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.
Bibliographical noteFunding Information:
Funding: Support for this study was provided by The UWI Campus Research and Publication (CR&P) Fund [CRP.3.NOV16.8(1)] and study and travel grant from The UWI for visiting Ulster University (UU) (both grants awarded to M.M.). Travel/subsistence grants for visiting UU were awarded to G.B. from the School for Graduate Studies and Research (CRP.5.OCT19.94) (The UWI) and the Dean’s Office, Faculty of Science and Technology (FST), as well as the Department of Life Sciences (FST, The UWI).
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- antibiotic resistance
- antimicrobial peptides
- ane; anfrog skin secretions
- norepinephrine stimulation
- peptidomic analysis
- Frog skin secretions
- Norepinephrine stimulation
- Peptidomic analysis
- Antibiotic resistance
- Antimicrobial peptides