NGC-HLB, a novel antimicrobial peptide from the skin secretion of Hylarana latouchii
Antimicrobial peptides from amphibian skin secretions are considered to play a significant role in the host defence mechanisms against bacterial infection. In this study, the identification and antimicrobial activity of a novel peptide named NGC-HLB (GLLSGILGAGKKIVCGLSGLC), is described. The peptide consists of 21 amino acid residues and was identified in the skin secretion of the Chinese broad-folded frog, Hylarana latouchii. The presence of the novel peptide in skin secretion was confirmed and its sequence was likewise confirmed through comparison between the masses of the peptide obtained from “shotgun” cloning and MALDI-TOF MS. NGC-HLB possessed broad-spectrum antimicrobial activity against Gram-positive Staphylococcus aureus (NCTC 10788), Gram-negative Escherichia coli (NCTC 10418) and the yeast Candida albicans (NCPF 1467) with minimal inhibitory concentrations of 32 μM, 64 μM and 32 μM, respectively. However, NGC-HLB showed strong haemolytic activity at the MICs for these three microorganisms. Besides, NGC-HLB showed no evident inhibition of three human cancer cell line including MCF7, H157 and PC3. All the results suggested that NGC-HLB could not directly be used as a new candidate for antimicrobial use in clinic. Taking its remarkable and broad-spectrum antimicrobial activity into consideration, the peptide would certainly require significant modification to become less toxic.
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