Antibacterial activity of some herbal extracts against fish pathogenic bacteria

Abstract

The study was conducted to determine the antibacterial activity of ten methanol herbal extracts (Psidium guajava, Eclipta prostrata, Houttuynia cordata, Andrographis paniculata, Couroupita guianensis, Elsholtzia ciliata, Artemisia vulgaris, Terminalia catappa, Wedelia chinensis, and Alpinia officinarum) against fish pathogenic bacteria (Streptococcus agalactiae, Edwardsiella ictaluri and Aeromonas hydrophila). The antibacterial activity was evaluated by disc diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The results indicated that: (i)The tested herbal extracts had different antibacterial activity on the three tested bacteria. The extracts of A. officinarum, T. catappa, and W. chinensis showed a broad spectrum antibacterial activity against all tested bacteria; (ii) The extracts of A. officinarum, T. catappa, and W. chinensis had the strongest antibacterial activity against S. agalactiae (MIC of 0.39 mg/mL, MBC of 12.5 mg/mL), E. ictaluri (MIC of 0.024 mg/mL, MBC of 3.13 mg/mL) and A. hydrophila (MIC of 1.56 mg/mL, MBC of 6.25 mg/mL), respectively. The obtained results showed that the extracts of A. officinarum, T. catappa, and W. chinensis will be good candidates for further studies in order to find out an alternative method for antibiotics in prevention and treatments in fish disease.