<p>Inappropriate platelet aggregation can cause blood coagulation and thrombosis. In this study, the effect of an ethanol extract of <i>Ramulus mori</i> (ERM) on blood circulation was investigated. The antithrombotic activity of ERM on rat carotid arterial thrombosis was evaluated <i>in vivo,</i> and the effect of ERM on platelet aggregation and blood coagulation time was evaluated <i>ex vivo</i>. To evaluate the safety of ERM, its cytotoxicity to platelets and its effect on tail bleeding time were assessed; ERM was not toxic to rat platelets and did not prolong bleeding time. Moreover, administering ERM to rats had a significant preventive effect on carotid arterial thrombosis <i>in vivo</i>, and significantly inhibited adenosine diphosphate- and collagen-induced platelet aggregation <i>ex vivo</i>, whereas it did not prolong coagulation periods, such as prothrombin time and activated partial thromboplastin time. The results suggest that ERM is effective in improving blood circulation via antiplatelet activity rather than anticoagulation activity.</p> <p><i>Ex vivo</i> antiplatelet effect of the ethanol extract of <i>Ramulus mori</i> containing 6.79% oxyresveratrol. Platelet aggregation was induced by (A) ADP and (B) collagen.</p
