids, resins, volatile oils, tannins in their molecular structure. Various plants having such radioprotective constitutes have been identified for their radioprotective action and compiled in the present study. Conclusion: As various studies have indicated the harmful effects of ionizing radiations on normal cells, to reduce these effects radioprotective agents are used before or after exposure to radiations. Compounds derived from natural sources are proved to have few side effects and they possess radioprotective property due to the presence of alkaloids, resins, volatile oils, tannins in their molecular structure. Various plants having such radioprotective constitutes have been identified for their radioprotective action and compiled in the present study.

Characteristic of the active substance of the Saccharomyces cerevisiae preparation having radioprotective properties

The paper describes some biological features of the radioprotective effect of double-stranded RNA preparation. It was found that yeast RNA preparation has a prolonged radioprotective effect after irradiation by a lethal dose of 9.4 Gy. 100 % of animals survive on the 70th day of observation when irradiated 1 hour or 4 days after 7 mg RNA preparation injection, 60 % animals survive when irradiated on day 8 or 12. Time parameters of repair of double-stranded breaks induced by gamma rays were estimated. It was found that the injection of the RNA preparation at the time of maximum number of double-stranded breaks, 1 hour after irradiation, reduces the efficacy of radioprotective action compared with the injection 1 hour before irradiation and 4 hours after irradiation. A comparison of the radioprotective effect of the standard radioprotector B-190 and the RNA preparation was made in one experiment. It has been established that the total RNA preparation is more efficacious than B-190. Survival on the 40th day after irradiation was 78 % for the group of mice treated with the RNA preparation and 67 % for those treated with B-190. In the course of analytical studies of the total yeast RNA preparation, it was found that the preparation is a mixture of single-stranded and double-stranded RNA. It was shown that only double-stranded RNA has radioprotective properties. Injection of 160 μg double-stranded RNA protects 100 % of the experimental animals from an absolutely lethal dose of gamma radiation, 9.4 Gy. It was established that the radioprotective effect of double-stranded RNA does not depend on sequence, but depends on its double-stranded form and the presence of “open” ends of the molecule. It is supposed that the radioprotective effect of double-stranded RNA is associated with the participation of RNA molecules in the correct repair of radiation-damaged chromatin in blood stem cells. The hematopoietic pluripotent cells that have survived migrate to the periphery, reach the spleen and actively proliferate. The newly formed cell population restores the hematopoietic and immune systems, which determines the survival of lethally irradiated animals.

The Effectiveness of Sulfotozifan in the Case of External Gamma Irradiation

No radiation protection agents have been found to date which would not have toxic side effects while having radioprotective action of unlimited duration. Based on the screening of organo-element chemical compounds, a novel radioprotector sulfotozifan was selected to prevent the acute radiation syndrome in animals. Sulfotozifan belongs to compounds of hazard class 3 (National Standard of the Russian Federation (GOST) 12.1:007.76). A single subcutaneous administration of sulfotozifan at a dose of 38.0 mg / kg of body weight 2-4 days prior to the radiation exposure of animals to an absolute lethal dose, protects 80-100% of the animals from the radiation death. The pretreatment of animals with sulfotozifan 2-4 days prior to the irradiation has a positive effect on the animals’ clinical condition, normalizes their hematological parameters, increases the levels of T and B lymphocytes, inhibits peroxidation of lipids (POL), reduces the concentration of malondialdehyde (MDA), the final product of POL, in the erythrocyte hemolysate and blood plasma, and also promotes a reduction in the formation of radiotoxins. By its organoleptic, physicochemical, and bacterioscopic characteristics, the meat from irradiated animals pretreated with sulfotozifan does not differ significantly from those of the meat from the control animals and thus meets GOST requirements.

Radioprotective effects of ultra-small citrate-stabilized cerium oxide nanoparticles in vitro and in vivo

Different radioprotective action mechanisms of CeO2 nanoparticles in vitro and in vivo are demonstrated and discussed.