Peptidomic analysis of skin secretions of the caribbean frogs leptodactylus insularum and leptodactylus nesiotus (Leptodactylidae) identifies an ocellatin with broad spectrum antimicrobial activity

Gervonne Barran, Jolanta Kolodziejek, Laurent Coquet, Jérôme Leprince, Thierry Jouenne, Norbert Nowotny, J. Michael Conlon*, Milena Mechkarska

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Ocellatins are peptides produced in the skins of frogs belonging to the genus Leptodactylus that generally display weak antimicrobial activity against Gram-negative bacteria only. Peptidomic analysis of norepinephrine-stimulated skin secretions from Leptodactylus insularum Barbour 1906 and Leptodactylus nesiotus Heyer 1994, collected in the Icacos Peninsula, Trinidad, led to the purification and structural characterization of five ocellatin-related peptides from L. insularum (ocellatin-1I together with its (1-16) fragment, ocellatin-2I and its (1-16) fragment, and ocellatin-3I) and four ocellatins from L. nesiotus (ocellatin-1N, -2N, -3N, and -4N). While ocellatins-1I, -2I, and -1N showed a typically low antimicrobial potency against Gram-negative bacteria, ocellatin-3N (GIFDVLKNLAKGVITSLAS.NH2) was active against an antibiotic-resistant strain of Klebsiella pneumoniae and reference strains of Escherichia coli, K. pneumoniae, Pseudomonas aeruginosa, and Salmonella typhimurium (minimum inhibitory concentrations (MICs) in the range 31.25-62.5 μM), and was the only peptide active against Gram-positive Staphylococcus aureus (MIC = 31.25 μM) and Enterococcus faecium (MIC = 62.5 μM). The therapeutic potential of ocellatin-3N is limited by its moderate hemolytic activity (LC50 = 98 μM) against mouse erythrocytes. The peptide represents a template for the design of long-acting, non-toxic, and broad-spectrum antimicrobial agents for targeting multidrug-resistant pathogens.

Original languageEnglish
Article number718
Pages (from-to)1-15
Number of pages15
Issue number10
Publication statusPublished - Oct 2020
Externally publishedYes


  • Antibiotic resistance
  • Antimicrobial peptides
  • Frog skin secretions
  • Hemolysis
  • Leptodactylus
  • Norepinephrine stimulation
  • Ocellatins
  • Peptidomic analysis
  • Phylogenetics
  • Trinidad

ASJC Scopus subject areas

  • Microbiology
  • Biochemistry
  • Pharmacology, Toxicology and Pharmaceutics(all)
  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)

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