171 resultados para radical-scavenging capacity
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Abstract The use of agroindustrial residues is an economical solution to industrial biotechnology. Coffee husk and pulp are abounding residues from coffee industry which can be used as substrates in solid state fermentation process, thus allowing a liberation and increase in the phenolic compound content with high added value. By employing statistical design, initial moisture content, pH value in the medium, and the incubation temperature were evaluated, in order to increase the polyphenol content in a process of solid state fermentation by Penicillium purpurogenum. The main phenolic compounds identified through HPLC in fermented coffee residue were chlorogenic acid, caffeic acid, and rutin. Data obtained through HPLC with the radical absorbance capacity assay suggest the fermented coffee husk and pulp extracts potential as a source of phenolic acids and flavonoids. Results showed good perspectives when using P. purpurogenum strain to enhance the liberation of phenolic compounds in coffee residues.
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Abstract Optimization of polyphenols extraction from plum (Prunus salicina Lindl.) was evaluated using response surface methodology. The Box-Behnken experimental results showed the optimal conditions involved an extraction temperature of 59 °C, a sonication time of 47 min, and an ethanol concentration of 61% respectively. The maximum extraction yield of total polyphenols was 44.74 mg gallic acid equivalents per gram of dried plum at optimal conditions. Polyphenol extracts exhibited stronger antioxidant activities than Vc by evaluating of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical scavenging activity. Furthermore, polyphenol extracts (IC50 = 179 g/mL) showed obvious inhibitory effects on xanthine oxidase. These findings suggest that polyphenol extracts from P. salicina can be potentially used as natural antioxidant and xanthine oxidase inhibitory agents.
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INTRODUCTION: The capacity to overcome the oxidative stress imposed by phagocytes seems to be critical for Candida species to cause invasive candidiasis. METHODS: To better characterize the oxidative stress response (OSR) of 8 clinically relevant Candida sp., glutathione, a vital component of the intracellular redox balance, was measured using the 5,5'-dithiobis-(2-nitrobenzoic acid (DTNB)-glutathione disulfide (GSSG) reductase reconversion method; the total antioxidant capacity (TAC) was measured using a modified method based on the decolorization of the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic) acid radical cation (ABTS*+). Both methods were used with cellular Candida sp. extracts treated or not with hydrogen peroxide (0.5 mM). RESULTS: Oxidative stress induced by hydrogen peroxide clearly reduced intracellular glutathione levels. This depletion was stronger in Candida albicans and the levels of glutathione in untreated cells were also higher in this species. The TAC demonstrated intra-specific variation. CONCLUSIONS: Glutathione levels did not correlate with the measured TAC values, despite this being the most important non-enzymatic intracellular antioxidant molecule. The results indicate that the isolated measurement of TAC does not give a clear picture of the ability of a given Candida sp. to respond to oxidative stress.
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AbstractMany well-established methods for determining the antioxidant capacities in several samples have been described in literature. However, DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) are the main two methods that utilize radicals as spectrophotometric probes for analysis. Nevertheless, these methods have certain limitations because of their slower kinetics, solvent polarity effects, the hydrophilicity and lipophilicity of the compounds, chemical costs, etc. In this study, a spectrophotometric method for determining the antioxidant capacity in beverages was developed based on an exploration of the cation radical derived from DEPD. This method was based on the oxidation of aromatic amines with Fe(III) ions at pH 4.0, which leads to their corresponding purple cation radicals (DEPD•+) with λmax values at 500 and 540 nm. The addition of an antioxidant after the formation of the radical leads to a reduction in color intensity that is proportional to the antioxidant concentration in the medium. Results obtained using this method were compared with the Folin-Ciocalteau, ABTS and DPPH methods in terms of applications in wines, teas, and infusions samples. Linear correlation analysis at a 95% confidence level was employed to compare the results, which were in good agreement with a correlation coefficient of r > 0.9000. Thus, the developed method was simple, accurate, and consistent with other assays for the determination of the total amount of phenolic compounds and antioxidant capacity.
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A novel, rapid and cost-effective trifluoperazine dihydrochloride (TFPH) decolorization assay is described for the screening of antioxidant activity. A chromogenic reaction between TFPH and potassium persulfate at low pH produces an orange-red radical cation with maximum absorption at 502 nm in its first-order derivative spectrum. TFPH was dissolved in distilled water to give a 100 mM solution. The TFPH radical cation solution was made by reacting 0.5 mL of the solution with K2S2O8 (final concentration: 0.1 mM) and diluting to 100 mL with 4 M H2SO4 solution. A linear inhibition of color production was observed with linearly increasing amounts of antioxidants, with correlation coefficients (R²) ranging from 0.999 to 0.983. The antioxidant capacity of standard solutions of an antioxidant was evaluated by comparing with the inhibition curve using Trolox as the standard. Comparison of antioxidant capacity determined with this newly developed TFPH assay and with the well-known 2,2'-azinobis-[3-ethylbenzthiazoline-6-sulfonic acid] (ABTS)-persulfate decolorization assay indicated the efficacy and sensitivity of the procedure. The proposed assay is less expensive (costs about US$4 per 100 assays) and requires only 20 min for preparation of radical cation solution in comparison with ABTS assay, in which almost 12-16 h are required for preparation of a stable ABTS radical cation solution. The present assay has the advantage over ABTS assay that it can be used to measure the antioxidant activity of the samples, which are naturally found at a pH as low as 1, because the radical cation itself has been stabilized at low pH.
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The aim of this work was to evaluate spices and industrial ingredients for the development of functional foods with high phenolic contents and antioxidant capacity. Basil, bay, chives, onion, oregano, parsley, rosemary, turmeric and powdered industrial ingredients (β-carotene, green tea extract, lutein, lycopene and olive extract) had their in vitro antioxidant capacity evaluated by means of the Folin-Ciocalteu reducing capacity and DPPH scavenging ability. Flavonoids identification and quantification were performed by High Performance Liquid Chromatography (HPLC). The results showed that spices presented a large variation in flavonoids content and in vitro antioxidant capacity, according to kind, brand and batches. Oregano had the highest antioxidant capacity and parsley had the highest flavonoid content. The industrial ingredient with the highest antioxidant capacity was green tea extract, which presented a high content of epigalocatechin gallate. Olive extract also showed a high antioxidant activity and it was a good source of chlorogenic acid. This study suggests that oregano, parsley, olive and green tea extract have an excellent potential for the development of functional foods rich in flavonoids as antioxidant, as long as the variability between batches/brands is controlled.
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O paradigma terapêutico para o CEC do andar inferior da boca sofreu modificações em decorrência da sobrevida. OBJETIVO: Estudo comparativo do esvaziamento cervical radical e seletivo. MATERIAL E MÉTODO: Análise de 460 pacientes atendidos no Depto. de CCP e ORL do Hospital Heliópolis, de 1978 a 2002. Para esvaziamento radical foram avaliados os padrões de metastatização dos níveis IV e V, para o seletivo a ocorrência e localização das recidivas. O método estatístico utilizado foi o teste do qui-quadrado. RESULTADOS: Nos esvaziamentos radicais a taxa de metastatização nos níveis IV e V foram 5,8% e 4,6%, nos pacientes cNO e de 9,9% (nível IV) e 5,9% (nível V) para cN+, enquanto o nível I isolado estava comprometido em 11,0% nos cN0 e 5,5% nos cN+. Nos esvaziamentos seletivos ocorreram 4 recidivas (4,1%) em 97 esvaziamentos nos pN0 e 2 (10,0%) em 20 esvaziamentos. Nos casos pN+, não houve vantagens na indicação de radioterapia sobre os não irradiados (5,6% e 5,7% respectivamente). CONCLUSÃO: É possível realizar esvaziamento seletivo no tratamento das metástases do andar inferior de boca.
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O tratamento do carcinoma da laringe tem como desafio a cura do paciente e a preservação do órgão. OBJETIVO: A avaliação dos subsítios na disseminação do carcinoma e a sua influência no tratamento cirúrgico da laringe, no controle local e na sobrevida. MATERIAL E MÉTODO: Cento e sessenta pacientes tratados na Escola Paulista de Medicina - Hospital São Paulo, no período de janeiro de 1998 a dezembro de 2004, foram compilados para análise da disseminação do carcinoma dos subsítios da laringe. Foram incluídos pacientes com seguimento mínimo de 2 anos, após diagnóstico e tratamento. A avaliação estatística foi: Teste X2, Teste de Fisher e a Curva de Kaplan-Meier. Forma de Estudo: Estudo de Coorte Histórica Longitudinal (Trabalho Clínico Retrospectivo). RESULTADOS: A comissura posterior e a infraglote, respectivamente, foram significantes para a laringectomia total: tumores glóticos AC: (p=0,03) AP: (p=0,0001); AC: (p=0,0007) AP: (p<0,0001). A infraglote foi significante nos tumores G+SG na AP: (p=0,04), e na taxa de óbitos AP: (p=0,03). CONCLUSÃO: A laringectomia total é o tratamento de eleição na presença de alto comprometimento da comissura posterior e da infraglote. Esta última pode comprometer a sobrevida, conforme a invasão local, mesmo na presença de margens cirúrgicas livres.
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This study evaluated the effects on the development and predatory capacity of Podisus nigrispinus fed on Spodoptera frugiperda that have ingested different concentrations of neem oil. The predatory capacity of Podisus nigrispinus was assessed, separating nymphs (fourth instar) and adults (males and females). The treatments consisted of S. frugiperda larvae reared in neem oil aqueous solutions (0.077, 0.359 and 0.599%), deltamethrin EC 25 (0.100%) and control arranged in a completely randomized design, with ten replicates. Insects were offered three larval densities (one, three and six), in the third or fourth instars. The predated larvae were examined at 24 and 48 hours after the beginning of the experiment. Biological parameters of Podisus nigrispinus were evaluated in groups of ten second-instar nymphs transferred to pots, in five replicates. Insects were offered 2-6 third and/or fourth-instar larvae reared in the same neem oil concentrations in a completely randomized design. The following parameters were evaluated: duration of each nymph stage (days), nymph mortality (%), weight of fifth-instar nymphs (mg), sex ratio, weight of males and females (mg) and longevity of unfed adults (days). The predatory capacity of nymphs and adults of Podisus nigrispinus was influenced by the neem oil at the concentrations of 0.359% and 0.599% in the highest density. The concentration of 0.359% lengthened the nymphal stage and the concentration of 0.599% reduced the weight of males.
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A cada dia surgem mais provas da importância da inovação radical ou revolucionária na determinação do sucesso das empresas, em longo prazo, no mercado competitivo atual. Embora esse reconhecimento tenha estado presente em muitas empresas sólidas, existem dúvidas no que diz respeito à maneira segundo a qual a inovação deve ser implementada. O presente artigo baseia-se em um estudo longitudinal de 12 projetos de inovação radical em 10 empresas maduras de grande porte, no período de seis anos. O ciclo de vida dos projetos de inovação radical é diferente daquele de projetos incrementais, devido ao grande número de incertezas e descontinuidades. Tais características exigem que os projetos de inovação radical sejam gerenciados de forma diversa daquela aplicada aos projetos incrementais. Demonstramos sete fatores estratégicos decisivos para realizar-se a implementação bem-sucedida da inovação radical.
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Este artigo oferece uma análise da aprendizagem nas organizações em condições de mudança radical, em que a reestruturação da organização foi motivada por uma mudança na ideologia e na propriedade. Discute-se que, nessas circunstâncias, a aprendizagem não representa necessariamente uma melhoria para o coletivo como um todo. A fonte empírica para este artigo é um estudo de caso da Telemig, uma das principais companhias brasileiras de telecomunicações. A pesquisa empregou múltiplos métodos e fontes permitindo uma investigação do conteúdo e do processo de aprendizagem, e de seus agentes ao longo do tempo. O estudo elabora e ilustra o conceito de "aprendizagem contestada", concluindo que este necessita ser incorporado à teoria da aprendizagem nas organizações.
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Calf serum and fetal bovine serum present great variability as to its growth promoting efficiency (GPE). As supplement of culture media to cultivate cells of animal origin they stimulate the "in vitro" multiplication and maintain cell viability. When fourteen lots of calf sera of variable GPE had the total protein contents as well as the percentages of serum fractions determined, no significant differences that could possibly explain the variability of the GPE were observed. Evaluation of the antiproteolytic activity of nineteen lots of calf serum and eighteen serum lots of younger calves showed that the former exhibited lower antiproteolytic titers (1:40 to 1:80) than the latter (1:80 to 1:160). Twelve lots of fetal bovine serum studied in parallel, showed the highest concentration of antiproteolytic factors, with titers equal to 1:320. Sera of bovine origin, but not fetal sera, are usually heat-inactivated, what was demonstrated to be responsible for the decrease of the antiproteolytic activity of 75% of the lots tested. This could explain the inability of certain heat-inactivated sera in promoting multiplication of some cells "in vitro", as verified with primary monkey kidney cells. The results obtained in this study indicated the convenience of submiting each lot of serum to be introduced in cell culture to previous determination of its characteristics, such as growth promoting efficiency, antiproteolytic activity and also toxicity, absence of extraneous agents, etc., in order to minimize the possibility of using serum lots of questionable quality, thus preventing not only the loss of cell lines, but also undesirable and sometimes expensive delays.
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Arcobacter spp. are emerging enteropathogens and potential zoonotic agents that can be transmitted by food and water, being considered a public health risk. The high isolation rate of these bacteria from poultry products suggests that it may be a major source of human infections. One hallmark for differentiating the genus Arcobacter fromCampylobacter includes their growing capacity at low temperatures (15-30 °C) under aerobic conditions. However, little is known about the population density variation of these bacteria at different refrigeration temperatures. The aim of this study was to determine the survival behavior of two different Arcobacter butzleri concentrations (104 CFU/mL and 107 CFU/mL) inoculated on chicken legs and held at two different refrigeration temperatures (4 and 10 °C) throughout storage time. Results have shown that A. butzleri had growing capacity both at 4 and 10 °C. No statistical difference between the survival trends was found for both bacterial concentrations and temperatures tested. This study shows that A. butzleri is a robust species with regard to storage temperature, and represents a potential health risk for poultry meat consumers.
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This paper reports reduction on the reproductive capacity of female mice infected with Schistosoma mansoni, either in the acute phase or in the chronic one of the disease. This decrease in the reproductive capacity was highly significant (93.3% and 86.7%, for the acute and chronic phases, respectively)..