3-Acyl-4-hydroxyquinolin-2(1H)-ones. Systemically Active Anticonvulsants Acting by Antagonism at the Glycine Site of the N-Methyl-D-Aspartate Receptor Complex

Article abstract of DOI:10.1021/jm00074a020

Most full antagonists at the glycine site of the NMDA receptor contain a carboxylic acid, which we believe to be detrimental to penetration of the blood-brain barrier.By consideration of a pharmacophore, novel antagonists at this site have been designed in which the anionic functionality is a vinylogous acid, in the form of a 4-hydroxyquinolin-2(1H)-one.In this series, a 3-substituent is necessary for binding, and correct manipulation of this group leads to compounds such as the 3-(3-hydroxyphenyl)propargyl ester 24 (L-701,273), with an IC50 for displacement of <3H>-L-689,560 binding of 0.17 μM and K_b against NMDA in the cortical slice of 1.39 μM.Compounds were tested for their ability to prevent audiogenic seizure in DBA/2 mice; the most potent compound in this series is the cyclopropyl ketone 42 (L-701,252), with an ED50 of 4.1 mg/kg ip.A model is proposed for binding to the glycine site, in which an important interaction is of a putative receptor cation with the ?-system of the 3-substituent.