RESUMO
BACKGROUND: Tetrabromobisphenol (TBBPA), a flame retardant compound, is considered a ubiquitous pollutant, with potential impact on the environment and human health. Several technologies have been applied to accelerate its degradation and minimize environmental impacts. Due to its aromaticity character, peroxidase enzymes may be employed to carry out its transformation in mild conditions. Therefore, the purpose of this work was to determine the capacity of the enzyme chloroperoxidase (CPO) to oxidize TBBPA in several water samples. METHODS: The oxidation capacity of CPO was evaluated in catalytic conditions using water samples from surface and groundwater, as well as effluents from wastewater treatment plants. The biocatalytic performance of CPO was improved due to its immobilization on nanofibers composed of polyvinyl alcohol and chitosan (PVA/chitosan). RESULTS: Free and immobilized CPO were able to transform more than 80% in short reaction times (60 min); producing more biodegradable and less toxic products. Particularly, the immobilized enzyme was catalytically active in a wider range of pH than the free enzyme with the possibility of reusing it up to five times. CONCLUSIONS: The biocatalytic oxidation of TBBPA under environmental conditions is highly efficient, even in complex media such as treated effluents of wastewater treatment plants.
Assuntos
Cloreto Peroxidase/química , Enzimas Imobilizadas/química , Retardadores de Chama , Nanofibras/química , Bifenil Polibromatos/química , Poluentes Ambientais/química , Oxirredução , Águas ResiduáriasRESUMO
Molecularly imprinted polymers (MIPs) were synthesized and used as sorbent for Bisphenol A (BPA) pipette tip solid-phase microextraction from urine samples and BPA analysis by gas chromatography coupled to mass spectrometry (GC-MS). The MIPs were synthesized by the sol-gel methodology. Aminopropyltriethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) were used as functional monomer and cross-linking reagent, respectively. BPA and tetrabromobisphenol A (TBBPA) were evaluated as template during MIP synthesis. The BPA-based MIP displayed slightly higher extraction efficiency than the TBBPA-based dummy molecularly imprinted polymer (DMIP), but the TBBPA-based DMIP was selected as sorbent to minimize interference from leaked template. Comparison of the TBBPA-based DMIP, BPA-based MIP, and non-imprinted polymer (NIP) extraction efficiencies attested that the TBBPA-based DMIP was selective. The synthesized polymers were characterized by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared spectroscopy (FTIR). The TBBPA-based DMIP was reused for over 100 times, which confirmed its robustness. The developed method was linear from 50 to 500ngmL-1. Precision values had coefficient of variation (CV) ranging from 4 to 14%. The accuracy relative standard deviation values (RSD) varied from -13.6 to 12.3%.
Assuntos
Compostos Benzidrílicos/urina , Cromatografia Gasosa-Espectrometria de Massas/métodos , Impressão Molecular/métodos , Fenóis/urina , Extração em Fase Sólida/métodos , Humanos , Limite de Detecção , Modelos Lineares , Bifenil Polibromatos/química , Propilaminas/química , Reprodutibilidade dos Testes , Silanos/químicaRESUMO
Indiscriminate use of synthetic substances has led to environmental contamination and increasing human and animal exposure to harmful chemicals. Polybrominated flame retardants (PBDEs), which serve as non-covalent additives that enhance the safety of a variety of commercial and consumer goods, are an important class among potentially damaging synthetic substances. Its use is very common in developing countries, including Brazil. In theory, 209 different PBDE congeners exist, and many are currently being used during the manufacture of several products. Unfortunately, PBDEs are easily released from the original products, promptly reaching the environment. Knowledge about the toxicological power of these substances is still limited, which has prevented environmental and regulatory authorities from conducting adequate risk assessments. This research addresses the genotoxic and mutagenic potential of PBDEs. The effects of HepG2 cells and Salmonella typhimurium exposure to six main representatives of PBDEs, namely tetrabromodiphenyl ether (BDE-47), pentabromodiphenyl ether (BDE-99 and BDE-100), hexabromodiphenyl ether (BDE-153 and BDE-154) and decabromodiphenyl ether (BDE-209), were evaluated. The comet assay revealed that all the assessed BDEs exerted genotoxic effects but induced no micronuclei formation in HepG2 cells. These BDEs had no significant mutagenic effects on the Salmonella typhimurium strains TA98 and TA100. Taken together, the results of the genomic instability assays showed that PBDEs can represent a risk to the health of directly and indirectly exposed population, because the assessed BDEs induce genotoxic effects in the HepG2 cell line.
Assuntos
Poluentes Ambientais/toxicidade , Retardadores de Chama/toxicidade , Éteres Difenil Halogenados/toxicidade , Mutagênicos/toxicidade , Ensaio Cometa , Poluentes Ambientais/química , Éteres Difenil Halogenados/química , Células Hep G2 , Humanos , Isomerismo , Testes para Micronúcleos , Peso Molecular , Testes de Mutagenicidade , Mutagênicos/química , Concentração Osmolar , Bifenil Polibromatos/química , Bifenil Polibromatos/toxicidade , Salmonella typhimurium/efeitos dos fármacos , Solubilidade , Temperatura de TransiçãoRESUMO
Brominated flame retardants are used in various consumer products to increase their resistance to fire and/or high temperatures. Polybrominated diphenyl ethers (PBDEs) are representatives of this class and among the most widely used congeners, and BDE-100 is produced on a large scale. There is a lack of toxicological data about these compounds, which has recently become a matter of concern to the scientific community. The mitochondria are recognized as the main energy-producing organelles, as well as playing a vital role in the maintenance of many cell functions. Therefore, mitochondria were used in the present work as an experimental model to evaluate the effects of the BDE-100 congeners at concentrations ranging from 0.1 µM to 50 µM. The results showed that high concentrations of BDE-100 were able to induce mitochondrial alterations. It was observed that the substance had an affinity for the hydrophilic portion of the mitochondrial membrane, as monitored by ANS, inhibiting the glutamate + malate-stimulated mitochondrial respiration and also inducing dissipation of the mitochondrial membrane potential, deregulation of calcium homoeostasis and mitochondrial swelling, the latter being insensitive to cyclosporin A (CsA) but partially inhibited by Ruthenium Red and N-ethyl maleimide. In addition, a significant reduction in mitochondrial ATP content was found, but on the other hand, no oxidative stress was observed after exposure of the mitochondria to BDE-100. These results show the key role of mitochondria in the cytotoxicity induced by BDE-100.
Assuntos
Retardadores de Chama/toxicidade , Mitocôndrias Hepáticas/efeitos dos fármacos , Bifenil Polibromatos/toxicidade , Trifosfato de Adenosina/biossíntese , Animais , Cálcio/metabolismo , Relação Dose-Resposta a Droga , Técnicas In Vitro , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias Hepáticas/metabolismo , Dilatação Mitocondrial/efeitos dos fármacos , Estrutura Molecular , Estresse Oxidativo/efeitos dos fármacos , Bifenil Polibromatos/química , Ratos , Ratos WistarRESUMO
A novel and efficient analytical methodology is proposed for extracting and preconcentrating polybrominated diphenyl ethers (PBDEs) from samples of environmental interest prior gas chromatography-mass spectrometry (GC-MS) analysis. It is based on the induction of micellar organized medium by using a non-ionic surfactant (Triton X-114) to extract the target PBDEs. To enable coupling the efficient extracting technique with GC analysis, ultrasound-assisted back-extraction (UABE) into an organic solvent was required. Several factors, including surfactant type and concentration, equilibration temperature and time, ionic strength, pH and buffers nature and concentration were studied and optimized over the extraction efficiency of the proposed technique. Under optimal experimental conditions, the target analytes were quantitatively extracted achieving an enrichment factor of 250 when 10mL aliquot of ultrapure water spiked with PBDE-standard mixture (10pgmL(-1) each PBDE) was extracted. Method detection limits (MDLs) calculated with aqueous PBDEs solutions as three times the signal-to-noise ratio (S/N), ranged from 1 to 2pgmL(-1) with RSDs values /=0.9987 and linear range of all PBDEs was 4-150pgmL(-1). The proposed methodology was validated by carrying out a recovery study by spiking the samples at two different concentration levels of PBDEs (10 and 50pgmL(-1) for waters samples). Recoveries values in the range of 96-106% for water samples were obtained showing satisfactory robustness of the method for analyzing PBDEs in water samples. The proposed methodology was applied for the analysis of PBDEs: 2,2',4,4'-tetraBDE (BDE-47), 2,2',4,4,5-pentaBDE (BDE-99), 2,2',4,4,6-pentaBDE (BDE-100) and 2,2,4,4',5,5'-hexaBDE (BDE-153) in water samples, including drinking, lake, river water and soil samples. Significant quantities of PBDEs were not found in the analyzed samples.