ABSTRACT
Cathepsin B is a member of the papain superfamily of cysteine proteases and has been implicated in the pathology of numerous diseases, including arthritis and cancer. As part of an effort to identify potent, reversible inhibitors of this protease, we examined a series of dipeptidyl nitriles, starting with the previously reported Cbz-Phe-NH-CH(2)CN (19, IC(50) = 62 microM). High-resolution X-ray crystallographic data and molecular modeling were used to optimize the P(1), P(2), and P(3) substituents of this template. Cathepsin B is unique in its class in that it contains a carboxylate recognition site in the S(2)' pocket of the active site. Inhibitor potency and selectivity were enhanced by tethering a carboxylate functionality from the carbon alpha to the nitrile to interact with this region of the enzyme. This resulted in the identification of compound 10, a 7 nM inhibitor of cathepsin B, with excellent selectivity over other cysteine cathepsins.
Subject(s)
Cathepsin B/antagonists & inhibitors , Dipeptides/chemical synthesis , Enzyme Inhibitors/chemical synthesis , Nitriles/chemical synthesis , Animals , Binding Sites , Crystallography, X-Ray , Dipeptides/chemistry , Drug Design , Enzyme Inhibitors/chemistry , Models, Molecular , Nitriles/chemistry , Rats , Structure-Activity RelationshipABSTRACT
Structure-activity relationships of a lead hydroxamic acid inhibitor of recombinant human stromelysin were systematically defined by taking advantage of a concise synthesis that allowed diverse functionality to be explored at each position in a template. An ex vivo rat model and an in vivo rabbit model of stromelysin-induced cartilage degradation were used to further optimize these analogs for oral activity and duration of action. The culmination of these modifications resulted in CGS 27023A, a potent, orally active stromelysin inhibitor that blocks the erosion of cartilage matrix.
Subject(s)
Cartilage/metabolism , Hydroxamic Acids , Matrix Metalloproteinase Inhibitors , Protease Inhibitors/pharmacology , Pyrazines , Administration, Oral , Animals , Binding Sites , Cartilage/drug effects , Chromatography, High Pressure Liquid , Enzyme-Linked Immunosorbent Assay , Humans , In Vitro Techniques , Kinetics , Models, Chemical , Rabbits , Rats , Recombinant Proteins/antagonists & inhibitors , Structure-Activity Relationship , Substance P/metabolism , SulfonamidesABSTRACT
A potent macrocyclic inhibitor of neutral endopeptidase (NEP) 24.11 was designed using a computer model of the active site of thermolysin. This 10-membered ring lactam represents a general mimic for any hydrophobic dipeptide in which the two amino acid side chains bind to an enzyme in a contiguous orientation. The parent 10-membered ring lactam was synthesized and exhibited excellent potency as an NEP 24.11 inhibitor (IC50 = 3 nM). In order to improve oral bioavailability, various functionality was attached to the macrocycle. These modifications lead to CGS 25155, an orally active NEP 24.11 inhibitor that slows down the degradation of the cardiac hormone atrial natriuretic factor, producing a lowering of blood pressure in the DOCA-salt rat model of hypertension.