Single cell gel electrophoresis assay: a new technique for human biomonitoring studies

Study of novel bidentate heterocyclic amine-based metal complexes and their biological activities: cytotoxicity and antimicrobial activity evaluation

Metallic antitumor drugs with heterocyclic ligands, such as novel AMI (amino methyl imidazole) complexes [Pd(AMI)Cl₂](1), [Cu(AMI)L¹](2), and [Cu(AMI)L²·2H₂O](3) where L¹ = oxalate and L² = malonate, were synthesized and characterized. Assessments included elemental analyses, mass spectrometry, Fourier transform-infrared spectroscopy, ultraviolet-visible spectroscopy, and thermal analysis. The cytotoxicity of AMI complexes compared to cisplatin was assessed using MTT (3-[4,5-dimethylthiazol-2-yl] 2,5diphenyl tetrazolium bromide) assay with breast (MCF-7) and cervical (HeLa) cancer cell lines. After treating these cells with the AMI complexes' IC₅₀ values for 48 h, malondialdehyde levels and catalase activity were used to assess oxidative stress, antioxidant activity was evaluated with DPPH radical scavenging method, comet assays assessed DNA damage, and DNA fragmentation was evaluated using the gel electrophoresis. In vitro, antimicrobial activity was assessed using a disc diffusion method. The anticancer activity results showed that IC₅₀ (half-maximal inhibitory concentration) values of complex one, two, and three against MCF-7 and HeLa cancer cells are 0.156 ± 0.0006, 0.125 ± 0.001, 0.277 ± 0.002 μM respectively for MCF-7 cells and 0.222 ± 0.0005, 0.126 ± 0.0009, 0.152 ± 0.001 μM respectively for HeLa cells. Complex two demonstrated strong anticancer activity against MCF-7 and Hela cells. The study of oxidative stress parameters revealed that Malondialdehyde levels increased in cancer cell lines treated with complexes compared to untreated cells. Catalase activity decreased in cells treated with palladium chelate. The DPPH radical scavenging assay results identified that complex one was a more potent antioxidant in MCF-7 and Hela cells than other complexes with SC₅₀ values of 227.5 ± 0.28 and 361 ± 1.2 μL/mL, respectively. The comet assay results showed that complex two caused significant DNA damage in MCF-7 and HeLa cancer cells treated. Antimicrobial assays identified complex three as the most effective. Copper complexes give better antifungal activity against A. flavus than the palladium complex. We conclude that complex two is the most active in both cell types and might be assessed as a clinically useful drug for breast cancer treatment. The significance of the current study is the synthesis of antitumor drugs containing heterocyclic ligands, such as novel AMI complexes, and the study of their biological activities.

Protective Effects of Hexarelin and JMV2894 in a Human Neuroblastoma Cell Line Expressing the SOD1-G93A Mutated Protein

Amyotrophic lateral sclerosis (ALS) is an incurable motor neuron disease whose etiology remains unresolved; nonetheless, mutations of superoxide dismutase 1 (SOD1) have been associated with several variants of ALS. Currently available pharmacologic interventions are only symptomatic and palliative in effect; therefore, there is a pressing demand for more effective drugs. This study examined potential therapeutic effects of growth hormone secretagogues (GHSs), a large family of synthetic compounds, as possible candidates for the treatment of ALS. Human neuroblastoma cells expressing the SOD1-G93A mutated protein (SH-SY5Y SOD1^G93A cells) were incubated for 24 h with H₂O₂ (150 µM) in the absence, or presence, of GHS (1 µM), in order to study the protective effect of GHS against increased oxidative stress. The two GHSs examined in this study, hexarelin and JMV2894, protected cells from H₂O₂-induced cytotoxicity by activating molecules that regulate apoptosis and promote cell survival processes. These findings suggest the possibility of developing new GHS-based anti-oxidant and neuroprotective drugs with improved therapeutic potential. Further investigations are required for the following: (i) to clarify GHS molecular mechanisms of action, and (ii) to envisage the development of new GHSs that may be useful in ALS therapy.

Effect of Coffee and Cocoa-Based Confectionery Containing Coffee on Markers of DNA Damage and Lipid Peroxidation Products: Results from a Human Intervention Study

The effect of coffee and cocoa on oxidative damage to macromolecules has been investigated in several studies, often with controversial results. This study aimed to investigate the effect of one-month consumption of different doses of coffee or cocoa-based products containing coffee on markers of DNA damage and lipid peroxidation in young healthy volunteers. Twenty-one volunteers were randomly assigned into a three-arm, crossover, randomized trial. Subjects were assigned to consume one of the three following treatments: one cup of espresso coffee/day (1C), three cups of espresso coffee/day (3C), and one cup of espresso coffee plus two cocoa-based products containing coffee (PC) twice per day for 1 month. At the end of each treatment, blood samples were collected for the analysis of endogenous and H2O2-induced DNA damage and DNA oxidation catabolites, while urines were used for the analysis of oxylipins. On the whole, four DNA catabolites (cyclic guanosine monophosphate (cGMP), 8-OH-2'-deoxy-guanosine, 8-OH-guanine, and 8-NO2-cGMP) were detected in plasma samples following the one-month intervention. No significant modulation of DNA and lipid damage markers was documented among groups, apart from an effect of time for DNA strand breaks and some markers of lipid peroxidation. In conclusion, the consumption of coffee and cocoa-based confectionery containing coffee was apparently not able to affect oxidative stress markers. More studies are encouraged to better explain the findings obtained and to understand the impact of different dosages of these products on specific target groups.

Hexarelin Modulation of MAPK and PI3K/Akt Pathways in Neuro-2A Cells Inhibits Hydrogen Peroxide-Induced Apoptotic Toxicity

Hexarelin, a synthetic hexapeptide, exerts cyto-protective effects at the mitochondrial level in cardiac and skeletal muscles, both in vitro and in vivo, may also have important neuroprotective bioactivities. This study examined the inhibitory effects of hexarelin on hydrogen peroxide (H₂O₂)-induced apoptosis in Neuro-2A cells. Neuro-2A cells were treated for 24 h with various concentrations of H₂O₂ or with the combination of H₂O₂ and hexarelin following which cell viability and nitrite (NO₂⁻) release were measured. Cell morphology was also documented throughout and changes arising were quantified using Image J skeleton and fractal analysis procedures. Apoptotic responses were evaluated by Real-Time PCR (caspase-3, caspase-7, Bax, and Bcl-2 mRNA levels) and Western Blot (cleaved caspase-3, cleaved caspase-7, MAPK, and Akt). Our results indicate that hexarelin effectively antagonized H₂O₂-induced damage to Neuro-2A cells thereby (i) improving cell viability, (ii) reducing NO₂⁻ release and (iii) restoring normal morphologies. Hexarelin treatment also reduced mRNA levels of caspase-3 and its activation, and modulated mRNA levels of the BCL-2 family. Moreover, hexarelin inhibited MAPKs phosphorylation and increased p-Akt protein expression. In conclusion, our results demonstrate neuroprotective and anti-apoptotic effects of hexarelin, suggesting that new analogues could be developed for their neuroprotective effects.

Broiler welfare is preserved by long-term low-dose oral exposure to zinc oxide nanoparticles: preliminary study

The potential public health risk through utilizing of zinc oxide nanoparticles (ZnO NPs) in food constitutes the major obstacle to the expansion of nanoparticle (NP) in food industry. Liver histology, bone marrow and liver genotoxicity, immunity, and oxidant status were investigated upon long-term ZnO NPs feed supplementation. One hundred and sixty male IR (Indian River) chicks were randomly allocated to one of the four dietary treatments: control, ZnO NPs at 10, 20, or 40 mg/kg for 42 days. This study revealed non-significant hepatic histopathological alterations and DNA damage and the treatment had no influence on body and organ weights, liver enzymes, lipid peroxidation (MDA), IgG, IgM, and interferon gamma (IFN-γ). This study suggests that low-dose (< 40 mg/kg diet) long-term ZnO NPs supplementation to broiler chicks has no observed potential adverse effects on normal histology of the liver, blood physiology, immune system, and DNA damage of liver and bone marrows, which are critical features for validating ZnO NPs for use in food. Further studies are required to evaluate the probable withdrawal period of ZnO NPs before approval as a dietary supplement in broiler or livestock diets.

Nobiletin ameliorates nonylphenol-induced testicular damage by improving biochemical, steroidogenic, hormonal, spermatogenic, apoptotic and histological profile

Nonylphenol (NP) is an environmental contaminant, which adversely affects the male fertility due to endocrine disruption and generation of oxidative stress. The current research was planned to assess the effects of nobiletin (NOB), a polymethoxyflavone, on NP-induced testicular damages. Twenty-four male rats were divided into 4 groups: control (0.1% DMSO), NP group (50 mg/kg), NP+NOB group (50 mg/kg + 25 mg/kg), and NOB group (25 mg/kg). Our results revealed that NP brought down the activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GSR), while elevated the level of thiobarbituric acid reactive substances (TBARS). Additionally, NP decreased the level of follicle-stimulating hormone (FSH), luteinizing hormone (LH), plasma testosterone, daily sperm production (DSP), epididymal sperm count, viability, motility, gene expression of testicular steroidogenic enzymes (StAR, 3β-HSD and 17β-HSD) and anti-apoptotic protein (Bcl-2), as well as number of spermatogenic cells belonging to various stages. Whereas, sperm (head, mid-piece/neck and tail) abnormalities, expression of apoptotic proteins (Bax and caspase-3), and histopathological damages were increased. However, NOB remarkably reversed all the damages caused by NP. Therefore, it is deduced that NOB could be used as a potential therapeutic to counter the NP-prompted oxidative stress and apoptotic damages in testes.

Influence of Kv11.1 (hERG1) K+ channel expression on DNA damage induced by the genotoxic agent methyl methanesulfonate

Besides their crucial role in cell electrogenesis and maintenance of basal membrane potential, the voltage-dependent K⁺ channel Kv11.1/hERG1 shows an essential impact in cell proliferation and other processes linked to the maintenance of tumour phenotype. To check the possible influence of channel expression on DNA damage responses, HEK293 cells, treated with the genotoxic agent methyl methanesulfonate (MMS), were compared with those of a HEK-derived cell line (H36), permanently transfected with the Kv11.1-encoding gene, and with a third cell line (T2) obtained under identical conditions as H36, by permanent transfection of another unrelated plasma membrane protein encoding gene. In addition, to gain some insights about the canonical/conduction-dependent channel mechanisms that might be involved, the specific erg channel inhibitor E4031 was used as a tool. Our results indicate that the expression of Kv11.1 does not influence MMS-induced changes in cell cycle progression, because no differences were found between H36 and T2 cells. However, the canonical ion conduction function of the channel appeared to be associated with decreased cell viability at low/medium MMS concentrations. Moreover, direct DNA damage measurements, using the comet assay, demonstrated for the first time that Kv11.1 conduction activity was able to modify MMS-induced DNA damage, decreasing it particularly at high MMS concentration, in a way related to PARP1 gene expression. Finally, our data suggest that the canonical Kv11.1 effects may be relevant for tumour cell responses to anti-tumour therapies.

Applications of CometChip for Environmental Health Studies

Environmental exposures have long been known to impact public health and safety. For example, exposures to airborne particulates, heavy metals in water, or certain industrial chemicals can contribute to aging and to risk of developing cancer and other diseases. Environmental factors can impact health in a variety of ways, but a key concern is DNA damage, which can lead to mutations that cause cancer. Cancer can take years to develop following chemical exposure; however, one way to predict carcinogenicity in a more practical time frame is by studying the chemical's ability to induce DNA damage. The comet assay (or single-cell gel electrophoresis assay) has been used successfully for genotoxicity testing. The comet assay allows for the detection of DNA strand breaks via analysis of DNA migration during electrophoresis. Previously, the Engelward laboratory, in collaboration with the Bhatia laboratory, developed the CometChip for measurements of DNA damage and repair. The CometChip is a high-throughput comet assay that improves user reproducibility and significantly shortens total assay time. Here, we describe how the high-throughput CometChip platform can be used to measure DNA damage in established cell lines, animal models, and human samples. We also discuss technical challenges associated with these studies and provide recommendations on how to achieve optimal results for researchers interested in adopting this assay.

Acute lethal and sublethal effects of four insecticides on the lacewing (Chrysoperla sinica Tjeder)

The lacewing, Chrysoperla sinica, is an important predatory insect, which plays an important role in the integrated pest management of agroforestry pests. However, the extensive use of insecticides negatively affects C. sinica. The acute toxicity, risk level, and, sublethal effects on growth and production, predation ability, protective enzyme activity and genotoxicity of four insecticides: indoxacarb, emamectin benzoate, imidacloprid and lambda-cyhalothrin to C. sinica were studied. The results showed that all four insecticides had lethal toxicity to larvae of C. sinica. Among them, emamectin benzoate had the highest toxicity with LC₅₀ value of 7.41 mg/L. The insecticides also had different effects on the growth and reproduction of C. sinica, of which lambda-cyhalothrin had the greatest impacts. Even at a very low LC₁ concentration (3.37 mg/L), it had strong impacts on the growth, reproduction and predatory ability of C. sinica. The four insecticides also caused a decrease in the predatory ability of the lacewing, of which lambda-cyhalothrin had the greatest effect. During the larval stage, the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were significantly decreased by the four insecticides. At the pupal and adult stages, the effects of the four insecticides on the activities of protective enzymes were different, and the activities of SOD, CAT and POD decreased or increased. Indoxacarb and lambda-cyhalothrin exposure induced DNA damage in the haemocytes of C. sinica and produced obvious genotoxicity. These results provide important scientific basis for the rational use of these insecticides and the protection and utilization of lacewing.

Genotoxic risk in health-care professionals occupationally exposed to low doses of ionizing radiation

The purpose of this study was to evaluate the potential influence of occupational ionizing radiation (IR) exposure on health professionals, assessing DNA damage using the comet and micronucleus (MN) assays and analyzing relative risks, correlations, and associated factors between outcomes and socioeconomic and lifestyle factors. Blood and buccal samples were collected from 36 workers, who actively participated in an imaging sector of a hospital, who were either exposed to IR directly or indirectly (9 internal control and 27 exposed), and 27 individuals living in the same city but with no occupational exposure (external control, unexposed/healthy). All radiation dosages performed on the 36 workers were less than 20 mSv/y, not exceeding the effective dose limit for occupational exposure. A questionnaire identified socioeconomic and lifestyle factors associated with the outcomes. The results of the MN assay showed a significant difference between both internal control and the exposed group when compared to the external control. For the comet assay, there were significant differences between the percent of tail DNA of the exposed group and external controls, but no difference was found between the exposed group and internal controls. Relative risk associations were found in time of exposure, hours worked per week, and perceived stress. Correlations were found between the outcomes and age, consumption of alcohol, and frequencies of X-rays during life. Variables that showed to be significant in the adjusted analysis were skin color and recent exposure to radiation. Albeit limited, the findings of this study suggest genotoxicity in both blood and buccal mucosa cells of workers exposed directly or indirectly to IR and that lifestyle and socioeconomic factors are associated and correlated with the risk of developing these outcomes.

Genotoxic risk in health-care professionals occupationally exposed to low doses of ionizing radiation

The purpose of this study was to evaluate the potential influence of occupational ionizing radiation (IR) exposure on health professionals, assessing DNA damage using the comet and micronucleus (MN) assays and analyzing relative risks, correlations, and associated factors between outcomes and socioeconomic and lifestyle factors. Blood and buccal samples were collected from 36 workers, who actively participated in an imaging sector of a hospital, who were either exposed to IR directly or indirectly (9 internal control and 27 exposed), and 27 individuals living in the same city but with no occupational exposure (external control, unexposed/healthy). All radiation dosages performed on the 36 workers were less than 20 mSv/y, not exceeding the effective dose limit for occupational exposure. A questionnaire identified socioeconomic and lifestyle factors associated with the outcomes. The results of the MN assay showed a significant difference between both internal control and the exposed group when compared to the external control. For the comet assay, there were significant differences between the percent of tail DNA of the exposed group and external controls, but no difference was found between the exposed group and internal controls. Relative risk associations were found in time of exposure, hours worked per week, and perceived stress. Correlations were found between the outcomes and age, consumption of alcohol, and frequencies of X-rays during life. Variables that showed to be significant in the adjusted analysis were skin color and recent exposure to radiation. Albeit limited, the findings of this study suggest genotoxicity in both blood and buccal mucosa cells of workers exposed directly or indirectly to IR and that lifestyle and socioeconomic factors are associated and correlated with the risk of developing these outcomes.

Elevated Serum Pb, Ni, Cd, and Cr Levels and DNA Damage in Exfoliated Buccal Cells of Teenage Scavengers at a Major Electronic Waste Dumpsite in Lagos, Nigeria

This study investigated the levels of Pb, Ni, Cd, and Cr in the blood, and DNA damage in exfoliated buccal cavity of scavenging teenagers at Alaba International electronic market, Nigeria. One hundred and ninety-nine blood samples were collected from scavenging teenagers in Alaba International market (n = 95) and the control group (n = 104). Blood Pb, Ni, Cd, and Cr concentrations were analyzed using graphite furnace atomic absorption spectrometry. Genotoxicity assessment was through exfoliated buccal cell micronucleus assay, while questionnaire was used to collect data on factors that can contribute to the blood heavy metal levels. The blood Pb of scavenging teenagers from Alaba International market varied from 2.84 to 189.44 μg/L compared to the control group with a range of 0.01 to 4.21 μg/L. The blood Cd (range = 0.38-12.35 μg/L), Cr (range = 0.20-19.03 μg/L), and Ni (range = 0.24-21.01 μg/L) were higher significantly in the Alaba group compared to the control group (Cd: range = 0.00-0.96 μg/L; Cr: range = 0.01-0.72 μg/L; and Ni: range = 0.00-0.28 μg/L). Frequencies of micronucleus, karyolysis, and pycnosis in the exfoliated buccal cells in Alaba group also increased significantly compared with the control group. Spearman correlation analyses indicated a positive correlation between the blood Pb, Ni, Cd, and Cr and induced micronucleus in the buccal exfoliated cells. Furthermore, data showed a positive correlation between Pb, Ni, Cd, and Cr and the duration of scavenging of the teenagers. However, a negative correlation was observed between educational status and Pb, Ni, Cd, and Cr. E-waste indiscriminate disposal and primitive recycling processes may be responsible for the high blood heavy metal levels, and consequently an increased DNA damage in exfoliated buccal cells in scavenging teenagers at Alaba International market. Graphical Abstract.

Toxicological profile of lipid-based nanostructures: are they considered as completely safe nanocarriers?

Nanoparticles are ubiquitous in the environment and are widely used in medical science (e.g. bioimaging, diagnosis, and drug therapy delivery). Due to unique physicochemical properties, they are able to cross many barriers, which is not possible for traditional drugs. Nevertheless, exposure to NPs and their following interactions with organelles and macromolecules can result in negative effects on cells, especially, they can induce cytotoxicity, epigenicity, genotoxicity, and cell death. Lipid-based nanomaterials (LNPs) are one of the most important achievements in drug delivery mainly due to their superior physicochemical and biological characteristics, particularly its safety. Although they are considered as the completely safe nanocarriers in biomedicine, the lipid composition, the surfactant, emulsifier, and stabilizer used in the LNP preparation, and surface electrical charge are important factors that might influence the toxicity of LNPs. According to the author's opinion, their toxicity profile should be evaluated case-by-case regarding the intended applications. Since there is a lack of all-inclusive review on the various aspects of LNPs with an emphasis on toxicological profiles including cyto-genotoxiciy, this comprehensive and critical review is outlined.

Association between occupational heat stress and DNA damage in lymphocytes of workers exposed to hot working environments in a steel industry in Southern India

Occupational heat stress apart from adverse heat-related health consequences also induces DNA damage in workers exposed to high working temperatures. We investigated the association between chronic heat exposures and Micronuclei (MN) frequency in lymphocytes of 120 workers employed in the steel industry. There was a significant increase in the MN-frequency in exposed workers compared to the unexposed workers (X² = 47.1; p < 0.0001). While exposed workers had higher risk of DNA damage (Adj. OR = 23.3, 95% CI 8.0-70.8) compared to the unexposed workers, among the exposed workers, the odds of DNA damage was much higher for the workers exposed to high-heat levels (Adj. OR = 81.4; 95% CI 21.3-310.1) even after adjusting for confounders. For exposed workers, years of exposure to heat also had a significant association with higher induction of MN (Adj. OR = 29.7; 95% CI 2.8-315.5). Exposures to chronic heat stress is a significant occupational health risk including damages in sub-cellular level, for workers. Developing protective interventions to reduce heat exposures is imperative in the rising temperature scenario to protect millions of workers across the globe.

Application of the comet assay for the evaluation of DNA damage from frozen human whole blood samples: Implications for human biomonitoring

This study proposes the application of the comet assay for the evaluation of DNA damage from frozen human whole blood samples that could be readily used in human biomonitoring and epidemiological studies. It was done on simply frozen whole blood samples collected from male volunteers (N = 60) aliquoted in small volumes and stored at -80 °C without the addition of cryopreservatives for a period of 5 years. To test the applicability of the alkaline comet assay for the evaluation of DNA damage in frozen whole blood, samples were quickly thawed at 37 °C and immediately embedded in an agarose matrix followed by an alkaline comet assay procedure. We concluded that the whole blood freezing and prolonged storage do not severely affect comet assay values, although background values were higher compared to our historical control data from the fresh whole blood. Even the influence of the variables tested, such as age, body mass index, smoking habit and alcohol consumption were in agreement with our previous data using fresh blood. The obtained results suggest that the comet assay could be applied to frozen blood samples, if properly stored, even for decades, which would certainly facilitate large-scale human biomonitoring and long-term epidemiological studies.

Application of the comet assay in human biomonitoring: An hCOMET perspective

The comet assay is a well-accepted biomonitoring tool to examine the effect of dietary, lifestyle, environmental and occupational exposure on levels of DNA damage in human cells. With such a wide range of determinants for DNA damage levels, it becomes challenging to deal with confounding and certain factors are inter-related (e.g. poor nutritional intake may correlate with smoking status). This review describes the effect of intrinsic (i.e. sex, age, tobacco smoking, occupational exposure and obesity) and extrinsic (season, environmental exposures, diet, physical activity and alcohol consumption) factors on the level of DNA damage measured by the standard or enzyme-modified comet assay. Although each factor influences at least one comet assay endpoint, the collective evidence does not indicate single factors have a large impact. Thus, controlling for confounding may be necessary in a biomonitoring study, but none of the factors is strong enough to be regarded a priori as a confounder. Controlling for confounding in the comet assay requires a case-by-case approach. Inter-laboratory variation in levels of DNA damage and to some extent also reproducibility in biomonitoring studies are issues that have haunted the users of the comet assay for years. Procedures to collect specimens, and their storage, are not standardized. Likewise, statistical issues related to both sample-size calculation (before sampling of specimens) and statistical analysis of the results vary between studies. This review gives guidance to statistical analysis of the typically complex exposure, co-variate, and effect relationships in human biomonitoring studies.

Assessment of neurohepatic DNA damage in male Sprague-Dawley rats exposed to organophosphates and pyrethroid insecticides

The current work was undertaken to test the genotoxic potential of chlorpyrifos (CPF), dimethoate, and lambda cyhalothrin (LCT) insecticides in rat brain and liver using the single cell gel electrophoresis (comet assay). Three groups of adult male Sprague-Dawley rats were exposed orally to one third LD₅₀of CPF, dimethoate, or LCT for 24 and 48 h while the control group received corn oil. Serum samples were collected for estimation of malondialdehyde (MDA) and glutathione peroxidase (GPx); the brain and liver samples were used for comet assay and for histopathological examination. Results showed that signs of neurotoxicity appeared clinically as backward stretching of hind limb and splayed gait in dimethoate and LCT groups, respectively. CPF, LCT, and dimethoate induced oxidative stress indicated by increased MDA and decreased GPx levels. CPF and LCT caused severe DNA damage in the brain and liver at 24 and 48 h indicated by increased percentage of DNA in tail, tail length, tail moment, and olive tail moment. Dimethoate induced mild DNA damage in the brain and liver at 48 h. Histopathological changes were observed in the cerebrum, cerebellum, and liver of exposed rats. The results concluded that CPF, LCT, and dimethoate insecticides induced oxidative stress and DNA damage associated with histological changes in the brain and liver of exposed rats.

Chronic occupational exposure endured by tobacco farmers from Brazil and association with DNA damage

Tobacco farming is an important economic income in Brazil, although it has been challenged as regard the occupational exposure to both pesticides and nicotine endured by farmers. Chronic occupational exposure to complex mixtures can lead to health hazardous. We examined genomic instability and epigenetic changes in tobacco farmers occupationally exposed to pesticide mixtures and nicotine at tobacco fields. DNA damage was assessed by alkaline comet assay in blood cells. Genomic DNA was isolated, and telomere length was measured using quantitative polymerase chain reaction assay. We measured 5-methyl-2'-deoxycytidine, a marker of global DNA methylation, and p16 promoter methylation. The oxidative profile was evaluated by trolox equivalent antioxidant capacity and lipid peroxidation (thiobarbituric acid reactive substances) in serum. Exposure parameters, plasma cotinine and inorganic element levels, were also measured. DNA damage was significantly elevated for farmers in relation to unexposed group (P < 0.001; Mann-Whitney test) and positively associated with years of exposure. Inverse relationship between DNA damage and total equivalent antioxidant activity was demonstrated for exposed and unexposed groups. Exposed group showed significantly shorter telomeres (P < 0.001; unpaired t-test) and DNA hypomethylation (P < 0.001; unpaired t-test), as well as p16 hypermethylation (P = 0.003; Mann-Whitney test). Lipid peroxidation was increased for exposed group in relation to unexposed one (P = 0.02; Mann-Whitney test) and presented a positive correlation with global DNA methylation (P = 0.0264). Farmers have increased plasma cotinine levels (P < 0.001) and inorganic elements (phosphorus, sulphur and chlorine) in relation to unexposed group. Elevated oxidative stress levels due to chronic occupational pesticide mixtures and nicotine exposure in tobacco farmers were associated with higher DNA damage, shorter telomeres and altered DNA methylation. Telomere-accelerated attrition due to exposure may be potential intermediate step before a disease state.

Natural tissue concentrations in adult Ambystoma maculatum and larval DNA damage from exposure to arsenic and chromium

Arsenic (As) and chromium (Cr) are two contaminants that are detected in aquatic and terrestrial habitats. Using the spotted salamander, Ambystoma maculatum, to assess impacts from these contaminants may be advantageous as adults live and breed in such environments. Adult amphibians typically exhibit elevated tissue concentrations of contaminants present in their environment, while larval stages were found to exhibit increased sensitivity to pollutants. From January through March of 2015, during the spring breeding season, 5 adults and approximately 32 egg masses were collected from a local breeding site. Field levels of As and Cr ranged from 5.99 to 8.88 µg/L and 1.45 to 2 µg/L, respectively, while mean adult As tissue concentrations were 56.74 µg/g dry weight for heart, 0.92 µg/g for liver, and 1.21 µg/g for tail tissue. Mean tissue concentrations for Cr were 87.64 µg/g for heart, 1.47 µg/g for liver, and 6.92 µg/g for tail. Developing larvae that were collected from the field and exposed in a lab setting for 12 d to 0.2 or 20 mg/L of either As or Cr displayed little DNA damage attributed to As, but marked damage due to exposure to 20 mg/L Cr when assessed using the comet assay. Exposure to a mixture of either 0.25:0.1 or 25:10 mg/L As and Cr resulted in significant DNA damage at the lower concentration of 0.25:0.1 mg/L. As adult spotted salamanders were found to possess high concentrations of these contaminants in cardiac tissue, and larvae were shown to be susceptible to DNA damage from increased exposures, assessing impacts and potential declines of amphibian populations exposed to As and Cr is needed.

Design, synthesis and pharmacological evaluation of N-benzyl-piperidinyl-aryl-acylhydrazone derivatives as donepezil hybrids: Discovery of novel multi-target anti-alzheimer prototype drug candidates

A new series of sixteen multifunctional N-benzyl-piperidine-aryl-acylhydrazones hybrid derivatives was synthesized and evaluated for multi-target activities related to Alzheimer's disease (AD). The molecular hybridization approach was based on the combination, in a single molecule, of the pharmacophoric N-benzyl-piperidine subunit of donepezil, the substituted hydroxy-piperidine fragment of the AChE inhibitor LASSBio-767, and an acylhydrazone linker, a privileged structure present in a number of synthetic aryl- and aryl-acylhydrazone derivatives with significant AChE and anti-inflammatory activities. Among them, compounds 4c, 4d, 4g and 4j presented the best AChE inhibitory activities, but only compounds 4c and 4g exhibited concurrent anti-inflammatory activity in vitro and in vivo, against amyloid beta oligomer (AβO) induced neuroinflammation. Compound 4c also showed the best in vitro and in vivo neuroprotective effects against AβO-induced neurodegeneration. In addition, compound 4c showed a similar binding mode to donepezil in both acetylated and free forms of AChE enzyme in molecular docking studies and did not show relevant toxic effects on in vitro and in vivo assays, with good predicted ADME parameters in silico. Overall, all these results highlighted compound 4c as a promising and innovative multi-target drug prototype candidate for AD treatment.

Assessment of DNA damage in blood lymphocytes of bakery workers by comet assay

The comet assay is widely used in screening and identification of genotoxic effects of different substances on people in either their working or living environment. Exposure to fuel smoke leads to DNA damage and ultimately different types of cancer. Using a comet assay, the present study aimed to assess peripheral blood lymphocyte DNA damage in people working in bakeries using natural gas, kerosene, diesel, or firewood for fuel compared to those in the control group. The subjects of this study were 55 people in total who were divided into four experimental groups, each of which comprised of 11 members (based on the type of fuel used), and one control group comprised of 11 members. Using CometScore, the subjects' peripheral blood lymphocytes were examined for DNA damage. All bakers, that is, experimental subjects, showed significantly greater peripheral blood lymphocyte DNA damage compared to the individuals in the control group. There was greater peripheral blood lymphocyte DNA damage in bakers who had been using firewood for fuel compared to those using other types of fuel to such an extent that tail moments (µm) for firewood-burning bakers was 4.40 ± 1.98 versus 1.35 ± 0.84 for natural gas, 1.85 ± 1.33 for diesel, and 2.19 ± 2.20 for kerosene. The results indicated that burning firewood is the greatest inducer of peripheral blood lymphocytes DNA damage in bakers. Nonetheless, there was no significant difference in peripheral blood lymphocyte DNA damage among diesel and kerosene burning bakers.

Changes of oxidative/antioxidative parameters and DNA damage in firefighters wearing personal protective equipment during treadmill walking training

[Purpose] The purpose of this study was to investigate the influence of personal protective equipment on the oxidant/antioxidant parameters and DNA damage in firefighters during training and recovery. [Subjects and Methods] Twelve male nonsmoking volunteer firefighters (35.1 ± 7.2 years) underwent two maximal treadmill training (9 METs, 6 km/h), within 2 weeks, one in regular clothes and one in personal protective equipment weighing 22.1 kg. Blood samples were obtained before, right after, and 40 min after training. Plasma conjugated dienes, total radical trapping antioxidant potential, erythrocytes antioxidant enzymes activities, and leukocyte DNA damage were measured. [Results] Wearing personal protective equipment during treadmill walking training resulted in increases of plasma conjugated dienes, total radical trapping antioxidant potential, and leukocyte DNA resistance to oxidative stress, which were recovered after in 40 min of rest. Erythrocyte antioxidant enzymes activities remained unchanged during the training either with regular clothes or personal protective equipment. [Conclusion] These results suggest that wearing personal protective equipment during firefighting work could induce oxidative stress, which was enough to produce DNA damage in leukocytes.

Lethal and sub-lethal effects on the Asian common toad Duttaphrynus melanostictus from exposure to hexavalent chromium

Chromium discharged in industrial effluents frequently occurs as an environmental pollutant, but the lethal and sub-lethal effects the heavy metal might cause in animals exposed to it have been insufficiently investigated. Selecting the amphibian Duttaphrynus melanostictus, we carried out laboratory tests to investigate the effects of short and long term exposure to hexavalent chromium (Cr(VI)) in both tadpoles and adult toads. The concentrations used were 0.002, 0.02, 0.2, 1.0 and 2.0mg/L, the first three corresponding to field levels. In vitro exposures were also carried out using toad erythrocytes and Cr(VI) concentrations of 0.0015, 0.003, 0.015, 0.03, 0.15mg/L. Mortality, growth retardation, developmental delays and structural aberrations were noted in the metal-treated tadpoles, with increasing incidence corresponding to increase in Cr(VI) level and duration of exposure. Many of the sub-lethal effects were evident with long term exposure to environmentally relevant levels of the toxicant. Changes in selected blood parameters and erythrocyte morphometry were also detected in Cr(VI) exposed toads, indicating anaemic and leucopenic conditions. In the genotoxicity study, DNA damage indicated by comet assay and increased micronuclei frequency, occurred at the low Cr(VI) concentrations tested. The multiple deleterious effects of exposure to chromium signal the need for monitoring and controlling the discharge of chromium to the environment. The dose-dependency and genotoxic effects observed in this widely distributed Asian toad indicates its suitability for monitoring heavy metal pollution in aquatic systems.

Evaluation of DNA damage and DNA repair capacity in occupationally lead-exposed workers

Occupational lead (Pb) exposure remains a significant concern for workers in Turkey. Health hazards of Pb exposure have been investigated in various test systems, but results regarding its potential genotoxic effects on exposed populations are contradictory. In this study, a control group and an exposed group were studied, each consisting of 25 male subjects. Blood lead levels (BLLs) were estimated by graphite furnace atomic absorption spectrometry. Genotoxic effects of Pb exposure were studied in leukocytes by comet and challenge assays. The effect of Pb exposure to DNA repair capacity was evaluated following in vitro hydrogen peroxide exposure. Pb-exposed workers had significantly higher BLLs than the control group ( p < 0.01). DNA damage in exposed workers had a significantly higher percentage of DNA in tail than the control group ( p < 0.05). In the challenge assay, it was found that the mean DNA% repair capacity was significantly decreased in Pb-exposed workers ( p < 0.01). The results indicated that occupational Pb exposure is associated with DNA damage and causes decrease in DNA% repair capacity, indicating a potential health concern for occupationally Pb-exposed populations.

Evaluation of oxidative stress and genotoxicity in organophosphorus insecticide formulators

The aim of this study was to evaluate genotoxicity and oxidative stress in workers who formulate organophosphorus (OP) pesticides. In this survey, blood leukocytes and erythrocytes of a group of 21 pesticide formulating workers and an equal number of control subjects were examined for genotoxicity and oxidative stress parameters. The mean comet tail length and mean comet length were used to measure DNA damage. Lipid peroxidation level, catalase, superoxide dismutase (SOD) and glutathione peroxidase activities in erythrocytes were analysed as biomarkers of oxidative stress. In addition, the acetylcholinesterase activity was measured as a biomarker of toxicity. The average duration of employment of workers in the factory was 97 months. Results indicated that chronic exposure (multiple5dose, greater than or equal to 6 months duration) to OP pesticides was associated with increased activities of catalase, SOD and glutathione peroxidase in erythrocytes. The level of lipid peroxidation and acetylcholinesterase activity did not show any significant differences between the two groups. The results also indicated that chronic exposure to OP pesticides was associated with increased DNA damage. It is concluded that human chronic exposure to OP pesticides may result in stimulated antioxidant enzymes and increased DNA damage in the absence of depressed acetylcholinesterase levels. Routine genotoxicity monitoring concomitant to acetylcholinesterase activity in workers occupationally exposed to OP insecticides is suggested.

Cytotoxic effects of tebufenozide in vitro bioassays

Tebufenozide is considered an environmentally friendly pesticide due to its specificity on target insects, but the effects on human are well studied. Studies on the toxicity of tebufenozide at molecular and cellular level is poorly understood. The present study reveals non-selective cytotoxic effects of tebufenozide, and the apoptotic mechanism induced by tebufenozide on HeLa and Tn5B1-4 cells. We demonstrate that the viability of HeLa and Tn5B1-4 cells is inhibited by tebufenozide in a time- and concentration-dependent manner. Intracellular biochemical assays showed that tebufenozide-induced apoptosis of two cell lines concurrent with a decrease in the mitochondrial membrane potential and an increase reactive oxygen species generation, the release of cytochrome-c into the cytosol and a marked activation of caspase-3. These results indicate that a mitochondrial-dependent intrinsic pathway contributes to tebufenozide induced apoptosis in HeLa and Tn5B1-4 cells and suggests potential threats to ecosystems and human health.

Assessing genotoxic effects in fish from a marine protected area influenced by former mining activities and other stressors

The goal of the current study was to evaluate different genotoxicity tools in order to assess a marine protected area (MPA) affected by former mining activities and urban settlements. A catfish (Cathorops spixii) was analyzed for genotoxic effects at the (i) molecular and at the (ii) chromosomal levels. Through factor analysis, genotoxicity was found to be linked to levels of metals bioaccumulated and PAH metabolites in the bile. Micronucleus and nuclear alteration were less vulnerable to the effects of confounding factors in mildly contaminated areas since they were more frequently associated with bioaccumulated metals than the DNA analysis. The different genotoxicity responses allowed for the identification of sources of pollution in the MPA. This approach was important for detecting environmental risks related to genotoxic contaminants in a mildly contaminated MPA.

Reduced DNA double-strand break repair capacity and risk of squamous cell carcinoma of the head and neck--A case-control study

Tobacco smoke and alcohol use play important roles in the etiology of squamous cell carcinoma of the head and neck (SCCHN). Smoking causes DNA damage, including double-strand DNA breaks (DSBs), that leads to carcinogenesis. To test the hypothesis that suboptimal DSB repair capacity is associated with risk of SCCHN, we applied a flow cytometry-based method to detect the DSB repair phenotype first in four EBV-immortalized human lymphoblastoid cell lines and then in human peripheral blood T-lymphocytes (PBTLs). With this blood-based laboratory assay, we conducted a pilot case-control study of 100 patients with newly diagnosed, previously untreated SCCHN and 124 cancer-free controls of non-Hispanic whites. We found that the mean DSB repair capacity level was significantly lower in cases (42.1%) than that in controls (54.4%) (P<0.001). When we used the median DSB repair capacity level in the controls as the cutoff value for calculating the odds ratios (ORs) with adjustment for age, sex, smoking and drinking status, the cases were more likely than the controls to have a reduced DSB repair capacity (adjusted OR=1.93; 95% confidence interval, CI=1.04-3.56, P=0.037), especially for those subjects who were ever drinkers (adjusted OR=2.73; 95% CI=1.17-6.35, P=0.020) and had oropharyngeal tumors (adjusted OR=2.17; 95% CI=1.06-4.45, P=0.035). In conclusion, these findings suggest that individuals with a reduced DSB repair capacity may be at an increased risk of developing SCCHN. Larger studies are warranted to confirm these preliminary findings.

Quantitative genotoxicity assays for analysis of medicinal plants: A systematic review

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal plants are known to contain numerous biologically active compounds, and although they have proven pharmacological properties, they can cause harm, including DNA damage.

AIM OF THE STUDY

Review the literature to evaluate the genotoxicity risk of medicinal plants, explore the genotoxicity assays most used and compare these to the current legal requirements.

MATERIAL AND METHODS

A quantitative systematic review of the literature, using the keywords "medicinal plants", "genotoxicity" and "mutagenicity", was undertakenQ to identify the types of assays most used to assess genotoxicity, and to evaluate the genotoxicity potential of medicinal plant extracts.

RESULTS

The database searches retrieved 2289 records, 458 of which met the inclusion criteria. Evaluation of the selected articles showed a total of 24 different assays used for an assessment of medicinal plant extract genotoxicity. More than a quarter of those studies (28.4%) reported positive results for genotoxicity.

CONCLUSIONS

This review demonstrates that a range of genotoxicity assay methods are used to evaluate the genotoxicity potential of medicinal plant extracts. The most used methods are those recommended by regulatory agencies. However, based on the current findings, in order to conduct a thorough study concerning the possible genotoxic effects of a medicinal plant, we indicate that it is important always to include bacterial and mammalian tests, with at least one in vivo assay. Also, these tests should be capable of detecting outcomes that include mutation induction, clastogenic and aneugenic effects, and structural chromosome abnormalities. In addition, the considerable rate of positive results detected in this analysis further supports the relevance of assessing the genotoxicity potential of medicinal plants.

Increased levels of etheno-DNA adducts and genotoxicity biomarkers of long-term exposure to pure diesel engine exhaust

Etheno-DNA adducts are biomarkers for assessing oxidative stress. In this study, the aim was to detect the level of etheno-DNA adducts and explore the relationship between the etheno-DNA adducts and genotoxicity biomarkers of the diesel engine exhaust (DEE)-exposed workers. We recruited 86 diesel engine testing workers with long-term exposure to DEE and 99 non-DEE-exposed workers. The urinary mono-hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) and etheno-DNA adducts (εdA and εdC) were detected by HPLC-MS/MS and UPLC-MS/MS, respectively. Genotoxicity biomarkers were also evaluated by comet assay and cytokinesis-block micronucleus assay. The results showed that urinary εdA was significantly higher in the DEE-exposed workers (p<0.001), exhibited 2.1-fold increase compared with the non-DEE-exposed workers. The levels of urinary OH-PAHs were positively correlated with the level of εdA among all the study subjects (p<0.001). Moreover, we found that the increasing level of εdA was significantly associated with the increased olive tail moment, percentage of tail DNA, or frequency of micronucleus in the study subjects (p<0.01). No significant association was observed between the εdC level and any measured genotoxicity biomarkers. In summary, εdA could serve as an indicator for DEE exposure in the human population.

Neuroprotective effect of Citrus unshiu immature peel and nobiletin inhibiting hydrogen peroxide-induced oxidative stress in HT22 murine hippocampal neuronal cells

BACKGROUND

Oxidative stress-induced cell damage is common in the etiology of several neurobiological disorders, including Alzheimer's disease and Parkinson's disease. In a case study, nobiletin-rich Citrus reticulata peels could prevent the progression of cognitive impairment in donepezil-preadministered Alzheimer's disease patients.

OBJECTIVE

In this study, we investigated the effects and underlying mechanism of nobiletin and Citrus unshiu immature peel (CUIP) water extract, which contains nobiletin as a major compound, on hydrogen peroxide-induced oxidative stress in HT22 cells, a murine hippocampal neuronal model.

MATERIALS AND METHODS

HT22 cells were treated with hydrogen peroxide in the presence or absence of various concentrations of CUIP and nobiletin. Cytotoxicity and apoptotic protein levels were measured by 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and Western blotting.

RESULTS

Pretreatment with CUIP and nobiletin inhibited cell death due to hydrogen peroxide. Hydrogen peroxide-induced the expression of phospho-Jun N-terminal kinases (p-JNK) and p-p38 proteins in HT22 cells; however CUIP and nobiletin suppressed p-JNK and p-p38 without changing JNK or p38. Regarding apoptosis, caspase 3, B-cell lymphoma 2 (Bcl-2), and Bax protein expression was determined. CUIP and nobiletin suppressed caspase 3 and Bax expression, but they induced Bcl-2 expression in HT22 cells.

CONCLUSION

These results show that CUIP and nobiletin can protect against hydrogen peroxide-induced cell death in HT22 neurons via mitogen-activated protein kinases and apoptotic pathways.

Antigenotoxic and antioxidant potentials of newly derivatized compound naringenin-oxime relative to naringenin on human mononuclear cells

We investigated antigenotoxic and antioxidative effects of newly derivatized compound naringenin-oxime (NG-Ox) compared to its mother compound naringenin (NG) against oxidative damage induced by hydrogen peroxide (HP) in human peripheral blood mononuclear cells (PBMC). Antigenotoxic activity was assessed using alkaline single cell gel electrophoresis assay (comet assay). Oxidative status was evaluated by measurement of total antioxidant status, total oxidant status and lipid hydroperoxide levels in the cells. Oxidative stress index was also calculated. Both NG and NG-Ox show a protective effect against HP-induced oxidative damage on PBMC and are able to reduce oxidative stress. The percentage of antigenotoxic and antioxidant potential progressively increased in a dose-dependent manner. However, these activities were found to be more significant in NG-Ox-treated cells than in NG-treated cells. Taken together, these observations provide evidences indicating that both NG and NG-Ox are able to protect cells against oxidative damage and apparently NG-Ox is more effective than NG.

The organophosphate insecticide chlorpyrifos confers its genotoxic effects by inducing DNA damage and cell apoptosis

The organophosphate insecticide chlorpyrifos (CPF) is known to induce neurological effects, malformation and micronucleus formation, persistent developmental disorders, and maternal toxicity in rats and mice. The binding of chlorpyrifos with DNA to produce DNA adducts leads to an increasing social concern about the genotoxic risk of CPF in human, but CPF-induced cytotoxicity through DNA damage and cell apoptosis is not well understood. Here, we quantified the cytotoxicity and potential genotoxicity of CPF using the alkaline comet assay, γH2AX foci formation, and the DNA laddering assay in order to detect DNA damage and apoptosis in human HeLa and HEK293 cells in vitro. Drosophila S2 cells were used as a positive control. The alkaline comet assay showed that sublethal concentrations of CPF induced significant concentration-dependent increases in single-strand DNA breaks in the treated cells compared with the control. The percentage of γH2AX-positive HeLa cells revealed that CPF also causes DNA double-strand breaks in a time-dependent manner. Moreover, DNA fragmentation analysis demonstrated that exposure to CPF induced a significant concentration- and time-dependent increase in cell apoptosis. We conclude that CPF is a strongly genotoxic agent that induces DNA damage and cell apoptosis.

Neuroprotective effects of Kukoamine B against hydrogen peroxide-induced apoptosis and potential mechanisms in SH-SY5Y cells

Oxidative stress mediates the cell damage in several neurodegenerative diseases, including multiple sclerosis, Alzheimer's disease (AD) and Parkinson's disease (PD). This study aimed at investigating the protective effects of Kukoamine B (KuB) against hydrogen peroxide (H2O2) induced cell injury and potential mechanisms in SH-SY5Y cells. Our results revealed that treatment with KuB prior to H2O2 exposure effectively increased the cell viability, and restored the mitochondria membrane potential (MMP). Furthermore, KuB enhanced the antioxidant enzyme activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) and decreased the malondialdehyde (MDA) content. Moreover, KuB minimized the ROS formation and inhibited mitochondria-apoptotic pathway, MAPKs (p-p38, p-JNK, p-ERK) pathways, but activated PI3K-AKT pathway. In conclusion, we believed that KuB may potentially serve as an agent for prevention of several human neurodegenerative and other disorders caused by oxidative stress.

Cellular uptake and toxicity effects of silver nanoparticles in mammalian kidney cells

The rapid progress and early commercial acceptance of silver-based nanomaterials is owed to their biocidal activity. Besides embracing the antimicrobial potential of silver nanoparticles (AgNPs), it is imperative to give special attention to the potential adverse health effects of nanoparticles owing to prolonged exposure. Here, we report a detailed study on the in vitro interactions of citrate-coated AgNPs with porcine kidney (Pk15) cells. As uncertainty remains whether biological/cellular responses to AgNPs are solely as a result of the release of silver ions or whether the AgNPs themselves have toxic effects, we investigated the effects of Ag(+) on Pk15 cells for comparison. Next, we investigated the cellular uptake of both AgNPs and Ag(+) in Pk15 cells at various concentrations applied. The detected Ag contents in cells exposed to 50 mg l(-1) AgNPs and 50 mg l(-1) Ag(+) were 209 and 25 µg of Ag per 10(6) cells, respectively. Transmission electron microscopy (TEM) images indicated that the Pk15 cells internalized AgNPs by endocytosis. Both forms of silver, nano and ionic, decreased the number of viable Pk15 cells after 24 h in a dose-dependent manner. In spite of a significant uptake into the cells, AgNPs had only insignificant toxicity at concentrations lower than 25 mg l(-1) , whereas Ag(+) exhibited a significant decrease in cell viability at one-fifth of this concentration. The Comet assay suggested that a rather high concentration of AgNP (above 25 mg l(-1) ) is able to induce genotoxicity in Pk15 cells. Further studies must seek deeper understanding of AgNP behavior in biological media and their interactions with cellular membranes.

Evaluation on antioxidant properties of sixteen plant species from Jeju Island in Korea

In this study, the antioxidant properties of 80 % ethanol extracts of 16 species of plants from Jeju Island in Korea were evaluated using various antioxidant assays, including the DPPH (1,1-Diphenyl-2-pricrylhydrazyl) radical scavenging, superoxide scavenging, xanthine oxidase inhibition and hydrogen peroxide scavenging activities. Among the 16 plant extracts tested, CN-13 showed strong antioxidant properties in the DPPH radical scavenging and hydrogen peroxide scavenging tests. The CN-13 ethanol extract was thus selected to be used for further experiments, and was separated into various fractions using four different organic solvents (n-hexane, methylene chloride, ethyl acetate and butanol). The ethyl acetate fraction of CN-13 extract evidenced strong DPPH radical scavenging properties as compared to the other fractions. The ethyl acetate fraction also strongly inhibited DNA-damage induced by hydrogen peroxide-oxidative damage in a mouse lymphoma (L5178Y-R) cell line. Moreover, a correlation between the total phenolic content of the extract, and its antioxidant property was reported.

Characterization of risk factors for DNA damage among paddy farm worker exposed to mixtures of organophosphates

This is a cross-sectional study conducted among paddy farmers to characterize potential risk factors that influence levels of DNA damage from exposure to mixtures of organophosphates. Comet assay was used to determine the level of DNA damage by measuring the comet tail length from the exfoliated buccal mucosa. The result suggests that farmers who chronically exposure to a mixture of organophosphates has at least 2-fold significant increase of DNA damage as compared with control group. Factor analysis and linear regression both suggest that DNA damage reported by farmers may influence individual, occupational, and residential factors and are reported as significant predictor factors, whereas this effect is mainly caused by individual factors among the control group. The findings of the present study suggest that either farmer or control group bear certain extent of genotoxic burden contributed by different risk factors.

Recent physical activity in relation to DNA damage and repair using the comet assay

BACKGROUND

Limited evidence suggests that very high-intensity exercise is positively associated with DNA damage but moderate exercise may be associated with DNA repair.

METHODS

Participants were 220 healthy, Washington State 50- to 76-year-olds in the validity/biomarker substudy of the VITamins And Lifestyle (VITAL) cohort, who provided blood samples and completed questionnaires assessing recent physical activity and demographic and health factors. Measures included nested activity subsets: total activity, moderate- plus high-intensity activity, and high-intensity activity. DNA damage (n = 122) and repair (n = 99) were measured using the comet assay. Multivariate linear regression was used to estimate regression coefficients and associated 95% confidence intervals (CIs) for relationships between MET-hours per week of activity and each DNA outcome (damage, and 15- and 60-minute repair capacities).

RESULTS

DNA damage was not associated with any measure of activity. However, 60-minute DNA repair was positively associated with both total activity (β = 0.21, 95% CI: 0.0057-0.412; P = .044) and high-intensity activity (β = 0.31, 95% CI: 0.20-0.60; P = .036), adjusting for age, sex, BMI, and current multivitamin use.

CONCLUSIONS

This study is the first to assess broad ranges of activity intensity levels related to DNA damage and repair. Physical activity was unrelated to DNA damage but was associated with increased repair.

Assessment of genotoxic effects of lead in occupationally exposed workers

The genotoxicological effects in 200 lead acid storage battery recycling and manufacturing industry workers in Hyderabad along with matched 200 controls were studied. The genetic damage was determined by comet, micronucleus (MN), and chromosomal aberration (CA) test in peripheral blood lymphocytes (PBL). The MN test was also carried out in buccal epithelial cells (BECs). Pb in ambient air, blood Pb (B-Pb) concentrations, and hematological parameters were measured. The superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione peroxidase (GPx), and malondialdehyde (MDA) formed were also studied. The results of the present study showed that there was a statistically significant (P < 0.01) increase in mean percent tail DNA, frequency of CA, and MN in PBL as well as in BEC as compared to controls. Pb in ambient air and B-Pb concentrations were found to be significantly higher (P < 0.01). The hematocrit, hemoglobin, and red blood cell values were significantly lowered in Pb-exposed workers in comparison to controls. SOD, GPx, and CAT levels were significantly decreased while GSH and MDA levels increased in exposed group when compared to control group. The present study suggests that environmental health standards should be enforced to control Pb contamination from battery industries to reduce human health risk.

Genetic Instability in Peripheral Lymphocytes as Biological Marker for Non-Small Cell Lung Cancer Patients in the South Indian State of Andhra Pradesh

Objectives

This study aims, first, at evaluating the DNA and chromosomal damage in non-small cell lung cancer (NSCLC) patients from the South Indian state of Andhra Pradesh, and then at correlating these results with possible confounding factors that might potentially play a role in causing genetic damage.

Methods

The study included 246 NSCLC patients (177 men and 69 women) and 250 healthy controls (180 men and 70 women) for the analysis of DNA and chromosomal damage using the comet assay and micronucleus test.

Results

Both DNA and chromosomal damage were found to be increased in NSCLC patients compared to healthy controls, and the extent of the damage was higher in males than female patients. The smoking status had a profound effect on the extent of DNA and chromosomal damage in NSCLC patients. The degree of genetic damage correlated with the stage of the disease. However, the histological status had no effect on the extent of DNA and chromosomal damage among NSCLC patients.

Conclusions

We here report, for the first time, that the NSCLC patients selected form the Andhra Pradesh population had increased DNA damage and higher mean micronucleus frequencies in peripheral lymphocytes, indicating a strong background level of genetic instability.

Drosophila comet assay: insights, uses, and future perspectives

The comet assay, a very useful tool in genotoxicity and DNA repair testing, is being applied to Drosophila melanogaster since around 15 years ago, by several research groups. This organism is a valuable model for all kind of processes related to human health, including DNA damage response. The assay has been performed mainly in vivo using different larvae cell types (from brain, midgut, hemolymph, and imaginal disk), but also in vitro with the S2 cell line. Since its first application, it has been used to analyze the genotoxicity and action mechanisms of different chemicals, demonstrating good sensitivity and proving its usefulness. Moreover, it is the only assay that can be used to analyze DNA repair in somatic cells in vivo, comparing the effects of chemicals in different repair strains, and to quantitate repair activities in vitro. Additionally, the comet assay in Drosophila, in vivo and in vitro, has been applied to study the influence of protein overexpression on genome integrity and degradation. Although the assay is well established, it could benefit from some research to determine optimal experimental design to standardize it, and then to allow comparisons among laboratories independently of the chosen cell type.

Neuroprotective effects of bikaverin on H2O2-induced oxidative stress mediated neuronal damage in SH-SY5Y cell line

The generation of free radicals and oxidative stress has been linked to several neurodegenerative diseases including Parkinson's disease, Alzheimer's disease, Huntington's disease, and Amyotrophic lateral sclerosis. The use of free radical scavenging molecules for the reduction of intracellular reactive oxygen species is one of the strategies used in the clinical management of neurodegeneration. Fungal secondary metabolism is a rich source of novel molecules with potential bioactivity. In the current study, bikaverin was extracted from Fusarium oxysporum f. sp. lycopersici and its structural characterization was carried out. Further, we explored the protective effects of bikaverin on oxidative stress and its anti-apoptotic mechanism to attenuate H2O2-induced neurotoxicity using human neuroblastoma SH-SY5Y cells. Our results elucidate that pretreatment of neurons with bikaverin attenuates the mitochondrial and plasma membrane damage induced by 100 µM H2O2 to 82 and 26% as evidenced by MTT and LDH assays. H2O2 induced depletion of antioxidant enzyme status was also replenished by bikaverin which was confirmed by Realtime Quantitative PCR analysis of SOD and CAT genes. Bikaverin pretreatment efficiently potentiated the H2O2-induced neuronal markers, such as BDNF, TH, and AADC expression, which orchestrate the neuronal damage of the cell. The H2O2-induced damage to cells, nuclear, and mitochondrial integrity was also restored by bikaverin. Bikaverin could be developed as a preventive agent against neurodegeneration and as an alternative to some of the toxic synthetic antioxidants.

Protective activity of a novel resveratrol analogue, HS-1793, against DNA damage in 137Cs-irradiated CHO-K1 cells

Resveratrol has received considerable attention as a polyphenol with anti-oxidant, anti-carcinogenic, and anti-inflammatory effects. Radiation is an important component of therapy for a wide range of malignant conditions. However, it causes damage to normal cells and, hence, can result in adverse side effects. This study was conducted to examine whether HS-1793, a novel resveratrol analogue free from the restriction of metabolic instability and the high dose requirement of resveratrol, induces a protective effect against radiation-induced DNA damage. HS-1793 effectively scavenged free radicals and inhibited radiation-induced plasmid DNA strand breaks in an in vitro assay. HS-1793 significantly decreased reactive oxygen species and cellular DNA damage in 2 Gy-irradiated Chinese hamster ovary (CHO)-K1 cells. In addition, HS-1793 dose-dependently reduced the levels of phosphorylated H2AX in irradiated CHO-K1 cells. These results indicate that HS-1793 has chemical radioprotective activity. Glutathione levels and superoxide dismutase activity in irradiated CHO-K1 cells increased significantly following HS-1793 treatment. The enhanced biological anti-oxidant activity and chemical radioprotective activity of HS-1793 maintained survival of irradiated CHO-K1 cells in a clonogenic assay. Therefore, HS-1793 may be of value as a radioprotector to protect healthy tissue surrounding tumor cells during radiotherapy to obtain better tumor control with a higher dose.

3,5,7,3',4'-pentamethoxyflavone, a quercetin derivative protects DNA from oxidative challenges: potential mechanism of action

DNA protection is one of the most important strategies in cancer therapy. Since quercetin and its derivatives are found to be potent antioxidant agents, they are able to scavenge radicals significantly. Therefore, we focused on the DNA protection activity of 3,5,7,3',4'-pentamethoxyflavone (PMF), a quercetin derivative isolated from Kaemperia parviflora. Although, PMF was found to be a very poor antioxidant compound, still it could remarkably protect DNA from oxidative damage. DNA binding assay showed that PMF bound to the minor groove of DNA, which suggests a possible mechanism for its DNA protective effects. Cellular toxicity assay on RAW 264.7 macrophages showed this compound is very safe for therapeutic applications.