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.