5-Lipoxygenase Inhibitors: Synthesis and Structure−Activity Relationships of a Series of 1-Aryl-2<i>H</i>,4<i>H</i>-tetrahydro-1,2,4-triazin-3-ones
作者:Pramila A. Bhatia、Clint D. W. Brooks、Anwer Basha、James D. Ratajczyk、Bruce P. Gunn、Jennifer B. Bouska、Carmine Lanni、Patrick R. Young、Randy L. Bell、George W. Carter
DOI:10.1021/jm960372b
日期:1996.1.1
Synthetic routes were developed to access a variety of novel 1-aryl-2H,4H-tetrahydro-1,2,4-triazin-3-one analogs which were evaluated as 5-lipoxygenase (5-LO) inhibitors. The parent structure, 1-phenylperhydro-1,2,4-triazin-3-one (4), was found to be a selective inhibitor of 5-LO in broken cell, intact cell, and human blood assays with IC50 values of 5-21 mu M. In a rat anaphylaxis model, 4 blocked leukotriene formation with an ED(50) = 7 mg/kg when administered orally. Compound 4 exhibited selectivity for inhibition of 5-LO with little activity against related enzymes: 12-LO from human platelets, 15-LO from soybean, and cyclooxygenase (COX) from sheep seminal vesicle. In pilot subacute toxicity testing, 4 did not produce methemoglobinemia in rats (400 mg/kg po daily for 9 days) or in dogs (200 mg/kg po daily for 28 days). These results indicated that the triazinone structure provided a 5-LO inhibitor template devoid of the toxicity problems observed in the related phenidone (1) and pyridazinone (3) classes of 5-LO inhibitors. The parent compound 4 is a selective, orally bioavailable 5-LO inhibitor which can serve as a useful reference standard for in vivo pharmacological studies involving leukotriene-mediated phenonmena.