New quinoline derivatives as nicotinic receptor modulators

Area of Science:

• Medicinal Chemistry
• Neuroscience
• Pharmacology

Background:

• Previous quinoline derivatives exhibited moderate selectivity for alpha7 nicotinic acetylcholine receptors (nAChRs) over alpha4beta2 nAChRs.
• There is a need for more selective alpha7 nAChR modulators for potential therapeutic applications.

Purpose of the Study:

• To synthesize novel azabicyclic or diazabicyclic compounds incorporating quinoline or isoquinoline scaffolds.
• To identify compounds with enhanced selectivity and specific activity profiles at alpha7 nAChRs.

Main Methods:

• Radioligand binding assays were performed on rat brain homogenates to assess affinity for alpha7* and alpha4beta2* nAChRs.
• Ion current suppression was measured in Xenopus oocytes expressing rat alpha4beta2 nAChRs and a chimeric nAChR.
• Calcium imaging experiments in Neuro2a cells were used to determine the functional activity (agonist or antagonist) at human alpha7 nAChRs.

Main Results:

• Four compounds (11, 13, 14, 16) showed at least 3-fold higher affinity for alpha7* nAChR compared to alpha4beta2* nAChR.
• Compound 11 exhibited the highest selectivity (>10-fold) with a Ki of approximately 100 nM for alpha7* nAChR.
• Compounds 11, 13, and 16 acted as agonists at human alpha7 nAChRs with EC50 values between 1.0-1.6 uM, while compound 7 showed antagonistic activity.

Conclusions:

• The structural modifications successfully enhanced the selectivity of quinoline derivatives for the alpha7 nAChR subtype.
• Novel agonistic compounds targeting alpha7 nAChRs were identified, offering potential for further drug development.