Synthesis and biological evaluation of 4-phenylquinazoline-2-carboxamides designed as a novel class of potent ligands of the translocator protein

A series of novel 4-phenylquinazoline-2-carboxamides (1–58) were designed as aza-isosters of PK11195, the well-known 18 kDa translocator protein (TSPO) reference ligand, and synthesized by means of a very simple and efficient procedure. A number of these derivatives bind to the TSPO with Ki values in the nanomolar/subnanomolar range, show selectivity toward the central benzodiazepine receptor (BzR) and exhibit structure–affinity relationships consistent with a previously published pharmacophore/topological model of ligand–TSPO interaction.