South African Herbal Science and Medicine Institute (SAHSMI)http://hdl.handle.net/11394/1392024-03-28T17:03:25Z2024-03-28T17:03:25ZIsolation and Characterization of Natural Products from Siphonochilus aethiopicusNdiitwani, Dowelani Clementhttp://hdl.handle.net/11394/97762023-03-25T00:02:30Z2009-01-01T00:00:00ZIsolation and Characterization of Natural Products from Siphonochilus aethiopicus
Ndiitwani, Dowelani Clement
Plants have formed the basis of traditional medicinal systems that have been in existence for thousands of years. Traditional medicines play an important role in protecting, maintaining and restoring the health of people. Therefore, information on folk medicinal uses of plants has in latter times received an intense renewed interest as a source in the search for potential new therapeutic agents. The aim of this study was to isolate and identify natural compounds from Siphonochilus aethiopicus which is a species from the Zingiberaceae family and is one of the most popular medicinal plants in South Africa. This species is used extensively in traditional African medicine for pain relief, asthma, coughs, colds, headaches, dysmenorrhoea and influenza. Extraction of leaves and rhizomes were performed sequentially with hexane, dichloromethane, ethyl acetate, methanol and water. The presences of organic compounds were screened using chromatogtaphic techniques. The screening revealed similarities between the leaves and rhizomes extracts which implies that in order to improve the sustainability of the plants only leaves need to be harvested. All HPLC chromatograms except for the methanol extract of leaves have shown prominent peak. Moreover, the HPLC results confirm that same compounds are present in both leaves and rhizomes. The antimicrobial activity of the rhizome aqueous extract was carried out against Gram positive (Staphylococcus aureus, Mycobacterium smegmatis) and Gram
negative (Pseudomonas aeruginosa) bacteria as well as fungus (Candida albicans). GC NMR and MS techniques were used for structural elucidation.
>Magister Scientiae - MSc
2009-01-01T00:00:00ZSynergistic effects of mixtures of the kresoxim-methyl fungicide and medicinal plant extracts in vitro and in vivo against Botrytis cinereaKnowles, Cindy-Leehttp://hdl.handle.net/11394/88212022-03-08T00:01:09Z2005-01-01T00:00:00ZSynergistic effects of mixtures of the kresoxim-methyl fungicide and medicinal plant extracts in vitro and in vivo against Botrytis cinerea
Knowles, Cindy-Lee
The fungus Botrytis cinerea is an opportunistic pathogen on a wide variety of
crops, causing a disease known as grey mould through infections via wounds or dead
plant parts. Synthetic fungicides for controlling this disease are fast becoming
ineffective due to the development of resistance. This, coupled with consumers' world
wide becoming increasingly conscious of potential environmental and health problems
associated with the build-up of toxic chemicals, (particularly in food products), have
resulted in pressure to reduce the use of chemical pesticide volumes as well as its
residues.
An emerging alternative to random chemical synthesis is the study and exploitation
of naturally occurring products with fungicidal properties. One group of compounds
known as strobilurins produced by Strobilurus species, woodland basidiomycete fungi,
is a good example of this phenomenon. Plants produce an enormous array of
secondary metabolites, and it is commonly reasoned that a significant part of this
chemical diversity serves to protect plants against plant pathogens. A problem with
plant-produced compounds as potential fungicides is that in the natural state, they are
generally only weakly active compared to synthetic fungicides.
There have been reports on the uses of mixtures of synthetic fungicides for the
control of plant pathogenic fungi. When utilized in two-way mixtures, such
fungicides may maintain or enhance the level of control of a pathogen at reduced
rates for both components utilized in combinations, or alone at normal rates. These
studies provide an important precedent for the idea of synergism. For this study, we
hypothesize that the addition of plant extracts may enhance the antifungal efficacy of
the synthetic strobilurin fungicide, kresoxim-rnethyl against B. cinerea. We selected
South African medicinal plant species such as Artemesia afra, Elyptropappus
rhinocerotis, Galenia africana, Hypoxis hemerocallidea, Siphonochilus aetheopicus,
Sutherlundia frutescence, Tulbaghia violacea and Tulbaghia alliaceae for this study.
For the in vitro study, indigenous medicinal plant extracts were prepared at twofold
dilution concentrations and combined with kresoxim-rnethyl at concentrations of
0.25 and 0.5% (w/v). The B. cinerea mycelial plug assays showed potent antifungal
inhibitory effects with the plant extract and kresoxim-rnethyl mixtures. Further
analyses of the mixtures indicate synergistic effects between the fungicide and plant
extracts. I surmise that these in vitro effects are also achievable in vivo.
Combinations of these agents represent an attractive avenue for the development of
new management strategies for controlling B. cinerea in the future.
A second study was conducted to analyse the final dose rates for synergistic
reactions for combinations of kresoxim-methyl and medicinal plant extracts against
B. cinerea in vivo. A series of two-fold concentrations of medicinal plant extracts
were combined with kresoxim-methyl to conduct decay inhibition studies on Granny
Smith apples. Synergistic effects were observed for many of the kresoxim-methyl
and plant extract combinations. I, therefore, came to the conclusion that indigenous
South African plant species produce modulators that potentiate the activity of
fungicides. Whether these synergistic effects are due to the inhibition of fungal
multi-drug resistant pumps require further studies at the molecular level. However,
these inhibitory effects are likely to be advantageous for developing fungicide
formulations and application strategies with low toxicity effects on the environment.
This approach not only makes it possible to reduce fungicide concentrations while
maintaining adequate decay control, but also ensures a reduction of the chemical
residue on the fruit.
Doctor Educationis
2005-01-01T00:00:00ZNitrogen and carbon costs of growth and antioxidant production during acclimation to environmental stress in two species of GethyllisDaniëls, Christiaan Winstonhttp://hdl.handle.net/11394/83912023-08-26T00:03:30Z2012-01-01T00:00:00ZNitrogen and carbon costs of growth and antioxidant production during acclimation to environmental stress in two species of Gethyllis
Daniëls, Christiaan Winston
Gethyllis multifolia L. Bolus and G. villosa Thunb. are winter-growing, summer blooming, deciduous and bulbous geophytes that grow naturally in the semi-arid succulent Karoo biome of South Africa. Both species grow under full sun conditions and have four distinctive growth phases: a winter (cold and wet) growing phase, leaf senescence phase towards spring, flowering phase during the hot and dry summer months, and fruit and leaf formation phase in autumn. The medicinal uses of this genus (including G. multifolia "Kukumakranka" and G. villosa "hairy kukumakranka") range from cures for colic, digestive disturbances, teething problems, fatigue, boils, bruises and insect bites, to being used as an aphrodisiac. Gethyllis multifolia is threatened in its natural habitat and is listed in the 'Vulnerable' category of the 'Red Data List of Southern African Plants' and the 'IUCN-World Conservation Union List of Plants'. The literature indicate that the habitats of both species are being exposed to drier conditions and is further threatened by the encroachment of invasive indigenous plant species. It is not
known to which extent these factors may pose a threat to the existence of both species. The first objective of this investigation was to determine the costs of vegetative and reproductive growth during the seasonal life cycle of the plant, using carbon (C) and nitrogen (N) as a physiological currency. The second objective was to elucidate a functional basis to explain the difference in the conservation status of
both species in their natural habitat. Both species were subjected to drought and shading as environmental stresses and the plant physiological performance was investigated via photosynthetic gas exchange. The third objective of the study was to evaluate the antioxidant content (total polyphenol, flavonol/flavone and flavanone content) and antioxidant capacity [ferric reducing antioxidant power
(FRAP), oxygen radical absorbance capacity (ORAC) and 2,2'-azino-di-3- ethylbenzthiazoline sulphonate (ABTS) radical cation scavenging ability] of natural populations and plant samples that were exposed to photo- and -drought environmental stresses. This study was done to elucidate the antioxidant profile of plant parts of natural populations as well as providing farmers, traditional healers and pharmaceutical companies with cultivation environmental conditions to enhance the antioxidant properties of the species. This investigation also
attempted to isolate and characterize, by means of thin-layer chromatography (TLC) and column chromatography (CC), natural compounds from both species to lend support to the purported antioxidant benefit of both species and to further lend support to claims made by traditional healers of the medicinal potential of the genus. This study, however, did not engage in any in viva studies or human trials
to support published literature of the medicinal benefits of the genus. The photosynthetic adaptation studies indicated that G. villosa had a better photosynthetic performance than G. multifolia during both drought and low light conditions because of the inability of G. multifolia to adapt to a wider range of environmental extremes. The C and N cost of growth and reproduction studies revealed that G. villosa had a more efficient resource utilisation strategy for both growth and reproduction. These physiological responses suggest that G. villosa, in general, has a more efficient survival strategy and that G. multifolia will struggle to adapt to drier environmental conditions, as well as growing in the
shade of encroaching invasive plant species. To conclude, this could be a contributing factor as to why G. multifolia is threatened in its natural habitat and G. villosa not. The antioxidant content-and -capacity study on natural populations of both species revealed the highest total polyphenol content, FRAP and ORAC values for the flowers and fruits of G. multifolia and G. villosa compared to other plant parts. These values were found to be in line with and in some cases higher than most commercial fruits and vegetables. The antioxidant activity during drought and photo-stress of the leaves, bulbs and roots was found to be highest in the roots of both species during drought stress. Gethyllis multifolia, in general, exhibited higher total polyphenol content than G. villosa, with the highest content measured during drought stress in the roots of G. multifolia. Phytochemical investigation of the leaves, bulbs and roots of G. multifolia and G. villosa revealed the presence of
tannins, flavonoids, phenolics, saponins, glycosides as well as essential oils, while alkaloids were absent. The chromatographic profiles of the leaves, bulbs and roots of both species further indicated that the roots of G. multifolia contained the highest concentration of natural products, compared to G. villosa and other plant parts. Further in-depth studies on the roots of G. multifolia led to the isolation and
characterization of three known flavonoids, of which one was also isolated as its endogenously acetylated derivative. In contrast to the fact that both species had a high polyphenol content and exhibited high antioxidant activity, the isolated compounds in this study revealed very low antioxidant activity. However, the literature revealed that some of these isolated compounds exhibit antifungal, antibacterial, anti angiogenic and anti carcinogenic properties in vitro, which could be ascribed to the medicinal applications of plant parts of certain species
belonging to this genus. Furthermore, this study suggests that further chemistry and pharmaceutical research on the genus, Gethyllis, in specific the flowers and fruit of these two species, be pursued.
Philosophiae Doctor - PhD
2012-01-01T00:00:00ZEffects of environmental growth conditions on the levels of sutherlandins 3 and 4 and sutherlandiosides B and D, in Sutherlandia frutescens (L.) R. Br.Whisgary, Darrynhttp://hdl.handle.net/11394/54102018-08-21T13:40:27Z2011-01-01T00:00:00ZEffects of environmental growth conditions on the levels of sutherlandins 3 and 4 and sutherlandiosides B and D, in Sutherlandia frutescens (L.) R. Br.
Whisgary, Darryn
Sutherlandia frutescens (L.) R. Br. (Fabaceae), indigenous to the Western Cape region of South Africa, is found in a Mediterranean-type climate known for its many environmental stressors that can influence the levels of metabolites found in plants. Sutherlandia frutescens contains many known potential active constituents among them, flavonoids such as sutherlandins 3 and 4 (Su3 and Su4) and terpenoids such as sutherlandiosides B and D (SuB and SuD). Whether the profiles and levels of Su3, Su4, SuB and SuD are significantly affected by the environmental factors found in this area is however, unknown. iBatech™ is an ethanolic plant extract that is manufactured by researchers in the Department of Medical Biosciences, UWC, for use as a pesticide. HPLC analysis performed on Lycopersicon species treated with the iBatech™ product have shown that it also caused an increase in the concentrations of total polyphenols in the plant (Klaasen et.al., unpublished data). Whether the treatment with iBatech™ might also cause an increase in the polyphenols such as sutherlandins 3 and 4 and sutherlandiosides B and D is also unknown. The objectives of this study were to determine the concentrations of sutherlandins 3 and 4 (Su3 and Su4) and sutherlandiosides B and D (SuB and SuD) in S. frutescens collected from different sites and after the treatment with the iBatech™ product. The specific objectives were: a) to locate and categorize sites where S. frutescens is grown, based on a selection of pertinent environmental growth factors, b) to determine and compare the concentrations of sutherlandins 3 and 4 and sutherlandiosides B and D in S. frutescens collected from the different environmental growth sites and after treatment with the iBatech™ product. To realize these objectives, S. frutescens samples were collected from eight different sites and broadly categorized into three environmental categories. A high-performance liquid chromatography (HPLC) method using diode array ultraviolet detection (HPLC-DAD) for the simultaneous analysis of flavonoids and terpenoids was developed and validated, and used for the profiling and determination of the average levels of sutherlandins 3 and 4 and sutherlandiosides B and D in the samples from the sites and that treated with the iBatech™ product. The Kruskal-Wallis test was used to determine statistically significant differences among the environmental categories. The post ANOVA, Dunn's Multiple Comparison test was performed to determine which groups were significantly different. The Mann-Whitney, two-tail, t-test was used to compare each environmental category to the standard and the column statistics of the raw data was analyzed to determine significant differences among samples from the same environmental category. In the samples collected from the sites, the values represent the average levels of metabolites for each environmental category whereas the significance values indicated were among samples from the same environmental category. The levels for sutherlandin 3 were Afriplex™ (Std.) 2495.08, the natural field (NF) 2810.33 (P=0.0005), the cultivated field (CF) 2519.81 and the greenhouse (GH) 2580.25. The levels for sutherlandin 4 were significantly different when comparing the (NF) 1495.67 (P=0.0001), (CF) 3114.42 (P=0.0140) and (GH) 2361.72 (P=0.0001), with the CF group showing the highest levels of Su4 and the NF showing the lowest. The levels for sutherlandioside B were (NF) 189.7 (P=0.0189), (CF) 594.56 (P=0.0140) and (GH) 326.72 (P=0.0001), however, the CF group showed the highest average levels for SuB. The levels for sutherlandioside D were (NF) 144.1 (P=0.0192), (CF) 544.37 (P=0.0308) and (GH) 387.49 (P=0.0001), with the NF category having the lowest average levels. In the iBatech™ treated samples, the values indicate the average levels of three samples in each treatment group. The levels for sutherlandin 3 were (control) 9758.43, the (50%) 2232.63 and the (100%) 2031.97 treatment groups. The levels for sutherlandin 4) were (control) 2241.63, the (50%) 2247.47 and the (100%) 2392.60, with the 100% treatment group having the highest levels. The levels for sutherlandioside B were (control) 289.66, the (50%) 284.93 and the (100%) 332.30. The levels for sutherlandioside D were (control) 282.77, the (50%) 280.60 and the (100%) 315.13 treatment groups, with the 100% treatment group having the highest levels. The levels of Su3, Su4, SuB and SuD were significantly different (P=0.0001) among all treatment groups. In conclusion, the data shows that only sutherlandin 4 (Su4) was significantly different when comparing the environmental groups. Due to the significant differences in the Su3, Su4, SuB and SuD levels among samples from the same group the levels of these metabolites cannot be correlated with the environmental groups.
>Magister Scientiae - MSc
2011-01-01T00:00:00Z