Structure-based Design of New Dihydrofolate Reductase Antibacterial Agents: 7-(benzimidazol-1-yl)-2,4-diaminoquinazolines

J Med Chem. 2014 Feb 13;57(3):651-68. doi: 10.1021/jm401204g. Epub 2014 Jan 16.


A new series of dihydrofolate reductase (DHFR) inhibitors, the 7-(benzimidazol-1-yl)-2,4-diaminoquinazolines, were designed and optimized for antibacterial potency and enzyme selectivity. The most potent inhibitors in this series contained a five-membered heterocycle at the 2-position of the benzimidazole, leading to highly potent and selective compounds that exploit the differences in the size of a binding pocket adjacent to the NADPH cofactor between the bacterial and human DHFR enzymes. Typical of these compounds is 7-((2-thiazol-2-yl)benzimidazol-1-yl)-2,4 diaminoquinazoline, which is a potent inhibitor of S. aureus DHFR (Ki = 0.002 nM) with 46700-fold selectivity over human DHFR. This compound also has high antibacterial potency on Gram-positive bacteria with an MIC versus wild type S. aureus of 0.0125 μg/mL and a MIC versus trimethoprim-resistant S. aureus of 0.25 μg/mL. In vivo efficacy versus a S. aureus septicemia was demonstrated, highlighting the potential of this new series.

MeSH terms

  • Animals
  • Anti-Bacterial Agents / chemical synthesis*
  • Anti-Bacterial Agents / pharmacokinetics
  • Anti-Bacterial Agents / pharmacology
  • Benzimidazoles / chemical synthesis*
  • Benzimidazoles / pharmacokinetics
  • Benzimidazoles / pharmacology
  • Drug Resistance, Bacterial
  • Folic Acid Antagonists / chemical synthesis*
  • Folic Acid Antagonists / pharmacokinetics
  • Folic Acid Antagonists / pharmacology
  • Humans
  • Mice
  • Microbial Sensitivity Tests
  • Models, Molecular
  • Quinazolines / chemical synthesis*
  • Quinazolines / pharmacokinetics
  • Quinazolines / pharmacology
  • Sepsis / drug therapy
  • Staphylococcal Infections / drug therapy
  • Staphylococcus aureus / drug effects
  • Staphylococcus aureus / enzymology
  • Streptococcus pneumoniae / drug effects
  • Structure-Activity Relationship
  • Tetrahydrofolate Dehydrogenase / metabolism*


  • Anti-Bacterial Agents
  • Benzimidazoles
  • Folic Acid Antagonists
  • Quinazolines
  • Tetrahydrofolate Dehydrogenase

Associated data

  • PDB/4LAE
  • PDB/4LAG
  • PDB/4LAH
  • PDB/4LEK