Characterization and Biological Activities of Ocellatin Peptides from the Skin Secretion of the Frog Leptodactylus pustulatus (Leptodactylidae; Amphibian)

MARANI MARIELA M.; DOURADO FLAVIO; QUELEMES PATRICK A.; RODRIGUES DE ARAUJO ALYNE; PERFEITO MÁRCIA L.G.; ALVES BARBOSA EDER; VÉRAZ LEIZ M.C.; COHELO ANDREIA R.; BARROSO ANDRADE ETIELLE; EATON PETER; FIGUEIRO LONGO JOAO P.; BENTES AZEVEDO RICARDO; DELERUE-MATOS MARÍA C.; LEITE JOSÉ R. S. A.

JOURNAL OF NATURAL PRODUCTS

AMER CHEMICAL SOC

Lugar: Washington; Año: 2015 vol. 78 p. 1495 - 1504

0163-3864

Eight new peptides were isolated from the skin secretion of the frog Leptodactylus pustulatus and their amino acid sequences determined by de novo sequencing and by cDNA cloning. Structural similarities between them and other antimicrobial peptides from the skin secretion of Leptodactylus genus frogs were found. Ocellatin-PT1 to -PT5 (25 amino acid residues) are amidated at the C-terminus while ocellatin-PT6 to -PT8 (32 amino acid residues) have free carboxylates. Antimicrobial activity, hemolytic tests and cytotoxicity against a murine fibroblast cell line were investigated. All peptides, except for ocellatin-PT2, have antimicrobial activity against at least one Gram-negative strain. Ocellatin-PT8 inhibited the growth of Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Salmonella choleraesuis strains with MICs in the 60-240 µM range. No significant effect was observed in human erythrocytes and in a murine fibroblast cell line after exposure to the peptides at MICs. A comparison between sequences obtained by both direct HPLC-MS de novo sequencing and by cDNA cloning demonstrates the secretion of mature peptides derived from a pre-pro-peptide structure.