title: Novel alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor antagonists: synthesis and structure-activity relationships of 6-(1H-imidazol-1-yl)-7-nitro-2,3(1H,4H)-pyrido[2,3-b]pyrazinedione and related compounds.
abstract: We have synthesized and evaluated azaquinoxalinediones 3a-c for their activity in inhibiting [3H]AMPA binding from rat whole brain. It was found that the azaquinoxalinedione nucleus functions as a bioisostere for quinoxalinedione in AMPA receptor binding. The detailed structure-activity relationships of 6- and/or 7-substituted 2,3(1H,4H)-pyrido[2,3-b]pyrazinedione derivatives 4, 7-1-, 13, 15 and 16 showed some differences in comparison with those of the corresponding substituted quinoxalinediones, including 6-(1H-imidazol-1-yl)-7-nitro-2,3-(1H,4H)-quinoxalinedione (1) (YM90K). The X-ray study exhibited that conformation of the 7-nitro group of 1.HCl was nearly coplanar with the quinoxaline ring, whereas the 6-imidazol-1-yl group was rotated with respect to the aromatic ring. From the glycine site on NMDA receptor binding study, it is indicated that bulkiness of 6-substituents on pyridopyrazinediones may be responsible for the selectivity against the glycine site. Among the series of azaquinoxalinediones, 6-(1H-imidazol-1-yl)-7-nitro-2,3(1H,4H)-pyrido[2,3-b]pyrazinedione (8c) exhibited a combination of the best affinity to AMPA receptors with a Ki value of 0.14 microM and selectivity against the glycine site (no affinity at 10 microM). In vivo, 8c also protected against sound-induced seizure in DBA/2 mice (minimum effective dose, 10 mg/kg ip).
authors.affiliation: Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Company Limited, Ibaraki, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Ohmori
authors.forename: H
authors.initials: H
authors.lastname: Kubota
authors.forename: M
authors.initials: M
authors.lastname: Shimizu-Sasamata
authors.forename: M
authors.initials: M
authors.lastname: Okada
authors.forename: S
authors.initials: S
authors.lastname: Sakamoto
mesh_terms: D000818:Animals; D000927:Anticonvulsants / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D008968:Molecular Conformation; D018696:Neuroprotective Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D051381:Rats; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors*; D013329:Structure-Activity Relationship
chemical_list: D000927:Anticonvulsants; D018696:Neuroprotective Agents; D018091:Receptors, AMPA