Novel class of amino acid antagonists at non-N-methyl-D-aspartic acid excitatory amino acid receptors. Synthesis, in vitro and in vivo pharmacology, and neuroprotection

• Published in: Journal of medicinal chemistry Vol. 34; no. 1; pp. 123 - 130
• Main Authors: Krogsgaard-Larsen, Povl, Ferkany, John W, Nielsen, Elsebet O, Madsen, Ulf, Ebert, Bjarke, Johansen, Joergen S, Diemer, Nils H, Bruhn, Torben, Beattie, David T, Curtis, David R
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-01-1991
• Subjects: 550201 - Biochemistry- Tracer Techniques; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; AMINO ACIDS; ANIMAL CELLS; ANIMALS; Autoradiography; BASIC BIOLOGICAL SCIENCES; Binding, Competitive; BIOCHEMICAL REACTION KINETICS; BIOLOGICAL FUNCTIONS; BODY; BRAIN; Brain - metabolism; CARBOXYLIC ACIDS; CENTRAL NERVOUS SYSTEM; Cerebral Cortex - drug effects; Cerebral Cortex - physiology; CHEMICAL PREPARATION; Chemistry; Dizocilpine Maleate - metabolism; Exact sciences and technology; FUNCTIONS; GLYCINE; Glycine - metabolism; Heterocyclic compounds; Heterocyclic compounds with n hetero atom and also o and/or s, se, te hetero atoms; HYDROGEN COMPOUNDS; Ibotenic Acid - analogs & derivatives; Ibotenic Acid - metabolism; Ibotenic Acid - pharmacology; IN VITRO; In Vitro Techniques; IN VIVO; Indicators and Reagents; ISOTOPE APPLICATIONS; Isoxazoles - chemical synthesis; Isoxazoles - chemistry; Isoxazoles - pharmacology; KINETICS; Male; MAMMALS; MEMBRANE PROTEINS; Molecular Structure; MONOCARBOXYLIC ACIDS; NERVE CELLS; NERVOUS SYSTEM; Neurons - drug effects; Neurons - physiology; ORGANIC ACIDS; Organic chemistry; ORGANIC COMPOUNDS; ORGANS; Preparations and properties; Propionates - chemical synthesis; Propionates - chemistry; Propionates - pharmacology; PROPIONIC ACID; PROTEINS; RATS; Rats, Inbred Strains; REACTION KINETICS; RECEPTORS; Receptors, N-Methyl-D-Aspartate - drug effects; Receptors, N-Methyl-D-Aspartate - metabolism; RODENTS; SOMATIC CELLS; Structure-Activity Relationship; STRUCTURE-ACTIVITY RELATIONSHIPS; SYNTHESIS; TRACER TECHNIQUES; Tritium; TRITIUM COMPOUNDS; VERTEBRATES; α-Aminoacid; Ether; Alcohol; Dicarboxylic acid; Antagonist; Biological activity; Oxygen nitrogen heterocycle; Biological receptor
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/jm00105a019

The isoxazole amino acid 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl) propionic acid (AMPA) (1), which is a highly selective agonist at the AMPA subtype of excitatory amino acid (EAA) receptors, has been used as a lead for the development of two novel EAA receptor antagonists. One of the compounds, 2-amino-3-[3-(carboxymethoxy)-5-methylisoxazol-4-yl]propionic acid (AMOA, 7), was synthesized via O-alkylation by ethyl chloroacetate of the amino acid protected AMPA derivative 4. The other compound, 2-amino-3-[2-(3-hydroxy-5-methylisoxazol-4-yl)-methyl-5-methyl-3-+ ++oxoisoxazolin -4-yl]propionic acid (AMNH, 14) was synthesized with use of 4-(chloromethyl)-3-methoxy-5-methylisoxazole (8) as the starting material. The intermediate 4-(chloromethyl)-2-(3-methoxy-5-methylisoxazol-4-yl)methyl-5-me thylisoxazolin- 3-one (11) was converted into the acetamidomalonate (12), which was stepwise deprotected to give 14. Compounds 7 and 14 were stable in aqueous solution at pH values close to physiological pH. Neither 7 nor 14 showed detectable affinities for the receptor, ion channel, or modulatory sites of the N-methyl-D-aspartic acid (NMDA) receptor complex. Quantitative receptor autoradiographic and conventional binding techniques were used to study the affinities of 7 and 14 for non-NMDA receptor sites. Both compounds were inhibitors of the binding of [3H]AMPA (IC50 = 90 and 29 microM, respectively). Compounds 14 and 7 were both very weak inhibitors of the high-affinity binding of radioactive kainic acid [( 3H]KAIN). Compound 14, but not 7, was, however, shown to be an inhibitor of low-affinity [3H]KAIN binding (IC50 = 40 microM) as determined in the presence of 100 mM calcium chloride. In the rat cortical slice preparation, 7 was shown to antagonize excitation induced by 1 with some selectivity, whereas 14 proved to be a rather selective antagonist of KAIN-induced excitation. Both antagonists showed very weak effects on the excitatory effects of NMDA. Compound 7 was a poor antagonist of excitation by quisqualic acid (2), whereas 14 did not affect excitation by this nonselective AMPA receptor agonist. On cat spinal neurones, both 7 and 14 reduced excitations by 1 and KAIN, but, again, the excitatory effects of 2 were much less sensitive. Compound 14 and, in particular, 7 effectively protected rat striatal neurones against the neurotoxic effects of KAIN, whereas the toxic effects of 1 were reduced only by 7. Neither antagonist showed protection against the cell damage caused by intrastriatal injection of the NMDA agonist quinolinic acid.