The effect of Angelica Dahurica extracts on platelet aggregation

Platelet aggregation is one of the important mechanisms in hemostasis. Improper platelet function may lead to bleeding or atherothrombosis. Angelica dahurica (AD) has been used in the mixture of Ya-Hom, a Thai herbal formulation, which is used for treatment of circulatory disorder. Imperatorin is one of the major chemical compounds in AD. The aims of this study were to investigate the effects of AD extracts (ADE) and imperatorin on arachidonic acid (AA)-, adenosine diphosphate (ADP)-, and collagen-induced platelet aggregation and their mode of action on platelet aggregation. 0.1 – 1 mg/ml of ADE and 10 – 300 µM of imperatorin were preincubated in platelet rich plasma (PRP) for 3 min before adding agonists. The results demonstrated that 1 mg/ml of ADE inhibited ADP- and collagen- induced platelet aggregation significantly by 62.82% (p=0.000) and 66.28% (p=0.002), while 300 µM of imperatorin inhibited ADP-induced platelet aggregation by 33.96% (p=0.012) compared with vehicle control but not inhibited collagen-induced platelet aggregation. Both ADE and imperatorin inhibited secondary phase of ADP-induced aggregation. ADE increased lag phase in collagen-induced platelet aggregation compared with vehicle control (367.78 vs. 116.35 sec, p=0.008). Both ADE and imperatorin could not inhibit AA-induced platelet aggregation but they could delay platelet aggregation. When induced platelet aggregation by ADP, ADE significantly increased cAMP levels (p=0.027), but did not affect on thromboxane B2 level. In conclusion, the antiplatelet property of ADE and imperatorin at least take part in adenylate cyclase – cAMP pathway.