title: Selective agonists at group II metabotropic glutamate receptors: synthesis, stereochemistry, and molecular pharmacology of (S)- and (R)-2-amino-4-(4-hydroxy[1,2,5]thiadiazol-3-yl)butyric acid.
abstract: Homologation of analogues of the central excitatory neurotransmitter glutamic acid (Glu), in which the distal carboxy group has been bioisosterically replaced by acidic heterocyclic units, has previously provided subtype selective ligands for metabotropic Glu receptors (mGluRs). The (S)-form of the 1,2,5-thiadiazol-3-ol Glu analogue, 2-amino-3-(4-hydroxy[1,2,5]thiadiazol-3-yl)propionic acid (TDPA, 6), is an 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor agonist, which in addition stereospecifically activates group I mGluRs. We have now synthesized the (S)- and (R)-forms of 2-amino-4-(4-hydroxy[1,2,5]thiadiazol-3-yl)butyric acid (homo-TDPA, 7) and shown that whereas neither enantiomer interacts with AMPA receptors, (S)- and (R)-7 appear to be selective and equipotent agonists at group II mGluRs as represented by the mGluR2 subtype. The activities of (S)- and (R)-7 are rationalized by conformational analysis, comparison with the potent and specific group II mGluR agonist (-)-LY379268 [(-)-12], and docking to a homology model of mGluR2.
authors.affiliation: NeuroScience PharmaBiotec Research Center, Department of Medicinal Chemistry, The Royal Danish School of Pharmacy, 2 Universitetsparken, DK-2100 Copenhagen, Denmark.
authors.forename: Rasmus P
authors.initials: RP
authors.lastname: Clausen
authors.forename: Hans
authors.initials: H
authors.lastname: Bräuner-Osborne
authors.forename: Jeremy R
authors.initials: JR
authors.lastname: Greenwood
authors.forename: Mette B
authors.initials: MB
authors.lastname: Hermit
authors.forename: Tine B
authors.initials: TB
authors.lastname: Stensbøl
authors.forename: Birgitte
authors.initials: B
authors.lastname: Nielsen
authors.forename: Povl
authors.initials: P
authors.lastname: Krogsgaard-Larsen
mesh_terms: D000596:Amino Acids / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology; D008958:Models, Molecular; D011869:Radioligand Assay; D051381:Rats; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists* / Q000378:metabolism; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013830:Thiadiazoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
chemical_list: C465772:2-amino-4-(4-hydroxy(1,2,5)thiadiazol-3-yl)butyric acid; D000596:Amino Acids; D019086:Bridged Bicyclo Compounds, Heterocyclic; C118218:LY 379268; D018094:Receptors, Metabotropic Glutamate; D013830:Thiadiazoles; C108822:metabotropic glutamate receptor 2