Novel β-Amino Acid Derivatives as Inhibitors of Cathepsin A

Abstract

Cathepsin A (CatA) is a serine carboxypeptidase distributed between lysosomes, cell membrane, and extracellular space. Several peptide hormones including bradykinin and angiotensin I have been described as substrates. Therefore, the inhibition of CatA has the potential for beneficial effects in cardiovascular diseases. Pharmacological inhibition of CatA by the natural product ebelactone B increased renal bradykinin levels and prevented the development of salt-induced hypertension. However, so far no small molecule inhibitors of CatA with oral bioavailability have been described to allow further pharmacological profiling. In our work we identified novel β-amino acid derivatives as inhibitors of CatA after a HTS analysis based on a project adapted fragment approach. The new inhibitors showed beneficial ADME and pharmacokinetic profiles, and their binding modes were established by X-ray crystallography. Further investigations led to the identification of a hitherto unknown pathophysiological role of CatA in cardiac hypertrophy. One of our inhibitors is currently undergoing phase I clinical trials.

Cardiac drug-drug interaction between HCV-NS5B pronucleotide inhibitors and amiodarone is determined by their specific diastereochemistry

“…Figure 5 shows the effects of CatA inhibitor ebelactone B (Ebel) and a novel, more selective CatA inhibitor, designated as compound 2a, SAR1, or SAR164653151617, on the previously described synergistic effects by L-ala, S P prodrugs in hiPSC-CM syncytia on FP rate and IMP amplitude measured in the CardioECR platform. To maximize the effects of CatA inhibitors, hiPSC-CM syncytia were pre-incubated with these reagents for 30 minutes prior to a second addition at time = 0, alone or combined with other test agents.…”

“…Ebelactone B was purchased from Enzo Life Sciences, Inc. (Farmingdale, NY, USA) and Santa Cruz Biotechnology, Inc. (Dallas, TX, USA). CatA inhibitor SAR164653 (also known as compound 2a, or SAR1)151617 was synthesized in house for research purposes.…”

Proteolytic Activation of Human Cathepsin A

“…Cleavage at a number of these sites can potentially remove the excision and blocking peptides to activate cathepsin A. For instance, human cathepsin A can be treated in vitro with trypsin and cathepsin L to generate mature cathepsin A with catalytic activity (13,23). Additionally, other cathepsins (beyond cathepsin A) can be activated by a variety of proteases (37).…”

“…In the proposed activation model, the 54-kDa monomer was processed into a large (32-kDa) and a small (20-kDa) subunit, covalently linked by two disulfide bonds (20,23). Nearly two decades later, the structure of mature cathepsin A bound to small-molecule inhibitors suggested a similar activation mechanism and described the removal of a 2-kDa excision peptide, although electron density was absent for a longer sequence (13). The maturation subdomain (254 -302) of precursor cathepsin A has multiple surface-exposed potential protease cleavage sites, lending support to the possibility that it is activated by proteolytic removal of a larger segment.…”

“…Cathepsin A is expressed ubiquitously and acts on multiple peptide hormones, including endothelin-1 (11) and angiotensin I, highlighting its importance in endocrine regulation (12). Inhibitors against cathepsin A are currently in phase I clinical trials for hypertension because of its central role in vasoregulation (13,14). Additionally, cathepsin A is a major hydrolase for converting peptidic prodrugs to active compounds (15).…”