A novel bioactive peptide from the defensive skin secretion of Phyllomedusa sauvagii
Amphibian skin contains large amounts of compounds which have biological activities. The research and exploitation of the peptides in amphibian skin secretions with antimicrobial or haemolytic activities has become increasingly popular. Many studies show that the antimicrobial peptides (AMPs) collected from amphibians have pharmacological and clinical potential. This thesis focuses on a novel peptide discovered from the skin secretion of Phyllomedusa sauvagii. Firstly, “shotgun” cloning was used to obtain the nucleotide and translated open-reading frame (ORF) amino acid sequence of this precursor-encoding cDNA. BLAST analysis indicated that the amino acid sequence of the novel peptide QUB-2909 (ALWKNMLKGIGKLAGQAALGAVKTLVGAE) belonged to the dermaseptin family. QUB-2909 was then synthesised by use of solid phase peptide synthesis. After being purified by RP-HPLC, the novel synthetic peptide was used to test for biological functions. The novel peptide QUB-2909 showed low antimicrobial activity against the Gram-negative bacterium E. coli, the Gram-positive bacterium S. aureus and the yeast C. albicans at a concentration of 128 μM and little haemolytic activity on horse red blood cells up to the highest concentration 512 μM, employed. Moreover, the novel peptide does not have the ability to prevent the growth of several cancer cells and induce contraction or relaxation of the smooth muscle.
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