To support ongoing clinical trials, the major human metabolites of psilocybin—psilocin-O-glucuronide and 4-hydroxyindole-3-acetic acid (4-HIAA)—along with putative minor metabolites and several deuterium-labeled derivatives, were synthesized on a preparative scale. When assayed for engagement at seven serotonin receptor subtypes using a BRET-based binding assay, only psilocin exhibited any discernible binding. Given the high cost and challenging preparation of these compounds, the work provides a comprehensive guide for researchers to access these resources, advancing both basic and clinical research with psilocybin and its metabolites.
Monoclonal antibodies were developed that specifically recognize (2R,6R)-hydroxynorketamine, a metabolite of ketamine linked to rapid antidepressant effects. An immunogenic bioconjugate was designed by attaching a 6-aminohexanoic acid linker to the pharmacophore and coupling it to a carrier protein. Mice immunized with this conjugate produced equivalent antibody titers to a racemic comparator. Hybridoma screening yielded the monoclonal antibody 6F11-HC1-LC2, which showed strong binding to (2R,6R)-hydroxynorketamine but no response to the (2S,6S) enantiomer in competitive ELISA. Surface plasmon resonance revealed sub-nanomolar affinity (0.4 nM) for (2R,6R)-hydroxynorketamine-BSA conjugates and over 150-fold selectivity over ketamine-BSA conjugates. These antibodies can be used in future studies to investigate the roles of hydroxynorketamine enantiomers in ketamine's antidepressant effects.