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Nowadays multiple heterogeneous chemicals affect the human body. They include drugs, household chemicals, dyes, food supplements and others. The human organism can modify, inactivate, and eliminate the chemicals by biotransformation enzymes. But it is well known that biotransformation can lead to toxification phenomenon. Individuals differ from each other by the rate of chemical modification that promotes accumulation of toxins and carcinogens in some patients. An N-acetyltransferase 2 enzyme participates in the aromatic amines second phase metabolism. This work reviews the acetyltransferase gene polymorphism possible role in diseases development including drug-induced organs damage.Gene of acetyltransferase has polymorphisms associated with two haplotypes of fast and slow substrate acetylation. Gene alleles combine in three genotypes: fast, intermediate, and slow acetylators. Acetylation rate plays a significant role in side effects development during tuberculosis treatment and cancer pathogenesis. Recently, new data described the role of enzyme in development of non-infectious diseases in the human. Scientists consider that slow acetylation genotype in combination with high xenobiotic load result in accumulation of toxic substances able to damage cells.Therefore, acetyltransferase genotyping helps to reveal risk groups of cancer and non-infectious disease development and to prescribe more effective and safe doses of drugs.

The work presents a review devoted to the metabolism and the mechanism of toxicity of seleniumcontaining supplements: elemental selenium, sodium selenite, diacetophenonyl selenide, selenopyrane, ebselen, dimethyl dipyrasolyl selenide and selenium-containing amino acids used for correction of selenium deficiency. Elemental selenium penetrating through cell walls, but not through transport channels demonstrates poorly predicted and difficultly regulated bioavailability. Sodium selenate is known to be the most toxic form of selenium in food. The metabolism of xenobiotic diacetophenonyl selenide resembles that of sodium selenide. The xenobiotic reacts with thiols, for instance, with the reduced form of glutathione leading to the formation of hydrogen selenide. Ebselen is not considered to be a well bioavailable form of selenium and thus possesses low toxicity. Xenobiotic selenopyrane eliminates selenium only in processes of xenobiotic liver exchange, and in our investigations - partially in acid-catalyzed hydrolysis. The metabolism of xenobiotic dimethyl dipyrasolyl selenide having low toxicity is poorly investigated. The toxicity of high doses of selenomethionine is determined by the possibility of incorporation in proteins and vitally important enzymes with dramatic changes of protein quaternary structure. The toxicity of high doses of methylselenocysteine seems to be caused by the lack of an exchange pool in the body and quick regeneration of hydrogen selenide from methylselenol which is formed as a result of enzymatic destruction of this amino acid. Also the issue of the most prospect selenium donor is discussed. The physiological compatibility, the low toxicity, the presence of an exchangeable pool in the organism, the antioxidantal properties and the simplicity of production indicate selenocystine as an optimal selenium donor.

Xenobiotics, including salts of heavy metals, determine the development of pathology of individual organs and systems of the body. Adrenal hormones occupy a key place in the regulation and maintenance of the organism basic functions. The study of morphological, biochemical and immunohistochemical changes in the adrenal cortex of pubescent male rats at exposure to the complex of heavy metal salts remains an actual aspect of modern morphology. The experiment involved 24 white adult male rats weighing 250–300 g, aged 7–8 months. The animals of the experimental group consumed ordinary drinking water saturated with a combination of heavy metal salts (Zn, Cu, Fe, Mg, Cr) for 60 days. Histological, biochemical (determination of the content of hormones COR – cortisol, DHS – dehydroepiandrosterone sulfate) and immunohistochemical (determination of the expression of proliferation marker Ki-67) methods were used. Long-term consumption of the combination of heavy metals salts by mature rats leads to thickening of the stromal component of the gland, the rupture of capillaries and the violation of rheological properties of blood. Chromatin condensation, its marginal location, and initial stages of necrobiotic changes have been found in the spongiocyte nuclear apparatus. For endocrinocytes of the zona glomerulosa and zona reticularis of the gland, a slight increase in proliferative activity has been revealed, while cells of the zona fasciculata were non-reactive. These results correlate with the results of biochemical research, according to which hormones of the zona reticularis – DHS were actively involved in the formation of adaptive reactions in the body of experimental animals at the 60-day period of administration of the complex of heavy metals salts. The results of complex studies indicate a weakening of the secretory activity of cells of the zona fasciculata, which adversely affects the development of compensatory-adaptive processes in the body and the course of the general adaptation syndrome in response to the action of the damaging agent.

The results of disperse analysis indicated degree of contamination of air and soil by xenobiotics. It depended on the clinical, radiographic and sonographic signs of articular syndrome in RA.