M-brucin, an antibacterial peptide against Staphylococcus epidermidis and Streptococcus pyogenes

Abstract

Brucin, a plant-derived specific antibacterial peptide against S. pyogenes was chemically synthesized and its amino acid sequence, NH2-His-Thr-Leu-Cys-Met-Asp-Gly-Gly-Ala-Thr-Tyr, was modified to improve the antibacterial activity. Only one from five-modified peptides with the sequence NH2-His-Thr-Leu-Cys-Met-Gly-Lys-Ala-Thr-Tyr possessed the antibacterial activity and it was designated as "M-Brucin". Structural analysis of M-Brucin indicaed that it was a random coil peptide with a molecular mass of 1248.43 Da. It was a positive charge peptide (net charge = +1) with a pI value of 8.21 and hydrophobicity ratio of 40%. The positive antimicrobial effect of M-Brucin was tested by agar dilution technique against 30 human-pathogenic bacteria and 1 fungus. Its inhibitory activity was against S. epidermidis and S. pyogenes DMST 17020 with IC50 values of 225 μM and 250 μM, respectively. Moreover, its inhibitory activity was identified as being as strong as penicillin G and chloramphenicol, with no toxicity to normal Vero cells. The results suggest that M-Brucin could be purposed for further development as a new drug to specific treatment of various human bacterial infectious diseases. © 2018 Thakorn Sornwatana et al.