Natália Brucker

Biomarkers of occupational exposure to air pollution, inflammation and oxidative damage in taxi drivers

Exposure to environmental pollutants has been recognised as a risk factor for cardiovascular events. 1-hydroxypyrene (1-OHP) is a biomarker of exposure to polycyclic aromatic hydrocarbons (PAHs) from traffic-related air pollution. Experimental studies indicate that PAH exposure could be associated with inflammation and atherogenesis. Thus, the purpose of this study was to evaluate whether the biomarker of PAH exposure is associated with biomarkers of inflammation and oxidative stress and if these effects modulate the risk of developing cardiovascular diseases in workers exposed to air pollution. This study included 60 subjects, comprising 39 taxi drivers and 21 non-occupationally exposed persons. Environmental PM2.5 and benzo[a]pyrene (BaP) levels, in addition to biomarkers of exposure and oxidative damage, were determined. Inflammatory cytokines (IL-1β, IL-6, IL-10, TNF-α, IFN-γ and hs-CRP) and serum levels of oxidised LDL (ox-LDL), auto-antibodies (ox-LDL-Ab) and homocysteine (Hcy) were also evaluated. PM2.5 and BaP exhibited averages of 12.4±6.9 μg m(-3) and 1.0±0.6 ng m(-3), respectively. Urinary 1-OHP levels were increased in taxi drivers compared to the non-occupationally exposed subjects (p<0.05) and were positively correlated with pro-inflammatory cytokines and negatively correlated with antioxidants. Furthermore, taxi drivers had elevated pro-inflammatory cytokines, biomarkers of oxidative damage, and ox-LDL, ox-LDL-Ab and Hcy levels, although antioxidant enzymes were decreased compared to the non-occupationally exposed subjects (p<0.05). In summary, our findings indicate that taxi drivers showed major exposure to pollutants, such as PAHs, in relation to non-occupationally exposed subjects. This finding was associated with higher inflammatory biomarkers and Hcy, which represent important predictors for cardiovascular events. These data suggest a contribution of PAHs to cardiovascular diseases upon occupational exposure.

Effects of low-level exposure to xenobiotics present in paints on oxidative stress in workers

Paints are composed of an extensive variety of hazardous substances, such as organic solvents and heavy metals. Biomonitoring is an essential tool for assessing the risk to occupational health. Thus, this study analyzed the levels of biomarkers of exposure for toluene, xylene, styrene, ethylbenzene, and lead, as well as the oxidative stress biomarker alterations in painters of an industry. Lipid peroxidation biomarker (MDA), delta-aminolevulinate dehydratase (ALA-D), nonprotein thyol groups, superoxide dismutase and catalase (CAT) were analyzed in exposed and nonexposed subjects. We estimated which of the paint constituents have the greatest influence on the changes in the biomarkers of oxidative stress in this case of co-exposure. The results demonstrated that despite the fact that all the biomarkers of exposure were below the biological exposure limits, the MDA levels and antioxidant enzyme activities were increased, while nonprotein thyol groups and ALA-D levels were decreased in painters when compared with nonexposed subjects. After statistic test, toluene could be suggested as the principal factor responsible for increased lipid peroxidation and inhibition of ALA-D enzyme; however, further studies on the inhibition of ALA-D enzyme by toluene are necessary.

Evaluation of genotoxicity and oxidative damage in painters exposed to low levels of toluene

Toluene is an organic solvent used in numerous processes and products, including industrial paints. Toluene neurotoxicity and reproductive toxicity are well recognized; however, its genotoxicity is still under discussion, and toluene is not classified as a carcinogenic solvent. Using the comet assay and the micronucleus test for detection of possible genotoxic effects of toluene, we monitored industrial painters from Rio Grande do Sul, Brazil. The putative involvement of oxidative stress in genetic damage and the influences of age, smoking, alcohol consumption, and exposure time were also assessed. Although all biomarkers of toluene exposure were below the biological exposure limits, painters presented significantly higher DNA damage (comet assay) than the control group; however, in the micronucleus assay, no significant difference was observed. Painters also showed alterations in hepatic enzymes and albumin levels, as well as oxidative damage, suggesting the involvement of oxidative stress. According to multiple linear regression analysis, blood toluene levels may account for the increased DNA damage in painters. In summary, this study showed that low levels of toluene exposure can cause genetic damage, and this is related to oxidative stress, age, and time of exposure.

Genotoxicity and oxidative stress in gasoline station attendants

We evaluated genotoxic effects of exposure to low levels of benzene, a class I human carcinogen, among gasoline station attendants (GSA). Oxidative stress and the protective effects of antioxidants on DNA damage were also analyzed. Although exposures were below ACGIH (American Conference of Governmental Industrial Hygienists) limits, the GSA group presented higher DNA damage indices and micronucleus frequencies, increased oxidative protein damage, and decreased antioxidant capacity relative to the control group. Duration of benzene exposure was correlated with DNA and protein damage. The biomarkers evaluated in this work may provide early signals of damage in subjects occupationally exposed to benzene.

N-acetylcysteine on oxidative damage in diabetic rats.

N-acetylcysteine (NAC) is a potent mucolitic agent and also an antioxidant. Its antioxidant action is due to its ability to stimulate reduced glutathione (GSH) synthesis, therefore maintaining intracellular levels. The aim of this study was to evaluate the effects of NAC administered intraperitoneally (i.p.) in a decreasing of oxidative tissue damage in the liver and kidney of alloxan-induced diabetic rats, especially on thiolic groups (nonproteic and proteic groups). Adult male Wistar rats (200–350 g) were used; diabetes was induced accordingly by a single i.p. injection of alloxan monohydrate, and the control group received a similar volume of the vehicle. Lipid peroxidation (LPO) biomarker (malondialdehyde; MDA), δ-ALA-D activity, GSH, superoxide dismutase (SOD), and glutathione peroxidase (GPx) were quantified to assess the oxidative stress. All tests were performed in tissue homogenates. Creatinine, urea, aspartate transaminase, and alanine transaminase were determined by commercial kits, using serum samples. A significant decrease in LPO (i.e., hepatic and renal) and an increase in δ-aminolevulinate dehydratase activity, especially in the renal tissue, were observed. Also, NAC at 75 mg/kg showed more effective restoration of oxidative stress biomarkers than NAC at 25 mg/kg. Our findings suggest that NAC can be used as an antioxidant agent in diabetes, exhibiting modulatory action on the oxidative stress biomarkers analyzed in this work. Moreover, these findings can contribute to others’ research, regarding the utilization of NAC to ALA-D activity restoration in the kidneys.

The relationships between exogenous and endogenous antioxidants with the lipid profile and oxidative damage in hemodialysis patients

BackgroundWe sought to investigate the relationships among the plasma levels of carotenoids, tocopherols, endogenous antioxidants, oxidative damage and lipid profiles and their possible effects on the cardiovascular risk associated with hemodialysis (HD) patients.MethodsThe study groups were divided into HD and healthy subjects. Plasma carotenoid, tocopherol and malondialdehyde (MDA) levels, as well as erythrocyte reduced glutathione (GSH), were measured by HPLC. Blood antioxidant enzymes, kidney function biomarkers and the lipid profiles were analyzed by spectrophotometric methods.ResultsPlasma lycopene levels and blood glutathione peroxidase (GPx) activity were significantly decreased in HD patients compared with healthy subjects. Total cholesterol, low-density lipoprotein cholesterol (LDL-c), creatinine, urea, MDA, GSH, superoxide dismutase (SOD) and catalase (CAT) were significantly increased in HD (p < 0.05). Lycopene levels were correlated with MDA (r = -0.50; p < 0.01), LDL-c (r = -0.38; p = 0.01) levels, the LDL-c/HDL-c index (r = -0.33; p = 0.03) and GPx activity (r = 0.30; p = 0.03). Regression models showed that lycopene levels were correlated with LDL-c (β estimated = -31.59; p = 0.04), while gender was correlated with the TC/HDL-c index and triglycerides. Age did not present a correlation with the parameters evaluated. GPx activity was negatively correlated with MDA levels and with the LDL-c/HDL-c and CT/HDL-c indexes.ConclusionsLycopene may represent an additional factor that contributes to reduced lipid peroxidation and atherogenesis in hemodialysis patients.

Evaluation of genotoxicity in workers exposed to benzene and atmospheric pollutants.

Gas station attendants and taxi drivers are occupationally exposed to xenobiotics which may be harmful to their health. Atmospheric pollutants and benzene can lead to DNA damage. Genotoxicity and mutagenicity assays can be used to evaluate the effects of these pollutants. We have evaluated genotoxicity and mutagenicity in workers occupationally exposed to xenobiotics, by application of the 8-hydroxy-2-deoxyguanosine (8-OHdG), comet, and micronucleus (MN) assays. Biomarkers of benzene and carbon monoxyde exposure were also measured: urinary t,t-muconic acid (t,t-MA) and carboxyhaemoglobin (COHb) in whole blood, respectively. The study groups comprised 43 gas station attendants (GSA), 34 taxi drivers (TD), and 22 persons without known occupational exposures (NE). Levels of t,t-MA in the GSA group were significantly elevated compared to the NE group (p<0.001), however these levels were below of levels established by ACGIH (American Conference of Governmental Industrial Hygienists). COHb levels were not significantly different between the TD and NE groups (p>0.05). DNA damage index (DI) and 8-OHdG levels were significantly higher for both the GSA and TD groups, compared to the NE group (p<0.001), but MN frequencies were not elevated. Spearman correlation analysis showed that the frequency of MN was positively correlated with 8-OHdG. A positive correlation between DNA DI levels and 8-OHdG was also observed. In conclusion, our results indicated that low levels of occupational exposure to benzene and atmospheric pollutants may be linked to genotoxicity and oxidative DNA damage.

Relationship between Inflammation and Oxidative Stress and Cognitive Decline in the Institutionalized Elderly

Objective. Cognitive impairment reduces quality of life and is related to vascular and neurodegenerative disorders. However, there is also a close relationship between these diseases and oxidative stress. Thus, the purpose of this study was to assess whether inflammation and oxidative damage are associated with low cognitive performance in the elderly with different housing conditions. Methods. The study groups consisted of 32 institutionalized and 25 noninstitutionalized Brazilian elderly subjects. Oxidative damage, inflammation markers, and cognitive function were evaluated. Results. The results demonstrated pronounced oxidative stress in the institutionalized elderly group, which also had a lower antioxidant status compared to noninstitutionalized subjects. High levels of proinflammatory cytokines were also observed in the institutionalized elderly. Furthermore, the raised levels of inflammatory markers were correlated with increased oxidative stress, and both were associated with low cognitive performance. However, based on multiple linear regression analysis, oxidative stress appears to be the main factor responsible for the cognitive decline. Conclusions. The findings suggest that individuals with lower antioxidant status are more vulnerable to oxidative stress, which is associated with cognitive function, leading to reduced life quality and expectancy.

Caenorhabditis elegans as an alternative in vivo model to determine oral uptake, nanotoxicity, and efficacy of melatonin-loaded lipid-core nanocapsules on paraquat damage

Caenorhabditis elegans is an alternative in vivo model that is being successfully used to assess the pharmacological and toxic effects of drugs. The exponential growth of nanotechnology requires the use of alternative in vivo models to assess the toxic effects of theses nanomaterials. The use of polymeric nanocapsules has shown promising results for drug delivery. Moreover, these formulations have not been used in cases of intoxication, such as in treatment of paraquat (PQ) poisoning. Thus, the use of drugs with properties improved by nanotechnology is a promising approach to overcome the toxic effects of PQ. This research aimed to evaluate the absorption of rhodamine B-labeled melatonin (Mel)-loaded lipid-core nanocapsules (LNC) by C. elegans, the application of this model in nanotoxicology, and the protection of Mel-LNC against PQ damage. The formulations were prepared by self-assembly and characterized by particle sizing, zeta potential, drug content, and encapsulation efficiency. The results demonstrated that the formulations had narrow size distributions. Rhodamine B-labeled Mel-LNC were orally absorbed and distributed in the worms. The toxicity assessment of LNC showed a lethal dose 50% near the highest dose tested, indicating low toxicity of the nanocapsules. Moreover, pretreatment with Mel-LNC significantly increased the survival rate, reduced the reactive oxygen species, and maintained the development in C. elegans exposed to PQ compared to those worms that were either untreated or pretreated with free Mel. These results demonstrated for the first time the uptake and distribution of Mel-LNC by a nematode, and indicate that while LNC is not toxic, Mel-LNC prevents the effects of PQ poisoning. Thus, C. elegans may be an interesting alternative model to test the nanocapsules toxicity and efficacy.

New insights into the chemistry and antioxidant activity of coumarins.

Coumarins are considered to be privileged structures due to their broad range of biological properties, including anticoagulant, anti-neurodegenerative, antioxidant, anticancer and antimicrobial activities. These interesting properties of coumarins can be ascribed to the chemical attributes of the 2H-chromen-2-one core; its aromatic ring can establish a series of hydrophobic, π-π, CH-π and cation-π interactions, and the two oxygen atoms in the lactone ring may hydrogen-bond to a series of amino acid residues in different classes of enzymes and receptors. Additionally, the double bond in the lactone helps to make the entire system planar, allows charge delocalization between the carbonyl group of the lactone and the aromatic ring and confers the characteristic fluorescence of this class of compounds, which can be explained by their preventing the trans-cis transformation of the double bond under ultraviolet (UV) irradiation. It is the possibility of radical delocalization in the 2H-chromen-2-one nucleus that makes most of the coumarins good antioxidants by acting as free radical scavengers, although some coumarins (mainly hydroxycoumarins) may also prevent the formation of free radicals by chelating metal ions. In this review, we provide a systematic analysis of the most important aspects surrounding the development of coumarins as antioxidants. Our analysis includes the synthesis of some complex antioxidant coumarins, strategies for structural modification to improve their antioxidant activities, qualitative/ quantitative structure-antioxidant relationships studies and the main in vitro assays used to evaluate their antioxidant properties.