Caracterização da produção de pigmentos e da atividade antioxidante de Nostoc spp. sob diferentes intensidades luminosas

• Autor(a) principal: Oliveira, Cristiane Alves de
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5353
• topic: Cianobactéria; Intensidade luminosa; Pigmentos; Compostos bioativos; Antioxidantes; Nutrição humana; Cyanobacteria; Light intensity; Pigments; Bioactive compounds; Antioxidants; Human nutrition; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::MICROBIOLOGIA AGRICOLA

Cyanobacteria used for centuries as a food has antioxidant mechanisms highly developed and production capacity higher than any other agricultural system, presenting a great potential as a source of natural antioxidant compounds, and various other compounds. One of the factors that interfere with the metabolism of photosynthetic organisms is the level of incident light, yet for cyanobacteria are not well understood the relations between luminosity, bioactive compounds and antioxidant activity. Under this approach, the objective of this study was to determine the influence of different light intensities on antioxidant activity of cyanobacteria of the genus Nostoc spp., and on the levels of some of the main antioxidant compounds found in their cells: the pigments phycobiliproteins (phycocyanin, allophycocyanin and phycoerythrin), carotenoids and chlorophyll, and phenolic compounds. The antioxidant activity was determined by the percentage of inhibition of the radical 2,2-diphenyl-1-picryl hydrazyl (DPPH ) and phenols were determined using the Folin-Cicalteau. The data from this study demonstrated that significant variations can occur for the pigment and antioxidant activity between narrow bands of light intensity, thus, a precise definition of the intensity applied through response curves previously constructed is necessary in according to biotechnological interest in question. The lowest intensities were more advantageous in terms of yield pigments, antioxidant potential and phenolic compounds. The decreased level of chlorophyll and phycobiliproteins in higher irradiances were observed, probably being prevention against photo-oxidative damage caused by free radical generation. However, for carotenoids was observed in some instances increase the content of higher irradiances, which could reflect their function as heat sinks of the light energy absorbed in excess and as antioxidant agents of the photosynthetic apparatus. The phycobiliproteins was the major contributor to total antioxidant status at lower intensities, while for higher intensities are the carotenoids. However, not always the behaviors observed were similar between the biocompostos contents and antioxidant activity, since this relationship may prove to be quite complex, requiring a qualitative and quantitative determination of many compounds that may have antioxidant properties and use of highly purified extracts. In addition, the methodology used to determine the antioxidant activity could also be a source of variation, generating inconsistent results between the content of bioactive compounds and antioxidant activity.