Lippia javanica is a widely spread woody shrub and the major traditional use is reflected in its vernacular name; fever tea and ‘koorsbossie'. An infusion of the leaves is also used as a decongestant for colds and coughs. Infusions may also be used topically to treat scabies and lice. A preliminary study indicated that the essential oil chemistry varies dramatically both within and between natural plant populations. As the antimicrobial activity is directly related to the specific composition of the oil, the activity also fluctuates. Lippia javanica species from various locations in Southern Africa were collected for a study into the essential oil content and antimicrobial activity. The hydrodistilled essential oils were analysed by GC/MS and a cluster analysis was performed on the essential oil dataset. From sixteen samples (representing five natural populations), five chemotypes were identified;
1. a carvone and limonene rich type,
2. a myrcenone rich type,
3. a limonene and piperitenone rich type,
4. an ipsenone and myrcene rich type and
5. a linalool rich type.
The myrcenone and linalool chemotypes have been mentioned in the literature but the carvone, ipsenone and piperitenone chemotypes have not previously been reported. The essential oil from Lippia javanica showed minimal activity against Staphylococcus aureus, Escherichia coli, and Bacillus cereus, and no apparent activity against Pseudomonas aeruginosa in a disk diffusion assay. The oil did however show activity against Candida albicans and Cryptococcus neoformans, in the same assay.
Principal supervisor: Prof AM Viljoen
Co-supervisor: Dr SF van Vuuren (WITS)