Design of potent, non-toxic antimicrobial agents based upon the structure of the frog skin peptide, pseudin-2

Tibor Pál, Ágnes Sonnevend, Sehamuddin Galadari, J. Michael Conlon

    Research output: Contribution to journalArticle

    Abstract

    Pseudin-2, a naturally occurring 24 amino-acid-residue antimicrobial peptide first isolated from the skin of the South American paradoxical frog Pseudis paradoxa, has weak hemolytic and cytolytic activity but also relatively low potency against microorganisms. In a membrane-mimetic environment, the peptide exists in an amphipathic α-helical conformation. Analogs of the peptide with increased cationicity and α-helicity were chemically synthesized by progressively substituting neutral and acidic amino acid residues on the hydrophilic face of the α-helix by lysine. Analogs with up to three L-lysine substitutions showed increased potency against a range of gram-negative and gram-positive bacteria (up to 16-fold) whilst retaining low hemolytic activity. The analog [d-Lys3, d-Lys10, d-Lys14]pseudin-2 showed potent activity against gram-negative bacteria (minimum inhibitory concentration, MIC=5 μM against several antibiotic-resistant strains of Escherichia coli) but very low hemolytic activity (HC50>500 μM) and cytolytic activity against L929 fibroblasts (LC50=215 μM). Increasing the number of l-lysines to four and five did not enhance antimicrobial potency further but increased hemolytic activity towards human erythrocytes. Time-kill studies demonstrated that the analog [Lys3, Lys10, Lys14, Lys 21]pseudin-2 at a concentration of 1×MIC was bacteriocidal against E. coli (99.9% cell death after 96 min) but was bacteriostatic against S. aureus. Increasing the hydrophobicity of pseudin-2, while maintaining the amphipathic character of the molecule, by substitution of neutral amino acids on the hydrophobic face of the α-helix by l-phenylalanine, had only minor effects on antimicrobial and hemolytic activities.

    Original languageEnglish (US)
    Pages (from-to)85-91
    Number of pages7
    JournalRegulatory Peptides
    Volume129
    Issue number1-3
    DOIs
    StatePublished - Jul 15 2005

    Fingerprint

    Anti-Infective Agents
    Anura
    Lysine
    Neutral Amino Acids
    Skin
    Escherichia coli
    Peptides
    Bacteria
    Substitution reactions
    Acidic Amino Acids
    Time and motion study
    Gram-Positive Bacteria
    Microbial Sensitivity Tests
    Cell death
    Fibroblasts
    Hydrophobicity
    Gram-Negative Bacteria
    Phenylalanine
    Hydrophobic and Hydrophilic Interactions
    Human Activities

    Keywords

    • Amphibian
    • Antimicrobial
    • Cytolytic
    • Hemolytic
    • Pseudin-2

    ASJC Scopus subject areas

    • Biochemistry
    • Physiology
    • Endocrinology
    • Clinical Biochemistry
    • Cellular and Molecular Neuroscience

    Cite this

    Design of potent, non-toxic antimicrobial agents based upon the structure of the frog skin peptide, pseudin-2. / Pál, Tibor; Sonnevend, Ágnes; Galadari, Sehamuddin; Conlon, J. Michael.

    In: Regulatory Peptides, Vol. 129, No. 1-3, 15.07.2005, p. 85-91.

    Research output: Contribution to journalArticle

    Pál, Tibor ; Sonnevend, Ágnes ; Galadari, Sehamuddin ; Conlon, J. Michael. / Design of potent, non-toxic antimicrobial agents based upon the structure of the frog skin peptide, pseudin-2. In: Regulatory Peptides. 2005 ; Vol. 129, No. 1-3. pp. 85-91.
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    abstract = "Pseudin-2, a naturally occurring 24 amino-acid-residue antimicrobial peptide first isolated from the skin of the South American paradoxical frog Pseudis paradoxa, has weak hemolytic and cytolytic activity but also relatively low potency against microorganisms. In a membrane-mimetic environment, the peptide exists in an amphipathic α-helical conformation. Analogs of the peptide with increased cationicity and α-helicity were chemically synthesized by progressively substituting neutral and acidic amino acid residues on the hydrophilic face of the α-helix by lysine. Analogs with up to three L-lysine substitutions showed increased potency against a range of gram-negative and gram-positive bacteria (up to 16-fold) whilst retaining low hemolytic activity. The analog [d-Lys3, d-Lys10, d-Lys14]pseudin-2 showed potent activity against gram-negative bacteria (minimum inhibitory concentration, MIC=5 μM against several antibiotic-resistant strains of Escherichia coli) but very low hemolytic activity (HC50>500 μM) and cytolytic activity against L929 fibroblasts (LC50=215 μM). Increasing the number of l-lysines to four and five did not enhance antimicrobial potency further but increased hemolytic activity towards human erythrocytes. Time-kill studies demonstrated that the analog [Lys3, Lys10, Lys14, Lys 21]pseudin-2 at a concentration of 1×MIC was bacteriocidal against E. coli (99.9{\%} cell death after 96 min) but was bacteriostatic against S. aureus. Increasing the hydrophobicity of pseudin-2, while maintaining the amphipathic character of the molecule, by substitution of neutral amino acids on the hydrophobic face of the α-helix by l-phenylalanine, had only minor effects on antimicrobial and hemolytic activities.",
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    AU - Sonnevend, Ágnes

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    AU - Conlon, J. Michael

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