Nonpeptide endothelin antagonists: from lower affinity pyrazol-5-ols to higher affinity pyrazole-5-carboxylic acids

Random screening of compounds in endothelin receptor (ETA and ETB) binding assays led to the discovery of a new class of pyrazol-5-ol ligands. Characterization of structural features crucial for binding activities of these pyrazol-5-ols, by structure–activity-relationship (SAR) studies, allowed us to design a novel class of pyrazole-5-carboxylic acids as more potent ET antagonists.