6 resultados para apocynin

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo (BDPI/USP)


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Apocynin has been extensively used as an inhibitor of NADPH oxidase (NOX) in many experimental models using phagocytic and non-phagocytic cells. Currently, there is some controversy about the efficacy of apocynin in non-phagocytic cells, but in phagocytes the reported results are consistent, which could be due to the presence of myeloperoxidase in these cells. This enzyme has been proposed as responsible for activating apocynin by generating its dimer, diapocynin, which is supposed to be the active compound that prevents NADPH oxidase complex assembly and activation. Here, we synthesized diapocynin and studied its effect on inhibition of gp91(phox) RNA expression. We found that diapocynin strongly inhibited the expression of gp91(phox)mRNA in peripheral blood mononuclear cells (PBMC). Only at a higher concentration, apocynin was able to exert the same effect. We also compared the apocynin and diapocynin efficacy as inhibitors of tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) production in response to lipopolysaccharide (LPS)-activated PBMC. Although apocynin did inhibit TNF-alpha production, diapocynin had a much more pronounced effect, on both TNF-alpha and IL-10 production. In conclusion, these findings suggest that the bioconversion of apocynin to diapocynin is an important issue not limited to enzymatic activity inhibition, but also for other biological effects as gp91(phox) mRNA expression and cytokine production. Hence, as diapocynin can be easily prepared from apocynin, a one-step synthesis, we recommend its use in studies where the biological effects of apocynin are searched. (C) 2010 Elsevier Inc. All rights reserved.

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Apocynin, a methoxy-substituted catechol (4-hydroxy-3-methoxyacetophenone), originally extracted from the roots of Picrorhiza kurroa, has been extensively used as a non-toxic inhibitor of the multienzymatic complex NADPH oxidase. We discovered that the analogous methoxy-substituted catechol, 4-Fluoro-2-methoxyphenol (F-apocynin), in which the acetyl group present in apocynin was changed to a fluorine atom, was significantly more potent as an inhibitor of NADPH oxidase activity, myeloperoxidase (MPO) chlorinating activity and phagocytosis of microorganisms by neutrophils; it was also as potent as apocynin in inhibiting tumor necrosis factor-alpha (TNF alpha) release by peripheral blood mononuclear cells. We attribute the increased potency of F-apocynin to its increased lipophilicity, which could facilitate the passage of the drug through the cell membrane. The inhibition of MPO chlorination activity, phagocytosis and TNF alpha release shows that apocynin and F-apocynin actions are not restricted to reactive oxygen species inhibition, but further studies are needed to clarify if these mechanisms are related. Like apocynin, F-apocynin did not show cell toxicity, and is a strong candidate for use in the treatment of inflammatory diseases. (C) 2011 Elsevier B.V. All rights reserved.

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Cardiovascular disease is less frequent in premenopausal women than in age-matched men or postmenopausal women. Moreover, the marked age-related decline in serum dehydroepiandrosterone (DHEA) level has been associated to cardiovascular disease. The aim of this study was to evaluate the effects of DHEA treatment on vascular function in ovariectomized rats. At 8 weeks of age, female Wistar rats were ovariectomized (OVX) or sham (SHAM) operated and 8 weeks after surgery both groups were treated with vehicle or DHEA (10 mg kg-1 week-1) for 3 weeks. Aortic rings were used to evaluate the vasoconstrictor response to phenylephrine (PHE) and the relaxation responses to acetylcholine (ACh) and sodium nitroprusside (SNP). Tissue reactive oxygen species (ROS) production and SOD, NADPH oxidase and eNOS protein expression were analysed. PHE-induced contraction was increased in aortic rings from OVX compared to SHAM, associated with a reduction in NO bioavailability. Furthermore, the relaxation induced by ACh was reduced in arteries from OVX, while SNP relaxation did not change. The incubation of aortic rings with SOD or apocynin restored the enhanced PHE-contraction and the impaired ACh-relaxation only in OVX. DHEA treatment corrected the increased PHE contraction and the impaired ACh-induced relaxation observed in OVX by an increment in NO bioavailability and decrease in ROS production. Besides, DHEA treatment restores the reduced Cu/Zn-SOD protein expression and eNOS phosphorylation and the increased NADPH oxidase protein expression in the aorta of OVX rats. The present results suggest an important action of DHEA, improving endothelial function in OVX rats by acting as an antioxidant and enhancing the NO bioavailability.

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Redox processes associated with controlled generation of reactive oxygen species (ROS) by NADPH oxidase (Nox) add an essential level of regulation to signaling pathways underlying physiological processes. We evaluated the ROS generation in the main visual relays of the mammalian brain, namely the superior colliculus (SC) and the dorsal lateral geniculate nucleus (DLG), after ocular enucleation in adult rats. Dihydroethidium (DHE) oxidation revealed increased ROS generation in SC and DLG between 1 and 30 days postlesion. ROS generation was decreased by the Nox inhibitors diphenyleneiodonium chloride (DPI) and apocynin. Real-time PCR results revealed that Nox 2 was upregulated in both retinorecipient structures after deafferentation, whereas Nox 1 and Nox 4 were upregulated only in the SC. To evaluate the role of ROS in structural remodeling after the lesions, apocynin was given to enucleated rats and immunohistochemistry was conducted for markers of neuronal remodeling into SC and DLG. Immunohistochemical data showed that ocular enucleation produces an increase of neurofilament and microtubule-associated protein-2 immunostaining in both SC and DLG, which was markedly attenuated by apocynin treatment. Taken together, the findings of the present study suggest a novel role for Nox-induced ROS signaling in mediating neuronal remodeling in visual areas after ocular enucleation. (C) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

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Reactive oxygen species (ROS) appear to be involved in several neurodegenerative disorders. We tested the hypothesis that oxidative stress could have a role in the hippocampal neurodegeneration observed in temporal lobe epilepsy induced by pilocarpine. We first determined the spatio-temporal pattern of ROS generation, by means of detection with dihydroethidium oxidation, in the CA1 and CA3 areas and the dentate gyrus of the dorsal hippocampus during status epilepticus induced by pilocarpine. Fluoro-Jade B assays were also performed to detect degenerating neurons. ROS generation was increased in CA1, CA3 and the dentate gyrus after pilocarpine-induced seizures, which was accompanied by marked cell death. Treatment of rats with a NADPH oxidase inhibitor (apocynin) for 7 days prior to induction of status epilepticus was effective in decreasing both ROS production (by an average of 20%) and neurodegeneration (by an average of 61%). These results suggest an involvement of ROS generated by NADPH oxidase in neuronal death in the pilocarpine model of epilepsy. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

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Exposure to air pollutants such as formaldehyde (FA) leads to inflammation, oxidative stress and immune-modulation in the airways and is associated with airway inflammatory disorders such as asthma. The purpose of our study was to investigate the effects of exposure to FA on the allergic lung inflammation. The hypothesized link between reactive oxygen species and the effects of FA was also studied. To do so, male Wistar rats were exposed to FA inhalation (1%, 90 min daily) for 3 days. and subsequently sensitized with ovalbumin (OVA)-alum by subcutaneous route One week later the rats received another OVA-alum injection by the same route (booster). Two weeks later the rats were challenged with aerosolized OVA. The OVA challenge of rats upon FA exposure induced an elevated release of LTB(4). TXB(2), IL-1 beta, IL-6 and VEGF in lung cells, increased phagocytosis and lung vascular permeability, whereas the cell recruitment into lung was reduced. FA inhalation induced the oxidative burst and the nitration of proteins in the lung Vitamins C, E and apocynin reduced the levels of LTB(4) in BAL-cultured cells of the FA and FA/OVA groups, but Increased the cell influx into the lung of the FA/OVA rats. In OVA-challenged rats, the exposure to FA was associated to a reduced lung endothelial cells expression of intercellular cell adhesion molecule 1 (ICAM-1) In conclusion, our findings suggest that FA down regulate the cellular migration into the lungs after an allergic challenge and increase the ability of resident lung cells likely macrophages to generate inflammatory mediators, explaining the increased lung vascular permeability Our data are indicative that the actions of FA involve mechanisms related to endothelium-leukocyte interactions and oxidative stress, as far as the deleterious effects of this air pollutant on airways are concerned. (C) 2010 Elsevier Ireland Ltd. All rights reserved.