Conformational flexibility of serotonin1A receptor ligands from crystallographic data. Updated model of the receptor pharmacophore.

Preparation and affinity to 5-HT1A and 5-HT2A receptors of new buspirone analogues 7-17 are reported. The compounds possess high to low affinity to 5-HT1A and moderate to low to 5-HT2A receptors. The crystal structures have been determined for compounds 11, 12, 13, and 14. For low affinity ligand (15) of 5-HT1A receptor conformational analysis was performed and compared with similar analyses performed for know high (buspirone 1) and very high (WY-48,723 2) affinity ligands of the receptor. Structure-activity relationship is discussed for the affinity to 5-HT1A receptor. A three-point pharmacophore explaining interactions of buspirone-like molecules with the receptor binding site is proposed.