Design, Synthesis, and Activity of a Series of Pyrrolidine-3-carboxylic Acid-Based, Highly Specific, Orally Active ET<sub>B</sub> Antagonists Containing a Diphenylmethylamine Acetamide Side Chain
作者:Gang Liu、Natasha S. Kozmina、Martin Winn、Thomas W. von Geldern、William J. Chiou、Douglas B. Dixon、Bach Nguyen、Kennan C. Marsh、Terry J. Opgenorth
DOI:10.1021/jm990171i
日期:1999.9.1
The endothelin (ET)-B receptor subtype is expressed on vascular endothelial and smooth muscle cells and mediates both vasodilation and vasoconstriction. On the basis of the pharmacophore of the previously reported ETA-specific antagonist 1, (ABT-627), we are reporting the discovery of a novel series of highly specific, orally active ETB receptor antagonists. Replacing the dibutylaminoacetamide group of 1 with a diphenylmethylaminoacetamide group resulted in antagonist 2 with a complete reversal of receptor specificity. Structure-activity relationship studies revealed that ortho-alkylation of the phenyl rings could further increase ETB affinity and also boost the ETA/ETB activity ratio of the resulting antagonists. A similar antagonism selectivity profile could also be achieved when one of the phenyl rings of the acetamide side chain was replaced with an alkyl group, preferably a tert-butyl group,(10h). Combining these features with modification of the a-aryl group of the pyrrolidine core, we have identified a potent antagonist (9k, A-308165) with over 27 000-fold selectivity favoring the ETB receptor and an acceptable pharmacokinetic profile (F = 24%) in rats.