Studies on an (S)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor antagonist IKM-159: asymmetric synthesis, neuroactivity, and structural characterization

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Lina Juknaite, Yutaro Sugamata, Kazuya Tokiwa, Yuichi Ishikawa, Satoshi Takamizawa, Andrew Eng, Ryuichi Sakai, Darryl S Pickering, Karla Frydenvang, Geoffrey T Swanson, Jette Sandholm Jensen Kastrup, Masato Oikawa

IKM-159 was developed and identified as a member of a new class of heterotricyclic glutamate analogs that act as AMPA receptor-selective antagonists. However, it was not known which enantiomer of IKM-159 was responsible for its pharmacological activities. Here, we report in vivo and in vitro neuronal activities of both enantiomers of IKM-159 prepared by enantioselective asymmetric synthesis. Employing (R)-2-amino-2-(4-methoxyphenyl)ethanol as a chiral auxiliary, (2R)-IKM-159 and the (2S)-counterpart were successfully synthesized in 0.70% and 1.5% yields, respectively, over total 18 steps. Both behavioral and electrophysiological assays showed that the biological activity observed for the racemic mixture was reproduced only with (2R)-IKM-159, whereas the (2S)-counterpart was inactive in both assays. Racemic IKM-159 was crystallized with the ligand-binding domain of GluA2, and the structure revealed a complex containing (2R)-IKM-159 at the glutamate binding site. (2R)-IKM-159 locks the GluA2 in an open form, consistent with a pharmacological action as competitive antagonist of AMPA receptors.
Original languageEnglish
JournalJournal of Medicinal Chemistry
Volume56
Issue number6
Pages (from-to)2283-2293
ISSN0022-2623
DOIs
Publication statusPublished - 2013

ID: 44730110