Anti-bacterial activity of Plumbago zeylanica L. roots on some pneumonia causing pathogens

Abstract

The anti bacterial activity of polar and non-polar extracts prepared from the roots of Plumbago zeylanica L. (Plumbaginaceae), a plant widely used in Ethiopian traditional medicine for various ailments were investigated using hole plate diffusion method against some pneumonia causing pathogens. The aqueous extract did not exhibit any activity while petroleum ether extract was found to have strong anti-bacterial effects as compared to the ethanol extract which showed a significant activity. Activity guided chromatographic purification of the petroleum ether extract led to the isolation of three compounds, of which the compound identified as 5-hydroxy-2-methyl-1, 4-naphthoquinone, plumbagin, found to be the active component on the tested microorganisms. Minimum inhibitory concentration value of this particular compound showed comparative activity resembling the commonly used broad spectrum antibiotic, tetracycline. The strong antibacterial effect of the petroleum ether extract is discussed to show that it was attributable to this compound rather than the other two that were found to have trace of activities.