Abstract: The effects of crude (F) and purified (FD1 and FS1) fucoidans from Sargassum on tail thrombosis in mice were studied. F was prepared by ultrasonic-assisted hot water extraction, alcohol precipitation and deproteinization using Sevag reagent. FD1 and FS1 were obtained by passing F through a DEAE C-52 cellulose column and a Sepharose CL-6B agarose gel column, respectively. The chemical composition of the three fucoidans was analyzed and their monosaccharide composition was determined by high performance liquid chromatography (HPLC). A mouse black tail model was established and used to evaluate the inhibition effect of the three fucoidans on thrombus formation, and the clotting time was determined by capillary method. The results showed that the polysaccharide content of the crude fucoidans was increased to different extents after being purified by the chromatographic columns. The sulphate content of FD1 was the highest and the fucose content of FS1 was the highest among the three fucoidans. Their monosaccharide composition was significantly different from other, but none contained arabinose. FS1 showed the highest fucoidan content. Ingestion of each fucoidan did not affect the body mass of mice, indicating their safety. The black tail length of mice treated with each fucoidan at all doses investigated was shorter than that of the model control group, and FD1 and FS1 inhibited thrombus formation in mice more effectively than F, with a significant difference being observed for FD1 at 60 mg/kg mb and FS1 at 15 mg/kg mb (P < 0.01). All three fucoidans could prolong the clotting time of mice in the order of decreasing effectiveness: FS1> FD1> F, and the clotting time of the high-dose FD1 group and the high-, medium- and low-dose FS1 groups were longer than that of the positive drug group.

Key words: Sargassum, fucoidan, purification, black tail, thrombus, coagulation