Polissacarídeos obtidos da alga marinha vermelha Gracilaria caudata j. agardh: estudo químico-estrutural e avaliação de atividade antioxidante

• Ano de defesa: 2016
• Autor(a) principal: Alencar, Poliana de Oliveira Cavalcante
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Bioquímica; Gracilaria; Agarana; Estrutura química; Estresse oxidativo; Chemical structure; Oxidative stress
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/18873

Red algae are natural sources of sulfated polysaccharides, which are widely used in the food and pharmaceutical industries. This study aims to obtain the total sulfated polysaccharides from the red seaweed Gracilaria caudata (PSG) through enzymatic extraction, determine their chemical structure and their antioxidant potential. Chemical analysis revealed that the obtained extract is comprised of 85% total sugars and 1% of contaminating proteins. Through Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), the PSG showed a percentage of 0.9% sulfur atoms and a degree of sulfation of 0.14%. The average molar mass of PSG was determined through gel permeation chromatography (GPC) and was determined as 116.51 kDa. The total sulfated olysaccharides were subjected to structural characterization tests through infrared Fourier transform spectroscopy and C13 and H1 Nuclear Magnetic Resonance (NMR) analysis, identifying the PSG as galactan from the agaran type. The in vitro antioxidant activity of PSG was determined using tests such as elimination of DPPH radical, chelation of ferrous ion and total antioxidant capacity. The results indicated that such polysaccharides have the capacity to scavenge free radicals significantly and in a concentration-dependent maner. The in vivo antioxidant activity of PSG was valuated in an oxidative stress model induced by 2,2'-azobis- -amidinopropane (AAPH) in rats, with subsequent dosage of antioxidant enzyme system markers, such as catalase (CAT) and superoxide dismutase (SOD), and the quantitation of oxidative damage markers such as nitrite and thiol. The results showed an improvement in the redox imbalance through increased CAT activity and increased SOD activity with the best response found at a dose of 3 mg / kg. Because of these results, the sulfated polysaccharide obtained from seaweed Gracilaria caudata shows potential for their being used in the food and pharmaceutical industry.