Bioassay-Directed Isolation and Structural Characterization of Major Bioactive Compounds against E.coli from Cordia sinensis Lam.stem Bark Extract

Recently, chemists worldwide have paid attention to the potential of medicinal plants as alternative sources for the isolation of novel metabolites with interesting biological and pharmaceutical properties . The genus Cordia belongs to the family Boraginaceae, with some 300 species distributed worldwide, mostly in the warmer regions of the World. According to literature survey, several uses in traditional medicine have been reported for different Cordia species. Cordia sinensis, which is a medicinal plant found widespread in the drier parts of Sudan, The bark of C. sinensis is used for stomach disorders, menstruation, bladder diseases, gastric ulcers and malaria in western Sudan. The goals of this study was to isolate and identify the structures of the most biologically active components against E.coli from the ethanol extract of C. sinensis bark. Bio-autographic technique was used to detect anti-bacterial components of the extracts and a bioassay-guided isolation approach was adopted wherein a combination of solvent?solvent partitioning and gravity column chromatography was used. Collected fractions were continuously screened in vitro for their ability to inhibit bacterial growth Three compounds considered as the most active component against E.coli were isolated. Chemical structures of the isolated compounds were elucidated using UV, IR, Ms and NMR data analysis and were identified as6-[3, 3-Dmethylallyl]-2,3-dihydrokaempfereol (Aromadendrin), 3, 5, 7, 4?-teterahydroxyflavanone (2,3-di-hydroxykaempfereol) and a steroidal saponin ( ?-sitosterol-3-O-D-glucoside.