Synthesis, Biological, and Computational Evaluation of Substituted 1-(2-Methoxyphenyl)-4-(1-phenethylpiperidin-4-yl)piperazines and 1-(2-Methoxyphenyl)-4-[(1-phenethylpiperidin-4-yl)methyl]piperazines as Dopaminergic Ligands

Abstract

Sixteen new 1-(2-methoxyphenyl)-4-(1-phenethylpiperidin-4-yl)piperazines and 1-(2-methoxyphenyl)-4-[(1-phenethylpiperidin-4-yl)methyl]piperazines were synthesized to be used as probes for mapping the dopamine D-2 receptor (D(2)DAR) arylpiperazine binding site. All compounds were evaluated for their affinity toward D(2)DAR in an in vitro competitive displacement assay. The most active one was 1-(2-methoxyphenyl)-4-{[1-(3-nitrophenethyl)piperidin-4-yl]methyl}piperazine (25) with an affinity of K-i = 54 nM. Docking analysis was conducted on all herein described compounds, whereas molecular dynamic simulation was performed on ligand 25 to establish its mode of interaction with D(2)DAR. Two possible docking orientations are proposed; the one with a salt bridge between the piperidine moiety and Asp114 of D(2)DAR is more stable.