A bioactive peptide, QUB-2048, from the defensive skin secretion of Phyllomedusa tomopterna

Amphibian skin secretion is deemed as a reservoir of bioactive compounds and antimicrobial peptides (AMPs) are among the most attractive of these. Due to antibiotic resistance and the eager need of developing new types of anti-infective drugs, such peptides are considered as an alternative therapeutic option due to their potent broad-spectrum antimicrobial activity.

Thus, AMPs are arousing great attention in pharmaceutical and biotechnical fields.<br>In this study, a ‘shotgun’ cloning procedure was employed to construct a skin secretion-derived cDNA library. A peptide precursor-encoding cDNA was successfully cloned from such a library of the tiger-legged monkey tree frog, Phyllomedusa tomopterna, and named QUB-2048. Subsequently, the predicted mature peptide, named QUB-2048 was isolated and identified by reverse-phase HPLC and MALDI-TOF mass spectrometry, and then chemically-synthesised by solid-phase peptide chemistry to facilitate assessment of bioactivity.<br>QUB-2048 was found to have potent antimicrobial activity against the yeast, Candida albicans and the Gram-positive bacterium, Staphylococcus aureus, against both of which the peptide displayed a minimum inhibitory concentration (MIC) of 4 µM, while displaying a comparatively less potent effect on the Gram-negative bacterium, Escherichia coli with an MIC of 32 µM. QUB-2048 also showed 20% lower haemolytic activity at a concentration of 32 µM compared to Triton X-100.