Studies on Anti-platelet Agents. II. Synthesis and Platelet-Inhibitory Activity of 5-Methyl-4-(3-pyridyl)-2-(substituted Benzimidazol-5-yl)imidazoles.
作者:Akito TANAKA、Kiyotaka ITO、Shigetaka NISHINO、Yukio MOTOYAMA、Hisashi TAKASUGI
DOI:10.1248/cpb.42.560
日期:——
A series of 5-methyl-4-(3-pyridyl)-2-(substituted benzimidazol-5-yl)imidazole derivatives was synthesized and tested for anti-platelet and vasodilatory activities. Some compounds were found to have potent activities and low acute toxicity. In particular, 5-methyl-4-(3-pyridyl)-2-(7-chloro-6-methoxy-2-methylbenzimidazol-5-yl)imidazole (26) and 5-methyl-4-(3-pyridyl)-2-(7-chloro-3-methoxy-2-methylbenzimidazol-5-yl)imidazole (33) exhibited 63% or 51% inhibition at a dose of 10 mg/kg for anti-patelet activity ex vivo in rats, respectively, while they showed no toxicity even at 180 or 100 mg/kg, respectively. Compound 33 also exhibited potent vasodilatory activity (ED50=11 μg/ml). Enzyme studies on these imidazoles showed that the novel imidazoles inhibit some snzymes which are involved in the platelet aggregation cascade such as cyclooxygenase, phosphodiesterase (PDE), and thromboxane A2 synthetase. The enzyme assay also suggested that the inhibitory activity on PDE may account for the vasodilatory activity of these imidazoles.
合成了一系列5-甲基-4-(3-吡啶基)-2-(取代苯并咪唑-5-基)咪唑衍生物,并测试了它们的抗血小板和扩血管活性。发现某些化合物具有较强的活性和低急性毒性。特别是,5-甲基-4-(3-吡啶基)-2-(7-氯-6-甲氧基-2-甲基苯并咪唑-5-基)咪唑(26)和5-甲基-4-(3-吡啶基)-2-(7-氯-3-甲氧基-2-甲基苯并咪唑-5-基)咪唑(33)在给药剂量为10 mg/kg时,分别在大鼠的抗血小板活性测试中表现出63%或51%的抑制率,而在180 mg/kg或100 mg/kg时,均未显示出毒性。化合物33还表现出较强的扩血管活性(ED50=11 μg/ml)。对这些咪唑的酶学研究表明,新型咪唑抑制了参与血小板聚集级联反应的一些酶,如环氧合酶、磷酸二酯酶(PDE)和血栓素A2合成酶。酶活性测试还表明,对PDE的抑制活性可能是这些咪唑的扩血管活性的原因。