ABSTRACT
Metallo-ß-lactamases (MBLs) are an emerging cause of bacterial antibiotic resistance by hydrolysing all classes of ß-lactams except monobactams, and the MBLs are not inhibited by clinically available serine-ß-lactamase inhibitors. Two of the most commonly encountered MBLs in clinical isolates worldwide - the New Delhi metallo-ß-lactamase (NDM-1) and the Verona integron-encoded metallo-ß-lactamase (VIM-2) - are included in this study. A series of several NH-1,2,3-triazoles was prepared by a three-step protocol utilizing Banert cascade reaction as the key step. The inhibitor properties were evaluated in biochemical assays against the MBLs VIM-2, NDM-1 and GIM-1, and VIM-2 showed IC50 values down to nanomolar range. High-resolution crystal structures of four inhibitors in complex with VIM-2 revealed hydrogen bonds from the triazole inhibitors to Arg228 and to the backbone of Ala231 or Asn233, along with hydrophobic interactions to Trp87, Phe61 and Tyr67. The inhibitors show reduced MIC in synergy assays with Pseudomonas aeruginosa and Escherichia coli strains harbouring VIM enzymes. The obtained results will be useful for further structural guided design of MBL inhibitors.
Subject(s)
Triazoles/pharmacology , beta-Lactam Resistance/drug effects , beta-Lactamase Inhibitors/pharmacology , Anti-Bacterial Agents/pharmacology , Catalytic Domain , Crystallography, X-Ray , Drug Synergism , Escherichia coli/drug effects , Escherichia coli/enzymology , Escherichia coli Proteins/metabolism , Klebsiella pneumoniae/drug effects , Meropenem/pharmacology , Molecular Structure , Protein Binding , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/enzymology , Small Molecule Libraries/chemical synthesis , Small Molecule Libraries/metabolism , Small Molecule Libraries/pharmacology , Structure-Activity Relationship , Triazoles/chemical synthesis , Triazoles/metabolism , beta-Lactamase Inhibitors/chemical synthesis , beta-Lactamase Inhibitors/metabolism , beta-Lactamases/metabolismSubject(s)
Anti-Bacterial Agents/pharmacology , Antifungal Agents/pharmacology , Antimicrobial Cationic Peptides/pharmacology , Bacteria/drug effects , Candida/drug effects , Diketopiperazines/pharmacology , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Antifungal Agents/chemical synthesis , Antifungal Agents/chemistry , Antimicrobial Cationic Peptides/chemical synthesis , Antimicrobial Cationic Peptides/chemistry , Diketopiperazines/chemical synthesis , Diketopiperazines/chemistry , Humans , Microbial Sensitivity TestsABSTRACT
In this communication, we report the synthesis and characterization of a library of small molecule antagonists of the human gonadotropin releasing hormone receptor based upon the 2-(4-tert-butylphenyl)-4-piperazinyl-benzimidazole scaffold via Cu-catalysed azide alkyne cycloaddition. Our main purpose was to find a more soluble compound based on the WAY207024 lead with nanomolar potency to inhibit the GnRH receptor. A late stage diversification by the use of click chemistry was, furthermore developed to allow for expansion of the library in future optimisations. All compounds were tested in a functional assay to determine the individual potency of inhibiting stimulation of the receptor by the endogenous agonist GnRH. In conclusion, we found that compound 8a showed improved solubility compared to WAY207024 and nanomolar affinity to GnRH receptor.
