Hybrid approach for the design of highly affine and selective dopamine D3 receptor ligands using privileged scaffolds of biogenic amine GPCR ligands Original Research Article

A series of compounds containing privileged scaffolds of the known histamine H1 receptor antagonists cetirizine, mianserin, ketotifen, loratadine, and bamipine were synthesized for further optimization as ligands for the related biogenic amine binding dopamine D3 receptor. A pharmacological screening was carried out at dopamine D2 and D3 receptors. In the preliminary testing various ligands have shown moderate to high affinities for dopamine D3receptors, for example, N-(4-{4-[benzyl(phenyl)amino]piperidin-1-yl}butylnaphthalen-2-carboxamide (19a) (hD3 Ki = 0.3 nM; hD2 Ki = 703 nM), leading to a selectivity ratio of 2343.