A sulfated fucan from the brown alga Laminaria cichorioides has mainly heparin cofactor II-dependent anticoagulant activity.

The major acidic polysaccharide from the brown alga Laminaria cichorioides is a complex and heterogeneous sulfated fucan. Its preponderant structure is a 2,3-disulfated, 4-linked alpha-fucose unit. The purified polysaccharide has a potent anticoagulant activity, as estimated by APTT assay ( approximately 40 IU/mg), which is mainly mediated by thrombin inhibition by heparin cofactor II. It also accelerates thrombin and factor Xa inhibition by antithrombin but at a lower potency. Sulfated fucan from L. cichorioides is a promising anticoagulant polysaccharide and a possible alternative for an antithrombotic compound due to its preferential heparin cofactor II-dependent activity.