Radioprotectors (synonym radioprotective drugs) is a chemical compound used to mitigate the harmful effects of ionizing radiation on the body. Radioprotectors are used only for the purpose of prevention and make it easier for radiation sickness. Introduction of radioprotectors after irradiation is ineffective. Conventionally, the radio protectors can be divided into two groups: 1) radioprotectors short-term, one-off actions, which are introduced into the organism in a short period of time before irradiation, and 2) radioprotectors prolonged action, which is administered repeatedly, usually in small doses up to radiation exposure. To radioprotectors first group includes most of the known effects of connections: for example, different aminothiol (Merklin, propain, aminoacylation and others), the amino acid cysteine, tsistamin, some biogenic amines, not containing sulfgidrile group, Lanovoy, aminofenola, some alcohols, some representatives of carbohydrates and other
There are several main hypothesis of the mechanism of action of radioprotectors of this group. 1. Hypothesis considering the radioprotectors as substances that cause temporary reduction of oxygen in the tissues. It is assumed that this reduces the possibility of formation of oxidative radicals and peroxides in the process of irradiation. Ultimately, this should lead to increased radiostacijas. 2. The hypothesis of the mechanism of action of radioprotectors as substances that inactivate free radicals. According to this view sulfa radioprotectors able to bind radicals produced by radiation treatment. It is supposed that in the result of this process oxidizing radicals not affect the molecules of the cells. 3. The idea of radioprotectors as chemical compounds that protect critical molecule of cells. The hypothesis assumes that as a result of chemical reactions sulfa radioprotectors react with sulfhydryl groups of biologically important molecules and thus "cover" them from the effects of ionizing radiation. 4. The idea of radioprotectors as compounds that increase radiostability biochemical systems. This hypothesis is based on the fact that the absolute majority of radioprotectors simultaneous action has radioprotective effect only if they are in subtoksicskih doses. This hampered different radiosensitive biochemical systems, such as the synthesis of DNA, oxidative phosphorylation in microstructures cells, formation of high energy compounds in the cell nucleus, and so on, the Mechanism of temporary inhibition of biochemical systems, in turn, is based on the ability of radioprotectors to enter into a chemical bond with molecules of enzymes. An essential role is played temporary formation of mixed-disulfidnye connection between radioprotectors and containing sulfgidrile group molecules of proteins-enzymes.
The mechanism radioprotective effect of radioprotectors prolonged action type biogenic stimulators (e.g. vitamins) is associated with a gradual increase of radioresistance of the body and by increasing the activity of compensatory and recovery processes. For example, a long introduction in the body of vitamins P reduces the possibility of formation of hemorrhage in irradiated animals. The mechanism of this phenomenon is due, in particular, the ability of vitamin e to suppress the activity of hyaluronidase - complex enzymes that cause the enzymatic degradation of hyaluronic acid. In turn one of the functions of this acid is that it "cement" connective tissue.
Currently, some of radioprotectors are pharmacopoeial means (for example, Marklin, tsistamin).