892 resultados para Oxidative radicals


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Although the exact cause of neuronal loss in Parkinson's disease is not known, evidence points to oxidative stress and the production of reactive oxygen species as the main events that occur in the substantia nigra pars compacta of the brain of parkinsonians. EGb761 is an extract of the leaves from the Ginkgo biloba tree that has been reported as an antioxidant and neuroprotective agent. The objective of this work was to perform a systematic review of the studies that analysed the effect of Ginkgo biloba extract on Parkinson's disease or Parkinsonism. This research was conducted using the following databases: Medline, PsycInfo, Cinahl, Sigle, Lilacs, Scielo, Cochrane Library, and Embase. Initially, we selected 32 articles. After a more detailed analysis, only 10 articles remained. One of the hypotheses for the positive effect of EGb761 on Parkinson's disease is the reduction or inhibition of monoamine-oxidase activity. This enzyme metabolises dopamine, inducing the formation of free radicals, which in turn damage nigrostriatal neurons. Another hypothesis is that the neuroprotective effect of EGb761 against 6-hydroxydopamine, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and MPP+ toxins. As there are few studies on the effect of EGb761 on humans, this review could contribute new data to further the discussion of this issue.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Melatonin is an endoleamine that has anti-inflammatory, immunomodulating and antioxidants properties. But there is a contradiction between the antioxidant effects of melatonin and glutathione (GSH). Therefore, the main objective of this work was to study the effect of melatonin on the oxidation of GSH and the effect of GSH on the oxidation of melatonin by peroxyl radicals generated by thermolysis of 2,2 -Azobis(2- amino-propane)-dihydrochloride (AAPH). The influence of the reaction conditions and the identity of the products of oxidation were also studied. The main products obtained during the oxidation of melatonin were its monohydroxylated derivative and N1-acetyl- N2-formyl-5-methoxykynuramine (AFMK), which is the product obtained by oxidative cleavage of the melatonin indole ring. By studying the buffer type, pH and the presence or absence of dissolved oxygen in the reaction system, it was observed that, the yield of AFMK was higher when the pH or the concentration of oxygen was increased. Comparing the reactivity of both molecules GSH and melatonin, it can be seen that intermediates radicals generated during the oxidation of melatonin are able to oxidize GSH itself. We propose that this chemical property could justify the recent reports that demonstrated the inability of melatonin to inhibit the oxidation of GSH in cells

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Background: Plant extracts have b een used as an alternative to the use of synthetic antioxidants in order to preserve oils fromoxidative degradation. Additionally, these extracts add special flavors and aromas to the food. Thus, the objective of this studywas to evaluate the effect of hydroethanolic extracts of fresh and freeze-dried rosemar y in the oxidative stability of soybean oilunder accelerated storage in an oven. Results: The application of the extracts in the oil showed that that freeze-dried extract was better in reducing the formation ofoxidation products, showing 8.6 meq kg−1of peroxides after 20 days of storage. On the other hand, the mixture of the naturalextract with t-butylhydroquinone conferred better oxidative stability index until the 20th day, 9.7 h. Both extracts prevented theloss of tocopherol, not d iffering between each other (P > 0.05), and present approximately 505 mg kg−1of residual tocopherols.The sensory evaluation revealed that consumers accepted equally the oils added and not added of the rosemary extracts. Conclusion: The extracts are therefore potential sources of natural antioxidants and they would be well accepted by consumersif applied by the food industry to replace synthetic antioxidants.