A Novel Ocellatin-P1 Isoform from Leptodactylus labyrinthicus Frog Skin Secretion: Purification, Biological Properties and Three-Dimensional Structure
Year: 2026
Type: article
Abstract: A novel ocellatin-P1 isoform was isolated and purified from the skin secretion of the pepper frog Leptodactylus labyrinthicus. The crude skin secretion was fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC) using a C8 column and the peptide was subsequently purified on a reversed-phase C18 column. Ocellatin-LB3 (as this isoform was named) was chemically sequenced by Edman degradation. This peptide is a linear C-terminally amidated molecule composed of 25 amino acid residues: 1GLLDTLKGAAKNVVGGLASKVMEKL25-NH2. Synthetic ocellatin-LB3 was active against Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa and inactive against Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis. In addition, the peptide reduced the Trypanosoma cruzi infection in L6 cells. At 64 µM it did not reduce erythrocytes or polymorphonuclear leukocytes, but did reduce mononuclear leukocyte counts, as detected by flow cytometry. No hemolytic activity was observed in red blood cells even at 128 µM. The peptide exhibited limited antiproliferative activity against MCF-7 and HeLa tumor cells at 128 µM. Pre-incubation with the peptide appeared to enhance N-formylmethionine-leucyl-phenylalanine (fMLP)-induced migration, indicating a potential additive or synergistic effect on human neutrophils. The three-dimensional structure of ocellatin-LB3 was investigated by circular dichroism (CD) and nuclear magnetic resonance (NMR). In the presence of sodium dodecyl sulfate (SDS), the peptide adopts an α-helical structure spanning residues Leu3–Lys24, which remains largely preserved even at 95 °C. NMR Hydrogen/Deuterium (H/D) exchange experiments suggest that ocellatin-LB3 adopts a preferential orientation when interacting with SDS micelles. Based on the similarity among ocellatins, and on the physicochemical and structural properties of this peptide, a possible membrane-mediated mode of action is proposed, although this remains to be experimentally validated.
DOI: 10.3390/ijms27083658
Authors: César Augusto Prías-Márquez, Eliane Santana Fernandes Alves, Carlos José Correia de Santana, Osmindo Rodrigues Pires Júnior, Eduardo Maffud Cilli, Fabiano José Queiroz Costa, Alice da Cunha Morales Álvares, Sonia Maria de Freitas, Isabel de Fátima Correia Batista, Rafael Marques Porto, Isabelle S. Luz, Ricardo B. Azevedo, João Paulo Stawiarski Miranda, Henrique de Oliveira Noronha, Marco Antônio Damasceno Faustino, Felipe da Silva Mendonca de Melo, Alexandra Maria dos Santos Carvalho, Izabela Marques Dourado Bastos, Wagner Fontes, Aline L. Oliveira, Luciano M. Lião, Mariana S. Castro
Language: English
Subfield: Microbiology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,499
OpenAlex ID: W7155003041