Results Of Comet Assay Research Articles

Cyto-genotoxic and DNA methylation changes induced by different crystal phases of TiO2-np in bronchial epithelial (16-HBE) cells

With the increase in use of TiO2-np, a better understanding of their safety is important. In the present study the effect of different crystal phases of TiO2-np (anatase, rutile and anatase: rutile mixture; 20–26nm) were studied for cyto-genotoxicity and global DNA methylation and hydroxymethylation. Cytotoxic response was observed at a concentration of 25μg/ml for the particles tested. Results of comet and micronucleus (with and without CytB) assays revealed significant genotoxic effect of these particles. Flow cytometry revealed cell cycle arrest in the S-phase. Based on the results, toxicity of the particles could be correlated with their physico-chemical properties (i.e. smaller size and hydrodynamic diameter and larger surface area), anatase form being the most toxic. From the results of the cyto-genotoxicity assays, concentrations were determined for the epigenetic study. Effect on global DNA methylation and hydroxymethylation levels were studied at cyto-genotoxic (25μg/ml), genotoxic (12.5μg/ml) and sub cyto-genotoxic (3.25μg/ml) concentrations using LC–MS/MS analysis. Though no significant changes were observed for 3h treatment schedule; significant hypomethylation were observed at 24h for anatase (significant at 3.25 and 25μg/ml), rutile (significant at 3.25 and 25μg/ml) and anatase: rutile mixture (significant at 25μg/ml) forms. The results suggest that epigenetic changes could occur at sub cyto-genotoxic concentrations. And hence for complete characterization of nanoparticle toxicity, epigenetic studies should be performed along with conventional toxicity testing methods.

Hazard identification of coal fly ash leachate using a battery of cyto-genotoxic and biochemical tests in Allium cepa

ABSTRACTLeaching of heavy metals from coal fly ash dumpsites is an environmental threat often polluting both groundwater and surface water. This led to a detailed investigation on the cyto-genotoxicity and oxidative stress associated with the fly ash leachate (FL). Allium cepa L. bulbs were exposed to three concentrations of FL. Response to FL resulted in a reduction of root growth, inhibition of cell viability by up to 50%, and decrease in mitotic indices (control: 10.27; FA:water 1:4–4.52) with increased frequency of chromosome aberrations (5.7 fold) and bi-nucleate cells. Results of comet assay indicated that approximately sixfold increase in genotoxicity of FL was congruent with the endpoints of oxidative stress evaluated. The malondialdehyde content, superoxide dismutase, guaiacol peroxidase and glutathione-S-transferase activities were elevated in the treated plants in a dose dependent manner. The elemental analysis of FL showed the presence of heavy metals like cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), cadmium (Cd), nickel (Ni), lead (Pb) and zinc (Zn). The study demonstrated that FL can cause adverse effects to the plants. Therefore, the disposal of coal fly ash should be handled with caution and prevented from contaminating the surroundings.

Protective effects of fraction 4a of polysaccharides isolated from Lycium barbarum against KBrO3-induced renal damage in rats.

Potassium bromate (KBrO3) is widely used as a food additive and is a major by-product of water disinfection. The aim of this study was to investigate the protective effects of fraction 4a of polysaccharides isolated from Lycium barbarum (LBP-4a) against renal damage induced by KBrO3 in rats and to determine the relevant mechanisms behind these effects. Male Wistar rats were divided into a normal control group, a KBrO3 control group, and LBP-4a(L) and LBP-4a(H) groups. With the exception of the normal control group, the rats in the other three groups were administered KBrO3 by intraperitoneal injection to induce renal damage. Before the induction of renal damage, rats in the LBP-4a(L) and LBP-4a(H) groups were pretreated with 50 mg per kg b.w. or 100 mg per kg b.w. LBP-4a, respectively, by intragastric administration. Clinical biochemical parameters and markers of oxidative damage were also determined. Treatment by administration of LBP-4a prior to challenge with KBrO3 prevented increases in the levels of nitrite, creatinine, urea nitrogen and uric acid in serum and increased the activities of antioxidant enzymes in kidney tissues. A comet assay and FCS results showed that pretreatment with LBP-4a also alleviated DNA damage and decreases in mitochondrial membrane potentials in renal cells. Histological studies further supported the above results and showed extensive renal damage in animals treated with KBrO3 and greatly reduced tissue injury in groups pretreated with LBP-4a. In conclusion, LBP-4a exhibited protective effects against renal damage induced by KBrO3, and the mechanism was closely correlated with a reduction in levels of lipid peroxidation and an increase in the activities of antioxidant enzymes in kidney tissues, which alleviated DNA damage and increased mitochondrial membrane potentials in renal cells. These observations provide the background for the further development of LBP-4a as a protective agent for use in the treatment of renal damage.

Genotoxic and Mutagenic Activity of Suvarna Bhasma

Genetic toxicity and mutagenicity of Suvarna Bhasma (SB), an Ayurvedic drug, was determined using a battery of tests. The results of In-vivo Micronucleus assay and COMET assay did not reveal any significant increase in % Micronucleus frequency(MN) in bone marrow cells of mice and DNA damage in blood lymphocytes respectively after the oral administration of SB at various concentrations (3,-30 mg/kg bw) in treated animals as compared to vehicle control in either sex. The invitro chromosome aberration (CA) assay carried out with and without metabolic activation at different concentrations of SB in human lymphocyte culture did not cause any effect on structural or numerical chromosome aberrations. Suvarna Bhasma did not induce any mutagenic activity in presence and absence of S9 fractions in Ames assay employing three strains of salmonella typhimurium TA98, TA100 and TA102.These results demonstrated that Suvarna Bhasma preparation evaluated in this study is not genotoxic and mutagenic at the concentrations tested under the experimental conditions.

Carbazole Aminoalcohols Induce Antiproliferation and Apoptosis of Human Tumor Cells by Inhibiting Topoisomerase I.

Novel carbazole aminoalcohols were designed and synthesized as anticancer agents. Among them, alkylamine-chain-substituted compounds showed the most promising antiproliferative activity, with IC50 values in the single-digit micromolar range against two human tumor cell lines. Topoisomerase I (topo I) is likely to be one of the targets of these compounds. Results of comet assays and molecular docking indicate that the representative compounds may act as topo I poisons, causing single-strand DNA damage by stabilizing the topo I-DNA cleavage complex. In particular, the most potent compound, 1-(butylamino)-3-(3,6-dichloro-9H-carbazol-9-yl)propan-2-ol (6), was shown to be able to induce G2 -phase cell-cycle arrest and apoptosis in HeLa cells.

Comet assay results of pilots exposed to pesticides

Comet assay results of pilots exposed to pesticides

Cytotoxic and anticancer activities of an acridine derivative; 11-chloro-3-methyl-3H-imidazo[4,5-a]acridine on 5637 cells

Acridine derivatives are capable of interacting with double-stranded DNA. Some essential enzymes such as DNA topoisomerase I, II and telomerase are the biological targets of these compounds in cancer chemotherapy. 11-chloro-3-methyl-3H-imidazo[4,5-a]acridine is a novel synthetic acridine derivative with antibacterial properties. Selective induction of apoptosis in tumor cells is the characteristic of some clinically effective anticancer drugs. In this study, the cytotoxicity and apoptosis inducing effects of 11-chloro-3-methyl-3H-imidazo[4,5-a]acridine on 5637 cancerous and HFF3 (human foreskin fibroblast) normal cells were investigated for the first time. The results of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay showed that the cytotoxic effects of 11-chloro-3-methyl-3H-imidazo[4,5-a]acridine were more pronounced on 5637 cells in comparison to HFF3 normal cells. 4′,6-diamidino-2-phenylindole staining of 5637 cells demonstrated the presence of condensed chromatin in majority of cells (60 %) which is indicative of apoptosis induction. Besides the results of comet assay revealed that 11-chloro-3-methyl-3H-imidazo[4,5-a]acridine treatment resulted in 10 folds greater DNA damage in cancerous cells (62 %) as compared to normal cells (6 %). Flow cytometry analysis of 5637 cells after propidium iodide staining revealed that 11-chloro-3-methyl-3H-imidazo[4,5-a]acridine causes apoptosis by cell cycle arrest in sub-G1 peak in a time-dependent manner. Moreover, evaluation of caspase 3 activity showed that this compound significantly increased caspase 3 activity in 5637 cells as compared with control cells. Therefore, it can be concluded that 11-chloro-3-methyl-3H-imidazo[4,5-a]acridine has selective cytotoxic and anticancer effects on 5637 cells and a high potential to induce apoptosis. This caspase-dependent apoptotic induction was resulted from DNA damage, which may arise from inhibition of DNA topoisomerase I and/or II activity. Although further studies are required to determine its mechanism in vivo, 11-chloro-3-methyl-3H-imidazo[4,5-a]acridine can be introduced as a potential anticancer compound for further investigations.

Evaluation of Genotoxic Effects of Asbestos on Occupationally Exposed Workers in Brazil

Abstract Genotoxic effects of occupational workers exposed to asbestos can be evaluated using different biomarkers as oxidative stress enzymes in conjuction with comet assay. This study assessed changes to oxidative stress enzymatic parameters and genotoxic damage in workers occupationally exposed and non-exposed to chrysotile asbestos, who attended the outpatient Clinic of the Center for Worker Health Studies and Human Ecology (CESTEH/ENSP/FIOCRUZ) in Brazil. Chest radiography and spirometry were performed to assess clinical progression of symptoms. The traditional visual score comet assay in peripheral whole blood cells was used to assess DNA damage, and oxidative stress was evaluated by measuring catalase (CAT) and glutathione S-transferase (GST) activities. Respiratory alterations were observed in 53% of workers exposed, as determined by pulmonary function and bronchodilation, and 6 workers were diagnosed with asbestosis. The comet assay was statistically significantly higher in the exposed group and individuals with asbestosis compared to the non-exposed group and individuals without asbestosis, respectively. Linear regression analysis showed that 28,4% and 50,5% of comet assay results were increased by exposure to asbestos and developed asbestosis. The results of CAT and GST were not difference between the groups. These results supports the association of genotoxic damage and the onset of asbestosis by chrysotile asbestos exposure in workers of this study.

Ecotoxicological effects of earthworm following long-term Dechlorane Plus exposure.

Dechlorane Plus (DP), similar to persistent organic pollutants, has been widely detected in environmental matrices, especially in sediment and soil. In this study, earthworms Eisenia fetida were exposed to 0.1, 0.5, 6.25 and 12.5 mg kg(-1) DP for 28 d. Lethality, oxidative stress, neurotoxicity and cellulase of E. fetida were assessed to investigate ecotoxicological effects of DP after long-term exposure. Results showed that the direct toxicity of DP was very low. However, death rate, as well as SOD activity, together with changes in activities of CAT, GSH-Px, and GSH levels, indicating that oxidative stress may play a significant role in DP exposure. In addition, DP also changes the AChE and cellulase activity of earthworms even under low DP concentration after long-term exposure. Moreover, comet assay results showed that DP exposure increased the levels of tDNA significantly (p < 0.05) even in the lowest treatment (0.1 mg kg(-1) DP). Combined with the results of enzyme activity, oxidative damage and comet assay, it can be suggested that earthworms experience more stress of DP during long-time exposure. This study provides insight into the toxicological effects of DP on earthworm model, and may be useful for risk assessment of DP on soil ecosystems.

The effect of gamma radiation on the Common carp (Cyprinus carpio): In vivo genotoxicity assessment with the micronucleus and comet assays

Radioactive wastes may be leached into freshwater, either accidentally or in industrial effluents. We have studied gamma radiation-induced DNA damage in the freshwater fish Cyprinus carpio. Fish were irradiated with 2–10Gy gamma radiation and genotoxic effects in blood cells were studied with the micronucleus (MN) and comet assays. Micronuclei and a dose-dependent increase in comet-tail DNA were seen in dose- and time-dependent studies. The highest % tail DNA was observed at 24h, declining until 72h, which may indicate the repair of radiation-induced DNA single-strand breaks after gamma radiation. However, double-stranded DNA damage may not have been repaired, as indicated by increased micronuclei at later periods. A positive correlation was observed between the comet and micronucleus assay results. This study confirms the mutagenic/genotoxic potential of gamma radiation in the Common carp, as well as the possible combined use of the micronucleus and comet assays for in vivo laboratory studies with fresh-water fish for screening the genotoxic potential of radioactive pollution.

In vivo genotoxicity and cytotoxicity assessment of cadmium chloride in peripheral erythrocytes of Labeo rohita (Hamilton)

Cadmium chloride (CdCl2) induced genotoxicity and cytotoxicity has been assessed in the peripheral blood erythrocytes of freshwater fish Labeo rohita exposed to 0.37 and 0.62mg/L of CdCl2 in water for 100 days. The blood samples of the fish were collected at different intervals (days 1, 3, 5, 10, 15, 30, 60 and 100) of exposure period to analyze DNA damage using comet assay and the occurrence of micronuclei and other cellular anomalies. The results of comet assay showed a significant increase in the mean percentage of tail DNA at both the concentrations. Exposure to CdCl2 also induced micronuclei in addition to many nuclear abnormalities such as nuclear bud, binucleates, lobed, notched and vacuolated nuclei. Cytoplasmic abnormalities like echinocytes, acanthocytes, notched, microcytes and cells with vacuolated cytoplasm were also observed. The metal exposed groups showed significant variation in the frequency of cellular abnormalities as well as the extent of DNA damage in comparison to controls. These frequencies increased significantly (p<0.05) in concentration dependent manner, peaking on 10th day while a decreasing trend was observed after 15 days of the exposure period.

Assessment of the in vivo genotoxicity of cadmium chloride, chloroform, and d,l-menthol as coded test chemicals using the alkaline comet assay

As part of the Japanese Center for the Validation of Alternative Methods (JaCVAM) international validation study of in vivo rat alkaline comet assays, we examined cadmium chloride, chloroform, and d,l-menthol under blind conditions as coded chemicals in the liver and stomach of Sprague–Dawley rats after 3 days of administration. Cadmium chloride showed equivocal responses in the liver and stomach, supporting previous reports of its poor mutagenic potential and non-carcinogenic effects in these organs. Treatment with chloroform, which is a non-genotoxic carcinogen, did not induce DNA damage in the liver or stomach. Some histopathological changes, such as necrosis and degeneration, were observed in the liver; however, they did not affect the comet assay results. d,l-Menthol, a non-genotoxic non-carcinogen, did not induce liver or stomach DNA damage. These results indicate that the comet assay can reflect genotoxic properties under blind conditions.

Induction of DNA base damage and strand breaks in peripheral erythrocytes and the underlying mechanism in goldfish (Carassius auratus) exposed to monocrotophos.

Using goldfish (Carassius auratus) as the model animal, the present study revealed the types of the DNA damage induced by monocrotophos, a highly toxic organophosphorus pesticide, and explored the mechanism underlying the DNA-damaging effect of this pesticide. Results of the alkaline comet assay showed that global DNA damage (including single- and double-strand breaks and alkali-labile sites) in peripheral erythrocytes of goldfish, measured as olive tail moment, was significantly increased by exposure to 0.01, 0.10, and 1.00mg/L monocrotophos for 24, 48, 96, and 168h. In particular, alkali-labile sites rather than single- or double-strand breaks, distinguished by the alkaline, pH 12.1, and neutral comet assays, were mainly induced by monocrotophos at 48h. Oxidative damage in DNA bases and telomeric DNA was investigated by using the alkaline comet assay combined with endonuclease III or formamidopyrimidine DNA glycosylase and with fluorescence in situ hybridization, respectively. Further, glutathione peroxidase activity significantly decreased at 24h but increased at 96 and 168h, and malondialdehyde concentrations significantly increased at 48h but gradually decreased at 96 and 168h, which indicated an over-production of reactive oxygen species (ROS) at short exposure durations, but effective scavenging at long exposure durations in the peripheral blood tissues. Accordingly, our results suggest that DNA damage induced by monocrotophos in fish blood cells is possibly due to the inhibition of ROS scavenging and resulted accumulation of ROS.

Melanoxoin reduces tumor growth in xenograft animial model and inhibits cell migration in human lung cancer cell lines.

Natural products remain the best sources of drugs and drug leads. Various anticancer drugs are derived from the natural products. In our previous studies, we found that methanol extract of Pterocarpus santalinus exhibited potent cytotoxicity and anti-inflammatory activities. Among the series of compounds isolated from Pterocarpus santalinus, melanoxoin demonstrated the highest cytotoxic effects with a IC50 of 1.98 μg/ml in human non-small cell lung cancer H1299 cells. The results showed that melanoxoin regulated the transcription of several cell cycle regulators in H1299 cells. Melanoxoin induced tubulin depolymerization, suggesting that melanoxoin causes G2/M arrest thus increasing apoptosis in tumor cell. The results of neutral comet assay showed that treatment with melanoxoin induced significant DNA damage in H1299 cells, while the in vivo efficacy of melanoxoin was revealed by the mice xenograft models. Clinical data showed that an increase (61%) of MET expression was observed in non-small cell lung cancer samples compared with adjacent normal tissues. HGF/c-Met signaling is involved in the cancer progression, metastasis and gefitnib resistance. In particular, we also found that melanoxoin can inhibit HGF-induced cell migration using the wound healing and transwell migration assay. Altogether, our results indicated that melanoxoin displays an outstanding inhibitory activity toward tumor growth and metastasis. Thus, it exerted great potential to be developed into novel anti-cancer agent.

Mutagenicity and DNA-damaging potential of clenbuterol and its metabolite 4-amino-3,5-dichlorobenzoic acid in vitro

The aim of this study was to evaluate in vitro toxicity of clenbuterol and its metabolite 4-amino-3,5-dichlorobenzoic acid. Cytotoxicity and pro-oxidative effect of both compounds were studied on human colon adenocarcinoma cell line SW 480. No significant cytotoxic effect of either compound was observed. Results of an Ames test on Salmonella typhimurium did not indicate mutagenic activity of clenbuterol on TA 98 and TA 100 strains, regardless of metabolic activation. Potential mutagenic effects of the highest clenbuterol concentration (2500 ng/ml) were observed on the TA 1535 strain. The obtained results of alkaline comet assay on isolated human lymphocytes suggested that both compounds induced an increase of primary DNA damage in a concentration-dependent manner. 4-ADBA was a slightly more potent inducer of primary DNA damage as compared to clenbuterol. Chromosomal aberration analysis showed that clenbuterol caused a statistically significant increase in the total number of aberrant cells only at the highest concentration tested (3% vs. 0.7% in the negative control). The results of this study might represent a solid frame for designing and planning future studies with both compounds, which should further clarify their mechanisms of action and genotoxic/cytogenetic effects relevant for human risk assessment.

Estimation of genotoxic and mutagenic potential of latex and methanolic leaves extract of Euphorbia helioscopia by comet assay and Ames test

ObjectiveTo investigate the genotoxic and mutagenic potentials of Euphorbia helioscopia (Family: Euphobiaceae) latex and methanolic leaves extract. MethodsComet assay was adopted to investigate genotoxicity potential and Maron and Ames protocol was followed to evaluate mutagenicity of standardized methanolic leaves extract and latex in concentrations of 10, 5, 2.5, 1.25, 0.625 µg/mL and 1 000, 200, 40, 8, 1.6 µg/mL respectively. ResultsLatex did not damage DNA in lymphocytes and could not produce revertant of Salmonella typhimurium (TA98) at any of the experimental concentrations. While, methanolic leaves extract showed 190.00 ± 0.51 revertants in Salmonella typhimurium (TA98) plate incubated with extract at 10 µg/mL and also damaged lymphocytes DNA at the same concentration. There was statistically significant difference, P < 0.05, at 10 µg/mL/plate concentration with reference to negative control. Pearson correlation was 0.948 showing high consistency between results of comet assay and Ames test. ConclusionIt was concluded that latex showed no mutagenic and genotoxic potentials at concentrations ranging from 1.6-1 000 µg/mL. Whereas, mutagenic and genotoxic potential threshold level of methanol leaves extract appeared at 10 µg/mL concentration, while remaining used concentrations were devoid of any toxicity.

Iron Oxide Nanoparticles Induced Oxidative Damage in Peripheral Blood Cells of Rat

Nanotechnology is a rapidly growing field that has elicited much concern due to a variety of applications in different fields such as industry, medicine, and cosmetics. These developments increase the concern among the general population. Hence, there is an urgent need to explore the possible human health effects of these nanomaterials. The present study is aimed to evaluate the cytotoxic and genotoxic effects of iron oxide nanoparticles (IONPs) in-vivo. In order to study the toxic effects, Wistar rats were administered intravenously with various doses of IONPs (Fe2O3) through caudal vein once in a week for 28 days, and various biochemical assays such as antioxidant enzymes activity (SOD, CAT, and GSH), lipid peroxidation, DNA damage and hematological parameters were evaluated. Genotoxicity was evaluated by comet assay and oxidative stress was measured by anti-oxidant enzymes. The results reveal that IONPs alter hematological factor such as RBC counts, WBC counts, neutrophils, monocytes and hemoglobin. A dose-dependent inhibition (p < 0.05) of antioxidant enzymes was found, and meanwhile the level of MDA elevated significantly (p < 0.05) in IONPs treated groups in dose-dependent manner; however comet assay results indicate that IONPs did not induce any significant DNA damage. The present study concluded that IONP affects inflammatory response, which induces the oxidative stress and may adversely affect the cellular function.

In vitro evaluation of the cellular effect of indium tin oxide nanoparticles using the human lung adenocarcinoma A549 cells.

Indium tin oxide (ITO) is widely used in liquid crystal displays (LCDs) or plasma and mobile phone displays. Elevated production and usage of ITO in such displays have led to increased concerns over the safety of industrial workers exposed to particulate aerosols produced during cutting, grinding and polishing of these materials. However, the cellular effects of ITO nanoparticles (NPs) are still unclear, although it has been reported that micro-scale ITO particles induce cytotoxicity. The aim of this study was to examine the potential of ITO NPs to induce cytotoxicity, oxidative stress, and DNA damage using human lung adenocarcinoma A549 cells. Here, stable dispersions of a medium containing ITO NPs were obtained using pre-adsorption and centrifugal fractionation methods, and the A549 cells were incubated in this medium. The ITO NPs showed low cytotoxic effects as shown by the WST-1 and LDH assays. Transmission electron microscopy observations showed the cellular uptake of ITO NPs. The ITO NPs increased the intracellular level of reactive oxygen species and the expression of the heme oxygenase 1 gene. Further, the results of alkaline comet assays showed that ITO NPs induced DNA damage. Thus, these results suggest that ITO NPs possess a genotoxic potential on human lung adenocarcinoma A549 cells.

Performance and data interpretation of the in vivo comet assay in pharmaceutical industry: EFPIA survey results

In genotoxicity testing of pharmaceuticals the rodent alkaline comet assay is being increasingly used as a second in vivo assay in addition to the in vivo micronucleus assay to mitigate in vitro positive results as recommended by the ICH S2(R1) guideline. This paper summarizes a survey suggested by the Safety Working Party of European Medicines Agency (EMA), and conducted by the European Federation of Pharmaceutical Industries and Associations (EFPIA) to investigate the experience among European pharmaceutical companies by conducting the in vivo comet assay for regulatory purpose. A special focus was given on the typology of the obtained results and to identify potential difficulties encountered with the interpretation of study data.The participating companies reported a total of 147 studies (conducted in-house or outsourced) and shared the conclusion on the comet assay response for 136 studies. Most of the studies were negative (118/136). Only about 10% (14/136 studies) of the comet assays showed a positive response. None of the positive comet assay results were clearly associated with organ toxicity indicating that the positive responses are not due to cytotoxic effects of the compound in the tissue examined. The number of comet assays with an equivocal or inconclusive response was rare, respectively <1% (1/147 studies) and 2% (3/147 studies). In case additional information (e.g. repeat assay, organ toxicity, metabolism, tissue exposure) would have been available for evaluation, a final conclusion could most probably have been drawn for most or all of these studies. All (46) negative in vivo comet assays submitted alongside with a negative in vivo micronucleus assay were accepted by the regulatory authorities to mitigate a positive in vitro mammalian cell assay following the current ICH S2 guidance. The survey results demonstrate the robustness of the comet assay and the regulatory acceptance of the current ICH S2 guidance.

Chemoprevention Against Arsenic-Induced Mutagenic DNA Breakage and Apoptotic Liver Damage in Rat Via Antioxidant and SOD1 Upregulation by Green Tea (Camellia sinensis) which Recovers Broken DNA Resulted from Arsenic-H2O2 Related in Vitro Oxidant Stress

Green tea (Camellia sinensis; CS) strongly reverses/prevents arsenic-induced apoptotic hepatic degeneration/micronecrosis and mutagenic DNA damage in in vitro oxidant stress model and in rat as shown by comet assay and histoarchitecture (HE and PAS staining) results. Earlier, we demonstrated a link between carcinogenesis and impaired antioxidant system-associated mutagenic DNA damage in arsenic-exposed human. In this study, arsenic-induced (0.6 ppm/100 g body weight/day for 28 days) impairment of cytosolic superoxide-dismutase (SOD1), catalase, xanthine-oxidase, thiol, and urate activities/levels led to increase in tissue levels of damaging malondialdehyde, conjugated dienes, serum necrotic-marker lactate-dehydrogenase, and metabolic inflammatory-marker c-reactive protein suggesting dysregulation at the transcriptional/signal-transduction level. These are decisively restrained by CS-extract (≥10 mg/ml aqueous) with a restoration of DNA/tissue structure. The structural/functional impairment of dialyzed and centrifugally concentrated (6–8 kd cutoff) hepatic SOD1 via its important Cys modifications by H2O2/arsenite redox-stress and that protection by CS/2-mercaptoethanol are shown in in vitro/in situ studies paralleling the present Swiss-Model-generated rSOD1 structural data. Here, arsenite(3+) incubation (≥10−8 μM + 10 mM H2O2, 2 hr) is shown for the first time with this low-concentration to initiate breakage in rat hepatic-DNA in vitro whereas, arsenite/H2O2/UV-radiation does not affect DNA separately. Arsenic initiates Fe and Cu ion-associated free-radical reaction cascade in vivo. Here, 10 μM of Cu(2+)/Fe(3+)/As(3+) +H2O2-induced in vitro DNA fragmentation is prevented by CS (≥1 mg/ml), greater than the prevention of ascorbate or tocopherol or DMSO or their combination. Moreover, CS incubation for various time with differentially and already degraded DNA resulted from pre-incubation in 10 μM As(3+)-H2O2 system markedly recovers broken DNA. Present results decisively suggest for the first time that CS and its mixed polyphenols have potent SOD1 protecting, diverse radical-scavenging and antimutagenic activities furthering to DNA protection/therapy in arsenic-induced tissue necrosis/apoptosis.