Abstract

The in vitro antimicrobial activity of the hexane, ethyl acetate and methanol extracts of the leaf of Tithonia diversifolia, and one sesquiterpene lactone 1 isolated from the ethyl acetate extract was studied. Of the fourteen strains of bacteria used, the ethyl acetate extract was the most active, showing inhibitory activity against five Gram +ve and two Gram –ve organisms. This was followed by the hexane extract and then methanol. The ethyl acetate fractions (TDE 2 – TDE 5, TDE 7, TDE 8 and TDE 10) showed varying degrees of inhibitory activity. The sesquiterpene lactone 1 showed activity against all the tested microorganisms, except Staphylococcus aureus and Bacillus cereus(MICs = 15.6 – 62.5 mg/ml for most stains). All the extracts, fractions and compound 1 showed activity against the fungus Candida albicans. The results of the present study indicate that the non-polar leaf extract of T. diversifoliacould be useful in the treatment of some disease conditions and the sesquiterpene lactone 1 could be a good candidate as a phytotherapeutic agent against some bacterial infections.

Key words: Tithonia diversifolia, antimicrobial activity, sequiterpene lactone.