title: Design and synthesis of [(2,3-dichlorophenyl)piperazin-1-yl]alkylfluorenylcarboxamides as novel ligands selective for the dopamine D3 receptor subtype.
abstract: The dopamine D3 receptor subtype has been recently targeted as a potential neurochemical modulator of the behavioral actions of psychomotor stimulants, such as cocaine. However, definitive behavioral investigations have been hampered by the lack of highly selective D3 agonists and antagonists. In an attempt to design a novel class of D3 ligands with which to study this receptor system, a series of chemically divergent compounds that possessed various structural features that exist within several classes of reputed D3 agents was screened and compared to the recently reported NGB 2904 (58b). On the basis of these results, a novel series of compounds was designed that included functional moieties that were required for high-affinity and selective binding to D3 receptors. All the compounds in this series included an aryl-substituted piperazine ring, a varying alkyl chain linker (C3-C5), and a terminal aryl amide. The compounds were synthesized and evaluated in vitro for binding in CHO cells transfected with human D2, D3, or D4 receptor cDNAs. D3 binding affinities ranged from K(i) = 1.4 to 1460 nM. The most potent analogue in this series, 51, demonstrated a D3/D2 selectivity of 64 and a D3/D4 selectivity of 1300. Structure-activity relationships for this class of ligands at D3 receptors will provide new leads toward the development of highly selective and potent molecular probes that will prove useful in the elucidation of the role D3 receptors play in the psychomotor stimulant and reinforcing properties of cocaine.
authors.affiliation: Medicinal Chemistry Section, National Institute on Drug Abuse-Intramural Research Program, 5500 Nathan Shock Drive, Baltimore, Maryland 21224, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Robarge
authors.forename: S M
authors.initials: SM
authors.lastname: Husbands
authors.forename: A
authors.initials: A
authors.lastname: Kieltyka
authors.forename: R
authors.initials: R
authors.lastname: Brodbeck
authors.forename: A
authors.initials: A
authors.lastname: Thurkauf
authors.forename: A H
authors.initials: AH
authors.lastname: Newman
mesh_terms: D000577:Amides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D016466:CHO Cells; D020650:Combinatorial Chemistry Techniques; D006224:Cricetinae; D015195:Drug Design; D005449:Fluorenes / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008024:Ligands; D010879:Piperazines / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D011869:Radioligand Assay; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D050637:Receptors, Dopamine D3; D050638:Receptors, Dopamine D4; D013329:Structure-Activity Relationship
chemical_list: D000577:Amides; C493593:DRD3 protein, human; C493599:DRD4 protein, human; D005449:Fluorenes; D008024:Ligands; C435937:N-(4-(4-(2,3-dichlorophenyl)piperazin-1-yl)butyl)(9-oxofluoren-4-yl)carboxamide; C116819:NGB 2849; C116818:NGB 2904; D010879:Piperazines; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D050638:Receptors, Dopamine D4