RESUMO
Isoprene is the dominant non-methane organic compound emitted to the atmosphere1-3. It drives ozone and aerosol production, modulates atmospheric oxidation and interacts with the global nitrogen cycle4-8. Isoprene emissions are highly uncertain1,9, as is the nonlinear chemistry coupling isoprene and the hydroxyl radical, OH-its primary sink10-13. Here we present global isoprene measurements taken from space using the Cross-track Infrared Sounder. Together with observations of formaldehyde, an isoprene oxidation product, these measurements provide constraints on isoprene emissions and atmospheric oxidation. We find that the isoprene-formaldehyde relationships measured from space are broadly consistent with the current understanding of isoprene-OH chemistry, with no indication of missing OH recycling at low nitrogen oxide concentrations. We analyse these datasets over four global isoprene hotspots in relation to model predictions, and present a quantification of isoprene emissions based directly on satellite measurements of isoprene itself. A major discrepancy emerges over Amazonia, where current underestimates of natural nitrogen oxide emissions bias modelled OH and hence isoprene. Over southern Africa, we find that a prominent isoprene hotspot is missing from bottom-up predictions. A multi-year analysis sheds light on interannual isoprene variability, and suggests the influence of the El Niño/Southern Oscillation.
Assuntos
Atmosfera/química , Butadienos/análise , Butadienos/química , Mapeamento Geográfico , Hemiterpenos/análise , Hemiterpenos/química , Imagens de Satélites , África , Austrália , Brasil , Conjuntos de Dados como Assunto , El Niño Oscilação Sul , Formaldeído/química , Radical Hidroxila/análise , Radical Hidroxila/química , Ciclo do Nitrogênio , Óxidos de Nitrogênio/análise , Óxidos de Nitrogênio/química , Oxirredução , Estações do Ano , Sudeste dos Estados UnidosRESUMO
The chemical oxidation of white wines through the Fenton reaction has been widely studied, wherein the primary species is the hydroxyl radical (OH). This radical possesses high oxidising power and may oxidise the primary components in wines. The Fenton reaction in wines is complex and includes the participation of phenolic compounds, organic acids, and metals. However, there has been no systematic study to date that relates wine composition to OH production in real white wines. In this paper, a multivariate model was generated using the partial least squares (PLS) algorithm, and linear correlations were established between wine composition and OH production. Based on the results, the variables were classified as either pro-oxidants (malic acid, p-coumaric acid, and caffeic acid, % prodelphinidins, procyanidins B1, Mn, Cu, and Zn) or antioxidants (cis-piceid, ellagic acid, gallic acid, proanthocyanins, glucose, and proton concentration). Finally, the pathways by which wine compounds participate in OH production are discussed.
Assuntos
Radical Hidroxila/metabolismo , Vinho/análise , Antioxidantes/análise , Antioxidantes/química , Cromatografia Líquida de Alta Pressão , Espectroscopia de Ressonância de Spin Eletrônica , Radical Hidroxila/análise , Análise dos Mínimos Quadrados , Análise Multivariada , Oxidantes/química , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
Exposure of white wine to oxygen can cause detrimental effects, such as loss of sensorial characteristics. New antecedents, to the oxidation of wine, establish the importance of the formation of metallic complexes with compounds with adjacent hydroxyls. These complexes could reduce iron, promoting the formation of radicals through the Fenton reaction. The formation of hydroxyl radical (OH) induced by air was found in all 18 white wines analysed by electronic paramagnetic resonance (EPR) spectroscopy. The variation in the OH production was related to the phenolic composition of the wines. The amount of these radicals was linearly related to 5 phenolic compounds (caffeic acid, protocatechuic acid, p-coumaric acid, gentisic acid and syringic acid). Therefore, in this study, the relationship between certain phenolic compounds and the induction and amplification of the OH production was established and was postulated to be a chemical oxidation pathway to the Fenton reaction.
Assuntos
Radical Hidroxila/análise , Fenóis/análise , Fenóis/química , Vinho/análise , Ácidos Cumáricos , Espectroscopia de Ressonância de Spin Eletrônica , Radical Hidroxila/síntese químicaRESUMO
Fenton reactions driven by dihydroxybenzenes (DHBs) have been used for pollutant removal via advanced oxidation processes (AOPs), but such systems have the disadvantage of DHB release into the aqueous phase. In this work, insoluble tannins from bark can be used to drive Fenton reactions and as a heterogeneous support. This avoids the release of DHBs into the aqueous phase and can be used for AOPs. The production of ·OH was investigated using a spin-trapping electron paramagnetic resonance technique (5-dimethyl-1-pyrroline-N-oxide/·OH) in the first minute of the reaction and a high-performance liquid chromatography-fluorescence technique (coumarin/7-hydroxycoumarin) for 20 min. The ·OH yield achieved using insoluble tannins from Pinus radiata bark was higher than that achieved using catechin to drive the Fenton reaction. The Fenton-like system driven by insoluble tannins achieved 92.6 ± 0.3 % degradation of atrazine in 30 min. The degradation kinetics of atrazine was linearly correlated with ·OH production. The increased reactivity in ·OH production and insolubility of the ligand are promising for the development of a new technique for degradation of pollutants in wastewater using heterogeneous Fenton systems.
Assuntos
Derivados de Benzeno , Poluentes Ambientais , Radical Hidroxila , Pinus/química , Taninos , Derivados de Benzeno/análise , Derivados de Benzeno/química , Poluentes Ambientais/análise , Poluentes Ambientais/química , Poluentes Ambientais/isolamento & purificação , Recuperação e Remediação Ambiental , Radical Hidroxila/análise , Radical Hidroxila/química , Solubilidade , Taninos/análise , Taninos/químicaRESUMO
BACKGROUND: The aim of the present study was to evaluate the in vitro antioxidant and free radical scavenging capacity of bioactive metabolites present in Newbouldia laevis leaf extract. RESULTS: Chromatographic and spectrophotometric methods were used in the study and modified where necessary in the study. Bioactivity of the extract was determined at 10 µg/ml, 50 µg/ml, 100 µg/ml, 200 µg/ml and 400 µg/ml concentrations expressed in % inhibition. The yield of the ethanolic leaf extract of N.laevis was 30.3 g (9.93%). Evaluation of bioactive metabolic constituents gave high levels of ascorbic acid (515.53 ± 12 IU/100 g [25.7 mg/100 g]), vitamin E (26.46 ± 1.08 IU/100 g), saponins (6.2 ± 0.10), alkaloids (2.20 ± 0.03), cardiac glycosides(1.48 ± 0.22), amino acids and steroids (8.01 ± 0.04) measured in mg/100 g dry weight; moderate levels of vitamin A (188.28 ± 6.19 IU/100 g), tannins (0.09 ± 0.30), terpenoids (3.42 ± 0.67); low level of flavonoids (1.01 ± 0.34 mg/100 g) and absence of cyanogenic glycosides, carboxylic acids and aldehydes/ketones. The extracts percentage inhibition of DPPH, hydroxyl radical (OH.), superoxide anion (O2 .-), iron chelating, nitric oxide radical (NO), peroxynitrite (ONOO-), singlet oxygen (1O2), hypochlorous acid (HOCl), lipid peroxidation (LPO) and FRAP showed a concentration-dependent antioxidant activity with no significant difference with the controls. Though, IC50 of the extract showed significant difference only in singlet oxygen (1O2) and iron chelating activity when compared with the controls. CONCLUSIONS: The extract is a potential source of antioxidants/free radical scavengers having important metabolites which maybe linked to its ethno-medicinal use.
Assuntos
Antioxidantes/isolamento & purificação , Bignoniaceae/química , Sequestradores de Radicais Livres/isolamento & purificação , Metaboloma/fisiologia , Extratos Vegetais/isolamento & purificação , Folhas de Planta/química , Flavonoides/análise , Radical Hidroxila/análise , Concentração Inibidora 50 , Quelantes de Ferro/isolamento & purificação , Peroxidação de Lipídeos/fisiologia , Nigéria , Óxido Nítrico/metabolismo , Fenóis/análise , Extratos Vegetais/farmacologia , Espécies Reativas de Oxigênio/isolamento & purificação , Metabolismo Secundário/fisiologia , Vitaminas/isolamento & purificação , Vitaminas/metabolismoRESUMO
BACKGROUND: The aim of the present study was to evaluate the in vitro antioxidant and free radical scavenging capacity of bioactive metabolites present in Newbouldia laevis leaf extract. RESULTS: Chromatographic and spectrophotometric methods were used in the study and modified where necessary in the study. Bioactivity of the extract was determined at 10 µg/ml, 50 µg/ml, 100 µg/ml, 200 µg/ml and 400 µg/ml concentrations expressed in % inhibition. The yield of the ethanolic leaf extract of N.laevis was 30.3 g (9.93%). Evaluation of bioactive metabolic constituents gave high levels of ascorbic acid (515.53 ± 12 IU/100 g [25.7 mg/100 g]), vitamin E (26.46 ± 1.08 IU/100 g), saponins (6.2 ± 0.10), alkaloids (2.20 ± 0.03), cardiac glycosides(1.48 ± 0.22), amino acids and steroids (8.01 ± 0.04) measured in mg/100 g dry weight; moderate levels of vitamin A (188.28 ± 6.19 IU/100 g), tannins (0.09 ± 0.30), terpenoids (3.42 ± 0.67); low level of flavonoids (1.01 ± 0.34 mg/100 g) and absence of cyanogenic glycosides, carboxylic acids and aldehydes/ketones. The extracts percentage inhibition of DPPH, hydroxyl radical (OH.), superoxide anion (O2 .-), iron chelating, nitric oxide radical (NO), peroxynitrite (ONOO-), singlet oxygen (1O2), hypochlorous acid (HOCl), lipid peroxidation (LPO) and FRAP showed a concentration-dependent antioxidant activity with no significant difference with the controls. Though, IC50 of the extract showed significant difference only in singlet oxygen (1O2) and iron chelating activity when compared with the controls. CONCLUSIONS: The extract is a potential source of antioxidants/free radical scavengers having important metabolites which maybe linked to its ethno-medicinal use.
Assuntos
Extratos Vegetais/isolamento & purificação , Sequestradores de Radicais Livres/isolamento & purificação , Folhas de Planta/química , Bignoniaceae/química , Metaboloma/fisiologia , Antioxidantes/isolamento & purificação , Fenóis/análise , Vitaminas/isolamento & purificação , Vitaminas/metabolismo , Flavonoides/análise , Extratos Vegetais/farmacologia , Peroxidação de Lipídeos/fisiologia , Quelantes de Ferro/isolamento & purificação , Espécies Reativas de Oxigênio/isolamento & purificação , Radical Hidroxila/análise , Concentração Inibidora 50 , Metabolismo Secundário/fisiologia , Nigéria , Óxido Nítrico/metabolismoRESUMO
A wardite mineral sample from Lavra Da Ilha, Minas Gerais, Brazil has been examined by vibrational spectroscopy. The mineral is unusual in that it belongs to a unique symmetry class, namely the tetragonal-trapezohedral group. The structure of wardite contains layers of corner-linked -OH bridged MO6 octahedra stacked along the tetragonal C-axis in a four-layer sequence and linked by PO4 groups. Consequentially not all phosphate units are identical. Two intense Raman bands observed at 995 and 1051cm(-1) are assigned to the ν1PO4(3-) symmetric stretching mode. Intense Raman bands are observed at 605 and 618cm(-1) with shoulders at 578 and 589cm(-1) are assigned to the ν4 out of plane bending modes of the PO4(3-). The observation of multiple bands supports the concept of non-equivalent phosphate units in the structure. Sharp infrared bands are observed at 3544 and 3611cm(-1) are attributed to the OH stretching vibrations of the hydroxyl units. Vibrational spectroscopy enables subtle details of the molecular structure of wardite to be determined.
Assuntos
Minerais/química , Radical Hidroxila/análise , Fosfatos/análise , Espectrofotometria Infravermelho , Análise Espectral RamanRESUMO
Reactive oxygen species (ROS) are integral components of the plant adaptive responses to environment. Importantly, ROS affect the intracellular Ca(2+) dynamics by activating a range of nonselective Ca(2+)-permeable channels in plasma membrane (PM). Using patch-clamp and noninvasive microelectrode ion flux measuring techniques, we have characterized ionic currents and net K(+) and Ca(2+) fluxes induced by hydroxyl radicals (OH(â¢)) in pea (Pisum sativum) roots. OH(â¢), but not hydrogen peroxide, activated a rapid Ca(2+) efflux and a more slowly developing net Ca(2+) influx concurrent with a net K(+) efflux. In isolated protoplasts, OH(â¢) evoked a nonselective current, with a time course and a steady-state magnitude similar to those for a K(+) efflux in intact roots. This current displayed a low ionic selectivity and was permeable to Ca(2+). Active OH(â¢)-induced Ca(2+) efflux in roots was suppressed by the PM Ca(2+) pump inhibitors eosine yellow and erythrosine B. The cation channel blockers gadolinium, nifedipine, and verapamil and the anionic channel blockers 5-nitro-2(3-phenylpropylamino)-benzoate and niflumate inhibited OH(â¢)-induced ionic currents in root protoplasts and K(+) efflux and Ca(2+) influx in roots. Contrary to expectations, polyamines (PAs) did not inhibit the OH(â¢)-induced cation fluxes. The net OH(â¢)-induced Ca(2+) efflux was largely prolonged in the presence of spermine, and all PAs tested (spermine, spermidine, and putrescine) accelerated and augmented the OH(â¢)-induced net K(+) efflux from roots. The latter effect was also observed in patch-clamp experiments on root protoplasts. We conclude that PAs interact with ROS to alter intracellular Ca(2+) homeostasis by modulating both Ca(2+) influx and efflux transport systems at the root cell PM.
Assuntos
Cálcio/farmacocinética , Radical Hidroxila/farmacologia , Pisum sativum/fisiologia , Poliaminas/metabolismo , Potássio/farmacocinética , Cálcio/análise , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Homeostase , Radical Hidroxila/análise , Transporte de Íons , Potenciais da Membrana/efeitos dos fármacos , Técnicas de Patch-Clamp , Pisum sativum/efeitos dos fármacos , Epiderme Vegetal/efeitos dos fármacos , Epiderme Vegetal/fisiologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/fisiologia , Potássio/análise , Protoplastos , Espécies Reativas de Oxigênio/análise , Espécies Reativas de Oxigênio/farmacologia , Especificidade da EspécieRESUMO
The antioxidant, antinociceptive, and anti-inflammatory activities of the ethanolic extract from leaves of Combretum duarteanum (EEC) were assessed in rodents through in vitro tests. The antioxidant activity was investigated by using thiobarbituric acid reactive species (TBARS), hydroxyl radical-scavenging, and scavenging activity of nitric oxide assays. The antinociceptive activity was investigated by using acetic acid-induced writhing, formalin, and hot-plate tests in mice. The anti-inflammatory activity was assessed in rats by using the carrageenan-induced hind-paw edema test and arachidonic acid-induced paw edema test. EEC possesses a strong antioxidant potential according to the TBARS, nitric oxide, and hydroxyl radical-scavenging assays; it also presented scavenger activity in all in vitro tests. After intraperitoneal injection, EEC (100, 200, and 400 mg/kg) significantly reduced the number of writhes (38.1%, 90.6%, and 97.8%, respectively) in a writhing test and the number of paw licks during phase 1 (30.5% and 69.5%, higher doses) and phase 2 (38.1%, 90.6%, and 97.8%, all doses) of a formalin test when compared with the control group. Naloxone (1.5 mg/kg, intraperitoneally) antagonized the antinociceptive action of EEC (400 mg/kg), and this finding suggests participation of the opioid system. Administration of 200 and 400 mg/kg (intraperitoneally) of EEC exhibited an anti-inflammatory activity in the carrageenin test, which was based on interference with prostaglandin synthesis. This finding was confirmed by the arachidonic acid test. Together, these results indicate that properties of EEC might be further explored in the search for newer tools to treat painful inflammatory conditions, including those related to pro-oxidant states.
Assuntos
Analgésicos/farmacologia , Anti-Inflamatórios/farmacologia , Antioxidantes/farmacologia , Combretum/química , Extratos Vegetais/farmacologia , Analgésicos/antagonistas & inibidores , Animais , Ácido Araquidônico/toxicidade , Carragenina/toxicidade , Relação Dose-Resposta a Droga , Edema/induzido quimicamente , Edema/tratamento farmacológico , Etanol , Radical Hidroxila/análise , Masculino , Camundongos , Naloxona/metabolismo , Óxido Nítrico/análise , Dor/tratamento farmacológico , Medição da Dor , Folhas de Planta/química , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Roedores , Substâncias Reativas com Ácido Tiobarbitúrico/análiseRESUMO
Mate (MT) is a popular South American beverage that has been used as a traditional medicine for centuries, spurring recent interest in its nutraceutical properties. MT is prepared as an infusion of leaves from the Yerba Mate (llex paraguriensis) tree. MT has been reported to have antioxidant properties in vitro and in vivo, but these have not been fully characterized in terms of effects against specific radicals. Accordingly, we examined the antioxidant effects of an MT infusion against hydroxyl and superoxide radicals in both chemical and cell culture assays. MT infusions were prepared at 3.10 g/L in boiling water and diluted to experimental dilutions from this stock. Electron spin resonance (ESR) experiments indicated that MT scavenged hydroxyl radicals (produced via the Fenton reaction) and superoxide radicals (produced via the xanthine/xanthine oxidase enzymatic reaction) at all concentrations tested (P < 0.05). Further controls indicated that superoxide radical scavenging was not due to xanthine oxidase inhibition. MT scavenged hydroxyl radicals and decreased cellular oxygen consumption in a dose-dependent manner in Cr(VI)-stimulated RAW 264.7 cells, based on ESR and oxygraph measurements (P < 0.05). Similarly, MT also inhibited hydroxyl-radical-induced lipid peroxidation and DNA damage in a dose-dependent manner in RAW 264.7 cells, based on malondialdehyde and Comet assay data (P < 0.05). This study indicates that MT possesses potent antioxidant effects against hydroxyl and superoxide radicals in both chemical and cell culture systems, as well as DNA-protective properties. These data further clarify the reported antioxidant effects of Yerba Mate infusions.
Assuntos
Dano ao DNA , Sequestradores de Radicais Livres/análise , Ilex paraguariensis/química , Espectroscopia de Ressonância de Spin Eletrônica , Radical Hidroxila/análise , Ilex paraguariensis/genética , Peroxidação de Lipídeos , Malondialdeído/análise , Folhas de Planta/química , América do SulRESUMO
Schisandra propinqua (Wall.) Baill.(Schisandraceae) is widely used as a Chinese folk medicine. In this study, activity-guided fractionation of the ethanol extract from the stem of Schisandra propinqua led to the isolation of four extracts. Subsequently, a neolignan 4,4-di(4-hydroxy-3-methoxyphenly)-2,3-dimethylbutanol was isolated from the EtOAc part of the stem of Schisandra propinqua, the free radical scavenging activities of which were researched in vitro. The present work demonstrated that extracts and pure compound possessed scavenging activities to DPPH, superoxide anions and hydroxy radical, and could depress lipid peroxidation reaction induced by oxygen radical produced by the Fe2+/cysteine system in vitro. This suggests that the traditional application of Schisandra propinqua in China may be related to its antioxidant activities, and the EtOAc part of the stems of Schisandra propinqua can be utilized as an effective source of antioxidants.
Assuntos
Antioxidantes/farmacologia , Lignanas/farmacologia , Peroxidação de Lipídeos/efeitos dos fármacos , Extratos Vegetais/farmacologia , Schisandra/química , Animais , Antioxidantes/química , Antioxidantes/isolamento & purificação , Compostos de Bifenilo , Radical Hidroxila/análise , Lignanas/química , Lignanas/isolamento & purificação , Masculino , Peróxidos/análise , Picratos , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Ratos , Ratos Wistar , Superóxidos/análiseRESUMO
We use recent aircraft measurements of a comprehensive suite of anthropogenic halocarbons, carbon monoxide (CO), and related tracers to place new constraints on North American halocarbon emissions and quantify their global warming potential. Using a chemical transport model (GEOS-Chem) we find that the ensemble of observations are consistent with our prior best estimate of the U.S. anthropogenic CO source, but suggest a 30% underestimate of Mexican emissions. We develop an optimized CO emission inventory on this basis and quantify halocarbon emissions from their measured enhancements relative to CO. Emissions continue for many compounds restricted under the Montreal Protocol, and we show that halocarbons make up an important fraction of the total greenhouse gas source for both countries: our best estimate is 9% (uncertainty range 6-12%) and 32% (21-52%) of equivalent CO2 emissions for the U.S. and Mexico, respectively, on a 20 year time scale. Performance of bottom-up emission inventories is variable, with underestimates for some compounds and overestimates for others. Ongoing methylchloroform emissions are significant in the U.S. (2.8 Gg/y in 2004-2006), in contrast to bottom-up estimates (< 0.05 Gg), with implications for tropospheric OH calculations. Mexican methylchloroform emissions are minor.
Assuntos
Poluentes Atmosféricos/análise , Efeito Estufa , Hidrocarbonetos Halogenados/análise , Monóxido de Carbono/análise , Clorofluorcarbonetos/análise , Etano Clorofluorcarbonos , Radical Hidroxila/análise , México , Tricloroetanos/análise , Estados UnidosRESUMO
Schisandra propinqua (Wall.) Baill.(Schisandraceae) is widely used as a Chinese folk medicine. In this study, activity-guided fractionation of the ethanol extract from the stem of Schisandra propinqua led to the isolation of four extracts. Subsequently, a neolignan 4,4-di(4-hydroxy-3-methoxyphenly)-2,3-dimethylbutanol was isolated from the EtOAc part of the stem of Schisandra propinqua, the free radical scavenging activities of which were researched in vitro. The present work demonstrated that extracts and pure compound possessed scavenging activities to DPPH, superoxide anions and hydroxy radical, and could depress lipid peroxidation reaction induced by oxygen radical produced by the Fe2+/cysteine system in vitro. This suggests that the traditional application of Schisandra propinqua in China may be related to its antioxidant activities, and the EtOAc part of the stems of Schisandra propinqua can be utilized as an effective source of antioxidants.
Assuntos
Animais , Masculino , Ratos , Antioxidantes/farmacologia , Lignanas/farmacologia , Peroxidação de Lipídeos/efeitos dos fármacos , Extratos Vegetais/farmacologia , Schisandra/química , Antioxidantes/química , Antioxidantes/isolamento & purificação , Compostos de Bifenilo , Radical Hidroxila/análise , Lignanas/química , Lignanas/isolamento & purificação , Picratos , Peróxidos/análise , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Ratos Wistar , Superóxidos/análiseRESUMO
The purpose of the present study was to evaluate the influence of instrumentation techniques associated with the smear layer removal, in the pH changes of the root surface. Thirty mandibular humans premolars were divided into three groups: Group I - instrumentation by Ohio technique and final cleaning with EDTA (3 minutes); Group II - instrumentation by Ohio technique and final cleaning with ultrasonic (1 minute); Group III - instrumentation by the ultrasonic technique and final cleaning with ultrasonic (1 minute). The pH was measured in the cavities prepared in the cervical, middle and apical thirds of the lateral wall of each root. The teeth were evaluated at the initiation of the experiment, and 3, 7, 14, 21, 30 days after of the intracanal dressing of the calcium hydroxide with camphorated p-monochlorophenol (Calen/PMCC). All the groups presented increasing pH values; group III presented the highest average pH, followed by groups II and I; the values for the apical third were lower than those of the middle and cervical thirds (anova and Tukey test). The results showed that the biomechanical preparation by the ultrasonic technique and smear layer removal with ultrasonic showing the highest diffusion of the calcium and hydroxyl ions from the intracanal dressing (P < 0.05).
Assuntos
Ácido Edético , Irrigantes do Canal Radicular , Preparo de Canal Radicular/instrumentação , Preparo de Canal Radicular/métodos , Camada de Esfregaço , Dente Pré-Molar , Cálcio/análise , Hidróxido de Cálcio , Cânfora , Clorofenóis , Combinação de Medicamentos , Humanos , Concentração de Íons de Hidrogênio , Radical Hidroxila/análise , UltrassomRESUMO
Angiotensin II, a profibrotic cytokine, plays a main role in the initiation of renal fibrogenesis at a very early stage leading to a progressive loss of renal function in unilateral ureteral obstruction (UUO). We studied the involvement of AT1 angiotensin II receptor in the physiopathology of tubulointerstitial fibrosis in UUO, focusing in the regulation of the oxidative stress state and in the HSP 70 expression, in renal tissue. UUO or control sham operation was perform to Wistar Kyoto rats after being treated with the AT1 angiotensin II receptor antagonist Losartan (10 mg/kg/day) in the drinking water for 15 days. Twenty four hours later, mRNA AT1 receptor expression was studied. Renal fibrosis was evaluated through TGFbeta expression and superoxide dismutase (SOD) activity, hydroxyl radicals, O2- and total antioxidant activity were measured by spectrophotometric assay. Immunohistochemical and Western blot analysis of HSP 70 were performed. A non-hypotensive dose of Losartan significantly down regulated the expression of AT1 receptor. Prevention of renal fibrogenesis by Losartan treatment was demonstrated by TGFbeta mRNA expression similar to control. Oxidative stress in obstructed kidney was evident since a decreased SOD activity and a two-fold increase in the concentration of hydroxyl radicals and O2- was observed when compared to the control. Losartan produced down regulation of ROS with recovery of the SOD activity and higher expression of HSP 70 compared to obstructed kidney of rats receiving vehicle. We can conclude that after 24 hr of UUO, protection against tubulointerstitial fibrosis by Losartan, independent from changes in blood pressure, includes decreased oxidative stress linked to upregulation of HSP 70 expression.
Assuntos
Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Proteínas de Choque Térmico HSP70/genética , Losartan/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Obstrução Ureteral/metabolismo , Animais , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Feminino , Fibrose/patologia , Fibrose/fisiopatologia , Proteínas de Choque Térmico HSP70/biossíntese , Radical Hidroxila/análise , Imuno-Histoquímica , Córtex Renal/metabolismo , Córtex Renal/patologia , Córtex Renal/fisiopatologia , RNA Mensageiro/análise , Ratos , Ratos Endogâmicos WKY , Espécies Reativas de Oxigênio/análise , Receptor Tipo 1 de Angiotensina/genética , Receptor Tipo 1 de Angiotensina/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Superóxido Dismutase/análise , Fator de Crescimento Transformador beta/análise , Fator de Crescimento Transformador beta/genética , Obstrução Ureteral/patologiaRESUMO
The fine-grained character of volcanic ash generated in the long-lived eruption of the Soufrière Hills volcano, Montserrat, West Indies, raises the issue of its possible health hazards. Surface- and free-radical production has been closely linked to bioreactivity of dusts within the lung. In this study, electron paramagnetic resonance (EPR) techniques have been used, for the first time, on volcanic ash to measure the production of radicals from the surface of particles. Results show that concentrations of hydroxyl radicals (HO*) in respirable ash are two to three times higher than a toxic quartz standard. The dome-collapse ash contains cristobalite, a crystalline silica polymorph that may cause adverse health effects. EPR experiments indicate, however, that cristobalite in the ash does not contribute to HO* generation. Our results show that the main cause of reactivity is removable divalent iron (Fe2+), which is present in abundance on the surfaces of the particles and is very reactive in the lung. Our analyses show that fresh ash generates more HO* than weathered ash (which has undergone progressive oxidation and leaching of iron from exposed surfaces), an effect replicated experimentally by incubating fresh ash in dilute acid. HO* production experiments also indicate that iron-rich silicate minerals are responsible for surface reactivity in the Soufrière Hills ash.
Assuntos
Radical Hidroxila/análise , Oxidantes/análise , Saúde Pública , Erupções Vulcânicas/efeitos adversos , Espectroscopia de Ressonância de Spin Eletrônica , Humanos , Ferro , Tamanho da Partícula , Medição de Risco , Índias OcidentaisRESUMO
The lining of the uterus and cervix might be injured by a variety of oxidation products of Cu in a Cu-IUD, including cuprous ions, dissolved and precipitated cupric ions, and reactive oxygen species such as superoxide radicals, hydrogen peroxide, and hydroxyl radicals. In this study, the human amnious WISH cell line was employed as a model of uterine cells in the presence of copper. The cell viability was decreased by elemental copper, which was alleviated up to 70% by the addition of catalase. The addition of copper oxychloride caused cell death in a dose-dependent manner. Hydroxyl radicals in the presence of copper were determined by the formation of malondialdehyde. Soluble cuprous chloride complexes are formed in the uterus by slowly entering oxygen. The complexes are partly oxidized to insoluble copper oxychloride. which damages the endometrium. Unoxidized cuprous ions migrate to the oxygen-rich cervix and are oxidized to copper oxychloride, causing cervix damage.
Assuntos
Anticoncepção/métodos , Cobre/metabolismo , Radical Hidroxila/efeitos adversos , Dispositivos Intrauterinos de Cobre/efeitos adversos , Útero/efeitos dos fármacos , Catalase/química , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Cobre/efeitos adversos , Relação Dose-Resposta a Droga , Feminino , Humanos , Radical Hidroxila/análise , Vermelho Neutro/química , Oxirredução , Substâncias Reativas com Ácido Tiobarbitúrico/análise , Doenças Uterinas/induzido quimicamente , Útero/citologiaRESUMO
Detection of hydroxyl free radicals is frequently performed by electron spin resonance (ESR) following spin trapping of the radical using 5,5-dimethylpyrroline N-oxide (DMPO) to generate a stable free radical having a characteristic ESR spectrum. The necessary ESR equipment is expensive and not readily available to many laboratories. In the present study, a specific and sensitive gas chromatography-mass spectrometry (GC/MS) method for detection of hydroxyl and hydroxyethyl free radicals is described. The DMPO or N-t-butyl-alpha-phenylnitrone (PBN) radical adducts are extracted and derivatized by trimethylsylilation and analyzed by GC/MS. To standardize the method, .OH and 1-hydroxyethyl radicals were generated in two different systems: 1) a Fenton reaction in a pure chemical system in the absence or presence of ethanol and 2) in liver microsomal suspensions where ethanol is metabolized in the presence of NADPH. In the Fenton system both radicals were easily detected and specifically identified using DMPO or PBN. In microsomal suspensions DMPO proved better for detection of .OH radicals and PBN more suitable for detection of 1-hydroxyethyl radicals. The procedure is specific, sensitive and potentially as useful as ESR.
Assuntos
Etanol/análise , Radical Hidroxila/análise , Óxidos N-Cíclicos , Radicais Livres/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Indicadores e Reagentes , Microssomos/metabolismo , Óxidos de Nitrogênio , Sensibilidade e Especificidade , Espectrometria de Massa de Íon Secundário , Marcadores de SpinRESUMO
The objective of this research is to chemically analyze calcium hydroxide pastes added to three hydrosoluble vehicles having different acid-base characteristics using polyethylene tubes implanted in subcutaneous connective tissue in a dog, evaluating the liberation of calcium and hydroxyl ions over a period of 7, 30, 45 and 60 days. The three vehicles were saline, anesthetic, and polyethylene glycol 400. Chemical analysis of the liberated calcium ions was done by means of conductimetry using EDTA for titration. Liberation of hydroxyl ions was determined by analogy of calcium ions liberated, which are in direct proportion to the molecular weight of calcium hydroxide.