The chemical structure of AA26-9 is based on a piperazine scaffold, a motif recognized for its serine hydrolase inhibitory capacity, particularly in the form of p-nitrophenoxy carbamate. The spectrum of AA26-9-inhibited enzymes spans several functional subclasses within serine hydrolases, including but not limited to lipases/phospholipases (e.g., AADACL1, ABHD6, ESD, FAAH, PAFAH2, LYPLA3), peptidases (e.g., APEH, PRCP, CTSA), and thioesterases (e.g., LYPLA1, LYPLA2), along with enzymes that have yet to be characterized (e.g., ABHD11, ABHD13, BAT5). One specific mode of action for AA26-9 involves the covalent carbamoylation of the serine nucleophile (S114) in its target enzyme LYPLA1, highlighting its mechanism of inhibiting serine hydrolase activity^[1].