Throughout the history of mankind, many infectious diseases have been
treated with plant extracts. Venereal infections are one such group and are regarded
as conditions that are highly responsive to traditional treatment. Aqueous, ethanol
and ethyl acetate extracts of 13 plants used in South Africa for the treatment of
venereal diseases were screened for in vitro antibacterial, antifungal, mutagenic and
antimutagenic activities.
Antibacterial activity was evaluated using the disc-diffusion and microdilution
assays to determine the minimal inhibitory concentration (MIC) values of the extracts.
The extracts were tested against the Gram-positive bacteria Bacillus subtilis and
Staphylococcus aureus, and the Gram-negative bacteria Escherichia coli and
Klebsiella pneumoniae. Among the plants tested, Gunnera perpensa, Harpephyllum
caffrum, Hypoxis latifolia and Ledebouria ovatifolia showed the best antibacterial
activity. The aqueous rhizome extract of Gunnera perpensa displayed good activity
against Gram-negative bacteria with an MIC value of 0.78 mg/ml, and against S.
aureus (0.78 mg/ml). Aqueous and ethanol extracts of H. caffrum bark were active
against both Gram-positive and Gram-negative bacteria. Hypoxis latifolia aqueous
corm extracts exhibited very good MIC values against K. pneumoniae (0.78 mg/ml),
E. coli and S. aureus (1.56 mg/ml). Ethanol and ethyl acetate bulb extracts of
Ledebouria ovatifolia displayed good activity against Bacillus subtilis bacteria with
MIC values of 0.78 mg/ml and 0.39 mg/ml respectively.
Antifungal activity was evaluated using the microdilution bioassay. Good
activity was shown by the ethanolic bark extracts of Bersama lucens and
Harpephyllum caffrum against Candida albicans. Only in the case of Harpephyllum
caffrum did aqueous extracts have activity against Candida albicans. In the Ames
test, all plant extracts showed a negative genotoxic response except for ethanol and
ethyl acetate bulb extracts of Cyrtanthus obliquus which induced mutations in TA98.
Moderate antimutagenic activity was observed with the ethyl acetate extract of G.
perpensa and the ethanolic extract of H. latifolia.
High antibacterial and antifungal activity detected with Harpephyllum caffrum
bark extracts resulted in an investigation on seasonal and geographical variation of
this inhibitory activity. Seasonal variation in antibacterial and antifungal activities was
investigated in order to determine the best collection time to ensure potential high
medicinal activity in plant preparations. The highest inhibitory activity was detected
with plant material collected in June and December 2003, with a decline in activity
when collections were made in September 2004. The chemical profiles of TLC
chromatograms were compared and little variation was found, particularly in the case
of plant material obtained from the Botanic Garden of the University of KwaZulu-Natal
and a 'Muthi' Shop in Pietermaritzburg.
Identification of active compounds from G. perpensa and H. caffrum was not
successful due to insufficient amounts of isolated fractions. / Thesis (Ph.D.)-University of KwaZulu-Natal, 2006.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/8554 |
| Date | January 2006 |
| Creators | Buwa, Lisa Valencia. |
| Contributors | Van Staden, Johannes. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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