Chemical characteristics and anticoagulant activities of a sulfated polysaccharide and its fragments from Monostroma latissimum

A sulfated polysaccharide from the green alga Monostroma latissimum was extracted in hot water and purified by ion-exchange and size-exclusion chromatography. Five sulfated polysaccharide fragments with different molecular weights were prepared from the sulfated polysaccharide by H2O2 degradation. The molecular weights of the parent sulfated polysaccharide and its fragments were 725.4, 216.4, 123.7, 61.9, 26.0 and 10.6 kDa, respectively. These sulfated polysaccharide preparations have high contents of rhamnose. Anticoagulant activities of the parent sulfated polysaccharide and its fragments were investigated by studying the activated partial thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT) using human plasma. The six sulfated polysaccharide preparations did not affect PT even at the concentration at which APTT and TT were prolonged. The sulfated polysaccharides fragments with molecular weights of 216.4–61.9 kDa had similar anticoagulant activities as the parent sulfated polysaccharide. A decrease in the molecular size of the sulfated polysaccharide fragments dramatically reduced their anticoagulant activities. The results indicated that molecular size had an important effect on the anticoagulant activity of the sulfated polysaccharide obtained from M. latissimum, and an even longer chain was necessary to achieve thrombin inhibition.