Detailed Characterization of the In Vitro Pharmacological and Pharmacokinetic Properties of -(2-Hydroxybenzyl)-2,5-Dimethoxy-4-Cyanophenylethylamine (25CN-NBOH), a Highly Selective and Brain-Penetrant 5-HT Receptor Agonist.

Therapeutic interest in augmentation of 5-hydroxytryptamine (5-HT) receptor signaling has been renewed by the effectiveness of psychedelic drugs in the treatment of various psychiatric conditions. In this study, we have further characterized the pharmacological properties of the recently developed 5-HT receptor agonist -2-hydroxybenzyl)-2,5-dimethoxy-4-cyanophenylethylamine (25CN-NBOH) and three structural analogs at recombinant 5-HT, 5-HT, and 5-HT receptors and investigated the pharmacokinetic properties of the compound. 25CN-NBOH displayed robust 5-HT selectivity in [H]ketanserin/[H]mesulergine, [H]lysergic acid diethylamide and [H]Cimbi-36 binding assays (/ ratio range of 52-81; / ratio of 37). Moreover, in inositol phosphate and intracellular Ca mobilization assays 25CN-NBOH exhibited 30- to 180-fold 5-HT/5-HT selectivities and 54-fold 5-HT/5-HT selectivity as measured by Δlog(/EC) values. In an off-target screening 25CN-NBOH (10 M) displayed either substantially weaker activity or inactivity at a plethora of other receptors, transporters, and kinases. In a toxicological screening, 25CN-NBOH (100 M) displayed a benign acute cellular toxicological profile. 25CN-NBOH displayed high in vitro permeability (P = 29 × 10 cm/s) and low P-glycoprotein-mediated efflux in a conventional model of cellular transport barriers. In vivo, administration of 25CN-NBOH (3 mg/kg, s.c.) in C57BL/6 mice mice produced plasma and brain concentrations of the free (unbound) compound of ∼200 nM within 15 minutes, further supporting that 25CN-NBOH rapidly penetrates the blood-brain barrier and is not subjected to significant efflux. In conclusion, 25CN-NBOH appears to be a superior selective and brain-penetrant 5-HT receptor agonist compared with (±)-2,5-dimethoxy-4-iodoamphetamine (DOI), and thus we propose that the compound could be a valuable tool for future investigations of physiologic functions mediated by this receptor.