Selective Targeting of Human and Animal Pathogens of the Helicobacter Genus by Flavodoxin Inhibitors: Efficacy, Synergy, Resistance and Mechanistic Studies

Abstract

Antimicrobial resistant (AMR) bacteria constitute a global health concern. Helicobacter pylori is a Gram-negative bacterium that infects about half of the human population and is a major cause of peptic ulcer disease and gastric cancer. Increasing resistance to triple and quadruple H. pylori eradication therapies poses great challenges and urges the development of novel, ideally narrow spectrum, antimicrobials targeting H. pylori. Here, we describe the antimicrobial spectrum of a family of nitrobenzoxadiazol-based antimicrobials initially discovered as inhibitors of flavodoxin: an essential H. pylori protein. Two groups of inhibitors are described. One group is formed by narrow-spectrum compounds, highly specific for H. pylori, but ineffective against enterohepatic Helicobacter species and other Gram-negative or Gram-positive bacteria. The second group includes extended-spectrum antimicrobials additionally targeting Gram-positive bacteria, the Gram-negative Campylobacter jejuni, and most Helicobacter species, but not affecting other Gram-negative pathogens. To identify the binding site of the inhibitors in the flavodoxin structure, several H. pylori-flavodoxin variants have been engineered and tested using isothermal titration calorimetry. An initial study of the inhibitors capacity to generate resistances and of their synergism with antimicrobials commonly used in H. pylori eradication therapies is described. The narrow-spectrum inhibitors, which are expected to affect the microbiota less dramatically than current antimicrobial drugs, offer an opportunity to develop new and specific H. pylori eradication combinations to deal with AMR in H. pylori. On the other hand, the extended-spectrum inhibitors constitute a new family of promising antimicrobials, with a potential use against AMR Gram-positive bacterial pathogens.

Merging Multi-OMICs with Proteome Integral Solubility Alteration Unveils Antibiotic Mode of Action

“…H. pylori (ATCC 700392) was grown as above at a final cell density of 10 5 cells/mL. A sample of 2.5 mL of this pre-inoculum were transferred to each well of a 24-well plate.…”

“…Essential metabolic pathways are a vast promising scenario for antimicrobial development. Flavodoxin, urease, menaquinone synthesis enzymes and respiratory complexes are among the most promising potential disease-specific targets for obtaining narrowspectrum anti-H. pylori agents [5][6][7] . In this study, we have used five compounds developed from a high-throughput screening conducted to identify inhibitors against H. pylori flavodoxin (Hp-Fld) 8 .…”

Biophysics of Nucleic Acids Celebrating the 75th Birthday of Professor Kenneth J. Breslauer

“…In fact, armed with experimental thermochemical and thermophysical data (e.g., ThermoML) [174], molecular simulations can predict specific physicochemical properties of compounds such as infinite dilution activity coefficients (IDAC), which essentially reflect interactions between a single solute molecule surrounded by solvent and may therefore provide valuable insights regarding the solvation energies of compounds [175]. The powerful combination of structural [153,176,177], computational [178,179], and experimental biophysical methods, including calorimetric techniques [180], can furnish invaluable information on the molecular forces driving ligand-target interactions, including the role of solvation in binding energetics.…”

Design, Synthesis, and Biological Investigations of Novel Carbamoylguanidinyl Nitrobenzoxadiazoles against Chitinolytic Enzymes

“…In the field of pesticides, nitrogen heterocyclic compounds have become an important direction of pesticide development due to their high efficiency, low toxicity, and good environmental compatibility. , 7-Nitrobenzo­[ c ] [1,2,5] oxadiazole is an organic compound containing a nitrogen heterocyclic structure. In the medical field, research has found that nitrobenzoxadiazol-based flavodoxin inhibitors IV-f and rac-IV-j have high bactericidal activity against Helicobacter pylori ( Hp ). , Meanwhile, studies have shown that NPI 12 and 17 have low micromolar effects on influenza viruses (Figure ). We found that 7-nitrobenzo­[ c ] [1,2,5] oxadiazole is mainly used in pharmaceutical anticancer drugs as well as in biofluorescence assays, and no pesticide applications have been reported.…”

“…In the medical field, research has found that nitrobenzoxadiazol-based flavodoxin inhibitors IV-f and rac-IV-j have high bactericidal activity against Helicobacter pylori (Hp). 29,30 Meanwhile, studies have shown that NPI 12 and 17 have low micromolar effects on influenza viruses (Figure 2). 31 We found that 7nitrobenzo[c] [1,2,5] oxadiazole is mainly used in pharmaceutical anticancer drugs as well as in biofluorescence assays, and no pesticide applications have been reported.…”