Biostructural and pharmacological studies of bicyclic analogues of the 3-isoxazolol glutamate receptor agonist ibotenic acid.
Frydenvang, K., Pickering, D.S., Greenwood, J.R., Krogsgaard-Larsen, N., Brehm, L., Nielsen, B., Vogensen, S.B., Hald, H., Kastrup, J.S., Krogsgaard-Larsen, P., Clausen, R.P.(2010) J Med Chem 53: 8354-8361
- PubMed: 21067182 
- DOI: https://doi.org/10.1021/jm101218a
- Primary Citation of Related Structures:  
3PD8, 3PD9 - PubMed Abstract: 
We describe an improved synthesis and detailed pharmacological characterization of the conformationally restricted analogue of the naturally occurring nonselective glutamate receptor agonist ibotenic acid (RS)-3-hydroxy-4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridine-7-carboxylic acid (7-HPCA, 5) at AMPA receptor subtypes. Compound 5 was shown to be a subtype-discriminating agonist at AMPA receptors with higher binding affinity and functional potency at GluA1/2 compared to GluA3/4, unlike the isomeric analogue (RS)-3-hydroxy-4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridine-5-carboxylic acid (5-HPCA, 4) that binds to all AMPA receptor subtypes with comparable potency. Biostructural X-ray crystallographic studies of 4 and 5 reveal different binding modes of (R)-4 and (S)-5 in the GluA2 agonist binding domain. WaterMap analysis of the GluA2 and GluA4 binding pockets with (R)-4 and (S)-5 suggests that the energy of hydration sites is ligand dependent, which may explain the observed selectivity.
Organizational Affiliation: 
Department of Medicinal Chemistry.