Antiplatelet and antithrombotic activities of salvianolic acid A

Introduction: Salvianolic acid A (SAA), the water-soluble phenolic acids in Salvia miltiorrhiza, has shown the most potent bioactivities, including protection against cerebral lesion, defense from oxidative damage and improvement of remembrance. In the present study, we studied the antiplatelet and antithrombotic effects of a newly synthesized SAA with different methods both in vitro and in vivo.

Materials and methods: We tested the effect of antithrombotic activity of SAA in arterio-venous shunt model. The effects of SAA on adenosine diphosphate (ADP)-, Thrombin-, Arachidonic acid- induced rat platelets aggregation were tested both in vivo and in vitro. The activity of SAA on washed human platelet aggregation was determined by ADP stimulation. We also evaluated its property of modulation of hemorheology, assessed its bleeding side effect by measuring coagulation parameters after intravenous administration for 5 days and investigated the potential mechanisms underlying such activities.

Results and conclusions: In vivo, SAA significantly reduced thrombus weight in the model of arterio-venous shunt. Meanwhile, SAA increased plasma cAMP level determined by radioimmunoassay in the same model. Intravenously administrated SAA (2.5-10 mg/kg) inhibited platelet aggregation induced by ADP in a dose-dependent manner. Notably, SAA did not affect coagulation parameters in rats after intravenous administration SAA for successive 5 days. In vitro, pretreatment with SAA on washed rat and human platelets significantly inhibited various agonists stimulated platelet aggregation and caused an increase in cAMP level in platelets activated by ADP. These findings support our hypothesis that SAA possesses antithrombotic activities. The antithrombotic effect might be related to its antiplatelet action and ability to modulate hemorheology without affecting coagulation system. The mechanisms underlying such activities may involve the induction of cAMP.