Phytochemical and Antibacterial activity study of the root extract of Ehretia cymosa

Abstract

Ehretia cymosa is a medicinal plant that is used for traditional medicine in many African countries including Ethiopia. The different plant parts of E. cymosa are used in traditional medicine for the treatment of several health problems such as Toothache, tetanus, dysentery, gastric ulcers, wound healing, and skin diseases. The aim of this study was to investigate chemical constituents, partially characterize isolated compounds of root extract of E. cymosa and testing antibacterial activities of crude extracts and isolated compounds. The successive extraction of the roots 500g powder was carried out using solvent systems n-hexane, dichloromethane, dichloromethane: methanol (50:50 % by volume), and methanol that afforded 2.5 g (0.5%), 3.5 g (0.7%), 15.5 g 3.1%) and 5 g (1%) of crude extracts respectively. Phytochemical screening that was carried out by employing standard procedures revealed the presence of secondary metabolites such as alkaloids, tannins, saponins, steroids, flavonoids, phenols, glycosides, and terpenoids. Thus, dichloromethane: methanol (50:50 % by volume) extract was subsequently subjected to chromatographic separation which led to the isolation of three compounds EC-1, EC-2, and EC-3. Crude extract of dichloromethane/methanol (1:1) was subjected to column chromatography and afforded three compounds partially characterized using spectroscopic UV-Vis and IR analysis. The in vitro antibacterial activity evaluation of the crude extracts and isolated compounds was done on four different bacterial strains S. auras, E. coli, P. aeruginosa, and S. pyogen using the gar diffusion method. Among the bacteria strains used in the study, S. pyogene showed the widest zone of inhibition for methanol extract even though other extracts were antibacterial active enough. The observed antibacterial activities of the crude extracts and isolated compounds justified the traditional use of plants for the treatment of different bacterial infections. Thus, further testing is recommended on a large number of bacterial strains to decide their potential as candidates in the development of antibacterial agents.