Effet des extraits d’Ephédra alata sur la croissance d’Escherichia coli responsable des infections nosocomiales

Abstract

This work focused on the study of the effect of extracts with methanol, ethyl acetate, aceton, chloroform and water from Ephedra alata harvested in Bechar. one of the germs responsible for nosocomial infections namely Escherichia coli. The extraction of the bioactive compounds was carried out from the aerial part of the plant E.alata . According to the ethnobotanical survey, the pharmacological importance of the plant seems to be ignored by a large part of the population (wilaya of Mostaganem). The methanolic extract and aqueous extract represent the highest yields, 22.5% and 19% comparing with with acetone, ethyl acetate and chloroform extracts. Phytochemical screening has shown the presence of various secondary metabolites in the aerial part of the plant such as alkaloids, polyphenols (tannins and flavonoids), terpenes and reducing compounds. The disk diffusion method in agar medium, showed a weak inhibitory activity of the extracts of the plant on the growth of E. coli. The results obtained show that the strain tested has a variable sensitivity against the four extracts and the chloroformed extract is inactive. The extract with polar ethyl acetate, exert the best antibacterial effect in E. coli; with average growth rates and lower inhibitory rates. The micro-dilution method in a liquid medium makes it possible to obtain the MIC of the methanolic extract of E. alata equal to 20 mg / ml and a bactericidal effect, the acetone extract has a MIC value equal to 156.25 mg / ml and a bactericidal effect and the ethyl acetate extract has a MIC value equal to 78 mg / ml and their effect is not determined. Solvent extracts with different polarities of Ephedra alata appear to exert a bactericidal effect in E.coli bacteria.