新穎抗血栓藥物Ctkf6f2之藥理作用及機轉之探討

Abstract

血管栓塞是由一系列血小板與凝血因子的異常所導致，對於心血管、腦血管及周邊血管造成一定程度的影響。經過一系列化合物的篩選，我們發現化合物Ctkf6f2具抑制血小板凝集的活性，並且在測試濃度中不影響細胞膜完整性。在人類血小板懸浮液中，Ctkf6f2呈濃度相關性的抑制由膠原蛋白(collagen)，花生四烯酸(A.A.)及U46619(TXA2類似物)所引起的血小板凝集，其IC50分別為3.4±0.6μM，3.2±1.0μM及1.17±0.2μM。 Ctkf6f2呈濃度相關抑制由collagen引起的 P-selectin表現量及TXB2的形成。在酵素活性分析方面，Ctkf6f2部分抑制thromboxane synthase的活性，但不影響COX-1酵素活性。且發現在U46619誘發血小板凝集的濃度反應曲線圖上，Ctkf6f2及5185對於TP受體呈現競爭性的拮抗作用。另一方面， 靜脈注射Ctkf6f2 (10 μg/g) 能顯著的抑制螢光素前處理之小鼠腸繫膜小靜脈血栓生成，且不影響小鼠的出血時間。同時，Ctkf6f2能有效抑制老鼠PRP之凝集反應，且更優於化合物5185。在肺栓塞實驗中，Ctkf6f2 能增加小鼠存活率及減少循環阻塞與栓子形成的數目。當口服給予Ctkf6f2 (80 mg/kg/day) 三天，Ctkf6f2證明能抑制血小板凝集且不會引起急性胃部之損傷，顯示其為口服有效之化合物。總結上述結果，Ctkf6f2於體內及體外實驗皆呈現強效抑制血小板之活性，此化合物具潛力進入未來的抗血栓藥物之研發。

Atherothrombosis is a systemic process that affects the cardiovascular, cerebrovascular, and peripheral arterial systems. The abnormality of platelet activation plays a key role in its pathogenesis. We screened a series of synthetic compounds and found Ctkf6f2, a derivative of compound 5185, possesses concentration-dependent inhibition on platelet aggregation of washed human platelets induced by collagen (IC50=3.4±0.6μM) , arachidonic acid (IC50=3.2±1.0μM) and U46619 (IC50=1.17±0.2μM). Ctkf6f2 inhibited P-selectin expression and TXB2 formation induced by collagen in a concentration-dependent manner. In the enzyme assay, we found Ctkf6f2 partially inhibited thromboxane synthase activity and had little effect on COX-1 enzyme. Moreover, Ctkf6f2 produced a right-shift of the concentration- response curve of U46619, indicating a competitive antagonism on TP receptor. On the other hand, Ctkf6f2 significantly inhibited thrombus formation of the irradiated mesenteric vessels in fluorescein sodium-pretreated mice without significantly affecting the bleeding time induced by tail transaction. In addition, Ctkf6f2 significantly impaired platelet aggregation of mice PRP induced by collagen and U46619 compared to compound 5185. In the pulmonary embolism model, Ctkf6f2 was proved to increase the survival rate, reduce the circulation obstruction and number of emboli formation. Also, it exerts antiplatelet potent upon oral administration. Taken together, Ctkf6f2 may become a new potent antithrombotic agent.