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Bioorg Med Chem Lett. 2013 Mar 1;23(5):1450-5. doi: 10.1016/j.bmcl.2012.12.054. Epub 2012 Dec 28.

Pharmacological properties and predicted binding mode of arylmethylene quinuclidine-like derivatives at the α3β4 nicotinic acetylcholine receptor (nAChR).

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  • 1Targacept, Inc. 200 East First Street, Suite 300, Winston-Salem, NC 27101, USA. david.kombo@targacept.com

Abstract

We have carried out a pharmacological evaluation of arylmethylene quinuclidine derivatives interactions with human α3β4 nAChRs subtype, using cell-based receptor binding, calcium-influx, electrophysiological patch-clamp assays and molecular modeling techniques. We have found that the compounds bind competitively to the α3β4 receptor with micromolar affinities and some of the compounds behave as non-competitive antagonists (compounds 1, 2 and 3), displaying submicromolar IC(50) values. These evidences suggest a mixed mode of action for these compounds, having interactions at the orthosteric site and more pronounced interactions at an allosteric site to block agonist effects. One of the compounds, 1-benzyl-3-(diphenylmethylene)-1-azoniabicyclo[2.2.2]octane chloride (compound 3), exhibited poorly reversible use-dependent block of α3β4 channels. We also found that removal of a phenyl group from compound 1 confers a partial agonism to the derived analog (compound 6). Introducing a hydrogen-bond acceptor into the 3-benzylidene quinuclidine derivative (compound 7) increases agonism potency at the α3β4 receptor subtype. Docking into the orthosteric binding site of a α3β4 protein structure derived by comparative modeling accurately predicted the experimentally-observed trend in binding affinity. Results supported the notion that binding requires a hydrogen bond formation between the ligand basic nitrogen and the backbone carbonyl oxygen atom of the conserved Trp-149.

Copyright © 2013 Elsevier Ltd. All rights reserved.

PMID:
23352509
[PubMed - indexed for MEDLINE]
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