Sulfonated Arylurea Derivatives are Potent Inhibitors of Human Neutrophil Elastase

Abstract

Human neutrophil elastase (HNE) is a serine protease in the chymotrypsin superfamily of enzymes. HNE has been reported to play important roles in inflammation, innate immune response, and tissue remodeling processes. Therefore, HNE has been actively pursued as a drug target, particularly for the treatment of cardiopulmonary diseases. Although thousands of molecules have been reported to inhibit HNE, yet very few have been tested in early clinical trials and with only marginal success. We report here a novel chemotype of heparin‐like sulfonated arylurea derivatives as potent and noncompetitive inhibitors of HNE. Using a chromogenic substrate hydrolysis assay, 14 heparin‐like sulfonated molecules were tested for their inhibitory activity against HNE. Only 12 molecules inhibited HNE with IC50 values of 0.22 – 88.3 μM. The inhibition of HNE by these molecules was NaCl‐dependent. Interestingly, a specific hexa‐sulfonated arylurea derivative inhibited HNE with an IC50 value of 0.22 μM via noncompetitive mechanism as demonstrated by Michaelis‐Menten kinetics. The hexa‐sulfonated derivative demonstrated 455‐, 221‐, 21‐fold selectivity indices over other heparin‐binding serine proteases including thrombin, factor Xa, and factor XIa, respectively. The molecule also demonstrated 381‐fold selectivity over factor XIIIa, a transglutaminase clotting factor with a potential heparin‐binding domain. The molecule did not show heparin‐like effects on clotting times of human plasma as determined by partial activated thromboplastin time and prothrombin time assays. A computational approach was exploited to identify the putative binding site for this novel class of HNE inhibitors. Overall, reported sulfonated arylurea derivatives serve as a new platform to develop potent, selective, and noncompetitive inhibitors of HNE for therapeutic purposes.Support or Funding InformationThis work was supported by NIGMS/NIH under award number SC3GM131986 and by IDeA program from NIGMS/NIH under grant number P20 GM103424 to RAAH. The content is solely the responsibility of the authors and does not necessarily represent the official views of NIH.