Structure and anticoagulant property of a sulfated polysaccharide isolated from the green seaweed Monostroma angicava

An anticoagulant-active polysaccharide PF2 was extracted with boiling water from the green seaweed Monostroma angicava, further purified by anion-exchange and size-exclusion chromatography. PF2 was a rhamnan-type sulfated polysaccharide with molecular weight of about 88.1 kDa. Results of chemical and spectroscopic analyses demonstrated that PF2 consisted of → 3)-α-l-Rhap-(1→ and →2)-α-l-Rhap-(1 → residues, with partially branches at C-2 of → 3)-α-l-Rhap-(1 → residues. Sulfate groups were substituted at C-3 of  → 2)-α-l-Rhap-(1 →  residues. The sulfated polysaccharide PF2 had a high anticoagulant action, and the mechanism of anticoagulant activity mediated by PF2 was mainly attributed to strong potentiation thrombin by heparin cofactor II. PF2 also exhibited weak effect on antithrombin-dependent thrombin or factor Xa inhibition. The fibrin(ogen)olytic activity and thrombolytic activity of PF2 were also evaluated. The investigation revealed that PF2 was a novel sulfated rhamnan differing from previously described sulfated polysaccharides from green seaweed and could be a potential anticoagulant polysaccharide.