Molecular Modulation of Muscarinic Antagonists. Synthesis and Pharmacological Profile of 2,2-diphenyl-2-ethylthioacetic and 3,3-diphenyl-3- ethylthiopropionic Acid Derivatives Characterized by a Dipeptide Spacer

The synthesis and preliminary pharmacological profile of a new series of muscarinic antagonists are reported. Discrepancies between binding and functional studies have been found as the compounds of the series do not discriminate among muscarinic subtypes but do show functional selectivity in tissue assays. The most interesting compound 7 shows a good potency and selectivity for the muscarinic M3 receptors present in guinea pig ileum and may be a new lead for further studies.