title: N-(3-fluoro-4-(4-(2-methoxy or 2,3-dichlorophenyl)piperazine-1-yl)butyl)arylcarboxamides as selective dopamine D3 receptor ligands: critical role of the carboxamide linker for D3 receptor selectivity.
abstract: N-(3-fluoro-4-(4-(2,3-dichloro- or 2-methoxyphenyl)piperazine-1-yl)butyl)arylcarboxamides were prepared and evaluated for binding and function at dopamine D3 receptors (D3Rs) and dopamine D2 receptors (D2Rs). In this series, we discovered some of the most D3R selective compounds reported to date (e.g., 8d and 8j, >1000-fold D3R-selective over D2R). In addition, chimeric receptor studies further identified the second extracellular (E2) loop as an important contributor to D3R binding selectivity. Further, compounds lacking the carbonyl group in the amide linker were synthesized, and while these amine-linked analogues bound with similar affinities to the amides at D2R, this modification dramatically reduced binding affinities at D3R by >100-fold (e.g., D3R K(i) for 15b = 393 vs for 8j = 2.6 nM), resulting in compounds with significantly reduced D3R selectivity. This study supports a pivotal role for the D3R E2 loop and the carbonyl group in the 4-phenylpiperazine class of compounds and further reveals a point of separation between structure-activity relationships at D3R and D2R.
authors.affiliation: Medicinal Chemistry Section, National Institute on Drug Abuse-Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, Maryland 21224, United States.
authors.forename: Ashwini K
authors.initials: AK
authors.lastname: Banala
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Levy
authors.forename: Sameer S
authors.initials: SS
authors.lastname: Khatri
authors.forename: Cheryse A
authors.initials: CA
authors.lastname: Furman
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Roof
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Mishra
authors.forename: Suzy A
authors.initials: SA
authors.lastname: Griffin
authors.forename: David R
authors.initials: DR
authors.lastname: Sibley
authors.forename: Robert R
authors.initials: RR
authors.lastname: Luedtke
authors.forename: Amy Hauck
authors.initials: AH
authors.lastname: Newman
mesh_terms: D000577:Amides / Q000138:chemical synthesis* / Q000737:chemistry; D019390:Arrestins / Q000737:chemistry; D001665:Binding Sites; D002460:Cell Line; D002626:Chemistry, Pharmaceutical / Q000379:methods; D015195:Drug Design; D006801:Humans; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D010879:Piperazines / Q000138:chemical synthesis* / Q000737:chemistry; D050637:Receptors, Dopamine D3 / Q000737:chemistry* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D000071557:beta-Arrestins
chemical_list: D000577:Amides; D019390:Arrestins; D008024:Ligands; D010879:Piperazines; D050637:Receptors, Dopamine D3; D011993:Recombinant Fusion Proteins; D000071557:beta-Arrestins