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Estudo do efeito protector da folha e fruto da espécie Arbutus unedo L. na danificação oxidativa em eritrócitos humanos

Mendes, Lídia Isaura Sousa
Fonte: [s.n.] Publicador: [s.n.]
Tipo: Dissertação de Mestrado
Publicado em //2010 POR
Relevância na Pesquisa
17.52%
Trabalho apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas; O Arbutus unedo L., vulgarmente designado por medronheiro, é uma planta endémica da região Mediterrânica amplamente utilizada na alimentação e na medicina tradicional devido às suas actividades biológicas. Estudos fitoquímicos realizados nesta espécie evidenciaram que os extractos da folha e fruto contêm diversos antioxidantes naturais. As folhas apresentam na sua constituição compostos fenólicos, tais como taninos, flavonóides e glicosídeos fenólicos e α-tocoferol, enquanto os frutos possuem também variados compostos fenólicos (antocianinas, derivados do ácido gálhico, taninos e flavonóides), vitamina C e E e carotenos. Assim, é de prever que a espécie Arbutus unedo L. tenha um considerável potencial antioxidante. No entanto, as propriedades antioxidantes desta espécie em membranas biológicas não foram até então avaliadas. Por esta razão, o presente trabalho deteve-se na avaliação do efeito protector dos extractos aquosos da folha e fruto de Arbutus unedo L. na danificação oxidativa induzida por radicais livres, utilizando como modelo celular in vitro o eritrócito humano. O 2...

Avaliação da actividade antioxidante da folha e fruto da espécie Dracaena draco L

Santos, Rui Pinho Moreira dos
Fonte: [s.n.] Publicador: [s.n.]
Tipo: Dissertação de Mestrado
Publicado em //2011 POR
Relevância na Pesquisa
17.72%
Trabalho apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas; O dragoeiro (Dracaena draco L.) é uma espécie arbórea, da família das Dracaenaceas, pertencente à flora da Macaronésia. Trata-se de uma das mais raras espécies arbóreas de Portugal, já mal representada tanto nos Açores como na Madeira. Tradicionalmente, a sua casca preparada por decocção era usada contra a atonia do tubo digestivo, diarreia, males estomacais, impurezas do sangue, catarros pulmonares, hemorragias e também como vermífugo e tónico. Em banhos e fomentos, este decocto era utilizado pela medicina popular no combate a tumores sifílicos. A seiva do tronco e dos ramos, conhecida por sangue-de-drago ou sangue-de-dragão, foi muito utilizada na medicina popular devido às suas propriedades antioxidantes e adstringentes. No entanto, até à data pouco se sabe no que concerne as propriedades biológicas da folha e fruto desta espécie. Por este motivo, o presente trabalho apresenta como objectivo a avaliação da actividade antioxidante de extractos aquosos de folha e fruto de dragoeiro através da sua acção protectora relativamente aos danos oxidativos induzidos por radicais livres em eritrócitos humanos. O 2...

Estudo do efeito protector do própolis de origem portuguesa na danificação oxidativa em eritrócitos humanos

Baltazar, Ana Filipa Marques Almeida
Fonte: [s.n.] Publicador: [s.n.]
Tipo: Dissertação de Mestrado
Publicado em //2010 POR
Relevância na Pesquisa
17.85%
Trabalho apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas.; O própolis é uma mistura complexa de substâncias resinosas de ampla utilidade para as abelhas e para o homem. O desenvolvimento crescente de novas técnicas analíticas tem permitido um considerável avanço na química dos produtos naturais, assim como na elucidação de suas estruturas moleculares. A composição química do própolis é complexa e está relacionada com a flora da região em que foi originada e a época da colheita. As suas actividades farmacológicas têm sido atribuídas aos compostos fenólicos, entre eles flavonóides e ácidos fenólicos, cujos teores têm sido propostos como parâmetros para o controle da qualidade. Devido às inúmeras propriedades benéficas do própolis, o seu uso comercial em produtos farmacêuticos, cosméticos e de higiene pessoal na forma de extractos líquidos é vasto. O presente trabalho teve como objectivo avaliar a actividade antioxidante do própolis de origem portuguesa em sistemas biológicos, utilizando como modelo celular in vitro o eritrócito humano. Pretendeu-se assim estudar o papel protector de extractos metanólicos obtidos do própolis proveniente de duas regiões portuguesas distintas...

Avaliação antioxidante de 3,5-dimetil isoxazol, pirazóis e tiazóis utilizando o método ORAC (capacidade de absorção de radicais oxigênio); Evaluation of antioxidant 3,5-dimethyl isoxazol pyrazoles and thiazoles using the ORAC method (absorption capacity oxygen radical)

Silva, Filipe André Nascimento
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 12/11/2010 PT
Relevância na Pesquisa
17.72%
Os radicais livres são espécies químicas que reagem rapidamente com diversos compostos e alvos celulares, por possuírem tempo de meia vida muito curto e serem espécies altamente instáveis. A formação destes compostos constitui uma ação contínua e fisiológica, cumprindo funções biológicas essenciais as quais ocorrem pela perda ou adição de um único elétron a um composto não radicalar. Estas reações podem ocorrer em processos bioquímicos do sistema imune ou químicos, causando prejuízo às células através da destruição de componentes, como proteínas, lipídios, açúcares e nucleotídeos. Sabe-se que existem compostos que são efetivos contra tais espécies, prevenindo os danos provocados pelo estresse oxidativo. O objetivo deste trabalho foi estudar compostos heterocíclicos que possuam nitrogênio em sua estrutura (azóis), que figuram na literatura como moléculas exemplares de compostos de aplicação farmacológica de amplo espectro. Dentre estes compostos foram analisados os derivados de pirazóis (26 compostos), tiazóis (7 compostos) e 1 isoxazol (3,5-dimetilisoxazol). Estes 34 compostos foram avaliados pela metodologia ORAC (Capacidade de Absorção de Radicais Oxigênio) a fim de determinar e/ou de avaliar seu potencial antioxidante. A escolha do método ORAC se deu pelo fato das moléculas estudadas apresentarem características hidrofílicas e lipofílicas...

Compostos de adição entre percloratos e nitratos de alguns lantanideos(III) e a N-(2-piridil) acetamida (AAPH)

Francisco Santos Dias
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 01/03/1977 PT
Relevância na Pesquisa
27.52%
Sob cuidadosas condições experimentais, em sistemas anidros, a reação da N-(2-piridil) acetamida (AAPH) com sais de alguns lantanídeos (III) em solução de acetonitrila, produz compostos sólidos que apresentam as sequintes composições estequiométricas: Ln(ClO4)3.4AAPH (onde Ln = Nd, Eu, Gd, Ho, Yb e Lu) e Ln(NO3)3.2AAPH (para Ln = La, Nd, Eu, Gd, Ho e Yb). Os compostos não são aparentemente higroscópicos, porém os adutos de nitratos quando triturados na atmosfera ambiente exibem tendências a higroscopicidade. Apresentam intervalos de fusão e/ou decomposição pequenos, que para os percloratos estão entre 222,6-237,7°C e para os nitratos, na faixa 173,0-193,1°C. Para os nitratos ao contrário dos percloratos verifica-se uma dificuldade para a obtenção de sistemas cristalizáveis. Provavelmente isto deve-se entre outros fatores, ao fato deste último ser um ânion fracamente coordenante, rninimizando reacões interferentes (competição) entre os íons lantanídeos (III) e os ligantes orgânicos. Todos os compostos de adição são solúveis em etanol e acetona; são pouco solúveis em acetato de etila, acetonitrila e nitrometano; e praticamente insolúveis em clorofórmio, éter etílico e tetracloreto de carbono. Os compostos foram caracterizados através de análise elementar...

Sintese e caracterização de compostos de adição de Zn(II), Ca(II) e Hg(II), com N-(2-piridil) acetamida, e estudo termodinamico dos respectivos haletos

Afonso Sena Gonçalves
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 31/12/1976 PT
Relevância na Pesquisa
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Neste trabalho foram preparados e caracterizados uma série de compostos entre sais de Zinco(II) , Cádmio(II) e Mercúrio (II), e a N-(2-piridil)acetamida (aapH), com as seguintes estequiometrias: MX2.2aapH (M = Zn, Cd e X = Cl, Br, I, NO3), MX2.1aapH (M = Cd e X = Cl, Br), Zn(ClO4)2.3aapH, HgCl2.2aapH e HgBr2.1aapH. Além da análise química elementar, os compostos foram caracterizados por espectroscopia vibracional, medidas de condutância molar e termogravimetria. Os estudos espectroscópicos, aliados aos de condutância, revelaram que em todos os compostos o metal liga-se à aapH pelo Nitrogênio piridínico, estando também os ânions coordenados, com exceção do perclorato. Todos também ligam-se pelo Oxigênio, a não ser o HgCl2.2aapH e CdCl2.2aapH. Os compostos apresentam provavelmente, diferentes estruturas, tendo algumas sido propostas. As curvas termogravimétricas permitiram algumas conclusões a respeito da estabilidade térmica dos compostos preparados. Com os compostos MX2.2aapH (M = Zn, Cd e X = Cl, Br, I), HgCl2.2aapH e HgBr2.1aapH, foram também realizados estudos termodinâmicos com base em medidas calorimétricas em solução, e em determinações de entalpias de combustão, entalpia padrão de formação, estimativas das capacidades caloríficas médias a pressão constante nas fases sólida...

Antioxidant activity of chitooligosaccharides upon two biological systems: Erythrocytes and bacteriophages

Fernandes, João C.; Eaton, Peter; Nascimento, Henrique; Gião, Maria S.; Ramos, Óscar S.; Belo, Luís; Santos-Silva, Alice; Pintado, Manuela E.; Malcata, F. Xavier
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2010 ENG
Relevância na Pesquisa
27.21%
Most of the reports to date on the antioxidant capacity of chitosans and chitooligosaccharides (COS) are based on strictly chemical methods. When studying antioxidants with potential in vivo applications, the method used to evaluate the antioxidant activity should be representative of the conditions in which the antioxidant might have a protective effect. In this work we evaluate the antioxidant activity of two COS mixtures and a low MW chitosan (LMWC) upon two biological oxidizable substrates – erythrocytes and phages, subjected to accelerated oxidation conditions. Our results suggest that COS/LMWC can be used as antioxidants in biological systems. All the tested compounds reduced either the hemolytic and DNA damage, by inhibiting H2O2- and AAPH-radicals. However, the results obtained for these biological assays did not reveal a dose dependence, contrary to the chemical assay, suggesting that the protective concentrations should be established, in order to prevent enhancement of the oxidative damage – i.e. a prooxidant effect.

Antioxidant effect of 4-nerolidylcatechol and -tocopherol in erythrocyte ghost membranes and phospholipid bilayers

Fernandes,K.S.; Silva,A.H.M.; Mendanha,S.A.; Rezende,K.R.; Alonso,A.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2013 EN
Relevância na Pesquisa
17.52%
4-Nerolidylcatechol (4-NC) is found in Pothomorphe umbellata root extracts and is reported to have a topical protective effect against UVB radiation-induced skin damage, toxicity in melanoma cell lines, and antimalarial activity. We report a comparative study of the antioxidant activity of 4-NC and α-tocopherol against lipid peroxidation initiated by two free radical-generating systems: 2,2′-azobis(2-aminopropane) hydrochloride (AAPH) and FeSO4/H2O2, in red blood cell ghost membranes and in egg phosphatidylcholine (PC) vesicles. Lipid peroxidation was monitored by membrane fluidity changes assessed by electron paramagnetic resonance spectroscopy of a spin-labeled lipid and by the formation of thiobarbituric acid-reactive substances. When lipoperoxidation was initiated by the hydroxyl radical in erythrocyte ghost membranes, both 4-NC and α-tocopherol acted in a very efficient manner. However, lower activities were observed when lipoperoxidation was initiated by the peroxyl radical; and, in this case, the protective effect of α-tocopherol was lower than that of 4-NC. In egg PC vesicles, malondialdehyde formation indicated that 4-NC was effective against lipoperoxidation initiated by both AAPH and FeSO4/H2O2, whereas α-tocopherol was less efficient in protecting against lipoperoxidation by AAPH...

Modification of protein surface hydrophobicity and methionine oxidation by oxidative systems

Chao, Chien-Chung; Ma, Yan-Shan; Stadtman, Earl R.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 01/04/1997 EN
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17.52%
Aging and some pathological conditions are associated with the accumulation of altered (inactive or less active) forms of enzymes. It was suggested that these age-related alterations reflect spontaneous changes in protein conformation and/or posttranslational modifications (e.g., oxidation). Because changes in protein conformations are often associated with changes in surface hydrophobicity, we have examined the effects of aging and oxygen radical-dependent oxidation on the hydrophobicity of rat liver proteins. As a measure of hydrophobicity, the increase in fluorescence associated with the binding of 8-anilino-1-naphthalene-sulfonic acid to hydrophobic regions on the proteins was used. By this criterion, the hydrophobicity of liver proteins of 24-month-old rats was 15% greater than that of 2-month-old animals. Exposure of liver proteins to a metal-catalyzed oxidation system (ascorbate/Fe(II)/H2O2) or a peroxyl radical generating system, 2,2′-azobis(2-amidino-propane) dihydrochloride (AAPH) led to increases of 2% or 30% in surface hydrophobicity, respectively. Treatment of liver proteins with the metal-catalyzed oxidation system led to a significant increase in reactive carbonyl content and to conversion of methionine residues to methionine sulfoxide residues. Treatment with AAPH led also to oxidation of methionine...

Oxidation of 8-Oxo-7,8-dihydro-2′-deoxyguanosine by Oxyl Radicals Produced by Photolysis of Azo Compounds

Shao, Jie; Geacintov, Nicholas E.; Shafirovich, Vladimir
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 17/05/2010 EN
Relevância na Pesquisa
17.52%
Oxidative damage to 8-oxo-7,8-dihydroguanine (8-oxoG) bases initiated by photolysis of the water-soluble radical generator 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) has been investigated by laser kinetic spectroscopy. In neutral oxygenated aqueous solutions, 355 nm photolysis of AAPH initiates efficient one-electron oxidation of the 8-oxodG nucleosides directly monitored by the appearance of the 8-oxodG•+/8-oxodG(-H)• radicals at 325 nm. The reaction kinetics are consisted with a mechanism that includes the transformation of the 2-amidinoprop-2-peroxyl radicals (ROO•) derived from photolysis of AAPH to more reactive 2-amidinoprop-2-oxyl radicals (RO•), which directly react with the 8-oxoG bases. The major pathways for the formation of end products of 8-oxoG oxidation include the combination of the 8-oxodG•+/8-oxodG(-H)• radicals with superoxide (O2•−) and ROO• radicals in approximately 1:1 ratios, as demonstrated by experiments with Cu, Zn superoxide dismutase to form dehydroguanidinohydantoin (Ghox) derivatives. This mechanism was confirmed by analysis of the end products produced by the oxidation of two substrates: (1) the 8-oxoG derivative 2′,3′,5′-tri-O-acetylguanosine (tri-O-Ac-G), and (2) the 5′-d(CCATC[8-oxoG]CTACC) sequence. The major products isolated by HPLC and identified by mass spectrometry methods were the tri-O-Ac-Ghox and 5′-d(CCATC[Ghox]CTACC products.

A New Oxidative Stress Model, 2,2-Azobis(2-Amidinopropane) Dihydrochloride Induces Cardiovascular Damages in Chicken Embryo

He, Rong-Rong; Li, Yan; Li, Xiao-Di; Yi, Ruo-Nan; Wang, Xiao-Yu; Tsoi, Bun; Lee, Kenneth Ka Ho; Abe, Keiichi; Yang, Xuesong; Kurihara, Hiroshi
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 01/03/2013 EN
Relevância na Pesquisa
18.12%
It is now well established that the developing embryo is very sensitive to oxidative stress, which is a contributing factor to pregnancy-related disorders. However, little is known about the effects of reactive oxygen species (ROS) on the embryonic cardiovascular system due to a lack of appropriate ROS control method in the placenta. In this study, a small molecule called 2,2-azobis(2-amidinopropane) dihydrochloride (AAPH), a free radicals generator, was used to study the effects of oxidative stress on the cardiovascular system during chick embryo development. When nine-day-old (stage HH 35) chick embryos were treated with different concentrations of AAPH inside the air chamber, it was established that the LD50 value for AAPH was 10 µmol/egg. At this concentration, AAPH was found to significantly reduce the density of blood vessel plexus that was developed in the chorioallantoic membrane (CAM) of HH 35 chick embryos. Impacts of AAPH on younger embryos were also examined and discovered that it inhibited the development of vascular plexus on yolk sac in HH 18 embryos. AAPH also dramatically repressed the development of blood islands in HH 3+ embryos. These results implied that AAPH-induced oxidative stress could impair the whole developmental processes associated with vasculogenesis and angiogenesis. Furthermore...

Antioxidant effect of 4-nerolidylcatechol and α-tocopherol in erythrocyte ghost membranes and phospholipid bilayers

Fernandes, K.S.; Silva, A.H.M.; Mendanha, S.A.; Rezende, K.R.; Alonso, A.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica
Publicado em 06/09/2013 EN
Relevância na Pesquisa
17.52%
4-Nerolidylcatechol (4-NC) is found in Pothomorphe umbellata root extracts and is reported to have a topical protective effect against UVB radiation-induced skin damage, toxicity in melanoma cell lines, and antimalarial activity. We report a comparative study of the antioxidant activity of 4-NC and α-tocopherol against lipid peroxidation initiated by two free radical-generating systems: 2,2′-azobis(2-aminopropane) hydrochloride (AAPH) and FeSO4/H2O2, in red blood cell ghost membranes and in egg phosphatidylcholine (PC) vesicles. Lipid peroxidation was monitored by membrane fluidity changes assessed by electron paramagnetic resonance spectroscopy of a spin-labeled lipid and by the formation of thiobarbituric acid-reactive substances. When lipoperoxidation was initiated by the hydroxyl radical in erythrocyte ghost membranes, both 4-NC and α-tocopherol acted in a very efficient manner. However, lower activities were observed when lipoperoxidation was initiated by the peroxyl radical; and, in this case, the protective effect of α-tocopherol was lower than that of 4-NC. In egg PC vesicles, malondialdehyde formation indicated that 4-NC was effective against lipoperoxidation initiated by both AAPH and FeSO4/H2O2, whereas α-tocopherol was less efficient in protecting against lipoperoxidation by AAPH...

Antcin C from Antrodia cinnamomea Protects Liver Cells Against Free Radical-Induced Oxidative Stress and Apoptosis In Vitro and In Vivo through Nrf2-Dependent Mechanism

Gokila Vani, M.; Kumar, K. J. Senthil; Liao, Jiunn-Wang; Chien, Shih-Chang; Mau, Jeng-Leun; Chiang, Shen-Shih; Lin, Chin-Chung; Kuo, Yueh-Hsiung; Wang, Sheng-Yang
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
17.85%
In this study, we investigated the cytoprotective effects of antcin C, a steroid-like compound isolated from Antrodia cinnamaomea against AAPH-induced oxidative stress and apoptosis in human hepatic HepG2 cells. Pretreatment with antcin C significantly protects hepatic cells from AAPH-induced cell death through the inhibition of ROS generation. Furthermore, AAPH-induced lipid peroxidation, ALT/AST secretion and GSH depletion was significantly inhibited by antcin C. The antioxidant potential of antcin C was correlated with induction of antioxidant genes including, HO-1, NQO-1, γ-GCLC, and SOD via transcriptional activation of Nrf2. The Nrf2 activation by antcin C is mediated by JNK1/2 and PI3K activation, whereas pharmacologic inhibition of JNK1/2 and PI3K abolished antcin C-induced Nrf2 activity. In addition, AAPH-induced apoptosis was significantly inhibited by antcin C through the down-regulation of pro-apoptotic factors including, Bax, cytochrome c, capase 9, -4, -12, -3, and PARP. In vivo studies also show that antcin C significantly protected mice liver from AAPH-induced hepatic injury as evidenced by reduction in hepatic enzymes in circulation. Further, immunocytochemistry analyses showed that antcin C significantly increased HO-1 and Nrf2 expression in mice liver tissues. These results strongly suggest that antcin C could protect liver cells from oxidative stress and cell death via Nrf2/ARE activation.

Charakterisierung der radikalfangenden Eigenschaften pflanzlicher Entzündungshemmer; Characterization of radical scavenging properties of herbal anti-inflammatory drugs

Germann, Ines Daniela
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
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17.94%
Bei entzündlichen Erkrankungen des Magen-Darm-Trakts wie Gastritis, Reizmagen und Reizdarm und bei entzündlichen Gelenkerkrankungen spielen reaktive Sauerstoffspezies eine wichtige Rolle. Da zur Behandlung häufig Phytopharmaka eingesetzt werden, wurden Iberogast ® und seine Einzelextrakte, Extrakte aus Weidenrinde, Teufelskrallenwurzel, Brennnesselblättern und Phytodolor ® und seine Einzelextrakte sowohl in rein chemischen Testsystemen (AAPH-Reaktion, Xanthin/ Xanthinoxidase-Reaktion) als auch in zellulären Modellen (Lungen-, Vollblut-, Leukozytenmodell) auf ihre radikalfangenden Eigenschaften hin untersucht. Für das Magen-Darm-Therapeutikum Iberogast ® und seine neun pflanzlichen Komponenten wurden in allen Testmodellen radikalfangende Effekte gefunden, wobei die Extrakte je nach Testsystem unterschiedlich stark wirksam waren. In den chemischen Testsystemen und im Lungenmodell war der Extrakt aus Pfefferminzblättern am wirksamsten. Im Leukozytenmodell senkte der Extrakt aus Kamillenblüten die verbleibende basale Radikalproduktion am stärksten, die Radikalproduktion nach Stimulation mit Zymosan wurde am stärksten durch den Pfefferminzblätterextrakt reduziert. Um die radikalfangenden Eigenschaften von Extrakten zu charakterisieren...

Untersuchungen zur Bedeutung von oxidativem Stress bei Präeklampsie; Investigations about the importance of oxidative stress in preeclampsia

Amraei Davijani, Felor
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
28.07%
Präeklampsie ist eine der häufigsten schwerwiegenden Schwangerschafts-Komplikationen, die durch Hypertonie, Proteinurie und Ödeme charakterisiert ist. Die Pathogenese ist weitgehend unklar. Viele Untersuchungen legen nahe, dass Präeklampsie mit oxidativem Stress im mütterlichen Organismus verbunden ist. In der vorliegenden Arbeit wurden zunächst Indikatoren des oxidativen Stresses durch in-vitro-Versuche charakterisiert. Dabei wurde mit H2O2, t-BHP, KO2 und Xanthin/XOD künstlicher oxidativer Stress im Plasma gesunder Probandinnen induziert. Zur Erfassung der Parameter für oxidativen Stress diente die gesamte antioxidative Kapazität (TRAP) sowie die Peakhöhe der Chemilumineszenz der AAPH-Reaktion (2,2’-Azobis (2-amidiniopropan)-hydrochlorid). Diese wurde durch die verwendeten Oxidantien vermindert. Zusätzlich wurden die Konzentrationen der Thiole im Plasma untersucht. Unter der Einwirkung der Oxidantien wurde eine Abnahme der freien Thiolgruppen, vor allem der an Proteine gebundenen, im Plasma festgestellt. Auf die Malondialdehyd-Konzentration hatte die Inkubation mit H2O2 keinen Effekt, t-BHP verursachte eine Zunahme. Auch bei der Wirkung auf die ATP-Konzentration in Erythrozyten wurde eine viel stärkere Abnahme des ATP durch t-BHP im Vergleich zu H2O2 gefunden. Danach wurde durch klinisch-chemische Blutanalyse der Frage nachgegangen...

Oxidation and glycoxidation of phosphatidylserine and their effect in immune response : a lipidomic approach

Maciel, Maria Elisabete Alves
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
17.85%
Phosphatidylserine (PS) is a member of the class of phospholipids, and is distributed among all cells of mammalians, playing important roles in diverse biological processes, including blood clotting and apoptosis. When externalized, PS is a ligand that is recognized on apoptotic cells. It has been considered that before externalization PS is oxidized and oxPS enhance the recognition by macrophages receptors, however the knowledge about oxidation of PS is still limited. PS, like others phospholipids, has two fatty acyl chains and one polar head group, in this case is the amino acid serine. The modifications in PS structure can occur by oxidation of the unsaturated fatty acyl chains and by glycation of the polar head group, due to free amine group, thus increasing the susceptibility to oxidative events. The main goal of this work was to characterize and identify oxidized and glycoxidized PS, contributing to the knowledge of the biological role of oxidation products of PS, as well as of glycated PS, in immune and inflammatory processes. To achieve this goal, PS standards (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho- L-serine (POPS), 1,2-dipalmitoyl-sn-glycero-3-phospho-L-serine (DPPS), 1- palmitoyl-2-linoleoyl-sn-glycero-3-phospho-L-serine (PLPS) and 1-palmitoyl-2- arachidonoyl-sn-glycero-3-phospho-L-serine (PAPS)) and glycated PS (PAPS and POPS) were induced to oxidize in model systems...

Nitric oxide-dependent NAD linkage to glyceraldehyde-3-phosphate dehydrogenase: possible involvement of a cysteine thiyl radical intermediate.

Minetti, M; Pietraforte, D; Di Stasi, A M; Mallozzi, C
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/10/1996 EN
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17.72%
Previous studies have demonstrated that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) undergoes NAD(H) linkage to an active site thiol when it comes into contact with .NO-related oxidants. We found that a free-radical generator 2,2'-azobis-(2-amidinopropane) hydrochloride (AAPH), which does not release either .NO or .NO-related species, was indeed able to induce the NAD(H) linkage to GAPDH. We performed spin-trapping studies with purified apo-GAPDH to identify a putative thiol intermediate produced by AAPH as well as by .NO-related oxidants. As .NO sources we used .NO gas and two .NO-donors, S-nitroso-N-acetyl-D,L-penicillamine and 3-morpholinosydno-nimine hydrochloride (SIN-1). Because SIN-1 produces .NO and a superoxide radical simultaneously, we also tested the effects of peroxynitrite. All the .NO-related oxidants were able to induce the linkage of NAD(H) to GAPDH and the formation of a protein free-radical identified as a thiyl radical (inhibited by N-ethylmaleimide). .NO gas and the .NO-donors required molecular oxygen to induce the formation of the GAPDH thiyl radical, suggesting the possible involvement of higher nitrogen oxides. Thiyl radical formation was decreased by the reconstitution of GAPDH with NAD+. Apo-GAPDH was a strong scavenger of AAPH radicals...

F1F0-ATPase, early target of the radical initiator 2,2'-azobis-(2-amidinopropane) dihydrochloride in rat liver mitochondria in vitro.

Beauseigneur, F; Goubern, M; Chapey, M F; Gresti, J; Vergely, C; Tsoko, M; Demarquoy, J; Rochette, L; Clouet, P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/12/1996 EN
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This study was designed to determine which enzyme activities were first impaired in mitochondria exposed to 2,2'-azobis-(2-amidinopropane) dihydrochloride (AAPH), a known radical initiator. EPR spin-trapping revealed generation of reactive oxygen species although malondialdehyde formation remained very low. With increasing AAPH concentrations, State-3 respiration was progressively depressed with unaltered ADP/O ratios. A top-down approach demonstrated that alterations were located at the phosphorylation level. As shown by inhibitor titrations, ATP/ADP translocase activity was unaffected in the range of AAPH concentrations used. In contrast, AAPH appeared to exert a deleterious effect at the level of F1F0-ATPase, comparable with dicyclohexylcarbodi-imide, which alters Fo proton channel. A comparison of ATP hydrolase activity in uncoupled and broken mitochondria reinforced this finding. In spite of its pro-oxidant properties, AAPH was shown to act as a dose-dependent inhibitor of cyclosporin-sensitive permeability transition initiated by Ca2+, probably as a consequence of its effect on F1F0-ATPase. Resveratrol, a potent antiperoxidant, completely failed to prevent the decrease in State-3 respiration caused by AAPH. The data suggest that AAPH...

Delayed oxidative degradation of polyunsaturated diacyl phospholipids in the presence of plasmalogen phospholipids in vitro.

Reiss, D; Beyer, K; Engelmann, B
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/05/1997 EN
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17.85%
The oxidative degradation of plasmalogen (alkenylacyl) phospholipids was analysed in the absence and the presence of polyunsaturated ester phospholipids by 1H-NMR and by chemical determination. Brain lysoplasmenylethanolamine (lyso-P-PE), brain P-PE and erythrocyte P-PE, containing an increasing number of intrachain double bonds at sn2, were oxidized with 2,2'-azobis-(2-amidinopropane hydrochloride) (AAPH; 2 or 10 mM) in Triton X-100 micelles (detergent/phospholipid 1:5, mol/mol). The formation of two peroxyl radicals was accompanied by the degradation of approx. one molecule of brain lyso-P-PE. On oxidation of brain P-PE or erythrocyte P-PE (320 nmol) with 2 mM AAPH, the (alpha-vinyl) methine 1H signal of the enol ether decreased more rapidly than the methine proton peak of intrachain double bonds. The rate of enol ether degradation increased in the order: erythrocyte P-PE>brain P-PE>brain lyso-P-PE. The disappearance of the polyunsaturated ester phospholipids 1-palmitoyl-2-arachidonoyl phosphatidylcholine (16:0/20:4-PC) and 1-palmitoyl-2-linoleoyl phosphatidylcholine (16:0/18:2-PC) (100 nmol), as induced by 10 mM AAPH, was nearly completely inhibited by the plasmalogens (25 nmol) in the first 30 and 60 min of incubation respectively...

Protection by Exogenously Added Coenzyme Q9 against Free Radical-Induced Injuries in Human Liver Cells

Kusumoto, Chiaki; Kinugawa, Tomoyo; Morikawa, Hitoshi; Teraoka, Mari; Nishida, Tadashi; Murawaki, Yoshikazu; Yamada, Kazuo; Matsura, Tatsuya
Fonte: the Society for Free Radical Research Japan Publicador: the Society for Free Radical Research Japan
Tipo: Artigo de Revista Científica
EN
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17.85%
Reduced coenzyme Q10 (CoQ10H2) is known as a potent antioxidant in biological systems. However, it is not yet known whether CoQ9H2 could act as an antioxidant in human cells. The aim of this study is to assess whether exogenously added CoQ9 can protect human liver cells against injuries induced by a water-soluble radical initiator, 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) and a lipid-soluble radical initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN). CoQ9-enriched cells were obtained by treatment of HepG2 cells with 10 µM CoQ9 liposomes for 24 h. CoQ9-enriched cells were exposed to 10 mM AAPH and 500 µM AMVN over 4 h and 24 h, respectively. The loss of viability after treatment with AAPH or AMVN was much less in CoQ9-enriched cells than in naive HepG2 cells. The decrease in glutathione and the increase in thiobarbituric acid-reactive substance after treatment with AAPH or AMVN were also suppressed in CoQ9-enriched cells. The incubation of CoQ9-enriched cells with AAPH or AMVN led to a decrease in cellular CoQ9H2 and reciprocal increase in cellular CoQ9 resulting from its antioxidant function. Taken together, it was demonstrated for the first time that exogenously added CoQ9 could prevent oxidative stress-mediated damage to human cells by virtue of its antioxidant activity.