Abstract
The essential oil composition of Vitex pooara, V. rehmannii, V. obovata ssp. obovata, V. obovata ssp. wilmsii and V. zeyheri was determined using gas chromatography and mass spectrometry. The in vitro antimicrobial activity of the essential oils was assessed on Staphylococcus aureus, Bacillus cereus and Escherichia coli and the minimum inhibitory concentration values recorded. All essential oils were moderately active with V. zeyheri being the most active (8, 4 and 16mg ml-1 for S. aureus, B. cereus and E. coli respectively). The in vitro antiinflammatory activity of the essential oils was evaluated using a 5-lipoxygenase assay and all essential oils effectively inhibited 5-lipoxygenase, a key enzyme in the inflammatory cascade with V. pooara producing the most promising activity (IC50 value of 25ppm). Using the essential oil data matrix, chemotaxonomic evidence is presented which supports the infrageneric placement of V. pooara in subgenus Vitex while the other four above mentioned taxa are placed in subgenus Holmskiodiopsis.
Alma B. Stevenson Endowment Fund for Medical Research National Research Foundation University of the Witwatersrand, Johannesburg, WITS
Acknowledgements — The authors are thankful to the National Research Foundation (Indigenous Knowledge Systems) and the Medical Faculty Research Endowment Fund, University of the Witwatersrand for financial support. Robertet (Grasse, France) is acknowledged for assistance in setting up the 5-lipoxygenase assay, and we are indebted to Dr CL Bredenkamp and Ms PM Burgoyne (NBI) for the identification and assistance with the collection of the plant material.