Spirulan from Blue‐Green Algae Inhibits Fibrin and Blood Clots: Its Potent Antithrombotic Effects

We investigated in vitro and in vivo fibrinolytic and antithrombotic activity of spirulan and analyzed its partial biochemical properties. Spirulan, a sulfated polysaccharide from the blue‐green alga Arthrospira platensis, exhibits antithrombotic potency. Spirulan showed a strong fibrin zymogram lysis band corresponding to its molecular mass. It specifically cleaved Aα and Bβ, the major chains of fibrinogen. Spirulan directly decreased the activity of thrombin and factor X activated (FXa), procoagulant proteins. In vitro assays using human fibrin and mouse blood clots showed fibrinolytic and hemolytic activities of spirulan. Spirulan (2 mg/kg) showed antithrombotic effects in the ferric chloride (FeCl₃)‐induced carotid arterial thrombus model and collagen and epinephrine‐induced pulmonary thromboembolism mouse model. These results may be attributable to the prevention of thrombus formation and partial lysis of thrombus. Therefore, we suggest that spirulan may be a potential antithrombotic agent for thrombosis‐related diseases.