Protective Effects of the Flavonoid Chrysin against Methylmercury-Induced Genotoxicity and Alterations of Antioxidant Status, In Vivo

The use of phytochemicals has been widely used as inexpensive approach for prevention of diseases related to oxidative damage due to its antioxidant properties. One of dietary flavonoids is chrysin (CR), found mainly in passion fruit, honey, and propolis. Methylmercury (MeHg) is a toxic metal whose main toxic mechanism is oxidative damage. Thus, the study aimed to evaluate the antioxidant effects of CR against oxidative damage induced by MeHg in Wistar rats. Animals were treated with MeHg (30 µg/kg/bw) in presence and absence of CR (0.10, 1.0, and 10 mg/kg/bw) by gavage for 45 days. Glutathione (GSH) in blood was quantified spectrophotometrically and for monitoring of DNA damage, comet assay was used in leukocytes and hepatocytes. MeHg led to a significant increase in the formation of comets; when the animals were exposed to the metal in the presence of CR, higher concentrations of CR showed protective effects. Moreover, exposure to MeHg decreased the levels of GSH and GSH levels were restored in the animals that received CR plus MeHg. Taken together the findings of the present work indicate that consumption of flavonoids such as CR may protect humans against the adverse health effects caused by MeHg

EVALUATION OF GLUTATHIONE S-TRANSFERASE GSTM1 AND GSTT1 POLYMORPHISMS AND METHYLMERCURY METABOLISM IN AN EXPOSED AMAZON POPULATION

Over the last decades, the presence of methylmercury (MeHg) in the Amazon region of Brazil and its adverse human health effects have given rise to much concern. The biotransformation of MeHg occurs mainly through glutathione (GSH) in the bile mediated by conjugation with glutathione S-transferases (GST). Epidemiological evidence has shown that genetic polymorphisms may affect the metabolism of MeHg. The aim of this study was to evaluate the association between GST polymorphisms, GSH, and Hg levels in blood (B-Hg) and in hair (H-Hg) of an Amazon population chronically exposed to the metal through fish consumption. Blood and hair samples were collected from 144 volunteers (71 men, 73 women). B-Hg and H-Hg levels were determined by inductively coupled plasma-mass spectrometry, and GSH levels were evaluated by a spectrophotometric method. GSTM1 and T1 genotyping evaluation were carried out by multiplex polymerase chain reaction (PCR). Mean levels of B-Hg and H-Hg were 37.7 +/- 24.5 mu g/L and 10.4 +/- 7.4 mu g/g, respectively; GSH concentrations ranged from 0.52 to 2.89 mu M/ml of total blood. Distributions for GSTM1/T1, GSTM1/GSTT1*0, GSTM1*0/T1, and GSTM1*0/GSTT1*0 genotypes were 35.4, 22.2, 25.0, and 17.4%, respectively. GSTT1 genotype carriers presented lower levels of B-Hg and H-Hg when compared to other genotypes carriers. In addition, GSTM1*0/GSTT1*0 individuals presented higher Hg levels in blood and hair than subjects presenting any other genotypes. There appeared to be no evidence of an effect of polymorphisms on GSH levels. Therefore, our data suggest that GST polymorphisms may be associated with MeHg detoxification.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional para o Desenvolvimento Cientifico e Tecnologico (CNPq)Coordenacao de Aperfeicoamento de Pessoal de Ensino Superior (CAPES/DS

Association Between miR-148a and DNA Methylation Profile in Individuals Exposed to Lead (Pb)

2018/24643-1 (São Paulo Research Foundation, FAPESP, Brazil), by the National Council for Scientific and Technological Development (Brazil) and by grant UID-BIM-00009-2020 (Foundation for Science and Technology, FCT, Portugal).Experimental and epidemiologic studies have shown that lead (Pb) is able to induce epigenetic modifications, such as changes in DNA methylation profiles, in chromatin remodeling, as well as the expression of non-coding RNAs (ncRNAs). However, very little is known about the interactions between microRNAs (miRNAs) expression and DNA methylation status in individuals exposed to the metal. The aim of the present study was to investigate the impact of hsa-miR-148a expression on DNA methylation status, in 85 workers exposed to Pb. Blood and plasma lead levels (BLL and PLL, respectively) were determined by ICP-MS; expression of the miRNA-148a was quantified by RT-qPCR (TaqMan assay) and assessment of the global DNA methylation profile (by measurement of 5-methylcytosine; % 5-mC) was performed by ELISA. An inverse association was seen between miR-148a and % 5-mC DNA, as a function of BLL and PLL (β = −3.7; p = 0.071 and β = −4.1; p = 0.049, respectively) adjusted for age, BMI, smoking, and alcohol consumption. Taken together, our study provides further evidence concerning the interactions between DNA methylation profile and miR-148a, in individuals exposed to Pb.publishersversionpublishe

Evaluation of antigenotoxic and antioxidant properties of the flavonoid quercetin and of the carotenoid bixin and norbixin against DNA-damage and alterations of redox status induced by mercury chloride and methylmercury, in vitro and in vivo

O mercúrio (Hg) é um dos metais mais tóxicos presente no meio ambiente e o principal mecanismo relacionado à sua toxicidade é a indução do estresse oxidativo; sua forma orgânica, metilmercúrio (MeHg) é a que apresenta maior toxicidade. A exposição ao Hg ocorre principalmente através da inalação por trabalhadores ocupacionalmente expostos em diversas indústrias e/ou através do consumo de peixes e outros alimentos aquáticos contendo este metal, como por exemplo, populações amazônicas que estão expostas ao MeHg, via dieta, através do consumo de peixes contaminados. Por outro lado, é pressuposto que alimentos ricos em antioxidantes possam prevenir os efeitos adversos à saúde causados pela exposição ao Hg. O flavonóide quercetina (QC) é o principal polifenol da dieta humana, encontrado principalmente em cebola e frutas cítricas e os carotenóides bixina (BIX) e norbixina (NOR) estão presentes em grandes quantidades no urucum, o qual é amplamente utilizado como condimento no Brasil. Assim sendo, o presente trabalho teve por objetivo avaliar os possíveis efeitos protetores do flavonóide QC e dos carotenóides BIX e NOR contra os diversos efeitos adversos causados pelo cloreto de mercúrio (HgCl2) e MeHg, em modelos experimentais in vitro e in vivo. Para tal, culturas de células de hepatoma humano (HepG2) e ratos machos Wistar foram expostos a diversas concentrações do metal, dos fitoquímicos bem como à suas associações. Determinações das concentrações de glutationa, malondialdeído, proteínas carboniladas, atividades das enzimas antioxidantes catalase e glutationa-peroxidase os quais refletem o estado redox das células e monitoramento do dano no material genético pelo uso do ensaio do cometa e determinações dos níveis de 8-hidroxi-2-deoxiguanosina foram realizados no presente estudo. Os resultados obtidos indicam que o Hg causa claros efeitos genotóxicos e leva a uma serie de alterações de parâmetros bioquímicos relacionados ao estado redox das células, in vitro e in vivo. Além disso, foi evidenciado que fitoquímicos, os quais são comumente encontrados na dieta de seres humanos, denominados QC, BIX e NOR protegem contra a instabilidade genética causada pelo metal e restabelece os distúrbios do estado redox das células causados pela exposição ao Hg.Mercury (Hg) is one of the most hazardous metals in the environment and the major process responsible for its toxicity is oxidative damage; its organic form methylmercury (MeHg) presents the highest toxicity. The main way of exposition to Hg is through inhalation by workers occupationally exposed in several industries and/or through consumption of fishes and other aquatic food with the metal, as Amazonian populations which are exposed to MeHg, via diet, by consumption of contaminated fishes. On the other hand, it is conceivable that antioxidants may play a protective role in the prevention of adverse effects of Hg. The flavonoid quercetin (QC) is the most abundant polyphenol of the human diet, found mainly in onions and citric fuits and the carotenoids bixin (BIX) and norbixin (NOR) are present in high concentrations in annatto, which is widely used as flavoring in Brazil. Therefore, the present study aims to evaluate the possible protective effects of the flavonoid QC and of the carotenoids BIX and NOR against the adverse effects caused by mercury chloride (HgCl2) and MeHg, in experimental models in vitro and in vivo. For this, human hepatoma cells (HepG2) cultures and male rats Wistar were exposed to several concentrations of the metal, of the phytochemicals as well as their associations. Determination of concentrations of glutathione, malondialdehyde, carbonil proteins, activity of the antioxidant enzymes catalase and glutathione-peroxidase, which reflect the redox status of the cells and monitoring of DNA-damage by use of comet assay and measurements of 8-hydroxi-2-deoxyguanosine levels were carried out in the present study. The results indicate that Hg cause clear genotoxic effects and lead to several alterations of biochemical parameters related to redox status of the cells, in vitro and in vivo. Moreover, it was observed that pythochemicals commonly found in the human diet, namely QC, BIX and NOR counteract the genetic instability induced by the metal and restore the disturbances of redox status of the cells caused by Hg exposition

Milk and Dairy Products Intake Is Associated with Low Levels of Lead (Pb) in Workers highly Exposed to the Metal

Lead (Pb) is a toxic metal, frequently associated with occupational exposure, due to its widespread use in industry and several studies have shown high Pb levels in workers occupationally exposed to the metal. The aim of this study was to evaluate the influence of milk and dairy products (MDP) on Pb levels in blood (B-Pb), plasma (P-Pb), and urine (U-Pb), in workers from automotive battery industries in Brazil. The study included 237 male workersinformation concerning diet and lifestyle were gathered through a questionnaire, and B-Pb, P-Pb, and U-Pb were determined by ICPMS. Mean B-Pb, P-Pb, and U-Pb were 21 +/- 12, 0.62 +/- 0.73 mu g/dL, and 39 +/- 47 mu g/g creatinine, respectively. Forty three percent of participants declared consuming 3portions/week of MDP (high-MDP intake). B-Pb and P-Pb were correlated with working time (r(s) = 0.21r(s) = 0.20p < 0.010). Multivariable linear regressions showed a significant influence of MDP intake on B-Pb (beta = -0.10p = 0.012) and P-Pb (beta = -0.16p < 0.010), while no significance was seen on U-Pb. Our results suggest that MDP consumption may modulate Pb levels in individuals highly exposed to the metalthese findings may be due to the Pb-Ca interactions, since the adverse effects of Pb are partially based on its interference with Ca metabolism and proper Ca supplementation may help to reduce the adverse health effects induced by Pb exposure.Sao Paulo Research Foundation (FAPESP)Coordination for the Improvement of Higher Education Personnel (CAPES)Univ Sao Paulo, Sch Pharmaceut Sci Ribeirao Preto, Dept Clin Analyses Toxicol & Food Sci, Ave Cafe S-N, BR-14040903 Ribeirao Preto, BrazilUniv Sao Paulo, Sch Med, Dept Dermatol, Ave Dr Eneas Carvalho Aguiar 470, Sao Paulo, BrazilFed Univ ABC, Ctr Nat & Human Sci, Ave Estados 5001, BR-09210580 Santo Andre, BrazilUniv Fed Sao Paulo, Inst Hlth & Soc, Dept Biosci, Rua Silva Jardim 136, BR-11015020 Santos, BrazilUniv Fed Sao Paulo, Inst Hlth & Soc, Dept Biosci, Rua Silva Jardim 136, BR-11015020 Santos, BrazilFAPESP: 2013/06033-8FAPESP: 2014/24981-3FAPESP: 2015/04786-4FAPESP: 2015/07277-3CAPESWeb of Scienc

Evaluation of the genotoxic and anti-genotoxic activities of Silybin in human hepatoma cells (HepG2)

Silybin (SB), a constituent of the medicinal plant Silybum marianum, is reported to be a potent hepatoprotective agent, but little is currently known regarding its genotoxicity, mutagenicity and potential chemopreventive properties. In this study, we evaluated the ability of SB to induce DNA migration and micronuclei (MN) formation in human hepatoma cells (HepG2). Also, possible preventive effects of SB on MN formation induced by three different mutagens, bleomycin (BLEO), benzo[a] pyrene (B[alpha] P) and aflatoxin B(1) (AFB(1)), were studied. To clarify the possible mechanism of SB antimutagenicity, three treatment protocols were applied: pretreatment, in which SB was added before the application of the mutagens; simultaneous treatment, in which SB was added during treatment and post-treatment, in which SB was added after the application of the mutagens. At concentrations up to 100 mu M, SB was non-genotoxic, while at a concentration of 200 mu M, SB induced DNA migration, generated oxidized DNA bases, reduced cell viability, decreased the replicative index of the cells and induced oxidative stress. It is noteworthy that SB was able to reduce the genotoxic effect induced by B[alpha] P, BLEO and AFB1 in pretreatment and simultaneous treatments but had no significant effect on DNA damage induction in post-treatment. Taken together, our findings indicate that SB presents anti-genotoxic activity in vitro, which suggests potential use as a chemopreventive agent.FAPESP Fundacao de Amparo a Pesquisa do Estado de Sao PauloConselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq )[304450/2003-0]FAPES

Bixin and norbixin protect against DNA-damage and alterations of redox status induced by methylmercury exposure in vivo

Populations in the Amazon are exposed to organic mercury via consumption of contaminated foods. These ethnic groups consume a specific plant seed annatto which contains certain carotenoids. The aim of this study was to find out if these compounds (bixin, BIX and norbixin, NOR), protect against DNA-damage caused by the metal. Therefore, rats were treated orally with methylmercury (MeHg) and with the carotenoids under conditions that are relevant to humans. The animals were treated either with MeHg (30 mu g/kg/bw/day), BIX (0.110 mg/kg/bw/day), NOR (0.011.0 mg/kg/bw/day) or combinations of the metal compound and the carotenoids consecutively for 45 days. Subsequently, the glutathione levels (GSH) and the activity of catalase were determined, and DNA-damage was measured in hepatocytes and leukocytes using single cell gel electrophoresis assays. Treatment with the metal alone caused a decrease in the GSH levels (35%) and induced DNA damage, which resulted in increased DNA migration after electrophoresis in liver and blood cells, whereas no effects were seen with the carotenoids alone. When BIX or NOR were given in combination with organic mercury, the intermediate and the highest concentrations of the carotenoids (1.0 and 10.0 mg/kg/bw/day BIX and 0.1 and 1.0 mg/kg/bw/day NOR) protected against DNA-damage. Furthermore, we found with both carotenoids, a moderate increase in the GSH levels in both metal-treated and untreated animals, while the activities of catalase remained unchanged. Our results indicate that consumption of BIX and NOR may protect humans against the adverse health effects caused by exposure to organic mercury. Environ. Mol. Mutagen., 2012. (c) 2012 Wiley Periodicals, Inc.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional para o Desenvolvimento Cientifico e Tecnologico (CNPq)Conselho Nacional para o Desenvolvimento Cientifico e Tecnologico (CNPq)Coordenacao de Aperfeicoamento de Pessoal de Ensino Superior (CAPES/DS)Coordenacao de Aperfeicoamento de Pessoal de Ensino Superior (CAPES/DS

Effect of Annatto on Micronuclei Induction by Direct and Indirect Mutagens in HepG2 Cells

Annatto (AN), a natural food colorant rich in carotenoids, has been reported as being an effective antioxidant, but little is known about its potential chemopreventive properties. In this Study, we evaluated the ability of AN to protect human hepatoma cells (HepG2) from micronucleus (MN) induction against three different mutagens: benzo(a)pyrene (B(a)P), doxorubicin (DXR), and methyl methanesulfonate (MMS). In an attempt to clarify the possible mechanism of anti mutagenicity of AN, three protocols of treatment were applied (pretreatment; simultaneous treatment, and post-treatment with AN following treatment with the mutagens). Also, cells exposed only to AN were assayed for cytotoxicity and mutagenicity. A dosage up to 10 mu g/ml of AN was devoid of mutagenic activity. Protective effects were seen on micronuclei induced by B(a)P and DXR using pre and simultaneous treatment, but AN had no significant effect on MN induction by MMS in any of the protocols. Our results also show that exposure of cells to concentrations of AN higher than 10 mu g/ml decreased cell viability. Taken together, our findings indicate that AN presents antimutagenic activity in vitro, but its protective effect is dependent on the mutagen and on type of treatment suggesting its potential use as a chemopreventive agent. Environ. Mol. Mutagen. 50:808-814, 2009. (C) 2009 Wiley-Liss, Inc.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq, Brazil)Fundacao de Amparo Pesquisa do estado de Sao Paulo (FAPESP

Dietary carotenoid lutein protects against DNA damage and alterations of the redox status induced by cisplatin in human derived HepG2 cells

Several epidemiological and experimental studies has been reported that lutein (LT) presents antioxidant properties. Aim of the present study was to investigate the protective effects of LT against oxidative stress and DNA damage induced by cisplatin (cDDP) in a human derived liver cell line (HepG2). Cell viability and DNA-damage was monitored by MU and comet assays. Moreover, different biochemical parameters related to redox status (glutathione, cytochrome-c and intracellular ROS) were also evaluated. A clear DNA-damage was seen with cDDP (1.0 mu M) treatment. In combination with the carotenoid, reduction of DNA damage was observed after pre- and simultaneous treatment of the cells, but not when the carotenoid was added to the cells after the exposure to cDDP. Exposure of the cells to cDDP also caused significant changes of all biochemical parameters and in co-treatment of the cells with LT, the carotenoid reverted these alterations. The results indicate that cDDP induces pronounced oxidative stress in HepG2 cells that is related to DNA damage and that the supplementation with the antioxidant LT may protect these adverse effects caused by the exposure of the cells to platinum compound, which can be a good predict for chemoprevention. (C) 2011 Elsevier Ltd. All rights reserved