Abstract: Fucoidan (F) from Sargassum henslowianum C. Agardh was extracted by ultrasonic-assisted hot water extraction and the extract was deproteinized by Sevag method and purified by DEAE C-52 anion exchange column chromatography. The chemical compositions of the crude (F) and purified (F1) fucoidan were analyzed and their monosaccharide compositions were determined by gas chromatography-mass spectrometry (GC-MS). Meanwhile, antithrombotic activity was evaluated by thrombolysis test in vitro, pulmonary embolism test and hemorrhage test in mice. The results showed that the contents of total saccharide, fucose and SO4 2- in F1 were increased and F1 was composed of more monosaccharides when compared with F. The bleeding time of low, middle and high dose of F1 were higher than each dose of F, and their effects at high dose were significantly higher than that of urokinase (P＜0.05, P＜0.01). Both F and F1 could reduce the mortality of pulmonary embolism model mice, and there was a extremely significant difference between high-dose F1 and the model group (P < 0.01). F and F1 could significantly prolong the bleeding time (P < 0.05, P ＜ 0.01). Compared to the heparin sodium control group, all dose groups showed a extremely significant difference (P < 0.01) and were significantly less effective in prolonging the bleeding time. These findings led to the conclusion that the crude and purified fucoidan from Sargassum henslowianum C. Agardh have good antithrombotic activity and cause little risk of bleeding and the antithrombotic effect of F1 is better than that of F.

Key words: Sargassum, fucoidan, antithrombosis