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.