Optimization of N-Benzoylindazole Derivatives as Inhibitors of Human Neutrophil Elastase

Abstract

Human neutrophil elastase (HNE) is an important therapeutic target for treatment of pulmonary diseases. Previously, we identified novel N-benzoylindazole derivatives as potent, competitive, and pseudoirreversible HNE inhibitors. Here, we report further development of these inhibitors with improved potency, protease selectivity, and stability compared to our previous leads. Introduction of a variety of substituents at position 5 of the indazole resulted in the potent inhibitor 20f (IC50~10 nM), and modifications at position 3 resulted the most potent compound in this series, the 3-CN derivative 5b (IC50= 7 nM); both derivatives demonstrated good stability and specificity for HNE versus other serine proteases. Molecular docking of selected N-benzoylindazoles into the HNE binding domain suggested that inhibitory activity depended on geometry of the ligand-enzyme complexes. Indeed, the ability of a ligand to form a Michaelis complex and favorable conditions for proton transfer between Hys57, Asp102 and Ser195 both affected activity.

Elaborate ligand-based modeling reveals new human neutrophil elastase inhibitors

“…Even in the case of 126 (the most potent hit), the central acetoactone linker can be viewed as a six-remembered ring resulting from hydrogen bonding the tautomeric enolic hydroxyl with the c-carbonyl. A similar trend can be noticed in recently published synthetic optimization of N-benzoylindazole derivatives as inhibitors of HNE (Crocetti et al, 2013).…”

Molecular docking analysis of curcumin analogues as human neutrophil elastase inhibitors

“…Several studies have been conducted recently to examine the binding interaction of inhibitors to the human neutrophil elastase structure (Siedle et al, 2002;Sivamani et al, 2012;Lucas et al, 2013;Crocetti et al, 2013;Radhakrishnan et al, 2013). In the present study, the aim is to understand the binding interactions between curcumin analogues and the active site of the human neutrophil elastase.…”

Asn347 Glycosylation of Corticosteroid-binding Globulin Fine-tunes the Host Immune Response by Modulating Proteolysis by Pseudomonas aeruginosa and Neutrophil Elastase

“…In-gel Digestion and Isolation of CBG Peptides-Gel bands corresponding to undigested intact CBG (55-60 kDa), the large CBG-Nt fragment (50)(51)(52)(53)(54)(55), and the small CBG-Ct fragment (5-10 kDa) were excised from the gels, diced, and washed with 100 mM NH 4 HCO 3 (aqueous) and 50% (v/v) acetonitrile. In-gel digestion was performed using modified porcine trypsin (Promega) (100 ng/gel band) overnight in 50 mM NH 4 HCO 3 (aqueous), pH 6.8, at 37°C.…”