ABSTRACT
In 2013, the Centers for Disease Control highlighted Clostridium difficile as an urgent threat for antibiotic-resistant infections, in part due to the emergence of highly virulent fluoroquinolone-resistant strains. Limited therapeutic options currently exist, many of which result in disease relapse. We sought to identify molecules specifically targeting C. difficile in high-throughput screens of our diversity-oriented synthesis compound collection. We identified two scaffolds with apparently novel mechanisms of action that selectively target C. difficile while having little to no activity against other intestinal anaerobes; preliminary evidence suggests that compounds from one of these scaffolds target the glutamate racemase. In vivo efficacy data suggest that both compound series may provide lead optimization candidates.
Subject(s)
Amino Acid Isomerases/antagonists & inhibitors , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/antagonists & inhibitors , Clostridioides difficile/drug effects , Enterocolitis, Pseudomembranous/drug therapy , Heterocyclic Compounds, 2-Ring/pharmacology , Phenylurea Compounds/pharmacology , Pyrroles/pharmacology , Quinolines/pharmacology , Amino Acid Isomerases/genetics , Amino Acid Isomerases/metabolism , Animals , Anti-Bacterial Agents/chemical synthesis , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Clostridioides difficile/enzymology , Clostridioides difficile/genetics , Clostridioides difficile/growth & development , Drug Design , Enterocolitis, Pseudomembranous/microbiology , Enterocolitis, Pseudomembranous/mortality , Enterocolitis, Pseudomembranous/pathology , Female , Gene Expression , Gram-Negative Bacteria/drug effects , Gram-Negative Bacteria/growth & development , Gram-Positive Bacteria/drug effects , Gram-Positive Bacteria/growth & development , Heterocyclic Compounds, 2-Ring/chemical synthesis , Mice , Mice, Inbred C57BL , Microbial Sensitivity Tests , Phenylurea Compounds/chemical synthesis , Pyrroles/chemical synthesis , Quinolines/chemical synthesis , Species Specificity , Structure-Activity Relationship , Survival AnalysisABSTRACT
We have developed a novel series of heteroaromatic BACE-1 inhibitors. These inhibitors interact with the enzyme in a unique fashion that allows for potent binding in a non-traditional paradigm. In addition to the elucidation of their binding profile, we have discovered a pH dependent effect on the binding affinity as a result of the intrinsic pK(a) of these inhibitors and the pH of the BACE-1 enzyme binding assay.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Enzyme Inhibitors/chemistry , Heterocyclic Compounds/chemistry , Amyloid Precursor Protein Secretases/metabolism , Crystallography, X-Ray , Drug Design , Enzyme Inhibitors/pharmacology , Heterocyclic Compounds/pharmacology , Hydrogen-Ion Concentration , Protein Binding , Structure-Activity RelationshipABSTRACT
A series of beta-site amyloid precursor protein cleaving enzyme (BACE-1) inhibitors containing a psi(CH2NH) reduced amide bond were synthesized. Incorporation of this reduced amide isostere as a non-cleavable peptide surrogate afforded inhibitors possessing low nanomolar potencies in both an enzymatic and cell-based assay.
Subject(s)
Amides/chemistry , Endopeptidases/metabolism , Protease Inhibitors/chemical synthesis , Amyloid Precursor Protein Secretases , Binding Sites , Immunoassay , Peptides/chemistry , Protease Inhibitors/pharmacology , Structure-Activity RelationshipABSTRACT
A small molecule nonpeptide inhibitor of beta-secretase has been developed, and its binding has been defined through crystallographic determination of the enzyme-inhibitor complex. The molecule is shown to bind to the catalytic aspartate residues in an unprecedented manner in the field of aspartyl protease inhibition. Additionally, the complex reveals a heretofore unknown S(3) subpocket that is created by the inhibitor. This structure has served an important role in the design of newer beta-secretase inhibitors.
