Phytochemistry and Antimicrobial Activity of Extracts from Medicinal Plant Olea africana and Olea europea

Abstract

Increase in prevalence of resistant microorganisms especially to synthetic drugs, has necessitated the need to search for new bioactive compounds having natural origin. Thus it was essential to determine the antibacterial activity of hexane, dichloromethane, ethyl acetate and methanol extracts of Olea africana and Olea europea. Phytochemical investigation of both Olea africana and             O. europea extracts indicated the presence alkaloids, flavones, flavanoids and tannins. Olea africana leaves extracts afforded two triterpenoids namely erythrodiol and uvaol which were obtained through repeated column chromatography. The compounds were characterized using Nuclear Magnetic Resonance (NMR) spectroscopy, MS spectroscopy and by comparison with literature values. The isolated triterpenoids exhibited moderate antibacterial activity whereas crude extracts exhibited relatively high antibacterial activity against Gram positive bacterial strains; methanol extracts inhibited growth and showed 12.4 mm zone of inhibition against Staphylococcus aureus, Erythrodiol exhibited higher antibacterial activity than uvaol against Gram positive bacteria Staphylococcus aureus with zones of inhibition of 5.2 mm and 5.0 mm respectively. None of the pure compounds showed significant activity against Gram negative bacteria Escherichia coli.  The results gives a scientific validity and credence to the ethno-medicinal use of this medicinal plant as a chewing stick.