Novel Aryloxyethyl Derivatives of 1-(1-Benzoylpiperidin-4-yl)methanamine as the Extracellular Regulated Kinases 1/2 (ERK1/2) Phosphorylation-Preferring Serotonin 5-HT1A Receptor-Biased Agonists with Robust Antidepressant-like Activity

Novel 1-(1-benzoylpiperidin-4-yl)methanamine derivatives were designed as "biased agonists" of serotonin 5-HT1A receptors. The compounds were tested in signal transduction assays (ERK1/2 phosphorylation, CAMP inhibition, Ca2+ mobilization, and beta-arrestin recruitment) which identified ERK1/2 phosphorylation-preferring aryloxyethyl derivatives. The novel series showed high 5-HT1A receptor affinity, >1000-fold selectivity versus noradrenergic alpha(1), dopamine D-2, serotonin 5-HT2A, histamine H-1, and muscarinic M-1 receptors, and favorable druglike properties (CNS-MPO, Fsp(3), LELP). The lead structure, (3-chloro-4-fluorophenyl) ( 4-fluor-4-(((2-(pyridin-2-yloxy)ethyl)amino)methyl)piperidin-1-yl)methanone (17, NLX-204), displayed high selectivity in the SafetyScreen44 panel (including hERG channel), high solubility, metabolic stability, and Caco-2 penetration and did not block CYP3A4, CYP2D6 isoenzymes, or P-glycoprotein. Preliminary in vivo studies confirmed its promising pharmacokinetic profile. 17 also robustly stimulated ERK1/2 phosphorylation in rat cortex and showed highly potent (MED = 0.16 mg/kg) and efficacious antidepressant-like activity, totally eliminating immobility in the rat Porsolt test. These data suggest that the present 5-HT1A receptor-biased agonists could constitute promising antidepressant drug candidates.