Assessing bioactivity of peptide QUB2003 from the skin secretion of the Waxy monkey tree frog Phyllomedusa sauvagii
Frog skin acts as a first line barrier of defence in amphibians, is important in their daily lives and is having significant implications in current biomedical science research. According to this research, amphibian skin secretion is a rich source of bioactive materials, including antimicrobial peptides (AMPs) and anticancer peptides (ACPs). The potentially-great advantages and broad action spectra of these bioactive peptides have increased the level of research interest for scientists searching for novel drugs and clinical applications. Since some of these active peptides have broad-spectrum antibacterial activity and anticancer activity, they therefore have the potential to become new antibiotics or new anticancer drugs. In this study, through “shotgun” cloning of peptide biosynthetic precursor-encoding cDNA, a peptide named QUB2003, was successfully identified in the defensive skin secretion of the South American hylid frog, Phyllomedusa sauvagii. Subsequently, the predicted mature peptide had its structure confirmed by mass spectrometry and was then chemically-synthesised using solid phase peptide synthesis to provide adequate material for functional research. Functional tests employed included antimicrobial assays, haemolytic assays and anticancer cell assays. The synthetic replicate of the peptide QUB2003, exhibited antimicrobial activity with MIC values against the Gram-positive bacterium, Staphylococcus aureus, the Gram-negative bacterium, Escherichia coli and the yeast, Candida albicans, of 32 µM, 256 µM and 32 µM, respectively, EC50=214.3 µM which possessed relatively strong haemolytic activity. The MB435, PC3, H157, U251MG cells were thus unaffected in growth by QUB2003, cells proliferations were 125.24%, 102.87%, 135.70%, 78.48%, respectively.
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