Cysteine proteinase inhibitors and inhibitor precursors

Abstract

Compounds are provided that are useful in inhibiting cysteine or serine proteinases. The compounds define a peptide backbone with a sulfur atom substituted in the backbone. A leaving group is associated, or bonded, to a carbon atom adjacent to the sulfur atom. The leaving group is displaceable either by hydrolysis under physiological conditions (with the hydrolyzed compound forming an aldehyde enzyme inhibitor) or by an active-site nucleophile of a cysteine or serine proteinase. When the leaving group is displaced by hydrolysis, then the compound functions as a protected derivative of the aldehyde functional group and is stabilized against oxidation or degradation, yet allows for release of the aldehyde moiety at the pharmacological site of action. The peptide sulfide analogues bearing a leaving group displaced by the active-site nucleophile covalently bond cysteine or serine proteinases and thus irreversibly inhibit these enzymes.