RESUMO
Produced water (PW) generated by oil companies is a highly impacting waste that contains chemicals such as metals and organic and inorganic compounds. Given its polluting potential, PW requires effective treatment before being discharged into the environment. Conventional treatments have limited efficiency in removing PW toxicity, so alternative approaches must be developed and standardized. In this context, treatment with adsorbent materials like magnetized vermiculite (VMT-mag) is highlighted. This work aimed to evaluate the efficiency of treatment with VMT-mag in reducing PW toxicity to aquatic biota. For this purpose, three aquatic species (the midge Chironomus riparius, the planarian Girardia tigrina, and the crustacean Daphnia magna) were exposed to untreated PW and to PW treated with VMT-mag at laboratory conditions. The assessed endpoints included mortality, growth, emergence, and developmental time of C. riparius; mortality, locomotion, feeding, and head regeneration of G. tigrina; and intrinsic population growth rate (r) and reproductive output of D. magna. The results showed that all the species exposed to raw PW were impaired: C. riparius had delayed development, G. tigrina had reduced locomotor activity and delayed head regeneration, and D. magna had reduced reproduction and delayed intrinsic population growth rate (r). Most of the analyzed parameters showed that treatment with VMT-mag diminished PW toxicity. Therefore, using VMT-mag to treat PW may be the key to reducing the PW effects on aquatic organisms.
Assuntos
Silicatos de Alumínio , Indústria de Petróleo e Gás , Eliminação de Resíduos Líquidos , Águas Residuárias , Poluentes Químicos da Água , Animais , Silicatos de Alumínio/química , Organismos Aquáticos , Daphnia , Água/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/toxicidade , Águas Residuárias/química , Eliminação de Resíduos Líquidos/métodos , Testes de ToxicidadeRESUMO
Polybrominated diphenyl ethers (PBDE) are ubiquitous environmental pollutants. Exposure to these chemicals has been associated with developmental neurotoxicity, endocrine dysfunctions, reproductive disorders, and hepatotoxicity. The widespread use of PBDE as flame retardants has culminated in daily exposure of humans and wildlife to these contaminants and resulted in their banned use. Thus assessment of the potential effects of each PBDE congener on living organisms has become cause for concern. The aim of this study was to (1) examine the effects of decabromodiphenyl ether (BDE)-209 on different functions of HepG2 cells and (2) investigate whether this congener is involved in mitochondrial toxicity. The use of multiple methods was employed to (i) study the influence of BDE-209 on mitochondrial permeability transition (MPT) process in mitochondria isolated from rat liver and (ii) determine the consequential cellular damage. Our results showed that BDE-209 induced matrix swelling related to MPT with 10 µM and ATP depletion with 0.1 µM. In addition, 0.5 µM BDE-209 reduced HepG2 cell viability, produced collapse of membrane potential, but increased levels of reactive oxygen species (ROS) after 48 h incubation. After 24 h with 5 µM treatment elevated levels of ROS, DNA fragmentation and cytochrome c release, accompanied by caspase 9 and caspase 3 activation was noted. Taken together, these results suggest that short-duration exposure (24 or 48 h) to 0.5 µM or 5 µM BDE-209 concentrations diminished HepG2 cell viability due to apoptosis associated with mitochondrial dysfunction.
Assuntos
Poluentes Ambientais/toxicidade , Retardadores de Chama/toxicidade , Éteres Difenil Halogenados/toxicidade , Fígado/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Animais , Morte Celular/efeitos dos fármacos , Células Hep G2 , Humanos , Masculino , Mitocôndrias/fisiologia , Ratos , Ratos WistarRESUMO
Apoptotic cell death is one of the main consequences of exposure to brominated flame retardants, including polybrominated diphenyl ethers. However, few of these compounds have had their potential toxicity investigated. BDE-154 is one of the most poorly studied polybrominated diphenyl ether (PBDE) congeners, but its level in the environment and in biological fluids is rising. In addition, its chemical structure differs from the other congeners with well-documented toxicity, so BDE-154 may display a distinct toxicity pattern. This study has evaluated how BDE-154 affects the human hepatoblastoma cell line (HepG2) and has looked into the impact of this congener on human health. In addition, this study has related the effects of BDE-154 with the effects of BDE-47 to clarify the mechanism of PBDE toxicity. The HepG2 cell line was exposed to BDEs for 24 and 48 hr and submitted to assays to examine proliferation, viability, mitochondrial membrane potential, reactive oxygen species accumulation, phosphatidylserine exposure, nuclear fragmentation and evaluation of pro-caspase 3, pro-caspase 9, cytochrome c release, and apoptosis inductor factor release by Western blot analysis. BDE-154 induced mitochondrial damage and led to apoptotic death of HepG2 cells, but these effects were less intense than the effects promoted by BDE-47. Unlike other extensively reported congeners, BDE-154 was only toxic at the higher tested concentrations, whereas BDE-47 cytotoxicity was evident even at lower concentrations. Hence, like the toxicity pattern of other classes of substances such as polychlorinated biphenyls, the toxicity pattern of BDEs also depends on their chemical structure and aromatic substituent.
Assuntos
Apoptose/efeitos dos fármacos , Retardadores de Chama/toxicidade , Éteres Difenil Halogenados/toxicidade , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Bifenil Polibromatos/toxicidade , Fator de Indução de Apoptose/metabolismo , Caspase 3/metabolismo , Caspase 9/metabolismo , Citocromos c/metabolismo , Células Hep G2 , Humanos , Espécies Reativas de Oxigênio/metabolismoRESUMO
Several studies have demonstrated that a balanced diet can contribute to better human health. For this reason, soy-based food and pure isoflavones (pills) are one of the most consumed. The association of this consumption and lower risks of chronic diseases and cancer is well established for the Asian population and has been attracting the attention of people worldwide, especially women at menopause who seek to alleviate the symptoms associated with the lack of estrogen. Despite positive epidemiological data, concerns still exist because of conflicting results found in scientific literature with relation to the role of isoflavones in breast and hormone-related cancers. The aim of our study was to investigate the cytotoxicity, induction of apoptosis, and changes in apoptosis-related genes of maximal physiological serum levels of the isoflavone genistein (Gen) in MCF-7 tumoral cells and in HB4a non-tumoral cells. In addition, induction of cell cycle arrest was also investigated. Only supraphysiological levels of Gen (50 and 100 µM) were cytotoxic to these cell lines. Concentrations of 10 and 25 µM did not induce apoptosis and significant changes in expression of the studied genes. Positive results were found only in cell cycle analysis: G0/G1 delay of MCF-7 cells in both concentrations of Gen and at 25 µM in HB4a cells. It is the first study investigating effects of Gen in the HB4a cell line. Thus, despite the lack of apoptosis induction (generally found with high concentrations), Gen at physiologically relevant serum levels still exerts chemopreventive effects through the modulation of cell cycle.
Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Neoplasias da Mama/fisiopatologia , Genisteína/farmacologia , Glycine max/química , Extratos Vegetais/farmacologia , Neoplasias da Mama/tratamento farmacológico , Feminino , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Genisteína/sangue , Humanos , Células MCF-7 , Extratos Vegetais/sangue , Fase de Repouso do Ciclo Celular/efeitos dos fármacosRESUMO
The ruthenium nitrosyl complex trans-[Ru(NO)(NH(3))(4)(py)](PF(6))(3) (pyNO), a nitric oxide (NO) donor, was studied in regard to the release of NO and its impact both on isolated mitochondria and HepG2 cells. In isolated mitochondria, NO release from pyNO was concomitant with NAD(P)H oxidation and, in the 25-100 microM range, it resulted in dissipation of mitochondrial membrane potential, inhibition of state 3 respiration, ATP depletion and reactive oxygen species (ROS) generation. In the presence of Ca(2+), mitochondrial permeability transition (MPT), an unspecific membrane permeabilization involved in cell necrosis and some types of apoptosis, was elicited. As demonstrated by externalization of phosphatidylserine and activation of caspase-9 and caspase-3, pyNO (50-100 microM) induced HepG2 cell death, mainly by apoptosis. The combined action of the NO itself, the peroxynitrite yielded by NO in the presence of reactive oxygen species (ROS) and the oxidative stress generated by the NAD(P)H oxidation is proposed to be involved in cell death by pyNO, both via respiratory chain inhibition and ROS levels increase, or even via MPT, if Ca(2+) is present.
Assuntos
Mitocôndrias Hepáticas/efeitos dos fármacos , Mitocôndrias Hepáticas/metabolismo , Doadores de Óxido Nítrico/farmacologia , Óxido Nítrico/metabolismo , Compostos Organometálicos/farmacologia , Rutênio/farmacologia , Trifosfato de Adenosina/metabolismo , Análise de Variância , Animais , Apoptose/efeitos dos fármacos , Caspases/metabolismo , Linhagem Celular Tumoral , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , Dilatação Mitocondrial/efeitos dos fármacos , NADPH Oxidases/metabolismo , Oxirredução , Ratos , Espécies Reativas de Oxigênio/metabolismoRESUMO
Mitochondria are important intracellular sources and targets of reactive oxygen species (ROS), while flavonoids, a large group of secondary plant metabolites, are important antioxidants. Following our previous study on the energetics of mitochondria exposed to the flavonoids quercetin, taxifolin, catechin and galangin, the present work addressed the antioxidant activity of these compounds (1-50 micromol/L) on Fe(2+)/citrate-mediated membrane lipid peroxidation (LPO) in isolated rat liver mitochondria, running in parallel studies of their antioxidant activity in non-organelle systems. Only quercetin inhibited the respiratory chain of mitochondria and only galangin caused uncoupling. Quercetin and galangin were far more potent than taxifolin and catechin in affording protection against LPO (IC(50) = 1.23 +/- 0.27 and 2.39 +/- 0.79 micromol/L, respectively), although only quercetin was an effective scavenger of both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radicals. These results, together with the previous study, suggest that the 2,3-double bond in conjugation with the 4-oxo function in the flavonoid structure are major determinants of the antioxidant activity of flavonoids in mitochondria, the presence of an o-di-OH structure on the B-ring, as occurs in quercetin, favours this activity via superoxide scavenging, while the absence of this structural feature in galangin, favours it via a decrease in membrane fluidity and/or mitochondrial uncoupling.
Assuntos
Antioxidantes/farmacologia , Flavonoides/farmacologia , Mitocôndrias Hepáticas/efeitos dos fármacos , Animais , Transporte de Elétrons , Peroxidação de Lipídeos , Masculino , Potenciais da Membrana/efeitos dos fármacos , Mitocôndrias Hepáticas/metabolismo , Ratos , Ratos WistarRESUMO
Monocrotaline is a pyrrolizidine alkaloid present in plants of the Crotalaria species, which causes cytotoxicity and genotoxicity, including hepatotoxicity in animals and humans. It is metabolized by cytochrome P-450 in the liver to the alkylating agent dehydromonocrotaline. We evaluated the effects of monocrotaline and its metabolite on respiration, membrane potential and ATP levels in isolated rat liver mitochondria, and on respiratory chain complex I NADH oxidase activity in submitochondrial particles. Dehydromonocrotaline, but not the parent compound, showed a concentration-dependent inhibition of glutamate/malate-supported state 3 respiration (respiratory chain complex I), but did not affect succinate-supported respiration (complex II). Only dehydromonocrotaline dissipated mitochondrial membrane potential, depleted ATP, and inhibited complex I NADH oxidase activity (IC50=62.06 microM) through a non-competitive type of inhibition (K(I)=8.1 microM). Therefore, dehydromonocrotaline is an inhibitor of the activity of respiratory chain complex I NADH oxidase, an action potentially accounting for the well-documented monocrotaline's hepatotoxicity to animals and humans. The mechanism probably involves change of the complex I conformation resulting from modification of cysteine thiol groups by the metabolite.
Assuntos
Alquilantes/farmacologia , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Complexo I de Transporte de Elétrons/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Mitocôndrias Hepáticas/efeitos dos fármacos , Monocrotalina/análogos & derivados , Trifosfato de Adenosina/metabolismo , Animais , Doença Hepática Induzida por Substâncias e Drogas/enzimologia , Relação Dose-Resposta a Droga , Complexo I de Transporte de Elétrons/antagonistas & inibidores , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias Hepáticas/enzimologia , Monocrotalina/farmacologia , Complexos Multienzimáticos/metabolismo , NADH NADPH Oxirredutases/metabolismo , Consumo de Oxigênio/efeitos dos fármacos , Ratos , Ratos Wistar , Partículas Submitocôndricas/efeitos dos fármacos , Partículas Submitocôndricas/enzimologiaRESUMO
We previously reported that the nonsteroidal anti-inflammatory drug, nimesulide (N-[4-nitro-2-phenoxyphenyl]-methanesulfonamide), is an uncoupler and oxidizes NAD(P)H in isolated rat liver mitochondria, triggering mitochondrial Ca2+ efflux or, if this effect is inhibited, eliciting mitochondrial permeability transition (Mingatto et al., Br. J. Pharmacol. 131:1154-1160, 2000). We presently demonstrated that nimesulide's hydroxylated metabolite (4-hydroxy nimesulide) lacks the uncoupling property of the parent drug, while keeping its ability to oxidize mitochondrial NADPH. In the presence of 10 microM Ca2+, low (5-50 microM) concentrations of 4-hydroxy nimesulide elicited mitochondrial permeability transition, as assessed by cyclosporin A-sensitive mitochondrial swelling, associated with mitochondrial Ca2+ efflux/membrane potential dissipation (Deltapsi), apparently occurring on account of the oxidation of mitochondrial protein thiols; no involvement of reactive oxygen species was observed. While nimesulide (0.5 or 1 mM, 30 h incubation) did not lead to significant HepG2 cell death, 4-hydroxy nimesulide caused a low extent (approximately 15%) of cell necrosis, partly prevented by cyclosporine A, suggesting the involvement of mitochondrial permeability transition. Both nimesulide and 4-hydroxy nimesulide caused NADPH oxidation and Deltapsi dissipation in HepG2 cells. Because such Deltapsi dissipation induced by the metabolite was almost completely inhibited by cyclosporine A, it probably results from the mitochondrial permeability transition. Therefore, mitochondrial permeability transition, in apparent association with NADPH oxidation, constitutes the most probable cause of HepG2 cell death elicited by 4-hydroxy nimesulide.
Assuntos
Mitocôndrias Hepáticas/efeitos dos fármacos , Sulfonamidas/farmacologia , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Glutationa/metabolismo , Dissulfeto de Glutationa/metabolismo , Humanos , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias Hepáticas/fisiologia , NADP/metabolismo , Oxirredução , Permeabilidade/efeitos dos fármacos , Ratos , Ratos Wistar , Compostos de Sulfidrila/metabolismoRESUMO
The isocoumarins (1-50 microM) paepalantine (9,10-dihydroxy-5,7-dimethoxy-1H-naptho(2,3c)pyran-1-one), 8,8'-paepalantine dimer, and vioxanthin isolated from Paepalanthus bromelioides, were assessed for antioxidant activity using isolated rat liver mitochondria and non-mitochondrial systems, and compared with the flavonoid quercetin. The paepalantine and paepalantine dimers, but not vioxanthin, were effective at scavenging both 1,1-diphenyl-2-picrylhydrazyl (DPPH(*)) and superoxide (O(2)(-)) radicals in non-mitochondrial systems, and protected mitochondria from tert-butylhydroperoxide-induced H(2)O(2) accumulation and Fe(2+)-citrate-mediated mitochondrial membrane lipid peroxidation, with almost the same potency as quercetin. These results point towards paepalantine, followed by paepalantine dimer, as being a powerful agent affording protection, apparently via O(2)(-) scavenging, from oxidative stress conditions imposed on mitochondria, the main intracellular source and target of those reactive oxygen species. This strong antioxidant action of paepalantine was reproduced in HepG2 cells exposed to oxidative stress condition induced by H(2)O(2).