Isolation of the anti-bacterial vernodalin from traditionally used Vernonia colorata

Leaf extracts of Vernonia colorata were screened for anti-bacterial activit y using the disc-diffusion assay. Micrococcos luteus, Klebsiella pneumoniae and Staphylococcus aureus were inhibited by ethyl acetate extracts, but no t by hexane and water extracts. The ethyl acetate extract was fractionated by silica vacuum chromatography and a chromatron using hexane:ethyl acetate gradients. The presence of anti-bacterial activity was confirmed by bioaut ography. The major anti-bacterial compound in the ethyl acetate leaf extrac t was identified by NMR as vernodalin. The minimal inhibitory concentration of vernodalin against S. aureus was 100 mug ml(-1).