Antiplatelet and antithrombotic activities of timosaponin B-II, an extract of Anemarrhena asphodeloides.

1. Antithrombotic agents are effective in the treatment of ischaemic stroke. Timosaponin B-II (TB-II) is a major active component of Anemarrhena asphodeloides Bunge (Liliaceae; rhizome) that has protective effects against cerebral ischaemic damage. The present study examined the antiplatelet and antithrombotic actions of TB-II. 2. In in vitro experiments, TB-II (20, 40 and 80 mg/mL) potently and dose-dependently inhibited ADP-induced platelet aggregation. Furthermore, 1, 3 and 6 mg/kg TB-II prolonged activated partial thromboplastin time by 9.29, 16.86 and 25.50%, respectively, but had no effect on the prothrombin time. Furthermore, 1, 3 and 6 mg/kg TB-II significantly reduced the wet weight, dry weight and length of the thrombi (%inhibition (based on wet weight): 13.6, 19.8 and 24.7%, respectively). 3. In a rabbit arteriovenous shunt model, 1, 3 and 6 mg/kg, i.v., TB-II had no effect on thrombus formation. Plasma euglobulin lysis time and fibrin degradation product were not affected by 1, 3 and 6 mg/kg TB-II, but plasminogen levels were decreased significantly by 14.4, 18.3 and 29.0%, respectively. 4. The results of the present study demonstrate significant antiplatelet and anticoagulation effects of TB-II and suggest that these actions could contribute to its neuroprotective effect against damage following cerebral ischaemia damage.