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Effects of hydrophobicity on the antifungal activity of alpha-helical antimicrobial peptides

Ziqing Jiang1, Bart Jan Kullberg, Hein van der Lee

  • 1Department of Biochemistry & Molecular Genetics, School of Medicine, University of Colorado-Denver, Aurora, CO 80045, USA.

Chemical Biology & Drug Design
|December 19, 2008
PubMed

Insights

Hydrophobicity impacts antimicrobial peptide activity differently across fungal types. Increasing hydrophobicity boosts activity against ascomycota but reduces it against zygomycota, while also increasing hemolytic activity. A modified peptide, D5, balances these effects.

Area of Science:

  • Biochemistry
  • Microbiology
  • Medicinal Chemistry

Background:

  • Antimicrobial peptides (AMPs) are crucial in innate immunity.
  • Hydrophobicity is a key factor influencing AMP activity and toxicity.
  • Understanding structure-activity relationships is vital for developing effective antimicrobial agents.

Purpose of the Study:

  • To investigate the role of hydrophobicity in the antifungal and antibacterial activity of D-V13K peptide analogs.
  • To compare the effects of varying hydrophobicity on different fungal classes (Zygomycota and Ascomycota).
  • To assess the impact of hydrophobicity on hemolytic activity and optimize peptide design for improved therapeutic index.

Main Methods:

  • Synthesis and characterization of D-V13K peptide analogs with varying hydrophobicity.
  • Antifungal susceptibility testing against Zygomycota and Ascomycota fungi.
  • Antibacterial activity assessment against Pseudomonas aeruginosa.
  • Hemolytic activity assays.
  • Therapeutic index calculation.

Main Results:

  • Antifungal activity against Zygomycota decreased with increasing hydrophobicity, while activity against Ascomycota increased.
  • Hemolytic activity significantly increased with higher hydrophobicity, with analog D4 being 286-fold more hemolytic than D1.
  • The therapeutic index was substantially better for the less hydrophobic D1 compared to D4.
  • Modified analog D5 demonstrated reduced hemolytic activity, enhanced antifungal activity against Zygomycota, and a 201-fold improved therapeutic index over D4.

Conclusions:

  • Hydrophobicity plays a dual role in the antifungal activity of D-V13K analogs, depending on the fungal class.
  • High hydrophobicity leads to increased toxicity (hemolysis), necessitating careful optimization.
  • Peptide analog D5 represents a successful strategy for balancing antifungal efficacy and reducing hemolytic activity, offering a promising therapeutic approach.

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