Zero Hunger (SDG 2), Good Health & Well-being (SDG 3)
Purification and antimicrobial properties of host-defence peptides in skin secretions of the Amazon River Frog Lithobates palmipes (Ranidae) Gervonne Barran 1* , J. Michael Conlon 2 , Milena Mechkarska 1 1 Department of Life Sciences, The University of the West Indies, St. Augustine Campus, Trinidad and Tobago, W.I. 2 Diabetes Research Centre, School of Biomedical Sciences, University of Ulster, N. Ireland, UK The genus Lithobates Fitzinger, 1843 (Anura: Ranidae) currently comprises 51 species of frogs from the New World, some of which have a complex evolutionary history. The skin secretions of the species studied-to-date contain abundance of host-defense peptides (HDPs) with a broad spectrum of biological activities that makes them suitable candidates for development into therapeutic agents. The Amazon River frog Lithobates palmipes (Spix, 1824) is widely distributed in the northern and Amazonian South America east of the Andes. No HDPs have been previously reported from this species. Peptidomic analysis (reversed-phase HPLC combined with MALDI-TOF mass spectrometry and automated Edman degradation) was used to characterize the HDPs in norepinephrine-stimulated skin secretions from L. palmipes collected in Trinidad. A total of ten peptides were purified and identified on the basis of amino acid similarity as belonging to the ranatuerin-2 family (ranatuerin-2PMa, -2PMb, -2PMc, and-2PMd), the brevinin-1 family (brevinin-1PMa, -1PMb, -1PMc and des(8-14)brevinin-1PMa) and the temporin family (temporin-PMa in C-terminally amidated and non-amidated forms). Brevinin-1PMa (FLPLIAGVAAKVLPKIFCAISKKC) showed potent growth inhibitory activity against antibiotic-resistant strains of the Gram-positive bacteria Staphylococcus aureus (MIC = 3 µM) and Enterococcus faecium (MIC = 6 µM) and was active against a reference strain of the Gram-negative bacterium Escherichia coli (MIC = 50 µM). Deletion of the sequence VAAKVLP from brevinin-1PMa in des(8-14)brevinin-1PMa resulted in a 10-fold decreased potency against S. aureus (MIC = 31.3 µM) and 20-fold against E. faecium (MIC = 125 µM) relative to the full-length peptide but potency against E. coli was not significantly different (MIC = 62.5 µM). Hemolytic activity was markedly reduced (> 50-fold). Temporin-PMa (FLPFLGKLLSGIF. NH2) inhibited growth of S. aureus (MIC = 16 µM) but the non-amidated form of the peptide lacked antimicrobial activity. In view of the fact that E. faecium has a high propensity to develop resistance to conventional antibiotics, des(8-14)brevinin-1PMa shows therapeutic potential as a template for development into an agent for use in infections caused by this bacterium.
P04
© The Author(s), 2023
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