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Compostos antioxidantes e sua importância nos organismos

Novaes, Gabriela Machado; Silva, Marcelo José Dias; Achkar, Marina Teixeira; Vilegas, Wagner
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 535-539
POR
Relevância na Pesquisa
36.27%
A large amount of external factors that can foster the emergence of free radicals in organisms has created a imminent need for understanding and technologies that enables the search of antioxidant componds and extraction of antioxidants from natural sources. These compounds have great potential for kidnapping free radicals which are highly harmful to organisms, being the principal responsible for the decrease in the shelf life of foods, and aging. These free radicals are also related to diseases such as AIDS, arthritis, diabetes, heart disease and others. Fruits and vegetables are true mines of compounds with antioxidant potential, its vitamins and phenolic compounds present an essential role in the nutrition of living beings acting as a defense against degradation of lipids and proteins, which indicates the importance of a diet rich in these nutrients, given that part of the antioxidant defenses of the body comes from the diet. This revision study aims to put in evidence the indispensable role of antioxidants in the survival of organisms.; A grande quantidade de fatores externos que podem propiciar o aparecimento de radicais livres nos organismos tem criado uma necessidade eminente de entendimento e investimento em tecnologias que possibilitem a procura e extração de compostos antioxidantes de fontes naturais. Estes compostos tem grande potencial de sequestro dos radicais livres que são altamente prejudiciais aos organismos...

Endogenous intracellular glutathionyl radicals are generated in neuroblastoma cells under hydrogen peroxide oxidative stress.

Kwak, H S; Yim, H S; Chock, P B; Yim, M B
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 09/05/1995 EN
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36.21%
We report the detection of endogenous intracellular glutathionyl (GS.) radicals in the intact neuroblastoma cell line NCB-20 under oxidative stress. Spin-trapping and electron paramagnetic resonance (EPR) spectroscopic methods were used for monitoring the radicals. The cells incubated with the spin trap 5,5-dimethyl-1-pyrroline 1-oxide (DMPO) were challenged with H2O2 generated by the enzymic reaction of glucose/glucose oxidase. These cells exhibit the EPR spectrum of the GS. radical adduct of DMPO (DMPO-.SG) without exogenous reduced glutathione (GSH). The identity of this radical adduct was confirmed by observing hyperfine coupling constants identical to previously reported values in in vitro studies, which utilized known enzymic reactions, such as horseradish peroxidase and Cu/Zn superoxide dismutase, with GSH and H2O2 as substrates. The formation of the GS. radicals required viable cells and continuous biosynthesis of GSH. No significant effect on the resonance amplitude by the addition of a membrane-impermeable paramagnetic broadening agent indicated that these radicals were located inside the intact cell. N-Acetyl-L-cysteine (NAC)-treated cells produced NAC-derived free radicals (NAC.) in place of GS. radicals. The time course studies showed that DMPO-.SG formation exhibited a large increase in its concentration after a lag period...

An in vivo ESR spin-trapping study: Free radical generation in rats from formate intoxication— role of the Fenton reaction

Dikalova, Anna E.; Kadiiska, Maria B.; Mason, Ronald P.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 20/11/2001 EN
Relevância na Pesquisa
36.21%
Electron spin resonance spectroscopy has been used to study free radical generation in rats with acute sodium formate poisoning. The in vivo spin-trapping technique was used with α-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN), which reacts with free radical metabolites to form radical adducts, which were detected in the bile and urine samples from Fischer rats. The use of [13C]-sodium formate and computer simulations of the spectra identified the 12-line spectrum as arising from the POBN/carbon dioxide anion radical adduct. The identification of POBN/⋅COdocumentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} setlength{oddsidemargin}{-69pt} egin{document} egin{equation*}{mathrm{_{2}^{-}}}end{equation*}end{document} radical adduct provides direct electron spin resonance spectroscopy evidence for the formation of ⋅COdocumentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} setlength{oddsidemargin}{-69pt} egin{document} egin{equation*}{mathrm{_{2}^{-}}}end{equation*}end{document} radicals during acute intoxication by sodium formate, suggesting a free radical metabolic pathway. To study the mechanism of free radical generation by formate...

Recurrent ischemia in the canine heart causes recurrent bursts of free radical production that have a cumulative effect on contractile function. A pathophysiological basis for chronic myocardial "stunning".

Bolli, R; Zughaib, M; Li, X Y; Tang, X L; Sun, J Z; Triana, J F; McCay, P B
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1995 EN
Relevância na Pesquisa
36.24%
Open-chest dogs (total number used, 117) underwent 10 5-min coronary occlusions (O) interspersed with 10 min of reperfusion (R). When systolic thickening fraction was measured 9 min after each R, the first O-R cycle was found to cause the largest decrement, with only a slight additional loss during the next four cycles and no further loss during the last five cycles (group IV), suggesting that the first few episodes of ischemia preconditioned the myocardium against the stunning induced by the last five episodes. However, different results were obtained when the total deficit of wall thickening during the final 4-h R interval was measured. The total deficit was similar after one and three 5-min O (groups V and VI, respectively), indicating that the first ischemic episode did precondition against the next two episodes; however, it was approximately 2.5-fold greater after 10 O (group IV) than after 3, indicating that the first 3 episodes failed to precondition against the next 7. Thus, at some point between the 4th and 10th O, the preconditioning effect was lost and recurrent ischemic episodes started to have a cumulative effect. Measurements of free radicals with alpha-phenyl N-tert-butyl nitrone (PBN) demonstrated a burst of free radical generation immediately after the 1st...

Free radical activity and left ventricular function after thrombolysis for acute infarction.

Davies, S W; Ranjadayalan, K; Wickens, D G; Dormandy, T L; Umachandran, V; Timmis, A D
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1993 EN
Relevância na Pesquisa
36.26%
BACKGROUND--Experimental data suggest that reperfusion injury involving free radicals contributes to the impairment of left ventricular function after successful thrombolysis. METHODS--In 72 patients presenting with acute myocardial infarction, markers of free radical activity were measured before streptokinase and two hours later. Thiobarbituric acid reactive material (TBA-RM) reflects lipid peroxidation by free radicals, and the concentration of plasma total thiols (34 patients) reflects oxidative stress. Coronary arteriography was performed at 18-72 hours after thrombolysis to determine coronary patency, and left ventricular function was assessed by ventriculography and from QRS scoring of the electrocardiogram. RESULTS--The infarct related artery was patent (Thrombolysis In Myocardial Infarction Trial grade 2 or better) in 60 (83%) and occluded in 12. In the 60 with a patent artery, the concentration of TBA-RM increased after streptokinase by (mean (SD)) 9.2 (14.0) nmol/g albumin, whereas in the 12 with an occluded artery TBA-RM decreased by 7.0 (11.3) nmol/g albumin (p < 0.01 between groups). In those with a patent artery the rise in TBA-RM associated with thrombolysis correlated with left ventricular ejection fraction (R = -0.41...

Free radical-induced inactivation of creatine kinase: influence on the octameric and dimeric states of the mitochondrial enzyme (Mib-CK).

Koufen, P; Rück, A; Brdiczka, D; Wendt, S; Wallimann, T; Stark, G
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/12/1999 EN
Relevância na Pesquisa
36.26%
Free radicals of X-ray-induced water radiolysis, either directly or indirectly via their reaction products, reduce the activity of both dimeric cytoplasmic muscle-type creatine kinase (MM-CK) and octameric mitochondrial creatine kinase (Mi-CK) to virtually zero. Similarly values of the characteristic D(37)-dose of enzyme inactivation (dose required to reduce enzyme activity to 37%) were found for the two isoenzymes of CK under identical conditions. Octamer stability was not significantly affected within the dose range considered. However, both the dissociation of octamers into dimers by a transition-state analogue complex (TSAC), and the reassociation of the dimers into octamers, showed dose-dependent reduction. Binding of the TSAC to the active centre was found to protect the enzyme against inactivation by free radicals. No protection was observed for the radiation-induced decrease of the endogenous tryptophan fluorescence. The experimental results are in line with the following interpretation: (i) the reduction of Mi(b)-CK dimer association is due to free radical-induced modification of Trp-264, situated at the dimer/dimer interface; (ii) the active-site Trp-223 is not a prime target for free radicals and is not involved in the inactivation of the enzyme; (iii) the inhibition of TSAC-induced dissociation of Mi(b)-CK...

Specific interaction of pancreatic elastase and leucocytes to produce oxygen radicals and its implication in pancreatitis.

Tsuji, N; Watanabe, N; Okamoto, T; Niitsu, Y
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1994 EN
Relevância na Pesquisa
36.27%
Many previous reports using experimental animal models of pancreatitis have suggested that oxygen free radicals play an important part in initiation and development of pancreatitis. Infiltration of inflammatory cells--that is, neutrophils, lymphocytes, and monocytes--has been seen in damaged pancreatic glands of animal models and patients with pancreatitis. As neutrophils are known to be the highest producer of oxygen free radicals among these inflammatory cells, it seems plausible that oxygen free radicals produced by neutrophils have some pathoaetiological meaning in pancreatitis. This study measured the superoxide production by neutrophils obtained from patients with acute and chronic pancreatitis and then examined the effects of pancreatic enzymes on superoxide production. Patients showed significantly higher superoxide production by 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA) stimulated neutrophils than healthy controls. Among the three pancreatic enzymes, amylase, trypsin, and elastase, elastase was the only one that increased the superoxide production by PMA stimulated neutrophils, by an increment of 1.5-fold. It also increased the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase prepared from PMA stimulated neutrophils by a factor of 2.1. High affinity and low affinity binding sites for elastase on neutrophils were identified. These results suggest that elastase plays a part in the development of pancreatitis by enhancing superoxide production of neutrophils.

In vivo detection of radicals in biological reactions.

Chance, B; Gao, G
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1994 EN
Relevância na Pesquisa
36.24%
In vivo detection of free radicals on a quantitative basis is essential for an establishment of their role in membrane, protein, and cell and tissue damage. This article compares optical methods, including chemiluminescence, electron paramagnetic resonance (EPR) and NMR methods for the study of free radicals and free radical damage, especially reperfusion injury neutrophil accumulation 6 hr after the ischemia/reperfusion insult. The chemiluminescence method is applied to an evaluation of the improved resistance to free radical stress due to transfection of creatine kinase in the mouse liver.

Prostaglandin synthase-mediated metabolism of carcinogens and a potential role for peroxyl radicals as reactive intermediates.

Marnett, L J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1990 EN
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36.22%
Prostaglandin-H synthase is unique among enzymes of the plant and animal kingdom in its ability to biosynthesize and metabolize hydroperoxides. Its cyclooxygenase activity oxygenates polyunsaturated fatty acids to hydroperoxy endoperoxides, and its peroxidase activity reduces the hydroperoxy group to hydroxy groups. Higher oxidation states of the peroxidase oxidize reducing substrates to electron-deficient derivatives that react with macromolecular nucleophiles. In the case of aromatic amines, the electron-deficient derivatives are mutagenic to bacterial and mammalian cells. beta-Dicarbonyl compounds and retinoic acid are oxidized to carbon-centered radicals that react with O2 to form peroxyl free radicals. Peroxyl radicals are the most stable oxy radicals and are able to diffuse some distance from the site of their generation. Peroxyl radicals are also formed during lipid peroxidation and in the reaction of polyunsaturated fatty acid hydroperoxides with metal complexes and metalloproteins. Peroxyl radicals epoxidize isolated doubled bonds of compounds such as 7,8-dihydroxy-7,8-dihydrobenzo(a)pyrene (BP-7,8-diol); 3,4-dihydroxy-3,4-dihydrobenzo(a)anthracene; and aflatoxin B1. The epoxide products represent the ultimate carcinogenic forms of the respective compounds. Techniques for quantitating the extent of peroxidase dependent or peroxyl radical-dependent metabolism in vivo make use of differences in the structure or stereochemistry of reactive intermediates formed by peroxidases relative to cytochromes P-450. Differences in the relative amounts of hydrolysis products and DNA adducts derived from anti- and syn-dihydrodiolepoxides following application of BP-7...

Production of oxygen-centered radicals by neutrophils and macrophages as studied by electron spin resonance (ESR).

Bannister, J V; Bannister, W H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1985 EN
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36.21%
Neutrophils and macrophages undergo a respiratory burst and an increase in the activity of the hexose monophosphate pathway in response to particulate or soluble agents. The increase in oxygen consumption was found to be associated with the production of oxygen-centered radicals. The ESR technique of spin trapping showed that besides a superoxide spin adduct, a hydroxyl spin adduct is also produced. ESR is considered to be the least ambiguous technique for the detection of free radicals. The spin-trapping agents used for oxygen-centered radical detection are usually nitrones. The most commonly used nitrone is 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), which reacts with O2-. to form 5,5-dimethyl-2-hydroperoxypyrroline-N-oxide (DMPO-OOH) and with OH. to form 5,5-dimethyl-2-hydroxypyrroline-N-oxide (DMPO-OH). Although spin-adduct formation is considered to be the most direct technique for the detection of free radicals, some disadvantages are encountered. There has been considerable interest in the isolation of the O2-. generating activity from phagocytic cells. The enzyme can be extracted with deoxycholate and gel filtration indicates that it is a high molecular weight complex. Maximum activity was between pH 7.0 and pH 7.5. The Km value was 15.8 microM for NADPH and 434 micron for NADH...

Free radical generation by ultrasound in aqueous and nonaqueous solutions.

Riesz, P; Berdahl, D; Christman, C L
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1985 EN
Relevância na Pesquisa
36.27%
The physical principles underlying the oscillatory behavior of minute gas bubbles in liquids exposed to ultrasound are reviewed. Results from mathematical analyses suggest that these oscillations sometimes become unstable leading to transient cavitation in which a bubble violently collapses during a single acoustic half-cycle producing high temperatures and pressures. The role that micronuclei, resonant bubble size, and rectified diffusion play in the initiation of transient cavitation is explained. Evidence to support these theoretical predictions is presented with particular emphasis on sonoluminescence which provides some non-chemical evidence for the formation of free radicals. Acoustic methods for conducting sonochemical investigations are discussed. In aqueous solutions transient cavitation initially generates hydrogen atoms and hydroxyl radicals which may recombine to form hydrogen and hydrogen peroxide or may react with solutes in the gas phase, at the gas-liquid boundary or in the bulk of the solution. The analogies and differences between sonochemistry and ionizing radiation chemistry are explored. The use of spin trapping and electron spin resonance to identify hydrogen atoms and hydroxyl radicals conclusively and to detect transient cavitation produced by continuous wave and by pulsed ultrasound is described in detail. The study of the chemical effects of cavitation in organic liquids is a relatively unexplored area which has recently become the subject of renewed interest. Examples of the decomposition of solvent and solute...

Correlation of Free Radical Yields with Strand Break Yields Produced in Plasmid DNA by the Direct Effect of Ionizing Radiation

Purkayastha, Shubhadeep; Milligan, Jamie R.; Bernhard, William A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 08/09/2005 EN
Relevância na Pesquisa
36.27%
The purpose of this study was to determine how free radical formation (fr) correlates with single strand break (ssb) and double strand break (dsb) formation in DNA exposed to the direct effects of ionizing radiation. Chemical yields have been determined of (i) total radicals trapped on DNA at 4 K, G(∑fr), (ii) radicals trapped on the DNA sugar, Gsugar(fr), (iii) prompt single strand breaks, Gprompt(ssb), (iv) total single strand breaks, Gtotal(ssb), and (v) double strand breaks, G(dsb). These measurements make it possible, for the first time, to quantitatively test the premise that free radicals are the primary precursors to strand breaks. G(∑fr) were measured by EPR applied to films of pEC (10 810 bp) and pUC18 (2686 bp) plasmids hydrated to Γ = 22 mol of water/nucleotide and X-irradiated at 4 K. Using these same samples warmed to room temperature, strand breaks were measured by gel electrophoresis. The respective values for pEC and pUC18 were G(∑fr) = 0.71 ± 0.02 and 0.61 ± 0.01 μmol/J, Gtotal(ssb) = 0.09 ± 0.01 and 0.14 ± 0.01 μmol/J, G(dsb) = 0.010 ± 0.001 and 0.006 ± 0.001 μmol/J, and Gtotal(ssb)/G(dsb) ~9 and ~20. Surprisingly, Gsugar(fr) ≈ 0.06 μmol/J for pUC18 films, less than half of Gtotal(ssb). This indicates that a significant fraction of strand breaks are derived from precursors other than trapped DNA radicals. To explain this disparity...

Immunolocalization of hypochlorite-induced, catalase-bound free radical formation in mouse hepatocytes

Bonini, Marcelo G.; Siraki, Arno G.; Atanassov, Boyko S.; Mason., Ronald P.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.24%
The establishment of oxidants as mediators of signal transduction has renewed the interest of investigators in oxidant production and metabolism. In particular, H2O2 has been demonstrated to play pivotal roles in mediating cell differentiation, proliferation and death. Intracellular concentrations of H2O2 are modulated by its rate of production and its rate of decomposition by catalase and peroxidases. In inflammation and infection some of the H2O2 is converted to hypochlorous acid, a key mediator of the host immune response against pathogens. In vivo HOCl production is mediated by myeloperoxidase, which uses excess H2O2 to oxidize Cl−. Mashino and Fridovich (1988) observed that a high excess of HOCl over catalase inactivated the enzyme by mechanisms that remain unclear. The potential relevance of this as an alternative mechanism for catalase activity control and its potential impact on H2O2-mediated signaling and HOCl-production compelled us to explore in depth the HOCl-mediated catalase inactivation pathways. Here, we demonstrate that HOCl induces formation of catalase protein radicals and carbonyls, which are temporally correlated with catalase aggregation. Hypochlorite-induced catalase aggregation and free radical formation that paralleled the enzyme loss of function in vitro were also detected in mouse hepatocytes treated with the oxidant. Interestingly...

Measuring “Free” Iron Levels in Caenorhabditis Elegans Using Low-Temperature Fe(III) Electron Paramagnetic Resonance Spectroscopy

Pate, Kira T.; Rangel, Natalie A.; Fraser, Brian; Clement, Matthew H. S.; Srinivasan, Chandra
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.22%
Oxidative stress, caused by free radicals within the body, has been associated with the process of aging and many human diseases. As free radicals, in particular superoxide, are difficult to measure, an alternative indirect method for measuring oxidative stress levels has been successfully used in E. coli and yeast. This method is based on a proposed connection between elevated superoxide levels and release of iron from solvent exposed [4Fe-4S] enzyme clusters, which eventually leads to an increase in hydroxyl radical production. In past studies using bacteria and yeast, a positive correlation was found between superoxide production or oxidative stress due to superoxide within the organism and EPR (electron paramagnetic resonance) detectable “free” iron levels. In the present study, we have developed a reliable and an efficient method for measuring “free” iron levels in C. elegans using low temperature Fe(III) EPR at g = 4.3. This method utilizes synchronized worm cultures grown on plates, which are homogenized and treated with desferrioxamine, an Fe(III) chelator, prior to packing the EPR tube. Homogenization was found not to alter “free” iron levels, while desferrioxamine treatment significantly raised these levels, indicating presence of both Fe(II) and Fe(III) in the “free” iron pool. The correlation between free radical levels and the observed “free” iron levels was examined by using heat stress and paraquat treatment. The intensity of the Fe(III) EPR signal and thus...

Oxidative Modification of Guanine Bases Initiated by Oxyl Radicals Derived From Photolysis of Azo Compounds

Shao, Jie; Geacintov, Nicholas E.; Shafirovich, Vladimir
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 20/05/2010 EN
Relevância na Pesquisa
36.24%
Oxidative damage to guanine 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 the neutral oxygenated aqueous solutions, 355 nm laser flash photolysis of AAPH generates a whole spectrum of free radicals including 2-amidinoprop-2-peroxyl (ROO•), 2-amidinoprop-2-oxyl (RO•), and superoxide (O2•−) radicals. These oxyl radicals with negligible absorption in a near UV – visible range were monitored in the reactions leading to the products with characteristic absorption spectra. This approach reveals that RO• radicals induce fast one-electron oxidation of 2′-deoxyguanosine (dG) to form guanine neutral radicals, dG(-H)•. In contrast, ROO• radicals do not react with observable rates with dG. The O2•− radicals were detected using a classical test reaction with tetranitromethane to form nitroform. The major pathway for formation of the end products of guanine oxidation is combination of the G(-H)• and O2•− radicals to form 2,5-diamino-4H-imidazolone (Iz). This mechanism was confirmed by analysis of the end products produced by oxidation of two substrates: (1) guanosine derivative 2′,3′...

Beyond free radical scavenging: Beneficial effects of edaravone (Radicut) in various diseases (Review)

KIKUCHI, KIYOSHI; TAKESHIGE, NOBUYUKI; MIURA, NAOKI; MORIMOTO, YOKO; ITO, TAKASHI; TANCHAROEN, SALUNYA; MIYATA, KEI; KIKUCHI, CHIEMI; IIDA, NARUMI; UCHIKADO, HISAAKI; MIYAGI, NAOHISA; SHIOMI, NAOTO; KURAMOTO, TERUKAZU; MARUYAMA, IKURO; MORIOKA, MOTOHIRO;
Fonte: D.A. Spandidos Publicador: D.A. Spandidos
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.26%
Free radicals play an important role in the pathogenesis of a variety of diseases; thus, they are an attractive target for therapeutic intervention in these diseases. Compounds capable of scavenging free radicals have been developed for this purpose and some, developed for the treatment of cerebral ischemic stroke, have progressed to clinical trials. One such scavenger, edaravone, is used to treat patients within 24 h of stroke. Edaravone, which can diffuse into many disease-affected organs, also shows protective effects in the heart, lung, intestine, liver, pancreas, kidney, bladder and testis. As well as scavenging free radicals, edaravone has anti-apoptotic, anti-necrotic and anti-cytokine effects in various diseases. Here, we critically review the literature on its clinical efficacy and examine whether edaravone should be considered a candidate for worldwide development, focusing on its effects on diseases other than cerebral infarction. Edaravone has been safely used as a free radical scavenger for more than 10 years; we propose that edaravone may offer a novel treatment option for several diseases.

Aberrant Free Radical Biology Is a Unifying Theme in the Etiology and Pathogenesis of Major Human Diseases

Domann, Frederick E.
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 17/04/2013 EN
Relevância na Pesquisa
36.24%
The seemingly disparate areas of oxygen toxicity, radiation exposure, and aging are now recognized to share a common feature—the aberrant production and/or removal of biologically derived free radicals and other reactive oxygen and nitrogen species (ROS/RNS). Advances in our understanding of the effects of free radicals in biology and medicine have been, and continue to be, actively translated into clinically tractable diagnostic and therapeutic applications. This issue is dedicated to recent advances, both basic discoveries and clinical applications, in the field of free radicals in biology and medicine. As more is understood about the proximal biological targets of aberrantly produced or removed reactive species, their sensors, and effectors of compensatory response, a great deal more will be learned about the commonalities in mechanisms underlying seemingly disparate disease states. Together with this deeper understanding, opportunities will arise to devise rational therapeutic interventions to decrease the incidence and severity of these diseases and positively impact the human healthspan.

In Vivo evidence of free radical generation in the mouse lung after exposure to Pseudomonas Aeruginosa bacterium: An ESR spin-trapping investigation

Sato, Keizo; Corbett, Jean; Mason, Ronald P.; Kadiiska, Maria B.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.28%
In the Pseudomonas aeruginosa-induced rodent pneumonia model, it is thought that free radicals are significantly associated with the disease pathogenesis. However, until now there has been no direct evidence of free radical generation in vivo. Here we used electron spin resonance (ESR) and in vivo spin-trapping with α-(4-pyridyl-1-oxide)-N-tert-butylnitrone to investigate free radical production in a murine model. We detected and identified generation of lipid-derived free radicals in vivo (aN = 14.86 ± 0.03 G and aHβ = 2.48 ± 0.09 G). To further investigate the mechanism of lipid radical production, we used modulating agents and knockout mice. We found that with GdCl3 (phagocytic toxicant), NADPH oxidase knockout mice (Nox2−/−), allopurinol (xanthine oxidase inhibitor), and Desferal (metal chelator), generation of lipid radicals was decreased; histopathological and biological markers of acute lung injury were noticeably improved. Our study demonstrates that lipid-derived free radical formation is mediated by NADPH oxidase and xanthine oxidase activation, and that metal-catalyzed hydroxyl radical-like species play important roles in lung injury caused by Pseudomonas aeruginosa.

Effects of Montelukast on free radical production in whole blood and isolated human polymorphonuclear neutrophils (PMNs) in asthmatic children

Al Saadi, Muslim M.; Meo, Sultan Ayoub; Mustafa, Ali; Shafi, Ahmed; Tuwajri, Ali S. Al
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.26%
Montelukast is a highly selective leukotriene-receptor antagonist (LTRA). It is widely used in the treatment of bronchial asthma, primarily as an adjunct to corticosteroids. Reactive oxygen species (ROSs) play an important role in the pathogenesis of asthma and oxidative stress contributing to the initiation and worsening of inflammatory respiratory disorders, such as asthma. Antioxidant drugs may have a role in minimizing or preventing damage in asthmatic children. The aim of this study was to assess the antioxidant effect of montelukast on the production of free radicals in the whole blood and polymorphonuclear neutrophils (PMNs) in asthmatic children. A group of 48 (38 males and 10 females), apparently healthy asthmatic children were recruited with ages ranging between 6 and 14 years. In asthmatic children, base line (premedication) and post medication free radicals activity in the whole blood and polymorphonuclear neutrophils (PMNs) was determined by measuring chemiluminescence (CL) response through chemiluminescence luminometer. Free radical productions were significantly decreased in the whole blood, when stimulated with Phorbol Myristate Acetate (p < 0.04) and Opsonised Zymosan (p < 0.05). The free radicals were also significantly decreased in isolated polymorphonuclear neutrophils (PMNs) when stimulated with Opsonised Zymosan (p < 0.05) after the post medication treatment of montelukast in asthmatic children. Montelukast decreased the reactive oxygen species production...

Application of EPR Spectroscopy to Examination of Free Radical Formation in Thermally Sterilized Flumetasone

Kościelniak-Ziemniak, Magdalena; Pilawa, Barbara
Fonte: Springer Vienna Publicador: Springer Vienna
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.26%
Thermal formation of free radicals in flumetasone sterilized according to the pharmaceutical norms at 160, 170 and 180 °C was examined by electron paramagnetic resonance (EPR) spectroscopy. The microbiological analysis was done. Similar free radical concentrations were measured for flumetasone sterilized at 160 and 170 °C. The concentration was considerably higher than that for flumetasone sterilized at 180 °C. Fast spin–lattice relaxation processes, homogeneously broadened EPR lines, and complex free radicals system characterize the heated flumetasone. Free radicals were not observed 30 days after thermal sterilization. Optimal temperatures of sterilization of flumetasone are 160 and 170 °C.