Blockade of glycoprotein IIb/IIIa mediates the antithrombotic activity of butanol fraction of Actinostemma lobatum Maxim.
OBJECTIVE
Actinostemma lobatum Maxim, a wildlife plant of Cucurbitaceae family, has been utilized for the prevention or treatment of cardiovascular diseases as a folk remedy in Korea. However, its scientific evidence remains unclear. Thus, in the present study, we examined the effects of butanol fraction of Actinostemma lobatum Maxim (BFALM) on the in vitro and in vivo antithrombotic activity and possible mechanisms were elucidated for the first time.


METHODS
To elucidate the antithrombotic mechanism of BFALM, platelet aggregation assay, coagulation assay, glycoprotein IIb/IIIa assay, thromboxane A(2) assay and in vivo pulmonary thromboembolism experiment were performed.


RESULTS
BFALM significantly inhibited collagen, adenosine diphosphate (ADP) and thrombin-induced platelet aggregation in a concentration dependent manner. Consistently, oral administration of BFALM resulted in a dose-dependent increase of survival rates of mice with pulmonary thromboembolism induced by intravenous injection of collagen and epinephrine. In mechanism assays for the antithrombotic activity of BFALM, BFALM significantly inhibited the fibrinogen binding to the platelet surface Glycoprotein IIb/IIIa (GP IIb/IIIa) receptor in a concentration dependent fashion, as well as reduced the level of thromboxane A(2) at 400microg/ml. Furthermore, BFALM significantly prolonged the prothrombin time (PT) and activated partial thromboplastin time (APTT) compared with untreated control.


CONCLUSIONS
These results suggest that BFALM may exert antithrombotic activity through inhibition of platelet aggregation via GP IIb/IIIa and thromboxane A(2) pathways, along with anticoagulatory activity through intrinsic and extrinsic pathways.
Kim
Kwan-Hyun
KH
Graduate School of East-West Medical Science, Kyunghee University, Yongin 446-701, Republic of Korea.
Lee
Hyo-Jung
HJ
Lee
Jae-Ho
JH
Jang
Yu-Sung
YS
Kim
Dae-Keun
DK
Shim
Bum-Sang
BS
Cho
Ki-Ho
KH
Ko
Seong-Gyu
SG
Ahn
Kyoo-Seok
KS
Kim
Sung-Hoon
SH
D000818:Animals; D001777:Blood Coagulation / Q000187:drug effects; D001792:Blood Platelets / Q000737:chemistry / Q000187:drug effects; D000440:Butanols / Q000737:chemistry; D019662:Cucurbitaceae / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D005343:Fibrinolytic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D039661:Integrin beta3 / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D008517:Phytotherapy; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects; D040201:Platelet Membrane Glycoprotein IIb / Q000378:metabolism*; D011655:Pulmonary Embolism / Q000188:drug therapy* / Q000378:metabolism; D012431:Rutin / Q000032:analysis; D016019:Survival Analysis; D013928:Thromboxane A2 / Q000032:analysis
D000440:Butanols; D005343:Fibrinolytic Agents; D039661:Integrin beta3; D010936:Plant Extracts; D040201:Platelet Membrane Glycoprotein IIb; D013928:Thromboxane A2; D012431:Rutin; D005340:Fibrinogen