G. D. Zasukhina

[Modification of repair DNA synthesis in mutagen-treated human fibroblasts during adaptive response and the antimutagenic effect of garlic extract].

Repair DNA synthesis (RDS) in human fibroblasts during the adaptive responses (ARs) induced by cadmium chloride (CdCl2), γ-radiation, and 4-nitroquinoline-1-oxide (4NQO) was compared in cells pretreated and not pretreated with garlic extract. The RDS was increased during the ARs induced CdCl2 and γ-irradiation. Garlic extract stimulated RDS in cells treated by the same mutagens. 3-Aminobenzamide (3AB), an inhibitor of poly(ADP-ribose) polymerase, decreased the RDS rate in cells treated with CdCl2 and γ-irradiation but had no significant effect on cells treated with 4NQO. It was demonstrated that DNA repair was involved into cell protection in different ways in the cases of antimutagen treatment and AR.

Individual Sensitivity to Genotoxic Effects of Nickel and Antimutagenic Activity of Ascorbic Acid

Cytotoxicity of nickel compounds was studied by stimulating the repair synthesis of DNA and counting lymphocyte micronuclei in workers of smelting shop of copper-nickel sulfide processing plant. Nickel content in the organism was evaluated by its concentrations in hair. Therapy with ascorbic acid (1 g/day for 1 month) led to a significant decrease in the number of micronuclei. The number of micronuclei before and after ascorbic acid treatment varied within a wide range in different individuals.

Antimutagenic activity of wheat β-purothionin Tk-AMP-BP

Antimutagenic activity on human RD cells was studied for β-purothionin Tk-AMP-BP isolated from seeds of wheat Triticum kiharae, which has high stress resistance. Cadmium chloride at 5 × 10−6 M was used as a mutagen. The numbers of DNA breaks in mutagen-treated and intact cells were inferred from the single-stranded to double-stranded DNA ratio and expressed as protection coefficients. The protective effect was simultaneously assayed for aqueous plant extracts known to possess antioxidant properties. Wheat thionin was the most active among all of the antimutagens examined; its protection coefficient reached 85–88% at micromolar peptide concentrations (8–32 μg/ml). Thus, wheat β-purothionin was for the first time demonstrated to be highly efficient in protecting human cell DNA from the damaging effect of cadmium chloride.

Antimutagens (β-purothionin and crown compound) as modulators of expression of genes involved in carcinogenesis in human cells

254 The level of gene expression reflects the amount of synthesized product. The expression of the majority of genes may vary under different conditions. Anticancer drugs that are used, for example, for the treatment of tumors, may serve as such modulators. However, the effect of a modulator depends on the genotype. For example, the authors of [1] showed that chemotheraa peutics enhanced expression of the MVP gene in subb jects carrying the mutant TT genotype ABCCIrs35605 and reduced it in subjects carrying the mutant genoo type TP53rs1042522. In this study, drugs whose antimutagenic activity was found by us earlier were tested as gene expression modulators. Antimutagens are compounds that weaken the damaging effect of physical mutagens (radiation) and chemical nature. The majority of antii mutagens also exhibit anticancer properties, which are often correlated with antioxidant activity; in addition, they can function as adaptogens, radioprotectors, and geroprotectors. To date, a vast number of herbal products have been tested, which were represented primarily by plant extracts and their components, vitamins, which, due to their multifaceted action, were shown to be effective antimutagens with respect to radiation and many chemical mutagens and to had a protective effect, increasing the antitumor reactivity [2, 3]. For examm ple, an antitumor effect of mistletoe extract and its major active ingredient lectin (inhibition of tumor cell proliferation in vitro combined with apoptosis inducc tion) was described [4]. The cytotoxic mechanisms of action of this medicine are associated with the inhibii tion of protein synthesis due to inactivation of riboo somes, activation of the caspase cascade, and change in the content of reactive oxygen species. At the organn ismal level, immunomodulatory effects were discov ered, such as increased activity of NK cells, elevated levels of cytokines, etc. The number of metastases in tumorrbearing animals that were administered with this extract reduced, and their lifespan significantly increased. The ability of mistletoe to stimulate the synthesis of βendorphin (pleasure neurotransmitter) in patients with breast cancer who received injections of the drug, which correlated with the life quality improvement, should also be mentioned. We demonstrated the antimutagenic activity of extracts of aloe vera, wheat, and green tea in human cells against cadmium chloride. Moreover, we discov ered the antimutagenic properties of the antimicrobial peptide βpurothionine isolated from stressstolerant wheat T. kiharae [5]. This positively charged polypepp tide is composed of 45 amino acid residues and exhibb its strong antimutagenic properties in …

Comparison of the antimutagenic activities of natural and synthetic substances in irradiated repair-defective human cells

269 The use of antimutagens that reduce the level of mutational transformations induced by physical and chemical factors is part of the problem of genetic safety. This study was the first to compare the activities of synthetic and natural preparations (a diazocrown compound and garlic extract (GE), respectively) in the repair-defective human cells where restoration of γ -induced DNA lesions is inhibited. Most antimutagens have antiradical activity, i.e., they neutralize free radicals that are the major injurious agents induced by radiation and many chemical mutagens, such as heavy metals [1]. We found previously that GE is an effective antimutagenic preparation neutralizing free radicals induced by radiation or cadmium chloride, which was demonstrated in the reaction of Fenton et al. [2, 3]. In addition, diazocrown compounds with antimutagenic activities no lower than that of GE were studied. However, unlike the natural antimutagen GE, the studied crown compounds displayed no antioxidant properties [3]. In this study, we used diazocrown compound 1 , which was in some tests more effective than other crown compounds similar in structure [4].

Mechanisms of human cell protection associated with genetic polymorphism

Systems ensuring protection of human cells against endogenous and exogenous mutagenic factors are considered in terms of genetic polymorphism. Some protection mechanisms are described, including those connected with capturing free radicals, biotransformation of xenobiotics, excision repair of DNA damage (excision of nitrous bases, nucleotides, mismatch repair). A special section is devoted to some issues of using antimutagens in context of genetic polymorphism. The problem of adaptive response is discussed, providing evidence for independence (in some cases) of DNA repair systems and the formation of adaptive response. Some results of the author obtained many years ago but still relevant are presented.

Antimutagenic and Antioxidant Activities of Crown Compounds in Comparison with the Effects of Garlic Extract

Antimutagenic activity of N-carboxyalkyl derivatives of aza- and benzoazacrown compounds was revealed and antimutagenic activity of garlic extract was confirmed. Specific genoprotective effect of crown compounds towards the effects of various mutagens was demonstrated. The antimutagenic effect of these compounds was not realized via antioxidant mechanisms, while the protective effect of garlic extract was associated with its antioxidant and reparative activities.

Comparative analysis of natural and synthetic antimutagens as regulators of gene expression in human cells under exposure to ionizing radiation

This paper studies the effect of plant peptides of thionine Ns-W2 extracted from seeds of fennel flower (Nigella sativa) and β-purothionine from wheat germs (Triticum kiharae), as well as a synthetic antimutagen (crown-compound), on the expression of several genes involved in the control of cellular homeostasis, processes of carcinogenesis, and radiation response in human rhabdomyosarcoma cells (RD cells), T-lymphoblastoid cell line Jurkat, and blood cells. All of these agents acted as antimutagens-anticarcinogens, reducing the expression of genes involved in carcinogenesis (genes of families MMP, TIMP, and IAP and G-protein genes) in a tumor cell. A pronounced reduction in the mRNA level of these genes was caused by thionine Ns-W2, and the least effect was demonstrated by β-purothionine. Antimutagens had very little effect on the mRNA levels of the several studied genes in normal blood cells. Thionine Ns-W2 in tumor cells resulted in a reduction of the content of oncogenic mature miR-21 but did not affect the mRNA level of gene p53 and mature miR-34, which was regulated by the activity of tumor suppressor p53. It was established that thionine Ns-W2 has a cytotoxic effect by inducing the death of RD cells and lymphoma. The exposure of these cells to ionizing radiation enhanced the inhibitory effect of thionine on expression of the genes involved in oncogenesis. These data indicate that thionine can be regarded as a promising anticarcinogen.

Antimutagenic Activity of Wheat Polypeptides in Human Cells Exposed to Cadmium Chloride

Antimutagenic effects of polypeptides isolated from Triticum kiharae wheat plantule extracts have been studied on human cells exposed to cadmium chloride. The most effective polypeptide Tk-AMP-BP β-purothionin exhibited higher antimutagenic activity than wheat water extract and another peptide isolated from the same wheat species, Tk-AMP-γ2 defensin; it also produced a pronounced antioxidant effect. This polypeptide can be used as a preventive agent for reducing the mutagenic potential of some environmental pollutants and for correction of human diseases associated with the defense system defects.

Modulation of gene expression by antimutagens in human cells differing in the sensitivity to mutagens

277 Evaluation of gene expression allows determina tion of the level of synthesized product. The parame ters of expression of the majority of genes for certain reasons vary, and the study of gene expression makes it possible to identify the indices of sensitivity of human cells to various exogenous factors (radiation, chemical mutagens, etc.), to detect specific molecular subtypes and their expression levels to assess the risk of develop ment of tumors and some human pathologies, as well as to predict the cell response to therapeutic interven tion.