Assessing bioactivity of a peptide from the skin secretion of Rana amurensis
So far, considerable numbers of antimicrobial peptides (AMPs) have been discovered in various amphibians, especially form the skin secretions of the frogs. Furthermore, some studies have proven that many AMPs exhibit potent antimicrobial or anticancer activities, which has attracted increasing interest from researchers studying novel drug leads. In this study, experiments were conducted to determine the biological activities of a peptide derived from the skin secretion of Rana amurensis. The biological activities that have been evaluated include antimicrobial activity, anticancer activity and haemolytic activity. Using the technique of ‘shot gun’ cloning, the peptide (FVSLLTNLLGLL.NH2) was found encoded by cloned skin secretion-derived cDNA. The peptide was then synthesised by solid-phase peptide synthesis methodology and identified through HPLC and MALDI-TOF mass spectrometry, and named QUB1301. The peptide was finally subjected to smooth muscle, antimicrobial, anticancer cell and haemolysis assays to determine the spectrum of bioactivity. According to the results, QUB-1301 had no effect on contracting or relaxing the four kinds of rat smooth muscles including bladder, ileum, uterus and artery. Moreover, this peptide was eventually found to show activity against S.aureus with the MIC at 64μM and the MBC at 128μM, but it was failed to inhibit the growth of E.coli and C.albicans. Also, QUB1301 was found to have low haemolytic activity at the concentration up to 512 μM. The growth of four cancer cell lines (U251MG, H157, PC3 and MB435S) was not inhibited by the peptide which means that QUB1301 possesses no obvious function as an anticancer agent.
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