Os biomarcadores do estresse oxidativo encontram-se elevados na urina e no plasma dos pacientes renais crônicos. A aldosterona (ALD) contribui para a lesão renal no modelo de rins remanescentes. Objetivos: 1- Determinar o efeito do antioxidante N-acetilcisteína (NAC) sobre a função renal e a aldosterona plasmática de animais com IRC. 2- Avaliar o efeito da NAC sobre a evolução da IRC, mesmo quando administrada tardiamente. 3- Avaliar os efeitos da NAC associada a Espironolactona (Spi). Material e Métodos: Ratos adultos Wistar machos foram submetidos a nefrectomia de 5/6 (Nx). No estudo 1: Animais foram tratados ou não com NAC na dose de (600mg/l na água de beber) iniciado 7dias após nefrectomia (Nx). Estudos de clearance foram realizados em todos os grupos, 21, 60 e 120 dias após Nx. No estudo 2: 6 animais foram tratados com NAC após 60 dias de Nx e estudados 120 dias após NX. No estudo 3: Os ratos foram tratados com Spi (1.5g/kg de dieta) associados ou não com NAC, ambos iniciados a partir do 7º dia da nefrectomia e estudados 60 dias após a Nx. Em todos os grupos foram avaliados: clearance de inulina (RFG, ml/min/100g peso); proteinúria (Uvpr., mg/24h); aldosterona plasmática (ng/dl); relação potássio/sódio urinário (UK/UNa), pressão arterial (mmHg), TBARS urinário (nmoles/24h) e o índice de glomeruloesclerose (%). Resultados: A ingestão média de NAC foi similar nos respectivos grupos tratados. Significante diminuição de TBARS (marcador de peroxidação lipídica), foi observada nos ratos Nx tratados com NAC (mesmo quando administrado tardiamente). O principal resultado deste estudo foi que a administração de NAC nos animais com nefrectomia de 5/6, protegeu a filtração glomerular (GFR) significativamente, com uma média de clearance de inulina de 0.45 ml/min (50% dos valores normais), mantendose estável 120 dias após a nefrectomia (0,51 ± 0,03). Ao contrário, GFR diminuiu progressivamente nos animais não tratados (0,16 ± 0,03). Nos animais Nx+NAC, a proteinúria, o índice de glomeruloesclerose e a pressão arterial, apresentaram diminuição após 120 dias de Nx e hipertrofia dos corações e das adrenais foram atenuadas. Estes efeitos benéficos estão associados com uma significante redução da aldosterona plasmática e da razão UK/UNa (marcador indireto da ação tubular da aldosterona) e foram observados mesmo com a administração tardia de NAC (60 dias após Nx). A mortalidade foi de 33% no grupo de Nx120, 25% no grupo Nx120+NAC e 10% nos animais Nx120+60NAC. No estudo 3: A espironolactona isoladamente diminuiu a proteinúria dos animais Nx, entretanto, quando associada a NAC promoveu maior proteção da filtração glomerular (Nx60 + NAC+Spi = 0,59±0,04 vs.Nx + 60 + NAC = 0,47 ± 0,05, p < 0,001) e menor pressão arterial (136±2mmHg) do que nos animais tratados apenas com NAC (154 ± 2 mmHg). Conclusões: 1. O antioxidante NAC exerceu efeito protetor sobre a filtração glomerular de ratos com insuficiência renal crônica, mesmo quando administrado tardiamente, além de diminuir as concentrações de aldosterona e TBARS, marcador de peroxidação lipídica. 2. A associação de NAC e espironolactona proporcionou efeito benéfico aditivo sobre a filtração glomerular, acompanhado de uma maior queda da pressão arterial. / Oxidative stress biomarkers are increased in urine and plasma from renal chronic patients. Aldosterone (ALD) contributes to the kidney lesion in the remnant kidney model. Objectives: This studies was carried out to: 1- Determine the effect of antioxidant N-acetylcysteine (NAC) on kidney function and plasma aldosterone on animals with chronic renal failure (CRF); 2- Evaluate the effect of NAC on the CRF evolution, even when administered at a later stage; 3- Evaluate the effects of NAC associated with spironolactone (SPI). Material and Methods: Adult male Wistar rats were submitted to 5/6 nephrectomy (Nx). In study 1: Animals were treated or not with NAC (600 mg/l in drinking water), started 7 days after Nx. Clearance studies were performed on all rats at 21, 60 and 120 days after Nx. In study 2: 6 rats were treated with NAC initiated 60 days after Nx and studied 120 days after Nx. In study 3: rats were treated with Spi (1.5 g/Kg diet) associated or not to NAC, both initiated 7 days after Nx-treated rats and studied 60 days after Nx. In all experiments the following were measured: inulin clearance (GRF, ml/min/100g body weight); proteinuria (Uvpr, mg/24h); plasma aldosterone (ng/dl); urinary potassium/sodium ratio (UK/UNa); blood pressure (mmHg); urinary TBARS (nmoles/24h) and glomerulosclerosis index (%). Results: Mean daily NAC ingestion was similar in respective treated groups. A significant decrease in urinary TBARS (an index of lipid peroxidation) was observed in the NAC treated rats even when administered at a later stage. The main new finding of this study is that NAC administration to 5/6-Nx rats protects the glomerular filtration rate (GFR) significantly, with a mean inulin clearance of 0.45 (50% of the normal values), remaining stable 120 days following nephrectomy (0.51±0.03). Conversely, GFR fell progressively in untreated rats (0.16±0.03). In Nx+NAC rats, proteinuria, glomerulosclerosis index and blood pressure all decreased by day 120, and heart and adrenal hypertrophy were attenuated. These beneficial effects were associated with a significant reduction in plasma aldosterone and urinary sodium/potassium (UK/UNa) ratio (indirect marker of aldosterone tubular action) and were observed even when NAC was administered later (60 days after Nx). Mortality was 33% in the Nx 120 group, 25% in the Nx120+NAC group and 14.3% in the Nx120 (Nx60+60NAC). In study 3: Spironolactone isolatedly decreased proteinuria in the Nx animals, however when associated with NAC it caused more protection of GFR (Nx60+NAC+Spi = 0.59±0.04 vs Nx60+NAC = 0.47 ± 0.05, p < 0.001) and lower blood pressure (136±2 mmHg) than in the animals treated only with NAC (154±2 mmHg). The combination of Spi and NAC lowered blood pressure and improve GFR protection. Conclusion: 1. In the remnant kidney model, NAC has a protective effect attributable to decreased plasma aldosterone and lower of lipid peroxidation indicative of thiobarbituric acid reactive substances (TBARS) lower levels, even in the later stages. 2. Combination of NAC and Spi showed an extra beneficial effect over glomerular filtration, and a higher decrease of blood pressure.

Beim neonatalen Atemnotsyndrom ist die Beatmung der Frühgeborenen mit hohen Sauerstoffpartialdrücken eine oft lebensrettende Therapie. Durch diese therapeutische Hyperoxie entstehen allerdings vermehrt reaktive Sauerstoffspezies, die an der Pathogenese verschiedener Lungenerkrankungen beteiligt sind. Ziel dieser Arbeit ist es, Modelle für oxidativen Stress in der Lunge zu entwickeln und die Mechanismen der oxidativen Schädigung näher zu charakterisieren. Folgende Modelle werden untersucht: 1. Untersuchung von isolierten Typ-II-Zellen aus Hyperoxie-exponierten bzw. Kontroll-Ratten (in vivo) und 2. Kultivierung isolierter Typ-II-Zellen in Gegenwart von H2O2 (in vitro). Wir zeigen in dieser Arbeit, das erst die Kultivierung von Typ-II-Zellen unter Basalbedingungen zu einem starken Anstieg der Expression von Hitzeschockproteinen (HSP) führt, wohingegen frisch isolierte Zellen keine HSP exprimieren. In Übereinstimmung mit der neueren Literatur schließen wir daraus, dass allein die basalen Zellkulturbedingungen für die Zellen ein Stressfaktor darstellen können. Unter 44-stündiger Hyperoxie steigt die Konzentration der PAF-ähnlichen Oxidationsprodukte von Phospholipiden (PAF-RC) lediglich im Blutplasma an, bleibt dagegen in der Lungenlavage unverändert. PAF-RC wirken über den Rezeptor des Thrombozyten-aktivierenden Faktors (PAF) proinflammatorisch und werden durch die PAF- Acetylhydrolase (PAF-AH) abgebaut. Unter Hyperoxie ist die PAF-AH-Aktivität im Blutplasma unverändert, in der Lavage jedoch auf ein Drittel vermindert. Wir nehmen daher an, dass die hyperoxische Lungenschädigung weder durch eine verminderte PAF-AH- Aktivität noch durch die direkte Peroxidation von Surfactantlipiden in den Alveolen vermittelt wird. Wahrscheinlich wird die pulmonale Sauerstofftoxizität durch die Lipidperoxidation im Blutgefäßsystem oder –plasma verursacht. Unter H2O2-Stress werden in den Typ-II-Zellen zum einen ungesättigte Surfactantlipide oxidiert, zum anderen wird die Aufnahme von Palmitinsäure in die Zelle und die Synthese von Phosphatidylcholin gehemmt. Der entscheidende Schritt ist dabei vermutlich die oxidative Hemmung eines Schlüsselenzyms der Phospholipidsynthese, der Glycerol-3- Phosphat-Acyltransferase (G3PAT). Die Konzentration der zellulären Antioxidantien Vitamin E und Glutathion ist scheinbar zu gering, um die G3PAT und die zellulären Lipide vor der v.a. initial sehr hohen H2O2-Belastung zu schützen. / Ventilation of preterm babies with infant respiratory distress syndrome (IRDS) using high oxygen pressures is often a life-saving therapy. A severe side effect of this therapeutic hyperoxia though, is the formation of reactive oxygen species that are involved in the pathogenesis of different lung diseases. This thesis is designed to develop models for oxidative stress in the lung and to further characterise the mechanisms of oxidative damage. The following models have been examined: 1. Examination of isolated type II cells from hyperoxia-exposed and control rats (in vivo). 2. Cultivation of isolated type II cells in the presence of H2O2 (in vitro). In this thesis we show that only by cultivating type II cells under basal conditions the expression of heat shock proteins (HSP) is strongly activated, whereas freshly isolated cells do not express HSP. We conclude in accordance with the newer literature, that the basal cell culture conditions alone can represent a stress factor for the cells. Under 44 hours of hyperoxia the concentration of the PAF-like oxidation products of phospholipids (PAF-RC) rises only in blood plasma, but not in the lung lavage. PAF- RC act proinflammatory via the platelet-activating factor (PAF) receptor and are degraded by the PAF-Acetylhydrolase (PAF-AH). Hyperoxia does not affect the PAF- AH-activity in blood plasma, but decreases it to one third in the lavage. According to these findings we assume that neither the decreased PAF-AH activity nor the direct peroxidation of surfactant lipids in the alveoli cause hyperoxic lung injury. More likely the pulmonary surfactant toxicity is caused by the lipid peroxidation in the blood vessel system or blood plasma. Under H2O2 stress unsaturated surfactant lipids in the type II cells are oxidated on the one hand, on the other hand the palmitic acid uptake in the cells as well as the phosphatidylcholine synthesis is inhibited. The oxidative inhibition of glycerol-3- phosphate-acyltransferase (GPAT), the key enzyme of phospholipid synthesis, is supposed to be the crucial step. It seems that the concentration of the antioxidants vitamin E and glutathione is not sufficient enough to protect the GPAT and the cellular lipids from the especially initially high concentrations of H2O2.

Introdução. Uma alimentação rica em antioxidantes pode prevenir e reparar danos oxidativos causados pelas espécies reativas de nitrogênio e oxigênio, como o dano no DNA e a peroxidação lipídica e pode reduzir o risco de câncer, aterosclerose e outras doenças degenerativas. A polpa do Caryocar Brasiliense Camb, mais conhecido como pequi, é uma fruta do cerrado brasileiro que possui altos níveis de antioxidantes como os carotenóides, vitamina C e E e compostos fenólicos. Objetivos. Verificar a atividade antioxidante do óleo e do extrato da polpa do pequi na diminuição do estresse oxidativo em um modelo experimental de carcinogênese pulmonar. Métodos. O estudo foi realizado em 40 camundongos BALB/C machos: 35 animais foram submetidos a duas doses intra-peritoniais de 1,5 g/kg de uretana (U = 5), 10 destes camundongos receberam por gavagem 15uL de óleo da polpa do pequi (UO = 10), 10 animais receberam gavagem de 15uL de extrato etanólico de polpa de pequi (UE = 10) e os 10 animais restantes receberam por gavagem 3?g/kg de betacaroteno (UB = 10). 5 camundongos não receberam as doses de uretana nem a gavagem (C = 5). Após 60 dias, os grupos foram sacrificados. A defesa antioxidante enzimática foi mensurada pelo teste bioquímico. A atividade antioxidante do óleo de pequi foi avaliada nos tecidos do pulmão pelo teste bioquímico de TBARS (substâncias reativas ao ácido tiobarbitúrico) e os danos do DNA pelo método de teste de cometa. A expressão gênica e protéica das óxido nítrico sintases foi analisada por biologia molecular e imunohistoquímica, respectivamente. Resultados. O parênquima pulmonar dos animais que receberam as doses de uretana apresentaram formações neoplásicas induzidas pela carcinogênese química, em contraste com o grupo Controle. Os grupos de animais que receberam as doses de uretana e foram suplementados com o betacaroteno, o óleo e o extrato de pequi apresentaram resultados importantes na diminuição do dano no DNA, na peroxidação lipídica e na expressão protéica e gênica das isoformas da óxido nítrico sintase (NOS1, NOS2 e NOS3) ao contrário dos animais que receberam apenas as doses de uretana. Conclusão. Concluiu-se que os diferentes compostos antioxidantes encontrados no óleo e no extrato do pequi são eficientes para diminuir a expressão das enzimas óxido nítrico sintase, o dano no DNA e a peroxidação lipídica em um modelo experimental de carcinogênese pulmonar induzida pelo uretana, sugerindo que essa fruta possa contribuir no tratamento de câncer de pulmão / Introduction. A daily consumption of foods that are rich in antioxidant compounds can prevent and repair the oxidative damage caused by reactive species of oxygen and nitrogen, such as DNA damage and lipid peroxidation and can reduce the risk of cancer, atherosclerosis and other degenerative diseases. The pulp of the Caryocar brasiliense camb, most known as pequi, has high levels of antioxidant compounds such as carotenoids, phenolic compounds and vitamin C and E. Objectives. Verify the antioxidant activity of the oil and extract of the pequi pulp in diminishing of the oxidative stress in an experimental model of lung cancer. Methods. The study was performed in 40 male BALB/c mices: 35 animals were submitted to two doses of 1,5g/kg intraperitoneal of urethane (U=5), 10 of these mices received by gavage 15uL of pequi pulp oil (UO=10), 10 animals received by gavage 15uL of ethanolic extract of pequi pulp (UE=10) and the other 10 animals received by gavage 3?g/kg of betacarotene (UB=10). 5 mices didn\'t receive the urethane doses neither the gavage (C=5). After 60 days, the groups were sacrificed. The enzymatic antioxidant defense was measured by biochemical test. The antioxidant activity of pequi oil was evaluated in the lung tissues by the biochemical TBARS test (Thiobarbituric acid-reactive substances) and the DNA damage by the comet test method. Nitric oxid Synthases gene and protein expression was analyzed by molecular biology and imunohistochemestry, respectively. Results. The pulmonary parenquima of animals that received the urethane doses showed neoplasic formations induced by the chemical carcinogenesis, in contrast with the control group. The groups of animals that received the urethane doses and the treatment with the oil, extract and betacarotene showed an important result in diminishing the DNA damage, lipid peroxidation, genic and protein expression of the nitric oxid synthase isoforms (NOS1,NOS2,NOS3), different from what we found in the group that just received the urethane doses. Conclusion. The different antioxidant components in the oil and extract of the pequi pulp are efficient to diminish the oxid nitric synthase isoforms, DNA damage and lipid peroxidation in an experimental model pulmonary chemical carcinogenesis, and suggest that the consumption of the fruit can be a good alternative to contribute in the treatment of lung cancer

Há mais de 20 anos a Catuama® vem sendo utilizada contra fadiga física e mental, disfunção sexual e astenia muscular. Nos últimos anos, diversos estudos demonstraram efeitos como ação antinociceptiva, antidepressiva, neuroprotetora, vasodilatadora e dilatadora dos corpos cavernosos. Dados do Laboratório de Investigação Médica da Disciplina de Emergências Clínicas da FMUSP (LIM-51) demonstraram que a Catuama® é capaz de reverter e prevenir a fibrilação ventricular (FV) induzida em coração isolado de coelho. Tendo em vista a comprovação de que a Catuama® possui efeito cardíaco significativo, tornou-se necessário investigar mais a fundo outras potenciais propriedades cardioprotetoras. Investigamos então se a Catuama® e a Trichila catigua podem oferecer proteção ao miocárdio submetido a isquemia e reperfusão em coração isolado de ratos quando administrados cronicamente. Ratos Wistar machos e adultos foram submetidos a um tratamento de 14 dias com Catuama®, T. catigua, Água destilada ou Tween 80 por gavagem. Ao término do tratamento, os animais foram anestesiados com pentobarbital e os corações retirados e perfundidos com solução de Krebs-Henseleit (KHB) pela aorta em sistema de Langendorff. Foi mantido fluxo constante de 8mL/minuto, temperatura de 36º C e oxigenação com 95% de oxigênio e 5% de gás carbônico. Os corações foram submetidos a uma isquemia global através de interrupção da perfusão por 30 minutos seguida de 2 horas de reperfusão. Para avaliar o grau de lesão causada pelo protocolo, analisamos os aspectos hemodinâmicos e biomoleculares. Foi possível observar uma melhora significativa em muitos dos parâmetros analisados. Os grupos que receberam os extratos de Catuama® e T. catigua mostraram área de necrose inferior a 16% da área total, enquanto os grupos Tween 80 e Água destilada apresentaram uma necrose superior a 60%. Além disso, a pressão desenvolvida no ventrículo esquerdo também apresentou melhora nos primeiros minutos de reperfusão, alcançando uma recuperação próxima de 70% da pressão préisquemica nos animais tratados com os extratos, enquanto os animais dos grupos Tween 80 e Água destilada apresentaram uma recuperação em torno de 20% da pressão desenvolvida. O mesmo ocorreu com a pressão diastólica dos grupos que receberam os extratos: nos primeiros minutos de reperfusão a pressão diastólica foi reduzida para valores inferiores a 30 mmHg durante a reperfusão, próximos dos pré-isquemicos, enquanto os outros dois grupos mantiveram valores elevados de pressão diastólica durante toda a reperfusão (Água destilada: 69,56+10,05 mmHg; Tween 80: 101,69+19,80 mmHg). Os grupos tratados com os extratos também apresentaram aumento na expressão de proteínas totais e de Catalase. Por outro lado, houve uma diminuição da peroxidação lipídica e de subprodutos do óxido nítrico. A Catuama® e a T. catigua já são amplamente usadas pela população e, devido a sua popularidade e acessibilidade, podem tornar-se aliadas para seres humanos com risco de doença cardíaca isquêmica. / For over 20 years Catuama® has been used against physical and mental fatigue, muscular asthenia and sexual dysfunction. In the last years, several studies have shown effects such as antinociceptive action, antidepressant, neuroprotective, vasodilator and effects in erectile-dysfunction. Data from the Medical Research Laboratory in the Department of Clinical Emergency demonstrated that Catuama® is able to reverse and prevent ventricular fibrillation (VF) induced in isolated rabbit hearts. Given the evidence that Catuama® has significant cardiac effects, it became necessary to proceed a deeper investigation on other potential cardioprotective properties. We investigated if Catuama® and Trichilia catigua may offer protection to the myocardium subjected to ischemia and reperfusion in the isolated rat heart. Adult male Wistar rats were treated during 14 days with Catuama®, T. catigua, Distilled Water or Tween 80 by gavage. At the end of the treatment, the animals were anesthetized with pentobarbital and their hearts removed and perfused with Krebs-Henseleit (KHB) through the aorta in a Langendorff system. Perfusion flow was kept constant at 8mL/minute, temperature 36° C; the preparation was aerated with 95% oxygen and 5% carbon dioxide. The hearts were submitted to global ischemia by stopping perfusion for 30 minutes followed by 2 hours of reperfusion. To assess the extension of the injury caused by the protocol, we analyzed the hemodynamic and molecular aspects. It was possible to observe a significant improvement in many parameters. The groups that received the extracts Catuama® and T. catigua showed necrotic area inferior to 16% of the total area, while the groups Tween 80 and Distilled Water showed higher than 60% necrosis. In addition, left ventricular developed pressure also improved in the first minutes of reperfusion, reaching a recovery of about 70% of pre-ischemic values in animals treated with the extracts, while animals in groups Tween 80 and Distilled Water showed a recovery around 20% of the developed pressure. The same occurred with diastolic pressure of the groups that received the extracts: in the first minutes of reperfusion, the diastolic pressure was reduced to below 30 mmHg during reperfusion, close to the pre-ischemic values, while in the other two groups diastolic pressure remained elevated throughout reperfusion (Distilled Water: 69.56 +10.05 mmHg; Tween 80: 101.69 +19.80mmHg). The groups treated with the extracts also showed increased expression of total protein and catalase. On the other hand, there was a decrease in lipid peroxidation products and nitric oxide. Catuama® and T. catigua are already widely used by the population and, due to their popularity and accessibility can become allies to humans at risk for ischemic heart disease.

L’objectif principal de ce travail est d’étudier les mécanismes d’oxydation lors de la photocatalyse (TiO2 irradié sous UV-A) appliquée à la dégradation des microorganismes et leurs effets sur les composants cellulaires. L'étude de l'efficacité antimicrobienne de TiO2 sur un panel de microorganismes (bactéries, spores, champignons) réalisée dans différents milieux (TiO2 en milieu riche, 'sec', en phase liquide) montre l’influence des méthodes d’évaluation, de test et de comptage sur les efficacités d’inactivation. Des études menées en présence de molécules scavengers d’anions superoxydes (O2°-) mettent en évidence l’implication des O2°- dans l’effet antibactérien et dans la peroxydation lipidique. Au niveau protéomique, diverses cibles d’action potentielles du TiO2 sont aussi proposées. Enfin, une partie applicative détermine l’efficacité antimicrobienne de dispositifs photocatalytiques équipés de mousses alvéolaires de β-SiC et de diodes électroluminescentes, et met en avant les propriétés auto-désinfectantes sous lumière solaire de textiles photocatalytiques fonctionnalisés par la technique layer-by-layer. / The main objective of this work is to study the oxidation mechanisms of UV-A photocatalysis on TiO2 applied to the degradation of microorganisms and their effects on cellular components. The study of the antimicrobial efficiency of TiO2 towards a panel of microorganisms (bacteria, spores, fungi) in different media (TiO2 in rich or 'dry' environment, in liquid phase) shows the influence of the evaluation methods, test and counting on the inactivation efficiency. Studies carried out in the presence of scavenger molecule of superoxide anions (O2°-) highlight the involvement of O2°- in the antibacterial effect and lipid peroxidation. Proteomics analysis leads to propose various potential targets of the TiO2 action. Finally, an application part deals with the design of photocatalytic devices based on LEDs and β-SiC alveolar foams for air disinfection, and of sunlight active self-disinfecting layer-by-layer functionalized photocatalytic textiles.

Os compostos fenólicos são substâncias amplamente distribuídas no reino vegetal, em particular nas frutas e em outros vegetais. Estes compostos, destacando-se flavonoides e os ácidos fenólicos, devido à estrutura molecular, podem apresentar a capacidade de inibir processos oxidativos. Além do mais, estão relacionados com a redução de risco de doenças crônicas não transmissíveis tais como: cardiovasculares, câncer, aterosclerose, entre outras. Considerando a elevada produção de caju em território brasileiro e a possibilidade da existência de compostos com potencial antioxidante no pedúnculo de caju , este trabalho teve por objetivo avaliar quantitativa e qualitativamente os compostos fenólicos, particularmente os ácidos fenólicos, e identificar a participação destes em processos metabólicos do organismo animal. Foram caracterizados quimicamente três clones distintos de pedúnculos de caju (CCP-76, CCP-09, BRS-189 e CCP-76 tratado) e na análise química, apresentaram um elevado teor de ácidos graxos monoinsaturados, predominando o ácido oléico, e de fenólicos totais. Os ácidos fenólicos identificados foram: gálico, protocatecuíco, p-cumárico, ferúlico, caféico e salicílico. Foram obtidos extratos aquoso (EAq) e alcoólico (EAlc) e frações de ácidos fenólicos a partir dos pedúnculos e, avaliados em sistemas modelo &#946;-caroteno/ácidolinoléico e em Rancimat. As frações de ácidos fenólicos exibiram expressiva atividade antioxidante no primeiro sistema e os extratos, no segundo, demonstraram fatores de proteção superior ao antioxidante sintético BHT. Pôde-se também verificar a capacidade antioxidante dos extratos e frações do clone CCP-76 no sistema de varredura do radical DPPH. Em ensaio experimental com ratos, em condição normal, foi administrado EAq (80 e 240 mg/kg, v.o.) ou fração de ácidos fenólicos livres (40 e 120 mg/kg, v.o.) obtidos do pedúnculo de caju CCP-76. Neste estudo, não se observou potencialização de todos os antioxidantes enzimáticos (superóxido dismutase, catalase e glutationas peroxidase e redutase), contudo pôde-se verificar a redução dos níveis de lipoperoxidação no tecido cerebral dando indícios de aumento do estado antioxidante nos animais. Também foi avaliado o potencial antioxidante do EAq e da fração de ácidos fenólicos livres sobre o dano hepático em ratos tratados com tetracloreto (CCl4) de carbono. A administração deste teve seu efeito corroborado pela avaliação dos parâmetros bioquímicos, ou seja, aumento exacerbado das enzimas hepáticas no plasma: alanina transaminase (ALT) e aspartato transaminase (AST); decréscimo da atividades da enzimas antioxidantes no fígado e elevação da produção de peróxidos lipídicos no tecido hepático. Nos ratos que receberam EAq (480 mg/kg, v.o.) não se observou alteração comparando-os aos animais tratados apenas com CCl4 . No entanto, a administração de fração de ácidos fenólicos livres, nas duas doses (40 e 120 mg/kg, v.o.), evidenciou pronunciado efeito contra a lesão hepática, com níveis reduzidos de AL T e AST plasmáticas, aumento da atividade das enzimas antioxidantes no fígado e prevenindo a lipoperoxidação hepática mediada pelo radical CCl3&#8226; a partir do CCl4. Estudos histológicos do tecido hepático confirmaram as avaliações bioquímicas exibindo preservação tecidual, supressão de degeneração vacuolar macro e microgoticular e de sinais necróticos nos ratos tratados com a fração de ácidos fenólicos livres do pedúnculo de caju. / Phenolic compounds are widely distributed in the plant kingdom, particularly fruits and vegetables. Due to their chemical structure, these compounds, in particular flavonoids and phenolic acids, are able to inhibit oxidative processes. Furthermore, can be used to reduce the risk of non-transmissible chronic diseases such as cardiovascular diseases, cancer and atherosclerosis. Taking into consideration the large production of cashew in Brazil and the possible existence of potentially antioxidant compounds present in the cashew apples, the aim of this study was to quantitatively and qualitatively evaluate the presence of phenolic compounds in cashew apple, particularly phenolic acids, and identify their role in metabolic processes in animals. The cashew apples of three distinct clones (CCP-76, CCP-09, BRS-189 and CCP-76 (processed)) were studied. The determination of fatty acids yielded a high concentration of monounsaturated fatty acids, mainly oleic acid, and of total phenolic compound. The phenolic acids found were: gallic, proteocatechuic, p-cumaric, ferulic, caffeic and salicylic acids. Both aqueous (EAq) and ethanolic (EAlc) extracts and phenolic acid fractions were obtained from the cashew apples and were evaluated in a &#946;-carotene/linoleate model system and Rancimat test. The phenolic acid fractions presented an expressive antioxidant activity in the &#946;-carotene/linoleate model system and the extracts, by the Rancimat test presented a protection factor higher than that of antioxidant additive, BHT. We also observed the antioxidant capacity of the extracts and fractions of the CCP-76 clone in the DPPH radical scavenging assay. In an experimental assay with rats, the EAq (80 and 240 mg/kg) or the free phenolic acid fraction (40 and 120 mg/kg) obtained from the cashew apple of CCP-76 clone was administered via the oral route. In this study, the enhancement of enzymatic antioxidants (superoxide dismutase, catalase, glutathione peroxidase and reductase) was not observed, nevertheless, a decrease in the amount of lipoperoxidation in the brain tissue was observed, suggesting that the ingestion of cashew might increase the antioxidative state in animals. Also, the antioxidant activity of EAq and of the free phenolic acid fraction from the cashew apple of CCP-76 clone was verified on the liver damage induced by carbon tetrachloride. The liver damage caused by the administration of carbon tetrachloride was detected by biochemical parameters, namely, the increase in the serum concentrations of alanine transaminase (ALT) and aspartate transaminase (AST) as well as a decrease in the activities of antioxidant enzymes and an increase in peroxidation in the liver. Rats who received EAq (480 mg/kg, p.o.) did not present alterations in any of the parameters evaluated, compared to the animals treated with carbon tetrachloride. On the other hand, the administration of free the phenolic acid fraction in doses of 40 and 120 mg/kg, p.o., had a pronounced effect in protecting against hepatic lesion, which was evidenced by the decrease in plasma ALT and AST, enhancing the activity of antioxidant enzymes and preventing lipoperoxidation mediated by the CCl3&#8226; radical generated by carbon tetrachloride. Histological studies were able to confirm the biochemical alterations observed in that the liver tissue obtained from rats treated with phenolic acid fractions extracted from cashew apple of CCP-76 clone presented a preserved tissue structure and suppression of macro and microgoticular vacuolar degeneration as well as of signs of necrosis.

Made available in DSpace on 2017-07-21T19:59:47Z (GMT). No. of bitstreams: 1 Tatiane Dobrzanski.pdf: 2071508 bytes, checksum: e3c3a02783ca0c1929ed8b2a83555230 (MD5) Previous issue date: 2015-02-25 / Excessive use of herbicides for weed control in agriculture causes a selective pressure on soil microbiota and waters near application area, changing environmental balance. Some microorganisms have developed metabolic pathways for degradation of these xenobiotics, although tolerance and degradation processes can generate free radicals and affect survival. This study aimed to analyze the system of responses from soil and water strains, submitted to selective pressure by the herbicide Callisto®. Strains CCT7729 and CCT7730, isolated from soil and water, respectively, were identified as Bacillus sp., and showed different degradation routes, with different metabolites, already described in the literature. Mesotrione and its metabolites, and especially its commercial product Callisto, affected cell viability and altered cell membrane lipids from the tested strains, however, Bacillus sp. CCT7729 presented a more efficient system of responses to oxidative stress. This strain exhibited a greater efficiency to degrade mesotrione, lower rates of peroxide, lower rates of MDA, SOD high activity and low activity of catalase, when compared to Bacillus sp. CCT7730. Changes in membrane lipids can be considered as a defense against oxidative stress strategy. These results indicated the existence from a variety of metabolic pathways for mesotrione degradation to Bacillus sp. Probably metabolites induce different levels of toxicity in bacteria, and Bacillus sp. CCT7730 possibly degraded mesotrione in even harmful compounds, unlike the water line. It is possible that these different responses are related to the home environments of each strain, suggesting plasticity responses of Bacillus sp. for adaptation to toxic substances in different environmental contexts. / O uso intenso de herbicidas para controle de ervas daninhas na agricultura provoca uma pressão seletiva na microbiota do solo e de águas próximas à área de aplicação, alterando o equilíbrio ambiental. Alguns microrganismos apresentam vias metabólicas de degradação desses xenobióticos, entretanto, a tolerância e os processos de degradação podem gerar radicais livres capazes de afetar a sobrevivência. Este trabalho teve como objetivo analisar o sistema de respostas de linhagens provenientes de solo e água, e que foram submetidas a pressão seletiva pelo herbicida Callisto. Uma linhagem isolada de cada um destes ambientes, identificadas respectivamente, como Bacillus sp. CCT7729 e Bacillus sp. CCT7730, apresentaram rotas de degradação diferenciadas, com metabólitos diferentes dos já descritos na literatura. O mesotrione, seus metabólitos, e principalmente o Callisto, afetaram a viabilidade celular das linhagens deste estudo e alteraram os lipídios de membrana celular, no entanto, Bacillus sp. CCT7729 apresentou um sistema de respostas ao estresse oxidativo mais eficiente. Esta linhagem exibiu uma maior eficiência em degradar o mesotrione, menores taxas de peróxido, menores taxas de MDA, atividade SOD elevada e uma baixa atividade da catalase, ao contrário de Bacillus sp. CCT7730. Modificações nos lipídios de membrana podem ser consideradas como uma estratégia de defesa contra estresse oxidativo. Os resultados também indicaram uma diversidade de vias metabólicas nas duas linhagens de Bacillus sp. para a degradação do mesotrione. Provavelmente os metabólitos induziram diferentes níveis de toxicidade nas bactérias, sendo que Bacillus sp. CCT7730 possivelmente degradou o mesotrione em compostos ainda nocivos, ao contrário da linhagem de água. É possível que essas diferentes respostas estejam relacionadas com os ambientes de origem de cada linhagem, sugerindo uma plasticidade de respostas apresentadas por linhagens Bacillus sp. para adaptação a substâncias tóxicas em diferentes contextos ambientais.

Les aliments riches en acides gras polyinsaturés (AGPI) à longue chaîne (LC) de la série n-3 sont recommandés pour leurs effets bénéfiques sur la santé humaine et en particulier dans la prevention du développement des maladies métaboliques. Or, la biodisponibilité de ces AGPI et leur impact métabolique pourraient être modulés par la nature chimique des molécules qui les véhiculent dans les aliments (triacylglycérols, TG ou phospholipides, PL). De plus, ces AGPI sont sensibles à la peroxydation lipidique. S’ils ne sont pas protégés de l’oxydation, ils peuvent former des espèces réactives toxiques comme le 4-hydroxy-hexénal (4-HHE). Dans ce contexte, le but de notre étude a été d’évaluer l’impact de l’enrichissement de régimes hyperlipidiques en AGPI n-3 (i) portés par des TG ou des PL et (ii) sous forme non-oxydée ou oxydée, sur l’inflammation et le stress oxydant métaboliques et d’en comprendre certains mécanismes liés à l’absorption intestinale et la réactivité du 4-HHE. D’une part, notre étude a confirmé que la consommation d’AGPI-LC n-3 empêche l’induction du stress oxydant et de l’inflammation lors d’un régime hyperlipidique chez la souris. Cependant, par rapport aux TG, les PL vecteurs d’AGPI n-3 permettent de réduire la taille des adipocytes et de stimuler le système antioxydant. D’autre part, notre étude a montré que la consommation d’AGPI n-3 oxydés de manière modérée aboutit à une élévation des concentrations plasmatiques de 4-HHE et des marqueurs inflammatoires. De plus, une activation des voies inflammatoires ainsi que du stress du réticulum endoplasmique ont été détectées au niveau de l’intestin grêle. Nos résultats in vivo et in vitro sur cellules intestinales Caco-2/TC7 indiquent que cela peut être dû en partie à une absorption au niveau intestinal du 4-HHE, produit d’oxydations des AGPI n-3. Dans le contexte du développement des aliments contenant des AGPI-LC n-3, nos résultats contribuent à identifier les structures vectrices de ces acides gras les plus efficaces du point de vue métabolique. En santé publique et en pratique clinique, nos résultats constituent une nouvelle base de réflexion pour la mise en place de bonnes pratiques de production et de conservation des aliments et des compléments nutritionnels enrichis en AGPI-LC n-3 pour éviter leur oxydation et ses possibles effets délétères. / Dietary intake of n-3 long chain (LC) polyunsaturated fatty acids (PUFA) are recommended for their beneficial effects on human health, especially to prevent the development of metabolic diseases. However, the bioavailability of these PUFAs and their metabolic impact could be modulated by their chemical carriers (triacylglycerols, TG or phospholipids, PL). In addition, these PUFA are susceptible to lipid peroxidation. If they are not protected from oxidation, they can form toxic reactive species such as 4-hydroxy-hexenal (4-HHE). In this context, the aim of our study was to evaluate the impact of enriching high-fat diets with n-3 PUFA (i) bound to TG or PL and (ii) in unoxidized or oxidized form on the generation of inflammation and oxidative stress, and to understand some underlying mechanisms associated with intestinal absorption and reactivity of 4-HHE. On the one hand, our study confirmed in mice that the consumption of n-3 PUFA protects against oxidative stress and inflammation induced by high-fat diets. However, compared to TG, n-3 PUFA in the form of PL reduce the size of adipocytes and stimulate the antioxidant system. On the other hand, our study showed that the consumption of moderately oxidized n-3 PUFA results in increased plasma concentrations of 4-HHE and of inflammatory markers. In addition, activation of inflammatory pathways as well as endoplasmic reticulum stress were detected in the small intestine. Our results in vivo and in vitro, using intestinal Caco-2/TC7 cells, indicate that this can be partly due to the intestinal absorption of the end-product of n-3 PUFA oxidation, 4-HHE. In the context of the development of foods containing LC n-3 PUFA, our results contribute to identify the most effective PUFA carriers on a metabolic standpoint. Regarding public health and clinical practice, our results provide new basis for the set up of best practices regarding production and storage of food and supplements enriched with LC n-3 PUFA to avoid their lipid oxidation and its possible deleterious effects.

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / O presente trabalho teve por objetivo estudar as respostas fisiolÃgicas e bioquÃmicas de clones de cajueiro anÃo-precoce (Anacardium occidentale L.) ao estresse salino. Os experimentos foram conduzidos em casa de vegetaÃÃo, sendo as plÃntulas cultivadas em vasos plÃsticos contendo vermiculita. No primeiro experimento, cinco clones de cajueiro anÃo-precoce foram submetidos aos tratamentos com NaCl a 0 (controle), 8 e 16 dS.m-1 de condutividade elÃtrica e objetivou selecionar clones com tolerÃncias diferenciadas ao estresse salino. Para isso, foram estudados os efeitos da salinidade no crescimento, nas trocas gasosas, no teor de Ãgua, na suculÃncia foliar, no potencial osmÃtico, nas concentraÃÃes de prolina, N-aminossolÃveis e carboidratos solÃveis e nos teores dos Ãons inorgÃnicos (Na+, Cl- e K+). A salinidade reduziu o crescimento das plÃntulas de todos os clones estudados. Os efeitos inibitÃrios do NaCl foram mais conspÃcuos na parte aÃrea do que nas raÃzes. O clone CCP 06 foi aquele que apresentou maior reduÃÃo no crescimento foliar, enquanto os clones BRS 189 e CCP 09 foram os que apresentaram as menores reduÃÃes. A salinidade inibiu a mobilizaÃÃo das reservas cotiledonÃrias, principalmente, na dose mais elevada de sal. A reduÃÃo no crescimento, pela salinidade, correlacionou-se com a reduÃÃo na taxa de fotossÃntese lÃquida. Os clones CCP 06 e BRS 189 apresentaram, respectivamente, a maior e a menor reduÃÃo na taxa fotossintÃtica a 8 dS.m-1. Embora a salinidade tenha reduzido a condutÃncia estomÃtica dos clones de cajueiro anÃo-precoce, essa reduÃÃo nÃo foi acompanhada por mudanÃas nas concentraÃÃes internas de CO2. Os clones estudados nÃo apresentaram alteraÃÃes, em funÃÃo da salinidade, no estado hÃdrico das folhas e raÃzes, porÃm, apresentaram reduÃÃes no potencial osmÃtico, favorecendo o ajustamento osmÃtico e, consequentemente, a manutenÃÃo da turgescÃncia dos tecidos. Sob condiÃÃes de estresse salino, os clones BRS 189 e CCP 09 foram os mais eficientes na regulaÃÃo do transporte do Ãon Na+ para a parte aÃrea da plÃntula, acumulando-o nas raÃzes. Em relaÃÃo ao Cl-, o clone CCP 09 mostrou-se o mais eficiente no controle do transporte desse Ãon. PorÃm, CCP 06 foi o clone que mais acumulou ambos os Ãons tÃxicos na parte aÃrea da planta. Com o aumento da salinidade, os teores de potÃssio dos clones estudados tiveram seus valores reduzidos apenas nas raÃzes. Na dose de 8 dS.m-1, o BRS 189 foi o clone que mais aumento suas concentraÃÃes de N-aminosolÃveis e prolina no suco radicular. Nesse mesmo nÃvel de sal, a salinidade aumentou a concentraÃÃo de carboidratos apenas nos clones CCP 06 e BRS 189. De posse destes resultados, o segundo experimento foi realizado com os clones CCP 06 e BRS 189 que foram os que se mostraram, respectivamente, o menos e o mais tolerante à salinidade. Esse experimento teve por objetivo estudar os efeitos da salinidade (NaCl a 8 dS.m-1) na atividade da H+-ATPase e na composiÃÃo e peroxidaÃÃo dos lipÃdios de membrana plasmÃtica isoladas de raÃzes das plÃntulas dos dois clones contrastantes. A salinidade estimulou a atividade da H+-ATPase apenas no clone tolerante, o BRS 189, sendo esse clone o que apresentou maior conteÃdo de esterÃis totais e menor relaÃÃo fosfolipÃdios totais (PLt)/ esterÃis totais (Et), tanto em condiÃÃes controle como de estresse. Esses resultados foram concordantes com o fato de ter sido o BRS 189 o clone que melhor excluiu o Na+ da parte aÃrea. Nesse clone nÃo foram observadas alteraÃÃes nos teores de malondialdeÃdo, diferentemente do que ocorreu com o CCP 06, cujos teores aumentaram com o estresse salino. A maior proteÃÃo da membrana plasmÃtica do clone BRS 189 ao dano oxidativo està de acordo com os maiores acÃmulos de prolina e N-aminossolÃveis observados nesse clone. Os principais fosfolipÃdios da membrana plasmÃtica isolada de raÃzes do clone BRS 189 foram fosfatilglicerol (PG), fosfatidiletalonamina (PE) e fosfatilserina (PS). A salinidade provocou alteraÃÃes nas proporÃÃes relativas dos fosfolipÃdios, sendo PE e fosfatidilinositol (PI) os que apresentaram maiores aumentos em relaÃÃo ao total, enquanto que fosfatidilglicerol (PG) e Ãcido fosfatÃdico (PA) foram os que apresentaram maiores reduÃÃes. A percentagem de PS, em relaÃÃo ao total, nÃo foi afetada pela salinidade. No entanto, a relaÃÃo entre essas mudanÃas na composiÃÃo lipÃdica do BRS 189 pela salinidade e o aumento na atividade da H+-ATPase necessita ser melhor investigada. / Early-dwarf cashew seedlings (Anacardium occidentale L.) were used in order to investigate the physiological and biochemical changes induced by salt stress. The seeds (nuts) were sown in plastics pots containing vermiculite moistened with either distilled water (control treatment) or NaCl solutions at 8 and 16 dS.m-1 of electrical conductivity (saline treatment), and kept in greenhouse throughout the experimental period. Uniform 28-day-old seedlings were used for the analyses. The first experiment aimed to select, among five clones (CCP 06, CCP 09, CCP 76, Embrapa 51 and BRS 189), the ones showing contrasting salt-tolerance. The effect of salinity on the growth, gas exchange, water content, leaf succulence, osmotic potential and inorganic (Na+, Cl-, K+) and organic (proline, soluble carbohydrates, quaternary ammonium compounds) solute concentration for both salt-sensitive and salt-tolerant clones was studied. Salinity inhibited the growth of all clones studied, being the inhibitory effect on shoot growth more conspicuous than in root growth. Clone CCP 06 leaf area was the most inhibited by salt stress, while clones BRS 189 and CCP 09 leaf areas were the least affected by salinity. Salt stress caused a great decrease in the cotyledon reserve mobilization especially at 16 dS.m-1. Growth reduction was correlated to the reduction in net photosynthetic rate. CCP 06 and BRS 189 showed the greatest and the lowest reduction in photosynthetic rate at 8 dS.m-1, respectively. Although, salinity reduced stomatal conductance, this reduction was not followed by changes in CO2 internal concentration. The water status, expressed as water content in relation to dry mass, was not changed by salt-stress. Salinity induced the lowering of osmotic potential both in leaves and roots of all clones studied. This osmotic adjustment might have lead to turgor maintenance of those tissues. The concentrations of Cl- and Na+ increased with increasing salt stress. Clones BRS 189 and CCP 09 accumulated more Na+ in the roots, and this could explain their efficiency in maintaining a lower ion concentration in shoots, i.e. they regulated more efficiently the transport of Na+ from roots to shoots. The regulation of Cl- transport to shoots was more efficient in clone CCP 09 than in the others. Salinity did not induce significant changes in leaves and stems K+ concentration, but it induced a reduction of K+ concentration in roots. Salinity also induced increases of quaternary ammonium compounds and proline concentration in BRS 189 root at 8 dS.m-1. In addition, this level of salinity increased soluble carbohydrates in the root sap especially in clones BRS 189 and CCP 06. During the second experiment, the effect of salt stress (NaCl at 8 dS.m-1) on the activity of H+-ATPase, lipid composition and peroxidation of root plasma membrane of both salt-tolerant (BRS 189) and salt- sensitive (CCP 06) clones were studied. The vanadate-sensitive H+-ATPase activity was studied in plasma membrane-enriched vesicles isolated by discontinuous sucrose gradient centrifugation from roots. ATP hidrolizing activity in this fraction was mostly inhibited by vanadate and scarcely, by azide and molybdate, indicating that it was essentially enriched in plasma membrane vesicles. Salinity induced a 1.3-fold increase in the H+-ATPase specific activity in roots of BRS 189 seedlings. Salinity had no appreciable effect on the hydrolytic activity of this enzyme during the growth of CCP 06 seedlings. Likewise, clone BRS 189 roots plasma membrane showed higher sterol content and lower phospholipids/total sterol ratio than clone CCP 06. Both properties could contribute to the decrease in Na+ influx or increase in Na+ efflux or âexclusionâ from roots. This could result in less Na+ being transported to the shoot, and thus explaining the higher salt-tolerance of clone BRS 189. The higher degree of root plasma membrane lipid peroxidation of clone, and the lower proline and ammonium quaternary compounds contents of CCP 06 when compared to BRS 189 could also explain the differences in salt-tolerance between the two clones. These organic solutes could protect and stabilize plasma membrane against oxidative stress. Phosphatidylglycerol (PG), phosphatidylethanolamine (PE) and phosphatidylserine (PS) were the major phospholipids in the plasma membrane from BRS 189 roots. Salinity induced increases in the relative proportions of PE and phosphatidylinositol (PI), while PG and PA were reduced. No changes were detected in PS in relation to control plant. The importance of lipid composition changes on H+-ATPase activity must be more studied.

Complexos diimínicos de cobre(II) têm despertado grande interesse como modelos estruturais e funcionais do sítio ativo de diversas proteínas e enzimas dependentes deste metal, particularmente aquelas relacionadas ao oxigênio molecular e seus derivados reduzidos. Embora sejam bons miméticos da SOD, uma enzima antioxidante, estes compostos também podem apresentar atividade peroxidásica considerável, causando danos oxidativos a diversos substratos. Neste trabalho, 3 novos complexos diimínicos de cobre(II), derivados de 2,3-butanodiona e 2-(2-aminofenil)benzimidazol, 2-(aminometil)benzimidazol ou 2-(2-aminoetil)piridina, foram sintetizados e posteriormente caracterizados através de análise elementar, medidas magnéticas e espectroscopia UV/Vis, IR e EPR, com a finalidade de verificar como modificações no ligante podem modular suas propriedades, especialmente frente a oxidantes biológicos, como peróxido de hidrogênio e peroxinitrito. Estes novos complexos preparados tiveram ainda suas propriedades comparadas às de espécies semelhantes, derivadas de piridinaldeído e etilenodiamina ou acetilpirazina e propilenodiamina, estudadas anteriormente. As propriedades antioxidantes dos complexos foram estimadas através da atividade catalítica acentuada na dismutação de radicais superóxidos, em comparação a complexos similares descritos na literatura, indicando que estas espécies são bons miméticos da SOD. Evidências da distorção tetraédrica ao redor do íon cobre, similar à observada na enzima nativa, foram obtidas através de parâmetros espectroscópicos característicos. Os novos complexos também mostraram atividade pró-oxidante, gerando radicais hidroxil em quantidades apreciáveis, em presença de peróxido de hidrogênio, detectados e identificados por EPR com a adição de captador de spin. Danos oxidativos promovidos por estas espécies complexas foram observados através da peroxidação lipídica de lipossomos de fosfatidilcolina de lecitina. Estes danos foram expressivamente aumentados em presença de íons nitrito e/ou bicarbonato. Sua atividade catalítica na decomposição do peroxinitrito, em presença e ausência de dióxido de carbono, bem como na nitração do 4-hidroxifenilacetato, mediada por peroxinitrito, foi também estudada através de medidas de cinética rápida (stopped-flow). Evidências de intermediários de reação foram obtidas através de mudanças significativas no espectro EPR. As propriedades eletroquímicas e a estabilidade termodinâmica relativa dessas espécies, estimada pela técnica de dicroismo circular, usando a albumina bovina como quelante fisiológico, foram também verificadas. Todos os estudos relatados foram desenvolvidos para melhor correlacionar a reatividade observada com determinadas características estruturais dos complexos de cobre preparados. / Many investigations on diimine copper(II) complexes have been carried out in order to mimic functional and structural properties of the active sites in proteins and enzymes dependent on this metal. Special interest has been focused on their reactivity toward molecular oxygen and its reduced derivatives, and more recently toward peroxynitrite. These diimine copper(II) complexes exhibited SOD-like activities, but have also shown considerable peroxidase activity, causing oxidative damage to different targets. In this work, some new diimine copper(II) complexes were prepared, derived from 2,3-butanedione and 2-(2-aminophenyl)benzimidazole, 2-(aminomethyl) benzimidazole or 2-(2-aminoethyl)pyridine, and characterized using UV/Vis, IR and EPR spectroscopy, elemental analysis and determination of the effective magnetic moment. Those complexes have also been compared to similar species, derived from pyridinaldehyde and ethylenediamine, or acetylpyrazine and propylenediamine, previously prepared. The studied complexes showed significant SOD activity, indicative of antioxidant properties, and a pronounced tetrahedral distortion around the copper ion, estimated by characteristic spectroscopic parameters. On the other hand, the new compounds also exhibited pro-oxidant activities, by generating hydroxyl radicals in the presence of hydrogen peroxide, detected by the spin-trapping EPR method. The extension of lipid peroxidation promoted by these diimine copper(II) complexes was also investigated, using liposomes of lecithin L-&#945;-phosphatidylcholine as membrane mimics. An enhancement of their peroxidase activity in the presence of bicarbonate and/or nitrite anion was also observed. Further, the decomposition of peroxynitrite, in the presence and absence of carbon dioxide, and the peroxynitrite-mediated nitration of 4-hydroxyphenylacetate, catalyzed by these copper compounds, was measured by stopped-flow kinetic runs. Evidence of intermediary species was provided by significant changes in the EPR spectra. Finally, their electrochemical properties were estimated by cyclic voltammetry and their relative thermodynamic stability was verified through the technique of circular dicroism, using a competitive reaction with albumin, a physiological Cu(II) chelator. All those studies were performed at the aim of correlating some structural characteristics to the observed reactivity of the diimine copper(II) complexes.