Abstract

Increase in prevalence of resistant microorganisms especially to synthetic drugs, has necessitated the need to search for new bioactive compounds having natural origin. Phytochemical investigation of Olea africana 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 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 showed 12.4 mm zone of inhibition against Staphylococcus aureus, Erythrodiol exhibited higher antibacterial activity than uvaol against Gram positive bacteria S. 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 give a scientific validity and credence to the ethno-medicinal use of this medicinal plant as a chewing stick.

Key words: Olea africana, triterpenoids, antibacterial activity.

Abbreviation

ATCC, American type culture collection; BCC, Belgian coordinated collection microorganisms; COSY, correlation spectroscopy; DCM, dichloromethane; HMBC, heteronuclear multiple-bond correlation spectroscopy; HSQC, Heteronuclear single quantum correlation spectroscopy; MH, Mueller Hinton; NMR, nuclear magnetic resonance; NOESY, nuclear overhauser effect spectroscopy; TLC, thin layer chromatograph; WHO, World Health Organization.