Optimizing cell permeation of an antibiotic resistance inhibitor for improved efficacy

J Med Chem. 2007 Nov 15;50(23):5644-54. doi: 10.1021/jm070643q. Epub 2007 Oct 23.


Benzo[b]thiophene-2-ylboronic acid, 1, is a 27 nM inhibitor of the class C beta-lactamase AmpC and potentiates the activity of beta-lactam antibiotics in bacteria that express this and related enzymes. As is often true, the potency of compound 1 against the enzymes is much attenuated in cell culture against Gram negative bacteria, where the minimum inhibitor concentration of compound 1 is in the mid-micromolar range. Here, we modulated the properties of this lead to enhance its ability to cross the membrane, using a combination of X-ray crystallography, structure-based design, and application of physical models of outer membrane crossing. This strategy led us to derivatives with substantially improved permeability. Also, the greater solubility of these compounds allowed us to measure their efficacy at higher concentrations than with the lead 1, leading to higher maximum potentiation of the antibiotic effect of ceftazidime on resistant bacteria.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anti-Bacterial Agents / chemical synthesis*
  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / pharmacology
  • Bacterial Proteins / chemistry
  • Boronic Acids / chemical synthesis*
  • Boronic Acids / chemistry
  • Boronic Acids / pharmacology
  • Cell Membrane Permeability
  • Crystallography, X-Ray
  • Drug Design
  • Drug Resistance, Bacterial*
  • Escherichia coli / drug effects
  • Kinetics
  • Membranes, Artificial
  • Microbial Sensitivity Tests
  • Models, Molecular
  • Solubility
  • Structure-Activity Relationship
  • Thiophenes / chemical synthesis*
  • Thiophenes / chemistry
  • Thiophenes / pharmacology
  • beta-Lactamases / chemistry


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Boronic Acids
  • Membranes, Artificial
  • Thiophenes
  • benzo(b)thiophene-2-ylboronic acid
  • AmpC beta-lactamases
  • beta-Lactamases