Variação sazonal em antioxidantes em folhas de plantas jovens de Caesalpinia echinata Lam. (pau-brasil)

Abstract

-(Seasonal variation in antioxidants in leaves of young plants of Caesalpinia echinata Lam. (brazilwood)). The urban environmental factors generate conditions of oxidative stress in plants. Cellular antioxidants, such as ascorbic acid (AA), thiols (Ti), peroxidases (POD) and superoxide dismutase (SOD) are induced to different levels depending on their capacity to tolerate stressing conditions. In the first part of this study we determined the profile of these defenses in leaves of different ages of young plants of C. echinata. The levels of antioxidants were similar in all leaves analyzed, independently of the age. Secondly, we evaluated the same antioxidants and glutathione (GSH) in 130 young plants kept in a greenhouse with constant monitoring of temperature, relative humidity and irradiance during 18 months, in order to establish the seasonal variations occurring in response to climatic factors. During this period, leaf antioxidants were analyzed every three months. In general, AA concentrations and POD activity in C. echinata were higher than the levels reported for other tropical tree species. Seasonal variations were observed. GSH concentration and POD activity were significantly influenced by temperature and SOD by temperature and humidity.Key words -ascorbic acid, Caesalpinia echinata, glutathione, peroxidases, superoxide dismutase, thiols RESUMO -(Variação sazonal em antioxidantes em folhas de plantas jovens de Caesalpinia echinata Lam. (pau-brasil)). O ambiente urbano pode gerar condições de estresse oxidativo nas plantas, levando à estimulação de antioxidantes como ácido ascórbico (AA), tióis (Ti), peroxidases (POD) e superóxido dismutase (SOD), em diferentes níveis, de acordo com sua capacidade de tolerar tais condições. Este estudo, em sua primeira fase, buscou conhecer o perfil destas defesas em folhas de plantas jovens de C. echinata com diferentes graus de desenvolvimento. Os níveis dos antioxidantes foram similares em todas as folhas analisadas. Em uma segunda fase, tais antioxidantes e a glutationa (GSH) foram avaliados em 130 plantas mantidas em casa de vegetação com monitoramento constante de temperatura, umidade relativa e irradiância, por um período de 18 meses, para estabelecer se variações sazonais nessas defesas ocorrem em resposta a fatores climáticos. Nesse período, os antioxidantes foliares foram analisados a cada três meses. Em geral, a concentração de AA e a atividade da POD foram altas em C. echinata, quando comparadas com as de outras espécies arbóreas tropicais. Houve variações nas defesas ao longo do tempo. A concentração de GSH e a atividade da POD mostraram ser influenciadas por mudanças na temperatura e a SOD foi estimulada em resposta à temperatura e à umidade relativa.Palavras-chave -ácido ascórbico, Caesalpinia echinata, glutationa, peroxidases, superóxido dismutase, tióis IntroduçãoA exploração descontrolada do pau-brasil (Caesalpinia echinata Lam., LeguminosaeCaesalpiniodeae), nos primeiros séculos da colonização, contribuiu significativamente para a redução de ...

Does rainfall affect the antioxidant capacity and production of phenolic compounds of an important medicinal species?

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