Semisynthetic Analogues of Toxiferine I and Their Pharmacological Properties at α7 nAChRs, Muscle-Type nAChRs, and the Allosteric Binding Site of Muscarinic M2Receptors

Journal of Natural Products
2014.0

Abstract

A new series of analogues of the calabash curare alkaloid toxiferine I was prepared and pharmacologically evaluated at α7 and muscle-type nAChRs and the allosteric site of muscarinic M2 receptors. The new ligands differ from toxiferine I by the absence of one (2a-c) or two (3a-c) hydroxy groups, saturation of the exocyclic double bonds, and various N-substituents (methyl, allyl, 4-nitrobenzyl). At the muscle-type nAChRs, most ligands showed similar binding to the muscle relaxant alcuronium, indicating neuromuscular blocking activity, with the nonhydroxylated analogues 3b (Ki = 75 nM) and 3c (Ki = 82 nM) displaying the highest affinity. At α7 nAChRs, all ligands showed a moderate to low antagonistic effect, suggesting that the alcoholic functions are not necessary for antagonistic action. Compound 3c exerted the highest preference for the muscle-type nAChRs (Ki = 82 nM) over α7 (IC50 = 21 μM). As for the allosteric site of M2 receptors, binding was found to be dependent on N-substitution rather than on the nature of the side chains. The most potent ligands were the N-allyl analogues 2b and 3b (EC0.5,diss = 12 and 36 nM) and the N-nitrobenzyl derivatives 2c and 3c (EC0.5,diss = 32 and 49 nM). The present findings should help delineate the structural requirements for activity at different types of AChRs and for the design of novel selective ligands.

Knowledge Graph

Similar Paper

Semisynthetic Analogues of Toxiferine I and Their Pharmacological Properties at α7 nAChRs, Muscle-Type nAChRs, and the Allosteric Binding Site of Muscarinic M<sub>2</sub>Receptors
Journal of Natural Products 2014.0
Pharmacological Characteristics and Binding Modes of Caracurine V Analogues and Related Compounds at the Neuronal α7 Nicotinic Acetylcholine Receptor
Journal of Medicinal Chemistry 2007.0
Probing the Pharmacophore for Allosteric Ligands of Muscarinic M<sub>2</sub>Receptors:  SAR and QSAR Studies in a Series of Bisquaternary Salts of Caracurine V and Related Ring Systems
Journal of Medicinal Chemistry 2004.0
6H,13H-Pyrazino[1,2-a;4,5-a′]diindole analogs: Probing the pharmacophore for allosteric ligands of muscarinic M2 receptors
Bioorganic &amp; Medicinal Chemistry Letters 2006.0
Delineating the activity of the potent nicotinic acetylcholine receptor agonists (+)-anatoxin-a and (−)-hosieine-A
Acta Crystallographica Section F Structural Biology Communications 2022.0
Annulated Heterocyclic Bioisosteres of Norarecoline. Synthesis and Molecular Pharmacology at Five Recombinant Human Muscarinic Acetylcholine Receptors
Journal of Medicinal Chemistry 1995.0
Design, synthesis and binding affinity of acetylcholine carbamoyl analogues
Bioorganic &amp; Medicinal Chemistry Letters 2013.0
Synthesis and biological activity of a novel class nicotinic acetylcholine receptors (nAChRs) ligands structurally related to anatoxin-a
Bioorganic &amp; Medicinal Chemistry Letters 2011.0
Muscarinic cholinergic agonists and antagonists of the 3-(3-alkyl-1,2,4-oxadiazol-5-yl)-1,2,5,6-tetrahydropyridine type. Synthesis and structure-activity relationships
Journal of Medicinal Chemistry 1991.0
Synthesis, Pharmacology, and Biostructural Characterization of Novel α<sub>4</sub>β<sub>2</sub>Nicotinic Acetylcholine Receptor Agonists
Journal of Medicinal Chemistry 2013.0