Trivalent ultrashort lipopeptides are potent pH dependent antifungal agents

J Med Chem. 2012 Feb 9;55(3):1296-302. doi: 10.1021/jm2014474. Epub 2012 Feb 1.

Abstract

The activity of antimicrobial peptides (AMPs) that contain a large proportion of histidine residues (pK(a) ∼ 6) depends on the physiological pH environment. Advantages of these AMPs include high activity in slightly acidic areas of the human body and relatively low toxicity in other areas. Also, many AMPs are highly active in a multivalent form, but this often increases toxicity. Here we designed pH dependent amphiphilic compounds consisting of multiple ultrashort histidine lipopeptides on a triazacyclophane scaffold, which showed high activity toward Aspergillus fumigatus and Cryptococcus neoformans at acidic pH, yet remained nontoxic. In vivo, treatment with a myristic acid conjugated trivalent histidine-histidine dipeptide resulted in 55% survival of mice (n = 9) in an otherwise lethal murine lung Aspergillus infection model. Fungal burden was assessed and showed completely sterile lungs in 80% of the mice (n = 5). At pH 5.5 and 7.5, differing peptide-membrane interactions and peptide nanostructures were observed. This study underscores the potential of unique AMPs to become the next generation of clinical antimicrobial therapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / chemical synthesis
  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / pharmacology
  • Antifungal Agents / chemical synthesis*
  • Antifungal Agents / chemistry
  • Antifungal Agents / pharmacology
  • Antimicrobial Cationic Peptides / chemical synthesis*
  • Antimicrobial Cationic Peptides / chemistry
  • Antimicrobial Cationic Peptides / pharmacology
  • Aspergillus fumigatus / drug effects
  • Candida albicans / drug effects
  • Cell Line
  • Cryptococcus neoformans / drug effects
  • Female
  • Gram-Negative Bacteria / drug effects
  • Gram-Positive Bacteria / drug effects
  • Hemolysis
  • Humans
  • Hydrogen-Ion Concentration
  • Lipopeptides / chemical synthesis*
  • Lipopeptides / chemistry
  • Lipopeptides / pharmacology
  • Lung / microbiology
  • Mice
  • Mice, Inbred ICR
  • Microbial Sensitivity Tests
  • Nanostructures
  • Polymers
  • Pulmonary Aspergillosis / drug therapy
  • Pulmonary Aspergillosis / microbiology
  • Structure-Activity Relationship

Substances

  • Anti-Bacterial Agents
  • Antifungal Agents
  • Antimicrobial Cationic Peptides
  • Lipopeptides
  • Polymers