δ-Thiolactones as Prodrugs of Thiol-Based Glutamate Carboxypeptidase II (GCPII) Inhibitors

Abstract

δ-Thiolactones derived from thiol-based glutamate carboxypeptidase II (GCPII) inhibitors were evaluated as prodrugs. In rat liver microsomes, 2-(3-mercaptopropyl)pentanedioic acid (2-MPPA, 1) was gradually produced from 3-(2-oxotetrahydrothiopyran-3-yl)propionic acid (5), a thiolactone derived from 1. Compound 1 was detected in plasma at concentrations well above its IC50 for GCPII following oral administration of 5 in rats. Consistent with the oral plasma pharmacokinetics, thiolactone 5 exhibited efficacy in a rat model of neuropathic pain following oral administration.