Heparinoid-active sulphated polysaccharides from marine algae as potential blood anticoagulant agents

Anticoagulant properties of marine algae have been extensively studied for the last 60 years. Sulphated polysaccharides (SPS) of three major divisions of marine algae, viz. Rhodophyta, Phaeophyta and Chlorophyta are reported to have such properties. Some of the active components have been chemically well characterized. Sulphated galactans and fucoidan sulphates from red and brown algae, respectively, and different sugar sulphates like arabinan, rhamnan sulphates, etc. from green algae are the active molecular species identified. Activity is related to the molecular size, type of sugar and sulphate content of the active component. Sulphate position, type of linkage and molecular geometry are also known to have a role in activity. The proposed mechanisms of action are predominantly on HC-II mediated antithrombin activities, direct antithrombin action (thrombin–fibrinogen complex) and minor AT-III involvements. Little anti-factor Xa and fibrinolytic activities are also proposed. Therapeutic interest of algal SPS as anticoagulant has recently been in focus. In future, algal SPS can be developed as anticoagulant/antithrombotic agents or could be used as a model for the same.