Aspirin prodrugs and related nitric oxide releasing compounds hold significant therapeutic promise, but they are hard to design because aspirin esterification renders its acetate group very susceptible to plasma esterase mediated hydrolysis. Isosorbide-2-aspirinate-5-salicylate is a true aspirin prodrug in human blood because it can be effectively hydrolyzed to aspirin upon interaction with plasma BuChE. We show that the identity of the remote 5-ester dictates whether aspirin is among the products of plasma-mediated hydrolysis. By observing the requirements for aspirin release from an initial panel of isosorbide-based esters, we were able to introduce nitroxymethyl groups at the 5-position while maintaining ability to release aspirin. Several of these compounds are potent inhibitors of platelet aggregation. The design of these compounds will allow better exploration of cross-talk between COX inhibition and nitric oxide release and potentially lead to the development of selective COX-1 acetylating drugs without gastric toxicity.

Isosorbide-2-benzyl carbamate-5-benzoate is a highly potent and selective BuChE inhibitor. Meanwhile, isosorbide-2-aspirinate-5-salicylate is a highly effective aspirin prodrug that relies on the salicylate portion to interact productively with human BuChE. By integrating the salicylate group into the carbamate design, we have produced isosorbide-2-benzyl carbamate-5-salicylate, an inhibitor of high potency (150 pM) and selectivity for human BuChE over AChE (666000) and CES2 (23000). Modeling and mutant studies indicate that it achieves its exceptional potency because of an interaction with the polar D70/Y332 cluster in the PAS of BuChE in addition to pseudosubstrate interactions with the active site.

In this study, we report the SAR and characterization of two groups of isosorbide-based cholinesterase inhibitors. The first was based directly on the clinically used nitrate isosorbide mononitrate (ISMN) retention of the 5-nitrate group and introduction of a series of 2-carbamate functionalities. The compounds proved to be potent and selective inhibitors of human plasma butyrylcholinesterase ( huBuChE). In the second group, the nitrate ester was removed and replaced with a variety of alkyl and aryl esters. These generally exhibited nanomolar potency with high selectivity for BuChE over acetylcholinesterase (AChE). The most potent and selective compound was isosorbide-2-benzyl carbamate-5-benzoate with an IC 50 of 4.3 nM for BuChE and >50000 fold selectivity over human erythrocyte AChE. Inhibition with these compounds is time-dependent, competitive, and slowly reversible, indicating active site carbamylation.

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