Anti-pathogenic bacterial activities of fractionated venom of king cobra (ophiophagus hannah)

Abstract

This study aimed at measuring the antibacterial activity of the semi-purified fractions isolated from King Cobra venom and investigated the mechanism of action. The protein fractions were isolated from King Cobra venom and designated F1-F7. The F5 showed the highest antibacterial activity and was further concentrated and separated by Sephadex G-75 column to obtain six fractions (F5.1-F5.6). The antibacterial assay showed that F5.1 could inhibit the growth of gram-positive S. aureus and gram-negative E. coli, S. aeruginosa and S. Typhimurium bacteria. The F5.1 showed antibacterial activity against S. aureus with the MIC of 1.8 µg/ml. Its molecular weight determined by SDS-PAGE was 69 kDa. The mechanism of action may be damaging the cytoplasmic membrane, as shown from the scanning electron microscopy. The MIC concentration of F5.1 also showed potent cytotoxicity on human PBMCs cells. The results obtained from this study indicated that the F5.1 had antibacterial activity against the S. aureus through membrane damage, however it was cytotoxic to normal human cells. In conclusion, this study provides basic information on antibacterial effect of the semi-purified F5.1 of King cobra venom. The F5.1 should be further purified or modified to obtain the potential antibacterial compound which will be safe to the normal human cells.