[STUDY OF TOTAL ANTIOOCIDANT STATUS OF THE ORGANISM AS A POSSIBLE BIOMARKER OF DOSE AND EFFECT OF RADIATION EXPOSURE].

In presented article, by means of a comparative analysis of the relationship between the dose-dependent alterations in the organism's redox status, measured by the innovative method developed by us and the standard methods used for assessing catalase and superoxide dismutase activity, and an end radiobiological effect, was attempted the preliminary assessment of the possibility to apply the parameter of blood plasma total antioxidant activity (TAA) as marker of dose and effect of radiation exposure. The experiments were carried out on white mice randomly divided into groups of irradiated and sham irradiated animals. The mice were exposed to a whole body gamma irradiation by source Cesium-137 (137Cs) at doses of 5 and 7 Gr, a dose rate of 1.1 Gr / min. After 5 days of beginning of observation in animals' blood measurements of the activity of antioxidant enzymes (superoxide dismutase - SOD and catalase - CAT) and total antioxidant activity by spectrophotometric method were evaluated. Parallel monitoring of animal survival was conducted. At the given stage of the study, applicability of OAA as a marker of dose-dependent alterations in antioxidant status was assessed by the criteria of sensitivity and linearity, and as a marker of the effect the strength of the relation between the antioxidant status indicators and the final radiobiological effect, measured by animal life span in post- radiation period (time-effect) For comparative analysis of the effects of radiation on the levels of antioxidant status indicators (SOD, catalase, OAA), ANOVA methods were used, the nature of the causal relationship between levels of antioxidant status and the life span of laboratory animals was analyzed on the basis of the Cox proportional intensity model with time covariates, preliminary processing of data, basic calculations and visualization of the results were carried out using a mathematical package that " STATISTIC 12". The received results testify to the significantly high sensitivity of the total redox-status indicator (OAA) to the dose of irradiation, which makes it possible with full justification to consider it as a promising candidate of the biological exposure dose marker. In addition, the indicator of the total antioxidant status (OAA) of the body allows predicting the dose dependence of the survival of laboratory mice more accurately than the indices of the activity of individual antioxidant enzymes (catalase and SOD), which makes it possible to consider it as a promising candidate for the biomarker of the dose and the effect of radiation exposure.

[RADIOPROTECTIVE ACTIVITY OF POLYMETOXY-LATED FLAVONOIDS OF CITRUS EXTRACT].

The aim of the study was to establish the radioprotective activity of citrus polymetoxylated flavonoids extract (CPMFE) on the X-irradiated rats. The experiments were carried out on white Wistar rats. Animals were irradiated with X rays in doses of 5 Gy and 7 Gy. The control group consisted the sham-irradiated rats. Part of animals of each group were treated with intramusculary injections of CPMFE (dose 30 mg/kg) during 7 days; blood was taken from the tail vein (0.5 ml) for detection of lipoperoxides (LOO.) content. On the 3rd day after irradiation 3 animals from each group were sacrificed (under ether anesthesia) and blood samples were taken for the study of antioxidant status. The activity of antioxidant enzymes (catalase (CAT) and superoxidedismutase (SOD)) was determined by the spectrophotometric method; the content of LOO.in the blood was determined by electron paramagnetic resonance (EPR) mrthod. In group of irradiated rats a sharp dose-dependent inactivation of blood antioxidant enzymes (SOD, CAT) and intensification of the lipid peroxidation were detected. The direct and feedback mechanism in the regulation of CAT and SOD activity, ensuring the implementation of antioxidant protection in the body was revealed. Under irradiation with 7Gy rapid death of animals (on 3-d day after irradiation the mortality of animals was 70%, and on the 5th day all died) were detected. During irradiation with dose 5 Gy the survival of animals increased (on the 8-th day after irradiation - 50% survival rate). CPMFE in dose-dependent manner supported the reduce the intensity of lipid peroxidation processes - at relatively low doses of radiation (5Gy) during the first 3 days the content of LOO.in the blood decreased insignificantly compared with indices in untreated animals, whereas with an increase in the dose of irradiation (7Gy) a statistically significant antiradical effect of CPMFE (a statistically significant decrease in the LOO. content) was detected. Under the effect of CPMFE in the blood of rats irradiated with a dose of 5 Gy and 7 Gy, the activity of CAT and SOD, not statistically significant tends to increase (more significant with a dose of 7 Gy). CPMFE did not affect the cumulative survival of animals irradiated with a dose of 5 Gy, but reduced the mortality of rats by 20% (on the 3rd day of irradiation), and contributed to an increase in the life expectancy of animals by 2 times (up to 7 days) in the case of dose 7 Gr. Based on the analysis of the research results, it can be assumed that under conditions of radiation damage, exogenous antioxidants synergistically with a dose-dependently activated endogenous non-enzymatic antioxidant system of the body (especially at 7Gy) contribute to the effective suppression of chain reactions of peroxidation, reduction of mortality and increase in life expectancy of animals.