Screening for new ligands of the MB327-PAM-1 binding site of the nicotinic acetylcholine receptor

Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved..

Intoxications with organophosphorus compounds (OPCs) effect a severe impairment of cholinergic neurotransmission that, as a result of overstimulation may lead to desensitization of nicotinic acetylcholine receptors (nAChRs) and finally to death due to respiratory paralysis. So far, therapeutics, that are capable to address and revert desensitized neuromuscular nAChRs into their resting, i.e. functional state are still missing. Still, among a class of compounds termed bispyridinium salts, which are characterized by the presence of two pyridinium subunits, constituents have been identified, that can counteract organophosphate poisoning by resensitizing desensitized nAChRs. According to comprehensive modeling studies this effect is mediated by an allosteric binding site at the nAChR termed MB327-PAM-1 site. For MB327, the most prominent representative of the bispyridinium salts and all other analogues studied so far, the affinity for the aforementioned binding site and the intrinsic activity measured in ex vivo and in in vivo experiments are distinctly too low, to meet the criteria to be fulfilled for therapeutic use. Hence, in order to identify new compounds with higher affinities for the MB327-PAM-1 binding site, as a basic requirement for an enhanced potency, two compound libraries, the ChemDiv library with 60 constituents and the Tocriscreen Plus library with 1280 members have been screened for hit compounds addressing the MB327-PAM-1 binding site, utilizing the [2H6]MB327 MS Binding Assay recently developed by us. This led to the identification of a set of 10 chemically diverse compounds, all of which exhibit an IC50 value of ≤ 10 µM (in the [2H6]MB327 MS Binding Assay), which had been defined as selection criteria. The three most affine ligands, which besides a quinazoline scaffold share similarities with regard to the substitution pattern and the nature of the substituents, are UNC0638, UNC0642 and UNC0646. With binding affinities expressed as pKi values of 6.01 ± 0.10, 5.97 ± 0.05 and 6.23 ± 0.02, respectively, these compounds exceed the binding affinity of MB327 by more than one log unit. This renders them promising starting points for the development of drugs for the treatment of organophosphorus poisoning by addressing the MB327-PAM-1 binding site of the nAChR.

Medienart:

E-Artikel

Erscheinungsjahr:

2024

Erschienen:

2024

Enthalten in:

Zur Gesamtaufnahme - volume:394

Enthalten in:

Toxicology letters - 394(2024) vom: 30. Apr., Seite 23-31

Sprache:

Englisch

Beteiligte Personen:

Sichler, Sonja [VerfasserIn]
Höfner, Georg [VerfasserIn]
Nitsche, Valentin [VerfasserIn]
Niessen, Karin V [VerfasserIn]
Seeger, Thomas [VerfasserIn]
Worek, Franz [VerfasserIn]
Paintner, Franz F [VerfasserIn]
Wanner, Klaus T [VerfasserIn]

Links:

Volltext

Themen:

Journal Article
Library screening
Ligands
MB327
MB327-PAM-1 binding site
MS Binding Assays
Nicotinic acetylcholine receptor
Pyridinium Compounds
Quinazoline derivatives
Receptors, Nicotinic
Salts

Anmerkungen:

Date Completed 01.04.2024

Date Revised 01.04.2024

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.toxlet.2024.02.004

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM368777537