Antithrombotic and profibrinolytic activities of eckol and dieckol

In order to develop new anticoagulant agents, two single compounds (eckol and dieckol) were isolated from Eisenia bicyclis and examined their anticoagulant activities by monitoring activated partial thromboplastin time (aPTT), prothrombin time (PT) as well as cell-based thrombin and activated factor X (FXa) generation activities. And the effects of eckol and dieckol on the expression of plasminogen activator inhibitor type 1 (PAI-1) and tissue-type plasminogen activator (t-PA) were tested in tumor necrosis factor-α (TNF-α) activated human umbilical vein endothelial cells (HUVECs). Data showed that eckol and dieckol prolonged aPTT and PT significantly and inhibited thrombin and FXa activities. They also inhibited the generation of thrombin or FXa in HUVECs. In accordance with these anticoagulant activities, eckol or dieckol showed anticoagulant effect in vivo. Furthermore, eckol and dieckol inhibited TNF-α induced PAI-1 production and the ratio between PAI-1 and t-PA was found to be significantly decreased by eckol and dieckol. Surprisingly, these anticoagulant and profibrinolytic effects of dieckol were better than those of eckol indicating that hydroxyl group in eckol positively regulated anticoagulant function of eckol. Therefore, these results suggest that eckol or dieckol possesses antithrombotic activities and provides a possibility to develop as an agent for the anticoagulation.