Chemical investigation of Finlaysonia obovata: part I--a rare triterpene acid showing antibacterial activity against fish pathogens

The antibacterial screening of extracts of the leaves of Finlaysonia obovata with hexane, chloroform and alcohol was carried out against fresh water fish pathogenic bacteria viz., Micrococcus Sp. (multidrug resistant strain), Aeromonas hydrophila, Pseudomonas aeruginosa, Vibrio alginolyticus, Staphylococcus aureus, Escherichia Coli, Edwardsiella tarda by disc-assay method. The hexane and chloroform extracts were found active against four and five pathogens, respectively. The highly active chloroform extract was taken up for fractionations, further screening and isolation of secondary metabolites by chromatographic techniques. The triterpene acid Urs-3beta-hydroxy-12-en-27-oic acid (3), which is very rarely found from plant sources is isolated first time from this plant along with known compounds; Lupeol acetate (1) and beta-Sitosterol (2). This article presents for the first time all the spectral data for Urs-3beta-hydroxy-12-en-27-oic acid (3), which showed moderate activity against four pathogens. This is the first report of antibacterial activity of a triterpene against fish pathogens.