Development and Optimization of Piperidyl-1,2,3-Triazole Ureas as Selective Chemical Probes of Endocannabinoid Biosynthesis

We
have previously shown that 1,2,3-triazole ureas (1,2,3-TUs)
act as versatile class of irreversible serine hydrolase inhibitors
that can be tuned to create selective probes for diverse members of
this large enzyme class, including diacylglycerol lipase-β (DAGLβ),
a principal biosynthetic enzyme for the endocannabinoid 2-arachidonoylglycerol
(2-AG). Here, we provide a detailed account of the discovery, synthesis,
and structure–activity relationship (SAR) of (2-substituted)-piperidyl-1,2,3-TUs
that selectively inactivate DAGLβ in living systems. Key to
success was the use of activity-based protein profiling (ABPP) with
broad-spectrum and tailored activity-based probes to guide our medicinal
chemistry efforts. We also describe an expanded repertoire of DAGL-tailored
activity-based probes that includes biotinylated and alkyne agents
for enzyme enrichment coupled with mass spectrometry-based proteomics
and assessment of proteome-wide selectivity. Our findings highlight
the broad utility of 1,2,3-TUs for serine hydrolase inhibitor development
and their application to create selective probes of endocannabinoid
biosynthetic pathways.