Discovery of NLX-266, an Orally Available and Metabolically Stable ERK1/2-Biased 5-HT_1AR Agonist with Superior Antidepressant and Antiparkinsonian Activity

We report the discovery of NLX-266 (<b>31</b>), an orally available and metabolically stable ERK1/2-biased 5-HT_1A receptor agonist, which demonstrates both enhanced antidepressant and antiparkinsonian-like activities. A new series of 1-(1-benzoylpiperidin-4-yl)methanamine derivatives were synthesized and screened for their affinity and selectivity toward the 5-HT_1A receptor. Notably, <b>31</b> exhibited exceptional binding affinity (p<i>K</i>_i > 10) and selectivity (>1000×) over the adrenergic α₁ and dopaminergic D₂ receptors. In vitro functional assays revealed that <b>31</b> preferentially activates ERK1/2 phosphorylation, correlating with significant antidepressant effects in the forced swim test in rats at low doses (MED = 0.63 mg/kg p.o.). Furthermore, <b>31</b> demonstrated potent antiparkinsonian effects by reversing haloperidol-induced catalepsy at very low doses (MED = 0.04 mg/kg p.o.). The pharmacokinetic profile of <b>31</b> indicates favorable exposure and a prolonged half-life following oral administration. These findings suggest that <b>31</b> is a promising candidate for future exploration aiming at treatment of depression and/or Parkinson's disease.