title: Synthesis and biological activity of (S)-2-amino-3-(2,5-dihydro-5-oxo-4-isoxazolyl)propanoic acid (TAN-950 A) derivatives.
abstract: (S)-2-Amino-3-(2,5-dihydro-5-oxo-4-isoxazolyl)propanoic acid (TAN-950 A (1)) is a novel amino acid antibiotic which shows a high affinity for glutamate receptors of the central nervous system. To improve the affinity for glutamate receptors, the structure-activity relationships of TAN-950 A derivatives 6a--o, 15a--o were investigated. Optically active TAN-950 A analogs 15a--h were synthesized starting with methyl (S)- and (R)-N-Boc-pyroglutamate (8) via acylation at the C-4 position followed by isoxazolone formation with hydroxylamine and subsequent deprotection reactions. The lactam 16, prepared from (RS)-aminoadipic acid, and dimethyl esters 19 of (R)- and (S)-aspartic acid were converted to (RS)-3-methyl-homo-TAN-950 A (15i) and optically active nor-TAN-950 A derivatives 15j--o, respectively, utilizing a similar sequence of reactions. Most of TAN-950 A derivatives 6a--o, 15a--o showed an affinity for glutamate receptors. The 3-alkyl derivatives 15b, d--g, especially, showed a high affinity for the quisqualate subtype-receptor and had a strong activating effect on the hippocampal neurons (glutamate agonistic activity). The (R)-enantiomer 15a of TAN-950 A had increased selectivity for the N-methyl-D-aspartate (NMDA) subtype-receptor. This selectivity was further enhanced by removal of the methylene group in the amino acid moiety of 15a. The most potent and selective NMDA agonistic activity was observed with (R)-3-methyl-nor-TAN-950 A (15m).
authors.affiliation: Chemistry Research Laboratories, Takeda Chemical Industries, Ltd., Osaka, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Tamura
authors.forename: Y
authors.initials: Y
authors.lastname: Matsushita
authors.forename: T
authors.initials: T
authors.lastname: Iwama
authors.forename: S
authors.initials: S
authors.lastname: Harada
authors.forename: S
authors.initials: S
authors.lastname: Kishimoto
authors.forename: K
authors.initials: K
authors.lastname: Itoh
mesh_terms: D000818:Animals; D000935:Antifungal Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D066298:In Vitro Techniques; D007555:Isoxazoles / Q000138:chemical synthesis / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D051381:Rats; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000935:Antifungal Agents; D007555:Isoxazoles; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; C071084:2-amino-3-(2,5-dihydro-5-oxo-4-isoxazolyl)propanoic acid