antibacterial activity of the eerial axtracts from xanthium brasilicum

antibacterial activity of the aerial extracts from xanthium brasilicum prepared in methanol, diethyl ether, petroleum benzene and an equal mixture of the three solvents were studied against bacterial laboratory standards and clinical isolates using the disk diffusion method. the best antibacterial results were obtained when methanol or the solvent mixture was used. the crude extract with the highest antibacterial activity was fractionated by silica gel chromatography and the biologically active fractions were subjected to thin layer chromatography. all bands were separated and tested for antibacterial activity and the compounds of the active (tlc) bands were identified by 1hnmr spectroscopy. the results showed the presence of two substances, a xanthanolide and a flavonoid.