Acyl Glucuronide of Oxidized Lenabasum (JBT‐101) as Human Major Metabolite: Identification, Large‐Scale Synthesis, and Activity Characterization

Abstract

AbstractA metabolite identification study of the phase 3 investigational drug lenabasum (JBT‐101) pinpointed a unique acyl glucuronide (AG) as a major human metabolite. Mass spectrometry data suggested five possible isomeric structures, i. e., a C9‐carboxyl glucuronide with one of the five methyl groups having been oxidized into a hydroxymethyl group. Total synthesis of the possible metabolites confirmed 1‐((6aR,10aR)‐1‐hydroxy‐3‐((R)‐1‐hydroxy‐2‐methyloctan‐2‐yl)‐6,6‐dimethyl‐6a,7,10,10a‐tetrahydro‐6H‐benzo[c]chromene‐9‐carboxyl)‐β‐D‐glucopyranuronic acid (5 b) as the major metabolite, with its absolute stereochemistry determined by 2D NMR analysis and X‐ray crystallography. To support an animal toxicity study, robust synthetic protocols were developed for large‐scale synthesis of 5 b, which include tetrahydrocannabinol skeleton formation, SeO2‐mediated allylic oxidation, Pinnick oxidation, glucuronidation, and phenol‐mediated p‐methoxybenzyl deprotection. 5 b showed no activity on cannabinoid receptors (Ki > 5 uM) and demonstrated a half‐life of 24.2 h in potassium phosphate buffer, suggesting that it is a highly stable AG with a low risk of toxicity from covalent binding to endogenous proteins or DNAs.