Flexible analogues of WAY-267,464: Synthesis and pharmacology at the human oxytocin and vasopressin 1a receptors.

A previously identified, non-peptidic oxytocin (OT) receptor agonist WAY-267,464 (1) and nine novel derivatives (3, 4a-7a, 4b-7b) were synthesised and evaluated in vitro with the aim of systematically exploring hydrogen bonding interactions and ligand flexibility. All analogues were subjected to competition radioligand binding assays at human oxytocin (OT) and arginine vasopressin 1a (V1a) receptors. Physiological activity was determined using whole cell IP1 accumulation assays. Under these conditions, WAY-267,464 had higher affinity for the V1a receptor compared to the OT receptor (8.5x more selective) with poor functional selectivity (2x selective for OT receptor agonism over V1a receptor antagonism). Methylation of the resorcinol moiety (3) reversed the OT receptor pharmacological profile, removing agonist activity and inducing antagonist activity, without altering V1a receptor pharmacology. All flexible tethered derivatives removed OT receptor affinity and activity resulting in the generation of highly selective V1a receptor ligands.