Katarína Kozics

Slovak Academy of Sciences, Presburg, Bratislavský, Slovakia

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Publications (15)40.16 Total impact

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    ABSTRACT: Nature is an attractive source of therapeutic compounds. In comparison to the artificial drugs, natural compounds cause less adverse side effects and are suitable for current molecularly oriented approaches to drug development and their mutual combining. Medicinal plants represent one of the most available remedy against various diseases. Proper examples are Salvia officinalis L. and Thymus vulgaris L. which are known aromatic medicinal plants. They are very popular and frequently used in many countries. The molecular mechanism of their biological activity has not yet been fully understood. The aim of this study was to ascertain if liver cells of experimental animals drinking extracts of sage or thyme will manifest increased resistance against oxidative stress. Adult Sprague-Dawley rats were divided into seven groups. They drank sage or thyme extracts for 2 weeks. At the end of the drinking period, blood samples were collected for determination of liver biochemical parameters and hepatocytes were isolated to analyze (i) oxidatively generated DNA damage (conventional and modified comet assay), (ii) activities of antioxidant enzymes [superoxide dismutase (SOD), glutathione peroxidase (GPx)] and (iii) content of glutathione. Intake of sage and thyme had no effect either on the basal level of DNA damage or on the activity of SOD in rat hepatocytes and did not change the biochemical parameters of blood plasma. Simultaneously, the activity of GPx was significantly increased and the level of DNA damage induced by oxidants was decreased. Moreover, sage extract was able to start up the antioxidant protection expressed by increased content of glutathione. Our results indicate that the consumption of S.officinalis and T.vulgaris extracts positively affects resistency of rat liver cells against oxidative stress and may have hepatoprotective potential.
    Mutagenesis 08/2015; DOI:10.1093/mutage/gev056 · 2.79 Impact Factor
  • D Slamenova · K Kozics · M Melusova · E Horvathova ·
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    ABSTRACT: We investigated activities of antioxidant enzymes (AEs), superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) in human HepG2 and hamster V79 cells treated with a scale of concentrations of hydrogen peroxide (H2O2), tert-butyl hydroperoxide (t-BHP) and methyl methanesulfonate (MMS). Cytotoxicity and genotoxicity of these substances were evaluated simultaneously. We have found out that H2O2, t-BHP and MMS predictably induce significant concentration-dependent increase of DNA lesions in both cell lines. Cytotoxicity detected in V79 cells with help of PE test was in a good conformity with the level of DNA damage. MTT test has proved unsuitable, except for MMS-treated V79 cells. Compared with human cells HepG2, hamster cells V79 manifested approximately similar levels of SOD and CAT but ten times higher activity of GPx. Across all concentrations tested the most significant increase of activity of the enzyme CAT was found in H2O2- and t-BHP-treated HepG2 cells, of the enzyme SOD in t-BHP- and MMS-treated V79 cells, and of the enzyme GPx in H2O2-treated V79 cells. We suggest that stimulation of enzyme activity by the relevant chemical compounds may result from transcriptional or post-transcriptional regulation of the expression of the genes CAT, SOD and GPx. Several authors suggest that moderate levels of toxic reactants can induce increase of AEs activities, while very high levels of reactants can induce their decrease, as a consequence of damage of the molecular machinery required to induce AEs. Based on a great amount of experiments, which were done and described within this paper, we can say that the above mentioned principle does not apply in general. Only the reactions of t-BHP affected HepG2 cells were consistent with this idea.
    Neoplasma 08/2015; 62(5). DOI:10.4149/neo_2015_086 · 1.87 Impact Factor
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    ABSTRACT: 7H-Dibenzo[c,g]carbazole (DBC) is a heterocyclic aromatic hydrocarbon that is carcinogenic in many species and tissues. DBC is a common environmental pollutant, and is therefore constantly exposed to sunlight. However, there are limited data exploring the toxicity of DBC photoexcitation products. Here, we investigated the impact of ultraviolet (UV) A radiation on the biological activity of DBC and its methyl derivatives, 5,9-dibenzo[c,g]carbazole and N-methyl dibenzo[c,g]carbazole, on human skin HaCaT keratinocytes. Co-exposure of HaCaT cells to UVA and DBC derivatives resulted in a sharp dose-dependent decrease in cell survival and apparent changes in cell morphology. Under the same treatment conditions, significant increases in DNA strand breaks, intracellular reactive oxygen species, and oxidative damage to DNA were observed in HaCaT cells. Consistent with these results, an apparent inhibition in superoxide dismutase, but not glutathione peroxidase activity, was detected in cells treated with DBC and its derivatives under UVA irradiation. The photoactivation-induced toxicity of individual DBC derivatives correlated with the electron excitation energies approximately expressed as the energy difference between the highest occupied and the lowest vacant molecular orbital. Our data provide the first evidence that UVA can enhance the toxicity of DBC and its derivatives. Photoactivation-induced conversion of harmless chemical compounds to toxic photoproducts associated with reactive oxygen species generation may substantially amplify the adverse health effects of UVA radiation and contribute to increased incidence of skin cancer. Environ. Mol. Mutagen., 2014. © 2014 Wiley Periodicals, Inc.
    Environmental and Molecular Mutagenesis 11/2014; 56(4). DOI:10.1002/em.21927 · 2.63 Impact Factor
  • M Melusova · D Slamenova · K Kozics · S Jantova · E Horvathova ·
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    ABSTRACT: For several thousand years natural products were successfully used to treat a variety of diseases and to maintain health in humans, but until now it is not fully known what causes these medicinal effects. In our study we assessed the cytotoxic, DNA-protective and pro-apoptotic effect of two frequently occurring natural compounds, carvacrol and rosemary essential oil, on human hepatoma HepG2 cells. In addition we examined the in vitro incision repair activity of liver cell extracts prepared from hepatocytes isolated from Sprague-Dawley (SD) rats fed with water containing carvacrol or rosemary oil. Using conventional and modified single cell gel electrophoresis we proved that incubation of HepG2 cells with selected concentrations of carvacrol and rosemary oil significantly protected cellular DNA against two dangerous oxidative agents, hydrogen peroxide (H2O2) and 2,3-dimethoxy-1,4-naphthoquinone (DMNQ). It is interesting that despite this DNA protection, the addition of both volatiles to the drinking water of SD rats had no effect on incision repair capacity of hepatocyte extracts. In this paper we also showed that carvacrol and rosemary oil can trigger apoptotic cell death pathways in HepG2 cells, which is probably connected with their cytotoxicity. Keywords: carvacrol, rosemary oil, cytotoxicity, comet assay, in vitro BER assay, apoptosis.
    Neoplasma 08/2014; 61(06). DOI:10.4149/neo_2014_084 · 1.87 Impact Factor
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    ABSTRACT: Selected components of plant essential oils and intact Rosmarinus officinalis oil (RO) were investigated for their antioxidant, iron-chelating and DNA-protective effects. Antioxidant activities were assessed using four different techniques. DNA-protective effects on human hepatoma HepG2 cells and plasmid DNA were evaluated with the help of the Comet assay and the DNA topology test, respectively. We observed that while eugenol, carvacrol and thymol showed a high antioxidative effectiveness in all assays used, RO manifested only anti-radical effect and borneol and eucalyptol did not express antioxidant activity at all. DNA-protective ability against hydrogen peroxide (H2O2)-induced DNA lesions manifested two antioxidants (carvacrol and thymol) and two compounds which do not show antioxidant effects (RO and borneol). Borneol was able to preserve not only DNA of HepG2 cells but also plasmid DNA against Fe2+-induced damage. In this article we evaluated our results in the light of experiences of other scientists.
    Journal of Agricultural and Food Chemistry 06/2014; 62(28). DOI:10.1021/jf501006y · 2.91 Impact Factor
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    ABSTRACT: The generation of reactive oxygen species (ROS) has been proposed as the underlying mechanism involved in the genotoxicity of iron oxide nanoparticles. The data published to date are, however, inconsistent, and the mechanism underlying ROS formation has not been completely elucidated. Here, we investigated the capacity of several surface-modified magnetite nanoparticles (MNPs) to generate ROS in A549 human lung adenocarcinoma epithelial cells and HEL 12469 human embryonic lung fibroblasts. All MNPs, regardless of the coating, induced significant levels of DNA breakage in A549 cells but not in HEL 12469 cells. Under the same treatment conditions, variable low levels of intracellular ROS were detected in both A549 and HEL 12469 cells, but compared with control treatment, none of the coated MNPs produced any significant increase in oxidative damage to DNA in either of these cell lines. Indeed, no significant changes in the total antioxidant capacity and intracellular glutathione levels were observed in MNPs-treated human lung cell lines regardless of surface coating. In line with these results, none of the surface-modified MNPs increased significantly the GPx activity in A549 cells and the SOD activity in HEL 12469 cells. The GPx activity was significantly increased only in SO-Fe3O4-treated HEL 12469 cells. The SOD activity was significantly increased in SO-PEG-PLGA-Fe3O4-treated A549 cells but significantly decreased in SO-Fe3O4-treated A549 cells. Our data indicate that oxidative stress plays, at most, only a marginal role in the genotoxicity of surface-modified MNPs considered in this study in human lung cells.
    Toxicology Letters 03/2014; 226(3). DOI:10.1016/j.toxlet.2014.02.025 · 3.26 Impact Factor
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    ABSTRACT: Salvia officinalis (SO) and Thymus vulgaris (TV) are medicinal plants well known for their curative powers. However, the molecular mechanisms responsible for these abilities of sage and thyme have not been fully understood yet. In this study we investigated the composition and the quantitative estimation of plant extracts, the protective effects of plant extracts against hydrogen peroxide- and 2,3-dimethoxy-1,4-naphthoquinone-induced DNA damage, and levels of enzymatic and non-enzymatic antioxidants (superoxide dismutase, glutathione peroxidase, glutathione) in human HepG2 cells. To measure antioxidative activity of plant extracts we used three assays: 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The results showed that the oxidant-induced DNA lesions were significantly reduced in cells pre-treated with the plant extracts studied. The observed DNA-protective activity could be explained by both elevation of GPx activity in cells pre-treated with SO and TV and antioxidant activity of SO and TV.
    Food Chemistry 12/2013; 141(3):2198-206. DOI:10.1016/j.foodchem.2013.04.089 · 3.39 Impact Factor
  • A Srancikova · E Horvathova · K Kozics ·
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    ABSTRACT: Cancer is one of the leading causes of death characterized by uncontrolled growth and spread of cancer cells. There are several hundred thousands of new cases of cancer worldwide. Clinical oncology is still challenged by toxicity and side effects of multimodal therapy strategies in which it is associated with poor prognosis for patients. There is an urgent necessity to develop novel therapy strategies and to utilize preventive potential of natural compounds. As the majority of anticancer drugs are of natural origin, natural products represent a valuable source for the identification and development of novel treatment options and chemopreventive mechanisms for cancer. This review is focused on the summary of published knowledges on the antioxidant and potential chemopreventive effects of biologically active substances present in the extracts of four plants of the family Lamiaceae (sage, thyme, rosemary and lavander) in different animal and in vitro systems. It is assumed that the chemopreventive and chemotherapeutic potential of natural compounds is the result of a combined action of several mechanisms. Keywords: sage, thyme, rosemary, lavender.
    Neoplasma 08/2013; 60(6). DOI:10.4149/neo_2013_076 · 1.87 Impact Factor
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    ABSTRACT: This paper presents comparisons of biological impacts of the oxidants H2O2 and t-BHP on human liver cells, and shows modulation of these effects by the phenolic compound carvacrol. To understand better how these oxidants exert their effect on DNA and on the activity of the enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx), we measured intracellular antioxidant glutathione (iGSH) and intracellular reactive oxidative species (iROS). DNA lesions corresponded to single-strand DNA breaks, alkali-labile lesions and formamido-pyrimidine-DNA-glycosylase(FPG)-sensitive sites. Pre-treatment of cells with carvacrol substantially decreased the number of H2O2-induced DNA lesions, but the number of t-BHP-induced DNA lesions was not reduced. Activities of both SOD and GPx were stimulated significantly by carvacrol and were reduced by the combined effect of carvacrol and oxidants. H2O2 and t-BHP alone influenced the level of antioxidant enzymes differently. While H2O2 did not markedly change the activity of SOD or GPx, lower concentrations of t-BHP stimulated activity of SOD and mainly GPx. The level of iROS was increased by both oxidants and decreased by carvacrol applied either alone or with oxidants. The level of iGSH was not influenced in any of the treatments tested. Our results show that although both oxidants induced oxidative stress and damaged cellular DNA, their influences on other molecular processes were different. The protective effect of carvacrol against DNA-damaging effects of H2O2 was unambiguous, but reduction by carvacrol of the DNA-damaging effect of t-BHP was not observed. These results suggest that the phenolic compound carvacrol contributes to the defence mechanisms of the human organism, but these beneficial effects are dependent on the origin and source of the actual oxidative stress.
    Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 07/2013; 757(1). DOI:10.1016/j.mrgentox.2013.03.014 · 3.68 Impact Factor
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    ABSTRACT: The human lung adenocarcinoma epithelial (A549) cells and the human embryo lung (HEL 12469) cells were used to investigate the uptake and cytotoxicity of magnetite nanoparticles (MNPs) with different chemically modified surfaces. MNPs uptake was an energy-dependent process substantially affected by the serum concentration in the culture medium. Internalized MNPs localized in vesicle-bound aggregates were observed in the cytoplasm, none in the nucleus or in mitochondria. All MNPs induced a dose- and time-dependent increase in cytotoxicity in both human lung cell lines. The cytotoxicity of MNPs increased proportionally with the particle size. Since the cytotoxicity of MNPs was nearly identical when the doses were equalized based on particle surface area, we suppose that the particle surface area rather than the surface modifications per se underlay the cytotoxicity of MNPs. In general, higher internalized amount of MNPs was found in HEL 12469 cells compared with A549 cells. Accordingly, the viability of the human embryo lung cells was reduced more substantially than that of the adenocarcinoma lung cells. The weak MNPs uptake into A549 cells might be of biomedical relevance in cases where MNPs should be used as nanocarriers for targeted drug delivery in tumor tissue derived from alveolar epithelial cells.
    Neoplasma 06/2012; 59(5):584-97. DOI:10.4149/neo_2012_075 · 1.87 Impact Factor
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    ABSTRACT: Experimental evidences suggest that most essential oils possess a wide range of biological and pharmacological activities that may protect tissues against oxidative damage. In this study, we investigated DNA-protective effect of borneol, a component of many essential oils, against oxidative DNA damage induced in primary cultures of rat hepatocytes. Borneol was added to drinking water of Sprague-Dawley rats and DNA resistance against oxidative agents was compared in hepatocytes originated from control and borneol-treated rats. Oxidative stress induced by visible light-excited methylene blue (MB/VL) or 2,3-dimethoxy-1,4-naphthoquionone (DMNQ) resulted in increased levels of DNA lesions measured by the modified single cell gel electrophoresis. Borneol (17 or 34 mg/kg body weight) added to drinking water of rats for 7 days reduced the level of oxidative DNA lesions induced in their hepatocytes by MB/VL or DMNQ. To explain the increased resistance of DNA towards oxidative stress, we measured the base-excision repair (BER) capacity in liver cell extracts of control and borneol-supplemented rats on DNA substrate of HepG2 cells containing oxidative damage. Our results showed that administration of borneol in drinking water had no effect on incision activity of hepatocytes isolated from supplemented rats. The spectrophotometric assessment of enzymatic antioxidants superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and the flow cytometric assessment of total intracellular glutathione (iGSH) in primary hepatocytes of borneol-supplemented rats showed no changes in SOD and GPx activities but higher iGSH content particularly in hepatocytes of higher borneol dose (34 mg/kg) supplemented rats in comparison to control animals. Despite the fact that borneol had no effect either on BER of oxidative DNA damage or on the levels of antioxidant enzymes and manifested no reducing power and radicals scavenging activity, it increased significantly the level of non-enzymatic antioxidant iGSH which could reduce the oxidative DNA lesions induced by MB/VL or DMNQ.
    Mutagenesis 04/2012; 27(5):581-8. DOI:10.1093/mutage/ges023 · 2.79 Impact Factor
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    ABSTRACT: Rosemary oil (RO) is popular in the Mediterranean region as a culinary additive which has the ability to protect delicate organs such as liver, brain and heart. We examined the effect of RO consumption on resistance of rat testicular cells (TCs) against DNA-damaging effects of the oxidative agents H2O2 and DMNQ and on the activity of the antioxidant enzymes glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). DNA lesions were detected by conventional and modified comet assay and the activities of GSH-Px and SOD were measured spectrophotometrically. Since TCs represent a mixture of haploid, diploid and tetraploid cells, we used flow cytometry for their differentiation and calculation of DNA-damaging effects of H2O2 and DMNQ in cells of different ploidy. The results showed that the oxidative DNA lesions were significantly reduced in TCs from rats administered RO; however, the activity of antioxidant enzymes did not differ in TCs from control and RO-supplemented rats.Highlights► Decrease in fertility of men initiated an interest in research of male germ cells. ► Increase in oxidative stress plays a role in the induction of sperm abnormalities. ► Consequences of DNA damage of male germ cells may be deleterious for offspring. ► Natural antioxidants might be helpful in preventing oxidative stress. ► A natural antioxidant which possesses various health benefits is oil of rosemary.
    Food Chemistry 11/2011; 129(1):64-70. DOI:10.1016/j.foodchem.2011.04.020 · 3.39 Impact Factor
  • K Kozics · Z Valovicova · D Slamenova ·
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    ABSTRACT: Flavonoids are plant derivatives of flavone of which chemical structure is characterized by various degrees of hydroxylation and glycosidic substitution. In the present study we investigated the protective effect of two structurally different groups of flavonoids against-benzo[a]pyrene (B(a)P)-induced genotoxic effects on human hepatocellular carcinoma (HepG2) cells. The first group of flavonoids: fisetin, kaempferol, galangin, quercetin, and luteolin, hydroxylated at the 3´,4´-position on the B ring, 3 - position of C ring and on the A ring was able to inhibit significantly B(a)P-induced genotoxic effects in a greater degree than the second group of flavonoids: chrysin, 7-hydroxyflavone, 7,8-dihydroxyflavone and baicalein (hydroxylated on the A ring) which showed a statistically significant inhibition of genotoxicity mainly at higher concentrations (10 and 25 µM). The tenth flavonoid tested rutin, which contains hydroxyl group at the position 3 of C ring, substituted by the sugar rutinose, was not able to inhibit effectively genotoxic changes induced by B(a)P. Our results, obtained with help of micronucleus test and single cell gel electrophoresis (comet assay) suggest that inhibition of B(a)P-induced DNA lesions and micronuclei correlates with the structural arrangement and organization of the hydroxyl groups in the molecular structure of the flavonoids tested.
    Neoplasma 01/2011; 58(6):516-24. DOI:10.4149/neo_2011_06_516 · 1.87 Impact Factor
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    ABSTRACT: trans-Resveratrol (t-RES) is one of the most relevant and extensively investigated stilbenes with a broad spectrum of biological activities. In contrast to the detailed knowledge of t-RES activities in biological systems, much less is known about the effects of higher hydroxylated stilbenes. Therefore, the aim of this study was to evaluate the protective effects (antioxidant activities) of t-RES and two analogues: the natural metabolite piceatannol (PCA) and the synthesized 3,3',4,4',5,5'-hexahydroxy-trans-stilbene (HHS) against H2O2-induced DNA damage in leukemic L1210, K562 and HL-60 cells using single-cell gel electrophoresis (SCGE). After 24 h pre-treatment of cells all compounds investigated significantly inhibited the incidence of DNA single strand breaks induced by H2O2. The protective effects of PCA and HHS in L1210 cells and of HHS in HL-60 cells were significantly higher compared to the activity of t-RES (+P < 0.05). In K562 cells the differences of the antioxidant activities of PCA and HHS, and of PCA in HL-60 cells were of much higher significance when compared to t-RES (++P < 0.01). In conclusion, we can prove that all stilbenes investigated, t-RES, PCA, and HHS, manifested potent antioxidant effects on three leukemic cell lines and the presence of ortho-dihydroxy structures enhanced the protective effect against DNA damage caused by .OH radicals.
    Oncology Reports 10/2006; 16(3):617-24. DOI:10.3892/or.16.3.617 · 2.30 Impact Factor
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    Zdenka Ovesná · Katarína Kozics · Darina Slamenová ·
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    ABSTRACT: Ursolic acid (UA) and oleanolic acid (OA) have similar chemical structures but differ in the position of one methyl group on the ring E. We investigated protective effects of these two triterpenoic acids against H(2)O(2)-induced DNA damage in leukemic L1210, K562 and HL-60 cells using single-cell gel electrophoresis (SCGE). We compared their protective effects (antioxidant activities) with respect to the different position of the methyl group in their chemical structures. After 24h pre-treatment of cells both compounds investigated inhibited significantly the incidence of DNA single strand breaks induced by H(2)O(2). The concentration range of UA and OA was in all experiments 2.5-10 micromol/l. The antioxidant activity of OA determined by SCGE was significantly higher compared to UA in L1210 ((+)P<0.05) and K562 cells ((+++)P<0.001). Significant difference of the antioxidant activities of the two compounds was evidently connected with the different position of the methyl group. The protective effect of OA was in HL-60 cells slightly lower compared to the activity of UA, but the difference between the protective effects of UA and OA was not significant. In conclusion we can say that both natural pentacyclic triterpenoic acids investigated, UA and OA, manifested potent antioxidant effects. The different position of one methyl group in their chemical structures caused moderately different biological activities of these compounds on three leukemic cell lines. To explore their mechanisms of action further investigation seems to be therefore worthwhile.
    Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 08/2006; 600(1-2):131-7. DOI:10.1016/j.mrfmmm.2006.03.008 · 3.68 Impact Factor

Publication Stats

181 Citations
40.16 Total Impact Points


  • 2006-2015
    • Slovak Academy of Sciences
      • • Cancer Research Institute
      • • Laboratory of Mutagenesis and Carcinogenesis
      Presburg, Bratislavský, Slovakia
  • 2014
    • Cancer Research Institute
      New York, New York, United States
  • 2012-2014
    • SAS Institute
      North Carolina, United States