RESUMO
Reactive oxygen species (ROS) are important mediators in a number of neurodegenerative diseases and molecules capable of scavenging ROS may be a feasible strategy for protecting neuronal cells. We previously demonstrated a powerful iron-chelating action of Guttiferone-A (GA), a naturally occurring polyphenol, on oxidative stress injuries initiated by iron overload. Here we addressed the neuroprotective potential of GA in hydrogen peroxide and glutamate-induced injury on rat's primary culture of cortical neurons and PC12 cells, respectively, and antioxidant properties concerning scavenging and anti-lipoperoxidative activities in cell-free models. The decrease in cell viability induced by each of the toxins, assessed by [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] (MTT) assay, was significantly attenuated by GA. In addition, GA was found to be a potent antioxidant, as shown by (i) inhibition of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical reduction (EC50=20.0 µM), (ii) prevention against chemically or electrochemically generated superoxide radicals, (iii) inhibition of spontaneous brain lipid peroxidation and (iv) interference with the Fenton reaction. These results indicate that GA exerts neuroprotective effects against H2O2 or glutamate toxicity and its antioxidant activity, demonstrated in vitro, could be at least partly involved. They also suggest a promising potential for GA as a therapeutic agent against neurodegenerative diseases involving ROS and oxidative damage.
Assuntos
Benzofenonas/farmacologia , Sequestradores de Radicais Livres , Fármacos Neuroprotetores , Animais , Compostos de Bifenilo/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Córtex Cerebral/citologia , Córtex Cerebral/efeitos dos fármacos , Corantes , Eletroquímica , Frutas/química , Garcinia/química , Ácido Glutâmico/toxicidade , Humanos , Peróxido de Hidrogênio , Ferro , Peroxidação de Lipídeos/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Células PC12 , Picratos/metabolismo , Prenilação , Ratos , Espécies Reativas de Oxigênio/metabolismo , Sais de Tetrazólio , TiazóisRESUMO
The vitamin E derivative (+)α-tocopheryl succinate (α-TOS) exerts pro-apoptotic effects in a wide range of tumors and is well tolerated by normal tissues. Previous studies point to a mitochondrial involvement in the action mechanism; however, the early steps have not been fully elucidated. In a model of acute promyelocytic leukemia (APL) derived from hCG-PML-RARα transgenic mice, we demonstrated that α-TOS is as effective as arsenic trioxide or all-trans retinoic acid, the current gold standards of therapy. We also demonstrated that α-TOS induces an early dissipation of the mitochondrial membrane potential in APL cells and studies with isolated mitochondria revealed that this action may result from the inhibition of mitochondrial respiratory chain complex I. Moreover, α-TOS promoted accumulation of reactive oxygen species hours before mitochondrial cytochrome c release and caspases activation. Therefore, an in vivo antileukemic action and a novel mitochondrial target were revealed for α-TOS, as well as mitochondrial respiratory complex I was highlighted as potential target for anticancer therapy.
Assuntos
Arsenicais/uso terapêutico , Complexo I de Transporte de Elétrons/antagonistas & inibidores , Leucemia Promielocítica Aguda/tratamento farmacológico , Mitocôndrias/efeitos dos fármacos , Óxidos/uso terapêutico , Tretinoína/uso terapêutico , alfa-Tocoferol/farmacologia , alfa-Tocoferol/uso terapêutico , Animais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Apoptose/efeitos dos fármacos , Trióxido de Arsênio , Caspases/metabolismo , Linhagem Celular Tumoral , Citocromos c/metabolismo , Modelos Animais de Doenças , Complexo II de Transporte de Elétrons/antagonistas & inibidores , Humanos , Leucemia Promielocítica Aguda/mortalidade , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos , Camundongos Transgênicos , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/metabolismo , Proteínas de Fusão Oncogênica/metabolismo , Estabilidade Proteica/efeitos dos fármacos , Ratos , Espécies Reativas de Oxigênio/metabolismo , Transplante IsogênicoRESUMO
Cisplatin is a highly effective chemotherapeutic agent which causes severe nephrotoxicity. Studies have suggested that reactive oxygen species, mainly generated in mitochondria, play a central role in cisplatin-induced renal damage. A wide range of antioxidants have been evaluated as possible protective agents against cisplatin-induced nephrotoxicity; however a safe and efficacious compound has not yet been found. The present study is the first to evaluate the protective potential of carvedilol, a beta-blocker with strong antioxidant properties, against the mitochondrial oxidative stress and apoptosis in kidney of rats treated with cisplatin. The following cisplatin-induced toxic effects were prevented by carvedilol: increased plasmatic levels of creatinine and blood urea nitrogen (BUN); lipid peroxidation, oxidation of cardiolipin; oxidation of protein sulfhydryls; depletion of the non-enzymatic antioxidant defense and increased activity of caspase-3. Carvedilol per se did not present any effect on renal mitochondria. It was concluded that carvedilol prevents mitochondrial dysfunction and renal cell death through the protection against the oxidative stress and redox state unbalance induced by cisplatin. The association of carvedilol to cisplatin chemotherapy was suggested as a possible strategy to minimize the nephrotoxicity induced by this antitumor agent.
Assuntos
Carbazóis/farmacologia , Cisplatino/toxicidade , Nefropatias/induzido quimicamente , Nefropatias/metabolismo , Mitocôndrias/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Propanolaminas/farmacologia , Animais , Antineoplásicos/toxicidade , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Nitrogênio da Ureia Sanguínea , Carvedilol , Creatinina/sangue , Interações Medicamentosas , Humanos , Malondialdeído/metabolismo , Mitocôndrias/metabolismo , Oxirredução , Ratos , Ratos Wistar , Estatísticas não ParamétricasRESUMO
The clinical use of cisplatin is highly limited by its nephrotoxicity, which has been associated with mitochondrial dysfunction. We investigated the protective effect of carvedilol, an antihypertensive with strong antioxidant properties, against the nephrotoxicity induced by cisplatin in rats. Carvedilol was able to counteract the renal damage by preventing the mitochondrial dysfunction induced by cisplatin. The mitochondrial eletrochemical potential, calcium uptake, respiration and the phosphorylative capacity were preserved by the co-administration of carvedilol. The mechanism of protection probably does not involve alterations in the cellular and sub-cellular distribution of cisplatin. The study suggests that carvedilol is a potential drug for the adjuvant nephroprotective therapy during cisplatin chemotherapy.
Assuntos
Antineoplásicos/toxicidade , Antioxidantes/farmacologia , Carbazóis/farmacologia , Cisplatino/toxicidade , Nefropatias/prevenção & controle , Mitocôndrias/efeitos dos fármacos , Propanolaminas/farmacologia , Animais , Anti-Hipertensivos/administração & dosagem , Anti-Hipertensivos/farmacologia , Antineoplásicos/administração & dosagem , Antioxidantes/administração & dosagem , Cálcio/metabolismo , Carbazóis/administração & dosagem , Carvedilol , Cisplatino/administração & dosagem , Rim/efeitos dos fármacos , Rim/metabolismo , Rim/ultraestrutura , Nefropatias/induzido quimicamente , Nefropatias/metabolismo , Masculino , Potenciais da Membrana/efeitos dos fármacos , Mitocôndrias/metabolismo , Consumo de Oxigênio/efeitos dos fármacos , Propanolaminas/administração & dosagem , Ratos , Ratos WistarRESUMO
One hypothesis for the etiology of cell damage arising from iron overload is that its excess selectively affects mitochondria. Here we tested the effects of acute iron overload on liver mitochondria isolated from rats subjected to a single dose of i.p. 500 mg/kg iron-dextran. The treatment increased the levels of iron in mitochondria (from 21 +/- 4 to 130 +/- 7 nmol/mg protein) and caused both lipid peroxidation and glutathione oxidation. The mitochondria of iron-treated rats showed lower respiratory control ratio in association with higher resting respiration. The mitochondrial uncoupling elicited by iron-treatment did not affect the phosphorylation efficiency or the ATP levels, suggesting that uncoupling is a mitochondrial protective mechanism against acute iron overload. Therefore, the reactive oxygen species (ROS)/H+ leak couple, functioning as a mitochondrial redox homeostatic mechanism could play a protective role in the acutely iron-loaded mitochondria.
Assuntos
Sobrecarga de Ferro/fisiopatologia , Complexo Ferro-Dextran/toxicidade , Mitocôndrias Hepáticas/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Trifosfato de Adenosina/metabolismo , Animais , Glutationa/efeitos dos fármacos , Glutationa/metabolismo , Injeções Intraperitoneais , Sobrecarga de Ferro/induzido quimicamente , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Mitocôndrias Hepáticas/metabolismo , Oxirredução/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismoRESUMO
The use of the classic aromatic antiepileptic drugs (AAEDs) has recently been expanded to a broad spectrum of psychiatric and neurological disorders. However, the clinical use of these drugs is limited by several adverse effects, mainly idiosyncratic hepatotoxicity. AAED-induced hepatotoxicity has been attributed to a defective detoxification by the epoxide hydrolase and accumulation of arene oxides. The underlying mechanism has been proposed as immune-mediated, but direct toxicity has also been suggested. In general, idiosyncratic drug-induced hepatotoxicity may be mediated, at least in part, by oxidative stress. On the other hand, the oxidative stress induced by the AAED metabolites has not been demonstrated yet. Therefore, in the present study we have evaluated the induction of oxidative stress by three classical AAEDs: carbamazepine, phenytoin and phenobarbital as well as by their metabolites. The toxic effects of the metabolites were evaluated by incubating the drug with rat liver microsomes. The AAED-induced oxidative stress was demonstrated by the increased malondialdehyde levels, oxidation of cardiolipin; oxidation of sulfhydryl proteins and alteration of the cellular redox status. Results suggest that the hepatotoxicity associated with AAED might be mediated by the oxidative stress induced by the drugs metabolites.
Assuntos
Anticonvulsivantes/toxicidade , Fígado/efeitos dos fármacos , Microssomos Hepáticos/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Animais , Anticonvulsivantes/metabolismo , Carbamazepina/metabolismo , Carbamazepina/toxicidade , Cardiolipinas/efeitos dos fármacos , Cardiolipinas/metabolismo , Masculino , Malondialdeído/metabolismo , Microssomos Hepáticos/metabolismo , Mitocôndrias Hepáticas/efeitos dos fármacos , Oxirredução/efeitos dos fármacos , Fenobarbital/metabolismo , Fenobarbital/toxicidade , Fenitoína/metabolismo , Fenitoína/toxicidade , Ratos , Ratos Wistar , Compostos de Sulfidrila/metabolismo , Testes de ToxicidadeRESUMO
The trypanocidal activity of racemic mixtures of cis- and trans-methylpluviatolides was evaluated in vitro against trypomastigote forms of two strains of Trypanosoma cruzi, and in the enzymatic assay of T. cruzi gGAPDH. The cytotoxicity of the compounds was assessed by the MTT method using LLC-MK2 cells. The effect of the compounds on peroxide and NO production were also investigated. The mixture of the trans stereoisomers displayed trypanocidal activity (IC50 approximately 89.3 microM). Therefore, it was separated by chiral HPLC, furnishing the (+) and (-)-enantiomers. Only the (-)-enantiomer was active against the parasite (IC50 approximately 18.7 microM). Despite being inactive, the (+)-enantiomer acted as an antagonistic competitor. Trans-methylpluviatolide displayed low toxicity for LLC-MK2 cells, with an IC50 of 6.53 mM. Furthermore, methylpluviatolide neither inhibited gGAPDH activity nor hindered peroxide and NO production at the evaluated concentrations.
Assuntos
Lactonas/química , Lactonas/farmacologia , Lignanas/química , Lignanas/farmacologia , Tripanossomicidas/química , Tripanossomicidas/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Linhagem Celular , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Estrutura Molecular , Óxido Nítrico/biossíntese , Relação Estrutura-AtividadeRESUMO
Idiosyncratic hepatotoxicity is a well-known complication associated with aromatic antiepileptic drugs (AAED), and it has been suggested to occur due to the accumulation of toxic arene oxide metabolites. Although there is clear evidence of the participation of an immune process, a direct toxic effect involving mitochondria dysfunction is also possible. The effects of AAED on mitochondrial function have not been studied yet. Therefore, we investigated, in vitro, the cytotoxic mechanism of carbamazepine (CB), phenytoin (PT) and phenobarbital (PB), unaltered and bioactivated, in the hepatic mitochondrial function. The murine hepatic microsomal system was used to produce the anticonvulsant metabolites. All the bioactivated drugs (CB-B, PB-B, PT-B) affected mitochondrial function causing decrease in state three respiration, RCR, ATP synthesis and membrane potential, increase in state four respiration as well as impairment of Ca2+ uptake/release and inhibition of calcium-induced swelling. As an unaltered drug, only PB, was able to affect mitochondrial respiration (except state four respiration) ATP synthesis and membrane potential; however, Ca2+ uptake/release as well as swelling induction were not affected. The potential to induce mitochondrial dysfunction was PT-B>PB-B>CB-B>PB. Results suggest the involvement of mitochondrial toxicity in the pathogenesis of AAED-induced hepatotoxicity.
Assuntos
Anticonvulsivantes/toxicidade , Carbamazepina/toxicidade , Mitocôndrias Hepáticas/efeitos dos fármacos , Fenobarbital/toxicidade , Fenitoína/toxicidade , Trifosfato de Adenosina/biossíntese , Animais , Anticonvulsivantes/metabolismo , Cálcio/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Carbamazepina/metabolismo , Relação Dose-Resposta a Droga , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/metabolismo , Mitocôndrias Hepáticas/metabolismo , Dilatação Mitocondrial/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Fenobarbital/metabolismo , Fenitoína/metabolismo , Ratos , Ratos WistarRESUMO
Cisplatin is a potent and widely used chemotherapeutic agent. Nephrotoxicity induced by this drug has been well documented. However, very little information is available on cisplatin-induced hepatotoxicity and its underlying mechanism remains unclear. High doses of cisplatin have been known to produce hepatotoxicity. Additionally, elevated expression of CYP 2E1 has been associated with enhanced cisplatin-induced hepatotoxicity. Several studies suggest that cisplatin toxicity occurs by the increased generation of reactive oxygen species (ROS) in mitochondria. Therefore, the present study examined, in vivo, the cisplatin-induced effects on hepatic mitochondrial structure and function as well as the occurrence of hepatocellular death by apoptosis. Adult male Wistar rats (200-220 g) were divided into two groups (n=8) treated as follows: (1) control group (saline solution, 1 ml 100 g(-1) body weight, i.p.) and (2) cisplatin group (10 mg kg(-1) body weight, i.p.). The animals were killed 72 h after the treatment. Hepatotoxicity was evidenced in the cisplatin group by the increased serum levels of alanine (ALT) and aspartate (AST) aminotransferases. The mechanism of cisplatin-induced hepatotoxicity was found to involve membrane rigidification; decreased GSH/GSSG ratio, ATP, GSH and NADPH levels; lipid peroxidation; oxidative damage of cardiolipin and protein sulfhydryl groups. Moreover, cell death by apoptosis was also demonstrated and the findings strongly suggest the participation of the mitochondrial signaling pathway in this process. Therefore, the results show the key role of mitochondria in the hepatotoxicity induced by cisplatin and delineate several mitochondrial processes that could be targeted in future cytoprotective therapy approaches.
Assuntos
Antineoplásicos/toxicidade , Apoptose/efeitos dos fármacos , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Cisplatino/toxicidade , Fígado/efeitos dos fármacos , Fluidez de Membrana/efeitos dos fármacos , Mitocôndrias Hepáticas/efeitos dos fármacos , Alanina Transaminase/sangue , Animais , Aspartato Aminotransferases/sangue , Cardiolipinas/metabolismo , Membrana Celular/efeitos dos fármacos , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Glutationa/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Injeções Intraperitoneais , Fígado/metabolismo , Masculino , Mitocôndrias Hepáticas/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar , Transdução de Sinais/efeitos dos fármacosRESUMO
Nephrotoxicity is the major dose-limiting factor of cisplatin chemotherapy. Reactive oxygen species generated in mitochondria are thought to be the main cause of cellular damage in such injury. The present study examined, in vivo, the protective potential of the hydroxyl radical scavenger dimethylthiourea (DMTU) against cisplatin-induced effects on renal mitochondrial bioenergetics, redox state and oxidative stress. Adult male Wistar rats (200 to 220 g) were divided into four groups of eight animals each. The control group was treated only with an intraperitoneal (i.p.) injection of saline solution (1 ml/100 g body weight). The second group was given only DMTU (500 mg/kg body weight, i.p, followed by 125 mg/Kg, i.p., twice a day until they were killed). The third group was given a single injection of cisplatin (10 mg/kg body weight, i.p.). The fourth group was given DMTU (500 mg/kg body weight, i.p.), just before the cisplatin injection (10 mg/kg body weight, i.p.), followed by injections of DMTU (125 mg/kg body weight, i.p.) twice a day until they were killed. Animals were killed 72 h after the treatment. Besides not presenting any direct effect on mitochondria, DMTU substantially inhibited cisplatin-induced mitochondrial injury and cellular death by apoptosis, suppressing the occurrence of acute renal failure. All the following cisplatin-induced effects were prevented by DMTU: (1) increased plasmatic levels of creatinine and blood urea nitrogen (BUN); (2) decreased ATP content, calcium uptake and electrochemical potential; (3) oxidation of lipids, including cardiolipin; and oxidation of proteins, including sulfhydryl, and aconitase enzyme, as well as accumulation of carbonyl proteins; (4) depletion of the antioxidant defense (NADPH and GSH) and (5) increased activity of the apoptosis executioner caspase-3. Our findings show the important role played by mitochondria and hydroxyl radicals in cisplatin-induced nephrotoxicity, as well as the effectiveness of DMTU in preventing the renal mitochondrial damage caused by cisplatin. These results strongly suggest that protection of mitochondria by hydroxyl radical scavengers may be an interesting approach to prevent the kidney tissue damage caused by cisplatin-chemotherapy.