The synthesis and CRF receptor binding affinities of several new series of N-aryltriazolo- and -imidazopyrimidines and -pyridines are described. These cyclized systems were prepared from appropriately substituted diaminopyrimidines or -pyridines by nitrous acid, orthoester, or acyl halide treatment. Variations of amino (ether) pendants and aromatic substituents have defined the structure-activity relationships of these series and resulted in the identification of a variety of high-affinity agents (Ki's < 10 nM). On the basis of this property and lipophilicity differences, six of these compounds (4d,i,n,x, 8k, 9a) were initially chosen for rat pharmacokinetic (PK) studies. Good oral bioavailability, high plasma levels, and duration of four of these compounds (4d,i,n,x) prompted further PK studies in the dog following both iv and oral routes of administration. Results from this work indicated 4i,x had properties we believe necessary for a potential therapeutic agent, and 4i1 has been selected for further pharmacological studies that will be reported in due course.
Acyl-CoA:cholesterol acyltransferase (ACAT) is the primary enzyme involved in intracellular cholesterol esterification. Arterial wall infiltration by macrophages and subsequent uncontrolled esterification of cholesterol leading to foam cell formation is believed to be an important process which leads to the development of fatty streaks. Inhibitors of the ACAT enzyme may retard this atherogenic process. We have recently discovered a series of imidazoles which are potent in vitro ACAT inhibitors in the J774 macrophage cell culture assay. This paper will describe the design, synthesis, and structure--activity relationship for this very potent series of compounds.
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