Screening Of Traditional Chinese Medicine Against Vibrio Sp. And Purification Of Antibacterial Compound From The Flowers Of Rosa Chinensis Jacq

Vibrosis is the major bacterial disease affecting marine and freshwater fishes in the world. The treatment of the bacterial diseases is mainly based on the use of antibiotics. However, environmental concerns, the emergence of antibiotic-resistant strains of fish pathogens and the damage to the fish limit the value of these compounds and has created a need for new antimicrobial agents.Ethanol extracts from 51 plants and 2 animals commonly used in the traditional Chinese medicine were selected against marine pathogenic Vibrio anguillarum and V.parahaemolyticus, utilizing the disc diffusion method. During this preliminary screening, the extracts of Prunus mume(Sieb.)Sieb.et Zucc., Terminalia chebula Retz. ,Canarium album Raeusch., Melaphis chinensis (Bell) Barker., Schisandra chinensis (Turcz.) Baill., Lonicera japonica Thunb., Cinnamomum cassia Presl.,Rheum officinale Baill. showed antibacterial activities against both Vibrio anguillarum and V.parahaemolyticus. The 9 extracts which showed antibacterial activities against both V.anguillarum and V.parahaemolyticus were tested successively against additional marine pathogenic Vibrios: V.harveyi , V.mimicus, V.alginolyticu, V. vulnificus, V. campbelli, V. fischeri, Aeromonas caviae , A. hydrophila and Edwardsiella tarda .The results showed that fruits of Prunus mume(Sieb.)Sieb.et Zucc., fruits of Terminalia chebula Retz. and fruits of Canarium album Raeusch. possessed antibacterial activity against all the tested bacteria;and the barks of Cinnamomum cassia Presl. greatly inhibited the growth of V.mimicus VIB298 (42-mm diam).The bioassay-guided fractionation method with a combination of extraction and multi-chromatography led to the isolation of an antibacterial compound whose structure was identified as gallic acid by spectroscopic analyses (ESI-MS¹H-NMR,¹³C-NMR,¹³C-dept)and TLC with standard sample. The compound showed antibacterial activity against the tested V.harveyi,V. parahaemolyticus ,V. alginolyticus ,V. anguillarum and V. vulnificus, but didn't show antibacterial activity against V.mimicus and V. campbelli, and the non-vibrio strains. Its minimum inhibitory concentration (MIC) against V. anguillarum CW1 was 25.6μg/mL (1.5×10^-1μmol/mL) when determined by the duplex dilution method in vitro, which was lower than that of a commonly used antibiotic kanamycin 51.2μg/mL (8.6×10^-2μmol/mL).