Abstract
Given their high neuroprotective potential, ligands that block GluN2B-containing N-methyl-D-aspartate (NMDA) receptors by interacting with the ifenprodil binding site located on the GluN2B subunit are of great interest for the treatment of various neuronal disorders. In this study, a novel class of GluN2B-selective NMDA receptor antagonists with the benzo[7]annulene scaffold was prepared and pharmacologically evaluated. The key intermediate, N-(2-methoxy-5-oxo-6,7,8,9-tetrahydro-5H-benzo[7]annulen-7-yl)acetamide (11), was obtained by cyclization of 3-acetamido-5-(3-methoxyphenyl)pentanoic acid (10 b). The final reaction steps comprise hydrolysis of the amide, reduction of the ketone, and reductive alkylation, leading to cis- and trans-configured 7-(ω-phenylalkylamino)benzo[7]annulen-5-ols. High GluN2B affinity was observed with cis-configured γ-amino alcohols substituted with a 3-phenylpropyl moiety at the amino group. Removal of the benzylic hydroxy moiety led to the most potent GluN2B antagonists of this series: 2-methoxy-N-(3- phenylpropyl)-6,7,8,9-tetrahydro-5H-benzo[7]annulen-7-amine (20 a, K i=10 nM) and 2-methoxy-N-methyl-N-(3-phenylpropyl)-6,7,8,9- tetrahydro-5H-benzo[7]annulen-7-amine (23 a, Ki=7.9 nM). The selectivity over related receptors (phencyclidine binding site of the NMDA receptor, σ1 and σ2 receptors) was recorded. In a functional assay measuring the cytoprotective activity of the benzo[7]annulenamines, all tested compounds showed potent NMDA receptor antagonistic activity. Cytotoxicity induced via GluN2A subunit-containing NMDA receptors was not inhibited by the new ligands. Benzylic OH not essential! A 10- to 11-step synthesis was performed to obtain cis- and trans-configured tetrahydrobenzo[7]annulenes with a 5-hydroxy moiety and various phenylalkylamino moieties at the 7-position. High affinity toward GluN2B-containing N-methyl-D-aspartate (NMDA) receptors was observed for cis-configured 3-phenylpropylamines. Unexpectedly, removal of the benzylic hydroxy group led to the most potent GluN2B antagonists of this series.
Original language | English (US) |
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Pages (from-to) | 741-751 |
Number of pages | 11 |
Journal | ChemMedChem |
Volume | 9 |
Issue number | 4 |
DOIs | |
State | Published - Apr 2014 |
Externally published | Yes |
Keywords
- benzo[7]annulenamines
- cytoprotective activity
- GluN2B
- NDMA receptors
- selectivity
- structure-affinity relationships
ASJC Scopus subject areas
- Biochemistry
- Molecular Medicine
- Pharmacology
- Drug Discovery
- General Pharmacology, Toxicology and Pharmaceutics
- Organic Chemistry