Discovery of Novel Oleamide Analogues as Brain-Penetrant Positive Allosteric Serotonin 5-HT2C Receptor and Dual 5-HT2C/5-HT2A Receptor Modulators

The serotonin 5-HT_2A receptor (5-HT_2AR) and 5-HT_2CR localize to the brain and share overlapping signal transduction facets that contribute to their roles in cognition, mood, learning, and memory. Achieving selective targeting of these receptors is challenged by the similarity in their 5-HT orthosteric binding pockets. A fragment-based discovery approach was employed to design and synthesize novel oleamide analogues as selective 5-HT_2CR or dual 5-HT_2CR/5-HT_2AR positive allosteric modulators (PAMs). Compound 13 (JPC0323) exhibited on-target properties, acceptable plasma exposure and brain penetration, as well as negligible displacement to orthosteric sites of ∼50 GPCRs and transporters. Furthermore, compound 13 suppressed novelty-induced locomotor activity in a 5-HT_2CR-dependent manner, suggesting 5-HT_2CR PAM, but not 5-HT_2AR, activity at the level of the whole organism at the employed doses of 13. We discovered new selective 5-HT_2CR PAMs and first-in-class 5-HT_2CR/5-HT_2AR dual PAMs that broaden the pharmacological toolbox to explore the biology of these vital receptors.