Synthesis and pharmacological profiling of analogues of benzyl quinolone carboxylic acid (BQCA) as allosteric modulators of the M1 muscarinic receptor.

Shailesh N Mistry, Celine Valant, Patrick M Sexton, Ben Capuano, Arthur Christopoulos, Peter J Scammells

Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.

Journal of medicinal chemistry 2013 Jun 27

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Established therapy in Alzheimer's disease involves potentiation of the endogenous orthosteric ligand, acetylcholine, at the M1 muscarinic receptors found in higher concentrations in the cortex and hippocampus. Adverse effects, due to indiscriminate activation of other muscarinic receptor subtypes, are common. M1 muscarinic positive allosteric modulators/allosteric agonists such as BQCA offer an attractive solution, being exquisitely M1-selective over other muscarinic subtypes. A common difficulty with allosteric ligands is interpreting SAR, based on composite potency values derived in the presence of fixed concentration of agonist. In reality these values encompass multiple pharmacological parameters, each potentially and differentially sensitive to structural modification of the ligand. We report novel BQCA analogues which appear to augment ligand affinity for the receptor (pK(B)), intrinsic efficacy (τB), and both binding (α) and functional (β) cooperativity with acetylcholine. Ultimately, development of such enriched SAR surrounding allosteric modulators will provide insight into their mode of action.

Citation

Shailesh N Mistry, Celine Valant, Patrick M Sexton, Ben Capuano, Arthur Christopoulos, Peter J Scammells. Synthesis and pharmacological profiling of analogues of benzyl quinolone carboxylic acid (BQCA) as allosteric modulators of the M1 muscarinic receptor. Journal of medicinal chemistry. 2013 Jun 27;56(12):5151-72