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1‑[3-(4-Butylpiperidin-1-yl)propyl]-1,2,3,4-tetrahydroquinolin-2-one (77-LH-28-1) as a Model for the Rational Design of a Novel Class of Brain Penetrant Ligands with High Affinity and Selectivity for Dopamine D4 Receptor

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journal contribution
posted on 2018-03-28, 00:00 authored by Fabio Del Bello, Alessandro Bonifazi, Gianfabio Giorgioni, Carlo Cifani, Maria Vittoria Micioni Di Bonaventura, Riccardo Petrelli, Alessandro Piergentili, Stefano Fontana, Valerio Mammoli, Hideaki Yano, Rosanna Matucci, Giulio Vistoli, Wilma Quaglia
In the present article, the M1 mAChR bitopic agonist 1-[3-(4-butylpiperidin-1-yl)­propyl]-1,2,3,4-tetrahydroquinolin-2-one (77-LH-28-1, 1) has been demonstrated to show unexpected D4R selectivity over D2R and D3R and to behave as a D4R antagonist. To better understand the structural features required for the selective interaction with the D4R and to obtain compounds unable to activate mAChRs, the aliphatic butyl chain and the piperidine nucleus of 1 were modified, affording compounds 214. The 4-benzylpiperidine 9 and the 4-phenylpiperazine 12 showed high D4R affinity and selectivity not only over the other D2-like subtypes, but also over M1–M5 mAChRs. Derivative 12 was also highly selective over some selected off-targets. This compound showed biased behavior, potently and partially activating Gi protein and inhibiting β-arrestin2 recruitment in functional studies. Pharmacokinetic studies demonstrated that it was characterized by a relevant brain penetration. Therefore, 12 might be a useful tool to better clarify the role played by D4R in disorders in which this subtype is involved.