Global Portrait of Protein Targets of Metabolites of the Neurotoxic Compound BIA 10–2474

Clinical investigation of the fatty acid amide hydrolase (FAAH) inhibitor BIA 10–2474 resulted in serious adverse neurological events. Structurally unrelated FAAH inhibitors tested in humans have not presented safety concerns, suggesting that BIA 10–2474 has off-target activities. A recent activity-based protein profiling (ABPP) study revealed that BIA 10–2474 and one of its major metabolites inhibit multiple members of the serine hydrolase class to which FAAH belongs. Here, we extend these studies by performing a proteome-wide analysis of covalent targets of BIA 10–2474 metabolites. Using alkynylated probes for click chemistry-ABPP in human cells, we show that des-methylated metabolites of BIA 10–2474 covalently modify the conserved catalytic cysteine in aldehyde dehydrogenases, including ALDH2, which has been implicated in protecting the brain from oxidative stress-related damage. These findings indicate that BIA 10–2474 and its metabolites have the potential to inhibit multiple mechanistically distinct enzyme classes involved in nervous system function.