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

Thakorn Sornwatana ,Teerakul Arpornsuwan ,Sittiruk Roytrakul ,Nuanchawee Wetprasit

doi:10.7324/japs.2018.8204

Abstract

Brucin, a specific antibacterial peptide against Strep. 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 â€œM-Brucinâ€. Structural analysis of M-Brucin indicated that it was a linear with 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 tested against Staph. epidermidis and Streptococcus pyogenes DMST 17020 with IC50 values of 225 ÂµM and 250 ÂµM, respectively. Moreover, its inhibitory activity was identified as being as strong as penicillin G and chloramphenicol, with no toxicity to normal Vero cell at the same concentration tested. The results suggest that MB may be further developed as an alternative drug for the treatment of the disease caused by Strep.

Highlights

Antimicrobial peptides (AMPs) are typically rich in hydrophobic residues, including Leu, Ile, Val, Phe and Trp, and they usually have an excess of cationic amino acids, which confers a net positive charge (Hancock and Haney, 2013)
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
One approach to improve the antibacterial activity of a peptide was to increase net positive charge and/or hydrophobicity on the peptide molecule

Summary

Introduction

Antimicrobial peptides (AMPs) are typically rich in hydrophobic residues, including Leu, Ile, Val, Phe and Trp, and they usually have an excess of cationic amino acids, which confers a net positive charge (Hancock and Haney, 2013). Pyogenes (group A streptococus, GAS) causes severe clinical diseases with high risk death. The diseases caused by GAS can be found from superficial infections to invasiveness for example pharyngitis, scarlet fever, Sornwatana et al / Journal of Applied Pharmaceutical Science 8 (02); 2018: 027-032 interaction promotes the adsorption of AMPs onto the microbial membrane (Nikken et al, 2013). We have designed a number of structurally modified peptides from Brucin to improve its antimicrobial activity. It was found that only one from the five modified Brucin peptides showed active antibacterial activity and we designated it as M-Brucin

Methods

Results

Discussion

Conclusion