Design, synthesis and evaluation of amphibian isolated peptides as antibacterial and antiproliferative agents

With the emergence of antibiotic resistance, people are trying to find alternatives to the classic antibiotics. Antimicrobial peptides have captured the attention to be developed as novel antibiotic agents. These peptides were discovered with a broad spectrum of bioactivities. In this study, three antimicrobial peptides, temporin-AW2-NH2, brevinin-2GHj and brevinin-1WY5 were studied. Temporin-AW2-NH2 and brevinin-2GHj were isolated and identified respectively from the skin secretions of Amolops wuyiensis and Sylvirana guentheri. The precursor cDNA sequence of these peptides were obtained using 'shotgun' molecular cloning. Brevinin-1WY5 was also an antimicrobial peptide identified from Amolops wuyiensis and it was reported previously. These peptides were chemically synthesised using the solid phase peptide synthesis method once the primary structure obtained. The synthesised peptides were identified and purified by MALDI-TOF MS and RP-HPLC. Several bioassays were performed to evaluate their bioactivities. Targeted modifications were designed based on the results which included increasing cationicity and hydrophobicity of the peptides, elimination of the highly conserved regions and modifications of the motif of the peptides such as the C-terminal amidation to study the structure-function relationships. The results of this study brought some ideas on the targeted modifications of AMPs. These modifications improve the bioactivities of peptides which may be developed as potential therapeutic agents.