Inhibitors of Cysteine Proteases

Abstract

The roles of cysteine proteases (CP) as protein degrading and protein processing enzymes both in physiological and pathological processes of mammals are well known. Furthermore, the key roles of CP;s in the life cycles of infectious agents like protozoa and viruses turn them into new important targets for anti-infective drugs. Thus, the effective inhibition of pathologically relevant cysteine proteases has raised increasing interest in drug development. One strategy to create CP inhibitors is the use of electrophilic moieties, which covalently bind to the cysteine residue of the active site of the target protease. In a previous approach we have selected the aziridine-2,3-dicarboxylic acid as weak electrophilic inhibitor fragment. In order to achieve effective enzyme inhibition this electrophile was incorporated into peptidic or peptidomimetic sequences addressing the substrate binding sites of the protease. High selectivity could be obtained with compounds, which bind into both the primed and non-primed substrate binding pockets. In a second approach the alpha,beta-unsaturated ketone of the well-known diuretic drug ethacrynic acid was found to be another appropriate electrophilic moiety. Derivatives thereof turned out to be new non-peptidic CP inhibitors. Results of inhibition assays obtained with these two inhibitor series on various proteases of human, protozoan, and viral origin, theoretical studies to investigate binding modes and inhibition mechanisms, and structure-activity relationships are presented. Furthermore, the results of in vitro assays on respective pathogens as well as the results of first toxicity studies are summarized.

Aziridine-2,3-Dicarboxylate-Based Cysteine Cathepsin Inhibitors Induce Cell Death inLeishmania majorAssociated with Accumulation of Debris in Autophagy-Related Lysosome-Like Vacuoles

“…We recently demonstrated that aziridine-2,3-dicarboxylate-based CP inhibitors 13b and 13e exhibit highly significant leishmanicidal activity in vitro (23). Both compounds were developed to inhibit parasitic cathepsin Llike enzymes (38,41). In the present study, we analyzed the ability of aziridine-2,3-dicarboxylate-based CP inhibitors 13b and 13e to affect the cysteine cathepsin activities in L. major promastigotes.…”

Rational Design of a Selective Covalent Modifier of G Protein βγ Subunits

“…Nevertheless, to avoid potential problems with GSH, other (less reactive) groups might be used in place of disulfides (e.g., monofluoroalkyl ketones and acyloxymethyl ketones) (Shaw, 1990;Krantz et al, 1991;Smith et al, 2002;Vicik et al, 2006). This strategy of avoiding inactivation by GSH by using monofluoroalkyl ketones and acyloxymethyl ketones has successfully been applied in the development of cysteine protease inhibitors (Vicik et al, 2006). Fig.…”

Dipeptide-derived nitriles containing additional electrophilic sites: Potentially irreversible inhibitors of cysteine proteases

“…Irreversible inhibitors are therefore attractive candidates for treating microbial infections and valuable tools for elucidating the in vivo functions of the enzyme. Compounds of different classes have been reported as irreversible inactivators of cysteine proteases 3 , including peptide-derived epoxides 2,4 and related aziridines 5 , diazoketones 6 , and Michael acceptors such as vinyl sulfones and peptidyl ene diones [7][8][9] . The inherent chemical reactivity of these agents limits their applicability due to unspecific reactions with other biomolecules.…”