科研之友
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摘要
Alternative sources of anticoagulants have arisen as a result of the increasing demand for safer anticoagulant clinical therapy, and the sulfated polysaccharides of seaweeds have gained attention in biomedicine. In this study, crude sulfated polysaccharide fractions (denominated Hf1, Hf2 and Hf3) were obtained from the red marine algaHalymenia floresia and the anticoagulant properties of a soluble crude polysaccharide fraction (Hf2s) were assayed. The three differential extractions yielded 38.6%. The polysaccharides are composed mainly of galactose, with small amounts of xylose and glucose. The anticoagulant properties of Hf2s containing 53.8% sulfate and 3% protein was also compared to those of heparin (193.0 IU mg-1) by assays of activated partial thromboplastin time (APTT) and thrombin time (TT) using normal human plasma. Hf2s showed a higheranticoagulant activity (68.4 IU mg-1) than those of Hf1s and Hf3s, whose activities were 37.6 and 36.6 IU mg-1, respectively. The compound was less active than heparin, but its anticoagulant mechanism suggested that it is dependent on cofactor heparin II to inhibit thrombin activity, but not on cofactors VIII and IX. Therefore, the polysaccharide from H. floresia interfered on coagulation cascade. O aumento da demanda por anticoagulantes para a terapia cl赤nica tem motivado a busca por fontes alternativas de anticoagulantes mais seguros e os polissacar赤deos sulfatados de algas marinhas t那m ganhado aten o na biomedicina. Objetivou-se obter fra es de polissacar赤deossulfatados brutos (denominadas Hf1; Hf2 e Hf3) da alga marinha vermelha Halymenia floresia e para avaliar as propriedades anticoagulantes de uma fra o polissacar赤dica bruta sol迆vel anticoagulante (Hf2s). As tr那s extra es diferenciais renderam 38,60%. Os polissacar赤deos s o principalmente compostos de galactose com pequenas quantidades de xilose e glucose. As propriedades anticoagulantes da Hf2s, contendo 53,80% de sulfato e 3% de prote赤nas, foram tamb谷m comparadas com a heparina (193,00 UI mg-1) pelo ensaio do tempo de tromboplastina parcial ativada (TTPA) e tempo de trombina (TT), usando plasma humano normal. A Hf2s apresentou maior atividade anticoagulante (68,40 UI mg-1) que Hf1s a Hf3s, cujas atividades foram 37,60 e 36,60 UI mg-1, respectivamente. O composto foi menos ativo que a heparina, mas sugere-se que o mecanismo anticoagulante seja dependente do cofator II da heparina para inibi o da atividade da trombina, exceto pelos cofatores VIII a IX. Portanto, o polissacar赤deo de H. floresia interferiu na cascata de coagula o.
