The discovery and functional study of a bioactive peptide, QUB-3273, from the skin secretion of the frog, Odorrana schmackeri
Anuran skin secretion is a mixture of bioactive substances which defend anurans from microorganisms. The main components include alkaloids, steroids, peptides and proteins. Peptides have been found its diverse bioactive roles, such as neurotransmitters, antibiotics and trypsin inhibitors. To solve the severe antimicrobial resistance, antimicrobial peptide gradually becomes a promising agent. In this study, the precursor-encoding cDNA sequence of QUB-3273 was identified from Odorrana schmackeri skin secretion. The alignment showed it was 88% identical to Brevinin-2GRb. This known mature peptide sequence was synthesised and purified. The minimal inhibitory concentration (MIC) of QUB-3273 was 16 µM (Escherichia coli, E. coli), 32 µM (Staphylococcus aureus, S. aureus), and 64 µM (Candida albicans, C. albicans), respectively. The results showed consistency with the bioactivities of most peptides in brevinin-2 family. QUB-3273 showed no significant effect on anti-proliferative of cancer cells. The haemolysis assay illustrated its relative low haemolytic activity with no more than 20% of hemolytical rate at 16 µM. Based on these results, QUB-3273 was proved to be a member of Brevinin-2 family. The discovery of QUB-3273 may promote further studies of frog skin peptides as the potential lead compounds for the drug discovery and clinical application.
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