ABSTRACT
Helichrysum (Asteraceae) is a large genus consisting of approximately 500 species of which
245 taxa are indigenous to southern Africa. Many Helichrysum species are widely used by the
indigenous population to treat various ailments, including coughs, colds, fever, infections,
headache, menstrual pain and as a treatment for wounds.
Medicinal uses are often not species-specific but often depend on the local availability.
Guided by the traditional use and the lack of scientific information, nine species of
Helichrysum were selected for this study. The essential oils were obtained through
hydrodistillation and methanol and acetone extracts of the plant material were prepared.
The essential oil composition was determined using GC-MS. The oil profiles were mostly
dominated by the presence of monoterpenes such as a-pinene, 1,8-cineole and p-cymene.
Monoterpenes were largely absent in the essential oil of H. felinum, but this oil was rich in
sesquiterpenes with high yields of b-caryophyllene.
The antimicrobial activity of the essential oils and plant extracts were of interest due to their
traditional use as an antiseptic. The antimicrobial activity of the essential oils and extracts was
determined by disc diffusion assays and, following this, the most active species were further
investigated using the minimum inhibition concentration (MIC) assay.
Helichrysum dasyanthum displayed the best activity against B. cereus (MIC = 16 mg/ml) and
was the only extract that exhibited activity against all three fungal strains tested (C.
neoformans, 1 mm; C. albicans, 3 mm; and A. alternata, 2 mm). The essential oil of H.
petiolare and H. felinum exhibited the most pronounced activity against the fungal strains in
the disc diffusion assay (C. albicans, 2mm).
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/4947 |
| Date | 10 June 2008 |
| Creators | Reddy, Dakshina |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 865763 bytes, application/pdf, application/pdf |
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