title: Synthesis and biological evaluation of analogues of 7-chloro-4,5-dihydro-4- oxo-8-(1,2,4-triazol-4-yl)-1,2,4-triazolo[1,5-a]quinoxaline-2-carboxylic acid (TQX-173) as novel selective AMPA receptor antagonists.
abstract: In recent papers (Catarzi, D.; et al. J. Med. Chem. 2000, 43, 3824-3826; 2001, 44, 3157-3165) we reported chemical and biological studies on 4,5-dihydro-4-oxo-1,2,4-triazolo[1,5-a]quinoxaline-2-carboxylates (TQXs) bearing different nitrogen-containing heterocycles at position-8. In particular, from these studies it emerged that both the 7-chloro-4,5-dihydro-4-oxo-8-(1,2,4-triazol-4-yl)-1,2,4-triazolo[1,5-a] quinoxaline-2-carboxylic acid TQX-173 (compound B) and its corresponding ethyl ester (compound A) were the most active and selective compounds of this series. In pursuing our investigation on the structure-activity relationships of these TQX derivatives, different electron-withdrawing groups (CF(3), NO(2)) were introduced at position 7 on the TQX ring system, replacing the 7-chloro substituent of B and of other selected 8-heteroaryltriazoloquinoxaline-2-carboxylates previously described. All the newly synthesized compounds were biologically evaluated for their binding at the Gly/NMDA, AMPA, and KA high-affinity receptors. Gly/NMDA binding assays were performed to assess the selectivity of the reported compounds toward the AMPA receptor. Compounds endowed with micromolar binding affinity for the KA high-affinity binding site were also evaluated for their binding at the KA low-affinity receptor. Some selected compounds were also tested for their functional antagonist activity at the AMPA and NMDA receptor-ion channel complex. The results obtained in this study have pointed out that 4,5-dihydro-7-nitro-4-oxo-8-(3-carboxypyrrol-1-yl)-1,2,4-triazolo[1,5-a]quinoxaline-2-carboxylic acid (9b) and its corresponding ethyl ester (9a) are the most potent and selective AMPA receptor antagonists reported to date among the TQX series.
authors.affiliation: Dipartimento di Scienze Farmaceutiche, Polo Scientifico, Universita'degli Studi di Firenze, Via Ugo Schiff, 6, Sesto Fiorentino (FI), Italy. daniela.catarzi@unifi.it
authors.forename: Daniela
authors.initials: D
authors.lastname: Catarzi
authors.forename: Vittoria
authors.initials: V
authors.lastname: Colotta
authors.forename: Flavia
authors.initials: F
authors.lastname: Varano
authors.forename: Francesca Romana
authors.initials: FR
authors.lastname: Calabri
authors.forename: Guido
authors.initials: G
authors.lastname: Filacchioni
authors.forename: Alessandro
authors.initials: A
authors.lastname: Galli
authors.forename: Chiara
authors.initials: C
authors.lastname: Costagli
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Carlà
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D004594:Electrophysiology; D066298:In Vitro Techniques; D011810:Quinoxalines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011869:Radioligand Assay; D051381:Rats; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors* / Q000378:metabolism; D018009:Receptors, Glycine / Q000187:drug effects / Q000378:metabolism; D018092:Kainic Acid Receptors / Q000187:drug effects / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism; D013329:Structure-Activity Relationship; D013570:Synaptic Membranes / Q000187:drug effects / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D014227:Triazines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D014230:Triazoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D011810:Quinoxalines; D018091:Receptors, AMPA; D018009:Receptors, Glycine; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate; D014227:Triazines; D014230:Triazoles; C481789:4,5-dihydro-7-nitro-4-oxo-8-(3-carboxypyrrol-1-yl)-1,2,4-triazolo(1,5-a)quinoxaline-2-carboxylic acid; C435935:TQX 173; C481788:ethyl 4,5-dihydro-7-nitro-4-oxo-8-(3-carboxypyrrol-1-yl)-1,2,4-triazolo(1,5-a)quinoxaline-2-carboxylate