Neste trabalho, estudou-se a degradação do bisfenol A (BPA) em solução aquosa através da fotólise direta sob radiação UV em 254 nm. Os experimentos foram realizados um reator fotoquímico tubular de vidro de 3,9 L, equipado com uma lâmpada de vapor de mercúrio de baixa pressão tubular concêntrica (36 W). Avaliaram-se os efeitos da taxa específica de emissão de fótons (0,87×10 18 ; 1,4×1018 e 3,6×1018 fótons L-1 s-1 ) e da concentração inicial de BPA (10 a 50 mg L-1 ), conforme um projeto experimental Doehlert. Os resultados dos experimentos indicaram que a degradação do BPA diminui com o aumento de sua concentração inicial, seguindo decaimento de pseudo primeira-ordem. A constante cinética de velocidade de degradação do BPA variou de 0,001 a 0,0066 min-1 , enquanto a porcentagem de degradação de BPA ao final de 120 minutos variou de 14 a 55%; já a remoção do carbono orgânico total variou entre 1,5 e 12,5%. Houve a formação de produtos persistentes e as espécies reativas de oxigênio (1 O2 oOH ) mostraram-se muito importantes durante a degradação do BPA. O rendimento quântico para fotólise de BPA foi de 0,0075 mol BPA mol fótons-1, determinado a partir dos dados experimentais através de um modelo matemático para degradação fotolítica do BPA em função do tempo. Para tanto, considerou-se um sistema de tratamento formado por um reator tubular e um tanque de mistura com recirculação entre eles, sendo o reator tubular tratado como uma série de três reatores contínuos de mistura perfeita (CSTR) associados entre si. Através da análise estatística dos dados experimentais para duas respostas (constante específica de degradação do BPA e porcentagem de degradação do BPA ao final de 120 minutos) avaliaram-se os efeitos das variáveis envolvidas (concentração inicial de BPA e taxa específica de emissão de fótons). / The aim of this study was to evaluate bisphenol A (BPA) degradation in aqueous solution by direct photolysis under UV radiation at 254 nm, considering the effects of the specific rate of photon emission (0.87×1018; 1.4×1018 and 3.6×1018 fótons L-1 s-1) and the initial BPA concentration (10-50 mg L-1), according to a Doehlert experimental design. The experiments were performed in a glass tubular photochemical reactor of 3.9 L equipped with a concentric low pressure mercury vapor lamp of 36 W. The experimental results indicated that BPA degradation decreases with increasing initial concentration, following pseudo first-order decay, and increases with increasing specific rate of photon emission. The values of the specific BPA degradation rate varied in the range 0.001-0.0066 min-1, while BPA percent degradation at 120 minutes of irradiation varied from 14 to 55%; TOC removal varied from 1.5 to 12.5%. Persistent degradation products were formed, and oxygen reactive species (1O2, oHO) showed to exhibit an important role during BPA degradation. The obtained quantum yield of BPA photolysis was 0.0075 mol BPA mol photons-1, determined from the experimental data through a mathematical model for BPA photolytic degradation versus time. With that aim a treatment system formed by a tubular reactor connected with a mixing tank with recirculation between them was considered; the tubular reactor was treated as a series of three associated continuous perfect mixing reactors (CSTR). Through statistical analysis of the experimental data for two responses (specific BPA degradation rate and BPA percent degradation at 120 minutes), the effects of the variables involved in BPA degradation (initial BPA concentration and specific rate of photon emission) were discussed.

This master thesis deals with the methods of measurement of singlet oxygen steady state concentrations in surface water and the factors affecting this concentration. The first part of this work shows theoretical background and an introduction to photochemistry of surface water with respect to the reactive oxygen species. The second part describes the methodology of conducted experiments and discuss its results with respect to current literature.

Dietas hiperlipídicas e a esteatose hepática são condições extremamente prevalentes. Trabalhos anteriores mostraram que a esteatose está associada a um aumento na geração de espécies reativas de oxigênio (ERO), e que isso pode mediar danos no fígado. Neste trabalho nós investigamos os possíveis mecanismos que desencadeiam os aumentos nas taxas de geração de ERO por meio da administração de dietas hiperlipídicas. Nós descobrimos que mitocôndrias de animais sujeitos a dietas hiperlipídicas não apresentaram diferenças significativas quanto a capacidade respiratória máxima e acoplamento, mas eram capazes de gerar mais ERO especificamente quando usados substratos do metabolismo de ácidos graxos. Além disso, foi observado que muitas isoformas de acil-CoA desidrogenases estavam mais expressas nos fígados de animais alimentados pela dieta hiperlipídica. No entanto, quando realizados ensaios de atividade enzimática apenas a acil CoA desidrogenase de cadeia longa (VLCAD) foi mais ativa. Estudos conduzidos com mitocôndrias permeabilizadas e expostas a grupos acil-CoA de diferentes tamanhos sugerem que a VLCAD pode ser uma fonte da produção aumentada de ERO em animais submetidos a dietas hiperlipídicas. Esta produção foi estimulada pela ausência de NAD+. Concluindo, nossos estudos descobriram uma nova fonte importante na geração de ERO estimulada por dietas hiperlipídicas, a VLCAD / High fat diets and accompanying hepatic steatosis are highly prevalent conditions. Previous work has shown that steatosis occurs concomitantly with enhanced reactive oxygen species (ROS) generation, which may mediate further liver damage. Here we investigated mechanisms leading to enhanced ROS generation following high fat diets (HFD). We found that mitochondria from HFD livers present no differences in maximal respiratory rates and coupling, but generate more ROS specifically when fatty acids are used as substrates. Indeed, many acyl-CoA dehydrogenase isoforms were found to be more highly expressed in HFD livers, although only the very long chain acyl-CoA dehydrogenase (VLCAD) was more functionally active. Studies conducted with permeabilized mitochondria and different chain length acyl-CoA derivatives suggest that VLCAD is a source of enhanced ROS production in mitochondria from HFD animals. This production is stimulated by the lack of NAD+. Overall, our studies uncover VLCAD as a novel, diet-sensitive, source of mitochondrial ROS

Submitted by Marcos Anselmo (marcos.anselmo@unipampa.edu.br) on 2018-09-26T19:14:34Z No. of bitstreams: 1 FRANCIANE CABRAL PINHEIRO 2017.pdf: 1590599 bytes, checksum: de1f617c03dded70f415d324f08c9791 (MD5) / Approved for entry into archive by Marcos Anselmo (marcos.anselmo@unipampa.edu.br) on 2018-09-26T19:14:53Z (GMT) No. of bitstreams: 1 FRANCIANE CABRAL PINHEIRO 2017.pdf: 1590599 bytes, checksum: de1f617c03dded70f415d324f08c9791 (MD5) / Made available in DSpace on 2018-09-26T19:14:53Z (GMT). No. of bitstreams: 1 FRANCIANE CABRAL PINHEIRO 2017.pdf: 1590599 bytes, checksum: de1f617c03dded70f415d324f08c9791 (MD5) Previous issue date: 2017-09-06 / O uso indiscriminado de antibióticos faz com que algumas cepas bacterianas desenvolvam defesas contra agentes antibacterianos, com o consequente aparecimento da resistência antimicrobiana. Bactérias como a Escherichia coli, que estão presentes na flora microbiana dos indivíduos, tem demostrado um aumento significativo na resistência à antibióticos, e junto deste aumento da resistência surge à busca por novos fármacos para combater estes microrganismos resistentes. Os compostos orgânicos de telúrio tem demostrado em estudos apresentar capacidade antimicrobiana frente à cepas de bactérias Gram-negativas e Gram-positivas. Esta classe de compostos tem seus efeitos relacionados principalmente à sua capacidade de oxidação de grupos tióis (SH). Este trabalho teve como objetivo verificar a atividade antimicrobiana do composto teluroacetileno 2-feniletinil-butiltelurio (PEBT), sobre cepas de E.coli, bem como estudar se o mecanismo de ação antimicrobiano está relacionado ao seu efeito pró-oxidante. Para a avaliação da atividade antimicrobiana do composto PEBT foram realizados os testes de: disco difusão com o composto nas concentrações de 1.28mg/disco, 0.128mg/disco, 0.0128mg/disco e 0.00128mg/disco; concentração inibitória mínima (CIM) com o composto nas concentrações de 3.84mg/ml; 1.92mg/ml; 0.96mg/ml; 0.48mg/ml; 0.24 mg/ml; 0.12 mg/ml; 0.06 mg/ml e 0.030mg/ml e curva de sobrevivência, com as 3 concentrações do composto 0.96 mg/ml; 1.92mg/ml e 3.84mg/ml(correspondentes ao 0,5CIM, CIM e 2CIM, respectivamente). Para avaliar se o mecanismo de ação do composto PEBT sobre a célula bacteriana, estava relacionado à sua atividade pro-oxidante, foram dosados os níveis de espécies reativas (ER); atividade das enzimas antioxidantes superóxido dismutase (SOD) e catalase (CAT), e para avaliar a oxidação de grupamentos tióis foi realizada a dosagem intracelular de níveis de tióis não proteicos (NPSH) nas culturas bacterianas em presença ou ausência do composto nas concentrações de 0.96 mg/ml; 1.92mg/ml e 3.84mg/ml. A fim de confirmar seu efeito pro-oxidante, foram adicionados os antioxidantes glutationa (GSH) e ácido ascórbico (AA) ao meio de cultura. Como resultado, nosso estudo mostrou a capacidade antimicrobiana do composto PEBT nas concentrações 1.28mg/disco e 0.128mg/disco através da formação de halos de inibição no teste de disco difusão, sendo a menor concentração do composto capaz de inibir o crescimento bacteriano de 1.92mg/ml, e no teste de curva de sobrevivência o composto foi capaz de causar a inviabilidade das células bacterianas após o tempo de 9 horas de exposição nas 3 diferentes concentrações 9 testadas. Nossos resultados demostram que a presença do composto nas 3 concentrações testadas levou ao aumento na produção de ER nas células da E. coli, concomitante a uma diminuição dos níveis de tióis intracelulares e redução na atividade das enzimas antioxidante SOD a CAT. Associado a isso, quando foi acrescido ao meio os antioxidantes GSH e AA, estes foram capazes de proteger a célula bacteriana do efeito antimicrobiano, através do desaparecimento do halo de inibição no teste de disco difusão. Contudo, nosso estudo sugere que o composto PEBT possui atividade antimicrobiana frente a cepas de E.coli, tendo como mecanismo de ação a geração de ER, oxidação de grupos tióis e diminuição das defesas antioxidantes da célula bacteriana. / The indiscriminate use of antibiotics causes some bacterial strains to develop defenses against antibacterial agents, with the consequent appearance of antimicrobial resistance. Bacteria such as Escherichia coli, which are present in the microbial flora of individuals, have shown a significant increase in resistance to antibiotics, and along with this increase of resistance comes the search for new drugs to combat these resistant microorganisms. Organic tellurium compounds have shown antimicrobial ability against strains of Gram-negative and Gram-positive bacteria. This class of compounds have these effects related to the oxidation of thiols groups. In this way, the objective of this work was to verify the antimicrobial activity of 2-phenylethynyl butyltelurium (PEBT) in strains of E. coli, as well as, to study if the antimicrobial action is related to its pro-oxidant effect. For the evaluation of the antimicrobial activity of the PEBT the following tests were performed: Disc diffusion with PEBT at the concentrations of 1.28; 0.128; 0.0128 and 0.00128 mg/disc; minimum inhibitory concentration (MIC) with PEBT at concentrations of 3.84; 1.92; 0.96; 0.48; 0.24; 0.12; 0.06 and 0.030 mg/ml; and survival curve, with PEBT at concentrations of 0.96; 1.92 and 3.84 mg/ml (corresponding to 0.5MIC, MIC and 2MIC, respectively). To evaluate if the antimicrobial action is related to its pro-oxidant effect we carried out the levels of extracellular reactive species (RS); activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) and levels of non-protein thiols (NPSH). In order to confirm its pro-oxidant effect, the antioxidants glutathione (GSH) and ascorbic acid (AA) were added to the culture medium. Our study has demonstrated that PEBT has antimicrobial capability at concentrations of 1.28 and 0.128 mg/disc by formation of inhibition halo in the diffusion disc test. Additionally, the lowest concentration of the compound capable of inhibiting bacterial growth was 1.92 mg/ml, and in the survival curve test the compound was able to cause bacterial cell infeasibility after the 9 hour exposure time at the concentrations of 0.96; 1.92 and 3.84mg/ml. Our results in biochemical analysis show that the presence of the PEBT at concentrations of 3.84; 1.92 and 0.96mg/ml is able to induce an increase in extracellular RS production in E. coli cells, concomitant with a decrease in intracellular thiol levels and a reduction in the activity of antioxidant enzymes SOD and CAT. Associated with these results, the addiction of GSH and AA to the medium was able to protect the bacterial cell from the antimicrobial effect of PEBT, by disappearance of the inhibition halo in the disc 11 diffusion test. Taken together, our results suggest that the PEBT presents antimicrobial activity against strains of E. coli and its action is related to the generation of RS, oxidation of thiol groups and decrease of the antioxidant defenses of the bacterial cell.

A Araucaria angustifólia é uma conífera nativa do Brasil que apresenta sementes recalcitrantes. Devido a sua importância econômica, foi intensamente explorada ao longo dos anos, encontrando-se atualmente classificada como espécie em perigo crítico de extinção pela International Union for Conservation of Nature. A embriogênese somática apresenta-se como uma ferramenta biotecnológica de grande valia na propagação de espécies recalcitrantes e de difícil propagação, com aplicação em programas de conservação, reflorestamento, e melhoramento genético vegetal. Estudos comparativos dos processos de embriogênese somática e zigótica têm permitido o conhecimento dos fatores bioquímicos, fisiológicos e genéticos que controlam o desenvolvimento do embrião, e o estabelecimento as condições artificiais para o correto desenvolvimento embrionário in vitro. O objetivo deste trabalho foi estudar a participação do ácido salicílico como sinalizador do processo de embriogênese zigótica e somática em A. angustifólia. Para tanto foi determinado o conteúdo de ácido salicílico livre e conjugado ao longo da embriogênese zigótica, e o efeito de sua suplementação em culturas embriogênicas com diferentes potenciais para a maturação. Para a embriogênese somática, a presença do ácido salicílico foi correlacionada com a geração de óxido nítrico e espécies reativas de oxigênio , e com a expressão do gene \"Somatic Embryogenesis Receptor Kinase\" (AaSERK). Os resultados obtidos demonstram que: a) ocorre um maior conteúdo de ácido salicílico na forma livre e conjugada nas etapas iniciais da embriogênese zigótica; b) a suplementação de ácido salicílico, nas concentrações de 0,5 a 2 mM, inibiram a indução de culturas embriogênicas; c) culturas embriogênicas incubadas em ácido salicílico apresentaram redução da síntese endógena de espécies reativas de oxigênio e aumento no conteúdo de óxido nítrico; d) a redução de espécies reativas de oxigênio indicou uma relação dose dependente com o ácido salicílico; e) a adição de um doador de óxido nítrico e um sequestrador inibiram a produção de espécies reativas de oxigênio; f) a expressão do gene AaSERK atingiu o maior nível no período de quatro horas de incubação em 0,1 mM de AS / Araucaria angustifolia is a conifer native of Brazil with recalcitrant seeds. Due to its economic importance, the exploration has been extensively over the years, currently this specie is classified as critically endangered by the International Union for Conservation of Nature. Somatic embryogenesis is presented as a biotechnological tool of great value in the propagation of recalcitrant species and difficult to spread, with applications in conservation, reforestation programs, and plant breeding. Comparative studies of the processes of zygotic and somatic embryogenesis has allowed the knowledge of biochemical, physiological and genetic factors that control embryo development, and the establishment artificial conditions for proper embryonic development in vitro. The objective of this work was to study the role of salicylic acid as a marker of zygotic embryogenesis and somatic process in A. angustifolia. Thus, we determined the content of free salicylic acid and conjugated along the zygotic embryogenesis, and the effect of their supplementation with different potential embryogenic cultures for maturation. For somatic embryogenesis, the presence of salicylic acid was correlated with the generation of nitric oxide, reactive oxygen species and in the gene expression \"Somatic embryogenesis Receptor Kinase\" (AaSERK). The results show that: a) there is an increased content of salicylic acid in free and conjugated form in the initial stages of zygotic embryogenesis; b) salicylic acid supplementation, in concentrations from 0.5 to 2 mM, inhibited the induction of embryogenic cultures; c) embryos incubated in salicylic acid decreased endogenous synthesis of reactive oxygen species and increase in content of nitric oxide; d) the reduction of reactive oxygen species indicated a dose-dependent relationship with salicylic acid; e) the addition of a nitric oxide donor and a kidnapper inhibited the production of reactive oxygen species; f) the expression of the gene AaSERK reached the highest level in four hours of incubation in 0.1 mM AS

by Yau Ming Hon. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 131-154). / Abstracts in English and Chinese. / Contents --- p.i / Acknowledgements --- p.ix / Abstract --- p.x / 槪論 --- p.xi / List of abbreviations --- p.xii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Reactive oxygen species (ROS) --- p.2 / Chapter 1.1.1 --- Hydrogen peroxide --- p.2 / Chapter 1.1.2 --- Superoxide anion --- p.3 / Chapter 1.1.3 --- Hydroxyl radical --- p.3 / Chapter 1.1.4 --- Carbon centered radical --- p.4 / Chapter 1.1.5 --- Nitric oxide --- p.4 / Chapter 1.2 --- Physiological roles of ROS --- p.5 / Chapter 1.2.1 --- Signal transduction --- p.5 / Chapter 1.2.2 --- Phagocytic activity --- p.6 / Chapter 1.3 --- Defense systems against ROS --- p.7 / Chapter 1.3.1 --- Endogenous antioxidant enzymes --- p.8 / Chapter 1.3.1.1 --- Catalase --- p.8 / Chapter 1.3.1.2 --- Superoxide dismutase --- p.8 / Chapter 1.3.1.3 --- Selenium-glutathione peroxidase --- p.9 / Chapter 1.3.1.4 --- Glutathione reductase --- p.10 / Chapter 1.3.1.5 --- Glutathione-S-transferases --- p.10 / Chapter 1.3.2 --- Non-enzymatic antioxidants --- p.12 / Chapter 1.3.2.1 --- Vitamin E (tocopherols and tocotrienols) --- p.12 / Chapter 1.3.2.2 --- Vitamin C (L-ascorbic acid) --- p.13 / Chapter 1.3.2.3 --- Glutathione --- p.14 / Chapter 1.3.2.4 --- Flavonoids and polyphenols --- p.15 / Chapter 1.3.2.5 --- Uric acid --- p.16 / Chapter 1.4 --- Roles of ROS in pathogenesis --- p.16 / Chapter 1.4.1 --- Liver diseases --- p.17 / Chapter 1.4.2 --- Genital malfunctioning --- p.19 / Chapter 1.5 --- "The traditional Chinese medicinal formula, Wu-zi-yan-zong-wan" --- p.19 / Chapter 1.5.1 --- Pharmacology of individual herbal components --- p.20 / Chapter 1.5.1.1 --- Semen Cuscuta --- p.20 / Chapter 1.5.1.2 --- Fructus Lycii --- p.21 / Chapter 1.5.1.3 --- Fructus Schisandrae --- p.21 / Chapter 1.5.1.4 --- Fructus Rubi --- p.22 / Chapter 1.5.1.5 --- Semen Plantaginis --- p.22 / Chapter 1.5.2 --- Effect of Wu-zi-yan-zong-wan on infertility --- p.23 / Chapter 1.5.3 --- Effect of Wu-zi-yan-zong-wan on liver disease --- p.23 / Chapter 1.6 --- Objectives of the present study --- p.24 / Chapter Chapter 2 --- Antioxidant Activity of Aqueous Extracts of the Herbal Components of Wu-zi-yan-zong-wan in in vitro Free Radical Generating Systems --- p.26 / Chapter 2.1 --- Introduction --- p.27 / Chapter 2.1.1 --- Application of in vitro ROS generating systems --- p.27 / Chapter 2.1.1.1 --- Superoxide generation --- p.27 / Chapter 2.1.1.2 --- Hydroxyl radical generation system --- p.28 / Chapter 2.1.1.3 --- "2,2'-Azobis(2-amidinopropane) dihydrochloride- induced hemolysis" --- p.28 / Chapter 2.1.1.4 --- Bleomycin-iron-dependent DNA damage --- p.28 / Chapter 2.1.2 --- Objective --- p.29 / Chapter 2.2 --- Materials and methods --- p.30 / Chapter 2.2.1 --- Materials --- p.30 / Chapter 2.2.2 --- Preparation of aqueous herbal extracts --- p.30 / Chapter 2.2.3 --- Superoxide-scavenging assay --- p.30 / Chapter 2.2.4 --- Microsome lipid peroxidation inhibition assay --- p.31 / Chapter 2.2.5 --- "2,2'-Azobis(2-amidinopropane) dihydrochloride-induced hemolysis inhibition assay" --- p.32 / Chapter 2.2.6 --- Bleomycin-iron-dependent DNA damage inhibition assay --- p.32 / Chapter 2.2.7 --- Statistical analysis --- p.33 / Chapter 2.3 --- Results --- p.34 / Chapter 2.3.1 --- Extraction yield --- p.34 / Chapter 2.3.2 --- Free radical scavenging activity of Wu-zi-yan-zong-wan extract --- p.34 / Chapter 2.3.3 --- Free radical scavenging activity of FR extract --- p.37 / Chapter 2.3.3.1 --- Superoxide-scavenging activity --- p.37 / Chapter 2.3.3.2 --- Effect on hydroxyl radical-induced lipid peroxidation --- p.37 / Chapter 2.3.3.3 --- Effect on AAPH-induced hemolysis --- p.40 / Chapter 2.3.3.4 --- Effect on bleomycin-iron-dependent DNA damage --- p.40 / Chapter 2.3.4 --- Pro-oxidant activity of FR extract --- p.40 / Chapter 2.3.5 --- Free radical scavenging activity of the remaining herbal extracts --- p.44 / Chapter 2.4 --- Discussion --- p.46 / Chapter Chapter 3 --- Effect of Aqueous Extract of the Herbal Components of Wu- zi-yan-zong-wan on tert-Butyl Hydroperoxide-Induced Oxidative Damage in Primary Rat Hepatocyte --- p.51 / Chapter 3.1 --- Introduction --- p.52 / Chapter 3.1.1 --- Primary rat hepatocyte as pharmacological model --- p.52 / Chapter 3.1.2 --- tert-Butyl hydroperoxide as an oxidative stress inducer --- p.53 / Chapter 3.1.3 --- Detection of ROS --- p.54 / Chapter 3.1.4 --- Objective --- p.55 / Chapter 3.2 --- Materials and methods --- p.56 / Chapter 3.2.1 --- Materials --- p.56 / Chapter 3.2.2 --- Primary rat hepatocyte isolation --- p.56 / Chapter 3.2.2.1 --- Liver perfusion --- p.56 / Chapter 3.2.2.2 --- Collagen pre-coated plates preparation --- p.57 / Chapter 3.2.2.3 --- Hepatocyte culture --- p.58 / Chapter 3.2.3 --- Drug treatment and oxidative stress induction --- p.58 / Chapter 3.2.4 --- Cytotoxicity assessment --- p.58 / Chapter 3.2.4.1 --- Lactate dehydrogenase leakage measurement --- p.59 / Chapter 3.2.4.2 --- MTT assay --- p.59 / Chapter 3.2.5 --- Cellular GSH content determination --- p.59 / Chapter 3.2.6 --- Protein determination by Lowry's method --- p.60 / Chapter 3.2.7 --- MDA measurement --- p.60 / Chapter 3.2.8 --- GSSG measurement --- p.61 / Chapter 3.2.9 --- ROS measurement with fluorescent dye --- p.61 / Chapter 3.2.10 --- "Vitamin C, vitamin E and butylated hydroxytoluene treatment" --- p.62 / Chapter 3.2.11 --- Antioxidant enzyme activity measurement --- p.62 / Chapter 3.2.11.1 --- Catalase activity measurement --- p.62 / Chapter 3.2.11.2 --- Superoxide dismutase activity measurement --- p.63 / Chapter 3.2.11.3 --- Glutathione peroxidase activity measurement --- p.63 / Chapter 3.2.11.4 --- Glutathione-S-transferases activity measurement --- p.63 / Chapter 3.2.11.5 --- Glutathione reductase activity measurement --- p.64 / Chapter 3.2.12 --- Statistical analysis --- p.64 / Chapter 3.3 --- Results --- p.65 / Chapter 3.3.1 --- Cytotoxicity of FR extract on rat hepatocyte --- p.65 / Chapter 3.3.2 --- Effect of tBHP and FR extract on hepatocyte viability --- p.65 / Chapter 3.3.3 --- Time-dependent effect of FR extract on tBHP-induced cytotoxicity --- p.69 / Chapter 3.3.4 --- Effect of tBHP and FR extract on hepatocyte GSH content --- p.69 / Chapter 3.3.5 --- Effect of tBHP and FR extract on GSSG formation in hepatocyte --- p.72 / Chapter 3.3.6 --- Effect of tBHP and FR extract on MDA formation in hepatocyte --- p.72 / Chapter 3.3.7 --- ROS-scavenging activity of FR extract in hepatocyte --- p.77 / Chapter 3.3.8 --- Effect of FR extract on antioxidant enzymes activities --- p.77 / Chapter 3.3.9 --- Comparison between typical antioxidants --- p.77 / Chapter 3.3.10 --- Effect of WZ and remaining herbal extracts on tBHP-induced oxidative damage in hepatocyte --- p.81 / Chapter 3.4 --- Discussion --- p.84 / Chapter Chapter 4 --- Effect of Aqueous Extract of Wu-zi-yan-zong-wan and Fructus Rubi on tert-Buty Hydroperoxide Induced Oxidative Damage in Mouse Model --- p.91 / Chapter 4.1 --- Introduction --- p.92 / Chapter 4.2 --- Materials and methods --- p.93 / Chapter 4.2.1 --- Materials --- p.93 / Chapter 4.2.2 --- Animal treatments --- p.93 / Chapter 4.2.3 --- Serum preparation --- p.94 / Chapter 4.2.4 --- Marker enzyme measurement --- p.94 / Chapter 4.2.5 --- Liver MDA and GSH determination --- p.95 / Chapter 4.2.6 --- Statistical analysis --- p.95 / Chapter 4.3 --- Results --- p.97 / Chapter 4.3.1 --- Effect of tBHP and FR extract on mouse serum ALT and AST activities --- p.97 / Chapter 4.3.2 --- Effect of tBHP and FR extract on mouse liver MDA and GSH content --- p.97 / Chapter 4.3.3 --- Effect of WZ extract on tBHP-induced increase in serum ALT and AST activities --- p.97 / Chapter 4.4 --- Discussion --- p.102 / Chapter Chapter 5 --- Characterization of the Active Antioxidant Principlein Aqueous Extract of FR --- p.105 / Chapter 5.1 --- Introduction --- p.106 / Chapter 5.2 --- Materials and methods --- p.107 / Chapter 5.2.1 --- Materials --- p.107 / Chapter 5.2.2 --- Chemical/physical treatments on FR extract --- p.107 / Chapter 5.2.3 --- Digestion with enzymes --- p.108 / Chapter 5.2.4 --- Antioxidant activity determination --- p.109 / Chapter 5.2.5 --- Chemical composition determination --- p.109 / Chapter 5.2.5.1 --- Uronic acid determination --- p.109 / Chapter 5.2.5.2 --- Hexose determination --- p.109 / Chapter 5.2.5.3 --- Tannin determination --- p.110 / Chapter 5.2.5.4 --- Protein determination --- p.110 / Chapter 5.2.6 --- Column chromatography --- p.110 / Chapter 5.2.6.1 --- Polyamide CC6 resin column chromatography --- p.111 / Chapter 5.2.6.2 --- Sephadex LH-20 gel column chromatography --- p.111 / Chapter 5.2.7 --- Antioxidant activity of commercially available tannin --- p.111 / Chapter 5.2.8 --- Bovine serum albumin precipitation --- p.112 / Chapter 5.2.9 --- Statistical analysis --- p.112 / Chapter 5.3 --- Results --- p.113 / Chapter 5.3.1 --- Effect of chemical/physical treatments on antioxidant activity of FR extract --- p.113 / Chapter 5.3.2 --- Effect of enzyme digestions on antioxidant activity of FR extract --- p.113 / Chapter 5.3.3 --- Chemical composition of FR extract --- p.118 / Chapter 5.3.4 --- Polyamide CC6 resin column chromatography --- p.118 / Chapter 5.3.5 --- Sephadex LH-20 gel column chromatography --- p.118 / Chapter 5.3.6 --- Antioxidant activity of commercially available tannin --- p.123 / Chapter 5.3.7 --- Effect of BSA precipitation on superoxide-scavenging activity --- p.123 / Chapter 5.4 --- Discussion --- p.127 / Conclusion --- p.131 / References --- p.132

Dietas hiperlipídicas e a esteatose hepática são condições extremamente prevalentes. Trabalhos anteriores mostraram que a esteatose está associada a um aumento na geração de espécies reativas de oxigênio (ERO), e que isso pode mediar danos no fígado. Neste trabalho nós investigamos os possíveis mecanismos que desencadeiam os aumentos nas taxas de geração de ERO por meio da administração de dietas hiperlipídicas. Nós descobrimos que mitocôndrias de animais sujeitos a dietas hiperlipídicas não apresentaram diferenças significativas quanto a capacidade respiratória máxima e acoplamento, mas eram capazes de gerar mais ERO especificamente quando usados substratos do metabolismo de ácidos graxos. Além disso, foi observado que muitas isoformas de acil-CoA desidrogenases estavam mais expressas nos fígados de animais alimentados pela dieta hiperlipídica. No entanto, quando realizados ensaios de atividade enzimática apenas a acil CoA desidrogenase de cadeia longa (VLCAD) foi mais ativa. Estudos conduzidos com mitocôndrias permeabilizadas e expostas a grupos acil-CoA de diferentes tamanhos sugerem que a VLCAD pode ser uma fonte da produção aumentada de ERO em animais submetidos a dietas hiperlipídicas. Esta produção foi estimulada pela ausência de NAD+. Concluindo, nossos estudos descobriram uma nova fonte importante na geração de ERO estimulada por dietas hiperlipídicas, a VLCAD / High fat diets and accompanying hepatic steatosis are highly prevalent conditions. Previous work has shown that steatosis occurs concomitantly with enhanced reactive oxygen species (ROS) generation, which may mediate further liver damage. Here we investigated mechanisms leading to enhanced ROS generation following high fat diets (HFD). We found that mitochondria from HFD livers present no differences in maximal respiratory rates and coupling, but generate more ROS specifically when fatty acids are used as substrates. Indeed, many acyl-CoA dehydrogenase isoforms were found to be more highly expressed in HFD livers, although only the very long chain acyl-CoA dehydrogenase (VLCAD) was more functionally active. Studies conducted with permeabilized mitochondria and different chain length acyl-CoA derivatives suggest that VLCAD is a source of enhanced ROS production in mitochondria from HFD animals. This production is stimulated by the lack of NAD+. Overall, our studies uncover VLCAD as a novel, diet-sensitive, source of mitochondrial ROS

Ce travail montre qu’une protéine non encore décrite dans les phagocytes, la PAT1 « Protein interacting with APP Tail 1 », interagit avec la partie cytosolique de la p22phox (composant du cytochrome b558 membranaire de la NADPH oxydase). Nous avons utilisé différentes approches pour montrer cette interaction : le système double hybride, la technique de GST-pull down, la microscopie confocale et la technique de co-immunoprécipitation. De plus, nous avons montré que la PAT1a recombinante augmente l’activité de la NADPH oxydase, in vitro dans un système acellulaire reconstitué, et dans les cellules intactes (monocytes et cellules COS-phox). Cette nouvelle interaction régule donc l’activation de la NADPH oxydase et la production des FRO. Par ailleurs, la liaison de PAT1 aux microtubules pourrait favoriser l’assemblage du complexe NADPH oxydase pendant son activation. Ceci pourrait conduire à l’identification de nouvelles cibles thérapeutiques qui préviennent la survenue des lésions tissulaires dans les maladies inflammatoires. / Reactive oxygen species (ROS) production by the phagocyte NADPH oxidase plays a crucial role in host defenses. NADPH oxidase is composed of the membrane flavocytochrome b558 components (p22phox and gp91phox/NOX2), and cytosolic components (p40phox, p47phox, p67phox and a small GTPase Rac1 or Rac2). In this work we identified PAT1 by double hybrid system as a potential partner of p22phox. The interaction between p22phox and PAT1a was further confirmed by in vitro GST pull-down assay, confocal microscopy and co-immunoprecipitation. Addition of recombinant PAT1a to the cell free-system enhanced NADPH oxidase activation and it’s over-expression in human monocytes and in COSphox cells increased ROS production in resting and fMLP-stimulated cells.These data clearly identify PAT1 as a novel regulator of NADPH oxidase activation in phagocytes.Inhibition of p22phox/PAT1 interaction could be used as new approach to limit ROS production by phagocytes at inflammatory sites.

Les NADPH oxydases constituent une famille d’enzymes dont la fonction est dédiée à la production de formes réactives de l’oxygène. NOX1, un des membres de cette famille, est abondamment exprimée dans le colon et sa dérégulation pourrait être associée aux maladies inflammatoires chroniques de l’intestin. Les mécanismes qui modulent l’activation de NOX1 demeurent mal connus. Au cours de ma thèse je me suis donc intéressée à l’étude de la phosphorylation de NOXA1 et NOXO1, deux sous-unités régulatrices du complexe NOX1 et ai démontré 1) que la phosphorylation de NOXA1 constitue un mécanisme de régulation négative de l’activité de NOX1 en vue de maintenir l’activité constitutive du complexe à un niveau adéquat et non excessif. 2) pour la première fois, que NOXO1β est phosphorylée et que cette phosphorylation entraîne une hyperactivation de NOX1. L’ensemble de ces données montre que NOX1 est finement régulée. Par ce biais, NOX1 pourrait être impliquée dans la défense anti-infectieuse de l’intestin. / The NOX family of NADPH oxidases are enzymes which function is dedicated to the production of reactive oxygen species. NOX1, a member of this family is expressed abundantly in the intestine and its disregulation could be linked to inflammatory diseases such as inflammatory bowel diseases. However, the molecular basis of NOX1 regulation remains unclear. During my thesis, I demonstrated that 1) NOXA1, the activator cytosolic subunit of the NOX1 complex, is phosphorylated and its phosphorylation prevents hyperactivation of NOX1 in order to maintain a constitutive activity which would not be too excessive. 2) phosphorylation of human NOXO1, the organizer subunit of the complex is a prerequisite of full activation of NOX1. Taken together, these results demonstrate that NOX1 is tightly regulated by phosphorylation events. By this mean, NOX1 could be involved in host immune defense of the intestine.

As espécies reativas de oxigênio são fundamentais na fisiologia espermática. No entanto, um desequilíbrio entre a produção e a capacidade antioxidante caracteriza o estresse oxidativo (EO). O espermatozoide é extremamente suscetível ao EO pois, dentre outras características, a membrana plasmática é rica em ácidos graxos poli-insaturados responsáveis por promoverem a fluidez necessária em processos fisiológicos como motilidade e fertilização. Por outro lado, essas insaturações são mais facilmente oxidadas e vulneráveis à peroxidação lipídica. Em função desta susceptibilidade, estas células dependem fortemente de compostos presentes no plasma seminal (PS) para a proteção contra esse evento. Dessa forma, a carnosina, dipeptídeo presente no PS pode ser uma das responsáveis pela proteção contra o acúmulo do MDA. No entanto, durante a criopreservação do sêmen equino é necessário retirar o PS. Em estudo recente, verificamos que esta remoção, torna os espermatozoides sensíveis ao subproduto extremamente deletério da peroxidação lipídica, o malondialdeído (MDA). Como a carnosina é removida junto com o plasma seminal durante a criopreservação, foram desenvolvidos 2 experimentos sequenciais visando a melhora da qualidade do sêmen criopreservado com adição de carnosina. Amostras de sêmen de sete garanhões foram tratadas com concentrações crescentes de carnosina adicionadas ao diluidor (1mM, 50mM e 100mM). Após a descongelação, as amostras foram divididas retrospectivamente em grupos de alta congelabilidade (AC: motilidade maior que 30%) e baixa congelabilidade (BC: motilidade menor que 30%). Amostras tratadas com 50mM apresentaram menor porcentagem de células com lesão de membrana plasmática e, quando tratadas com 100mM, células com maior amplitude do deslocamento lateral de cabeça. Amostras controle BC apresentaram menor porcentagem de células com DNA íntegro em relação às amostras AC. No entanto, houve um leve aumento na porcentagem de células com DNA íntegro em amostras BC com 100mM, não diferindo das amostras AC. Por outro lado, amostras BC criopreservadas com 50mM apresentaram maiores porcentagens de células com escore calculado de potencial de membrana mitocondrial e mais suscetíveis ao EO em relação ao controle. Apesar da proteção parcial, a maior suscetibilidade à peroxidação lipídica torna-se um problema, especialmente pelo fato de que espermatozoides equinos são mais suscetíveis ao MDA. Um motivo para este efeito seria a afinidade da carnosina em reagir com açúcares, o que poderia influenciar negativamente a atividade mitocondrial e o status oxidativo, ao diminuir a produção de piruvato pela via glicolítica. Desta forma, no experimento 2, amostras BC foram tratadas com a combinação de carnosina (0 e 50mM) e piruvato (0 e 5mM) em arranjo fatorial 2x2. Verificou-se que o tratamento com piruvato (5mM) proporcionou menos células com baixa atividade mitocondrial. Por outro lado, a carnosina (50mM), promoveu maior motilidade total, progressiva e células rápidas. Houve uma tendência de aumento nas células com velocidade progressiva e atividade mitocondrial na combinação de tratamentos. Não houve diferença entre os grupos na suscetibilidade ao EO que, no entanto, correlacionou-se negativamente com células móveis, rápidas e integridade de membrana plasmática e acrossomal. Estes resultados indicam que subprodutos da peroxidação lipídica, sendo o principal deles o MDA, podem causar danos ao DNA, às mitocôndrias e à cinética espermática. Neste contexto, a carnosina (100mM) parece ter um leve efeito protetor ao DNA contra o acúmulo de MDA. Além disto, 50mM de carnosina parece auxiliar na manutenção da velocidade progressiva e atividade mitocondrial quando associada ao piruvato (5mM). Assim, a carnosina e o piruvato podem ser utilizados na prevenção de crioinjúrias em amostras de baixa congelabilidade. / Reactive oxygen species (ROS) plays a key role in the sperm physiology. However, an imbalance between ROS production and antioxidant capacity characterize the oxidative stress (OE). The spermatozoa are extremely susceptible to EO because, among other characteristics, the plasma membrane is rich in polyunsaturated fatty acids responsible for promoting fluidity necessary in physiological processes such as motility and fertilization. However, these unsaturations are more easily oxidized and vulnerable to lipid peroxidation. Due to this susceptibility, these cells strongly depend on compounds present in the seminal plasma (SP) to protect against this event. Thus, carnosine, a dipeptide present in SP of stallions, may be a key factor on the protection against MDA accumulation. Nevertheless, during the equine sperm cryopreservation process, SP is removed. In a recent study, we observed that seminal plasma removal led to an increased susceptibility of equine spermatozoa to extremely deleterious product of lipid peroxidation, malondialdehyde (MDA). As the carnosine is removed together with the seminal plasma during cryopreservation, two sequential experiments were developed aiming to improve the quality of stallion cryopreserved semen by means of carnosine therapy. Samples from seven stallions were treated with increasing concentrations of carnosine added to the extender (1mM, 50mM and 100mM) and submitted to cryopreservation. After thawing, samples were classified as high freezeability (HF: total motility greater than 30%) and low freezeability (LF: total motility lower than 30%). Samples treated with 50mM presented lower percentage of sperm showing plasma membrane damage and, when treated with 100mM, a greater amplitude of the lateral head displacement was observed. Untreated LF samples showed a lower percentage of cells showing intact DNA in relation to HF samples. By contrast, when LF samples were treated with 100mM, there was an increase in the percentage of cells with intact DNA, which was similar to the HF samples. On the other hand, LF samples cryopreserved with 50mM had a higher percentage of cells showing high calculated mitochondrial membrane potential score and increased susceptibility to OE in relation to the control. Despite the partial protection, the increased susceptibility to lipid peroxidation is a concern since equine spermatozoa is highly vulnerable to the MDA. Those results could be due to the affinity of carnosine to react with sugars, which could negatively influence mitochondrial activity and an oxidative state by decreasing pyruvate production. Hence, in experiment 2, LF samples were treated with a combination of carnosine (0 and 50mM) and pyruvate (0 and 5mM) in a 2x2 factorial arrangement. We observed that samples treated with pyruvate (5mM) had decreased percentage of cells with low mitochondrial activity. On the other hand, carnosine (50mM) increased total motility, progressive motility and fast cells. We also observed a tendency to increased progressive velocity and mitochondrial activity in the combination of treatments. There was no difference on sperm susceptibility to OE between treatments. However, this variable correlated negatively with the percentage of motile and rapid cells as well as those showing intact membrane and acrosome. These results indicate that the byproduct of lipid peroxidation (MDA) may cause damage to DNA, mitochondria and sperm kinetics. In this context, carnosine (100mM) appears to have a mild protective effect on DNA against the accumulation of MDA. Furthermore, 50mM of carnosine seems to improve progressive velocity and mitochondrial activity when associated with pyruvate (5mM). Thus, carnosine and pyruvate can be used on cryoinjuries prevention in low freezeability samples.