Brucin, an antibacterial peptide derived from fruit protein of Fructus Bruceae, Brucea javanica (L.) Merr.

A novel antibacterial peptide specific to Streptococcus pyogenes was produced from dried fruit protein of Brucea javanica (L.) Merr. A mixture of active peptides from the fruit protein was produced in vitro by pepsin hydrolysis. The hydrolysate was purified by reverse-phase HPLC, and antimicrobial peptides active against Gram-negative and Gram-positive bacteria were analysed using SDS-PAGE and nanoLC-MS/MS. Here, four possible peptides were obtained and chemically synthesized for comparative study of the growth inhibition of Strep. pyogenes. One chemically synthesized peptide with a molecular mass of 1168.31 Da, His-Thr-Leu-Cys-Met-Asp-Gly-Gly-Ala-Thr-Tyr, showed the most potent antibacterial activity against Strep. pyogenes. This 11-amino acid peptide was named Brucin. Its bacterial inhibitory activity was 16-fold and 12.5-fold higher than penicillin G and chloramphenicol, respectively, with a MIC value of 20 μmol l(-1) . The results suggest that Brucin, a potent antibiotic peptide, may be developed as an alternative drug for the treatment of the disease caused by Strep. pyogenes.

CONCLUSIONS

An antibacterial peptide, named Brucin with specificity for Streptococcus pyogenes, was produced in vitro from dried fruit protein of Brucea javanica (L.) Merr. by pepsin-catalysed hydrolysis. Its inhibitory activity towards the Gram-positive bacteria was higher than penicillin G and chloramphenicol. The result suggested that Brucin may be applied for the treatment of the disease caused by Strep. pyogenes(*) .