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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Isolation and characterisation of secondary metabolites of two asteraceae species, Artemisia afra and Elytropappus rhinocerotis.

Gakuba, Emmanuel. January 2009 (has links)
In this study two medicinal plant species, namely Artemisia afra Jacq. ex. Willd and Elytropappus rhinocerotis Less. (L.f) (= Dicerotamnus rhinocerotis Koekemoer), both belonging to the family Asteraceae, have been investigated and different compounds isolated and characterised. Both species are important plants used in traditional medicine in general in Africa and particularly in South Africa. A. afra, commonly called "African wormwood" is one of 400 species belonging to the genus Artemisia and it is the only one indigenous to Africa. E. rhinocerotis is one of eight Elytropappus species which are all restricted to the Cape floristic region. The aim of this study was to investigate the phytochemistry of these species. In total fifteen compounds were isolated and characterised. From the E. rhinocerotis extract, four known compounds, labdanolic acid, methyl labdanolate, 6, 7- dimethoxycoumarin and a sesquiterpene viridiflorol were isolated. These compounds were not previously reported from E. rhinocerotis. Two different chemotypes of A. afra were studied and eleven compounds were isolated. These compounds include sesquiterpenes such as taurin, artesin, maritimin, artemin, norsantolinifolide, santolinifolide A, and reynosin, a flavonoid, 5- hydroxy-7,4-dimethoxyflavone, a coumarin called scopoletin or 7-hydroxy-6- methoxycoumarin and other aromatic compounds such as p-hydroxyacetophenone, and 2,4-dihydroxy-6-methoxyacetophenone. Except for taurin, scopoletin and 5-hydroxy-7, 4- dimethoxyflavone , none of these other compounds has been reported previously from A. afra. This study has shown that A. afra contains a large number of sesquiterpenoids, mostly from the eudesmane-type. Structural elucidation of different compounds was performed using mainly NMR spectroscopy. Other methods used for identification include LC-MS and infrared spectroscopy. The major compound, labdanolic acid, is known to selectively inhibit cyclooxygenase-2, an enzyme associated with inflammation. The presence of labdanolic acid in the plant may account for its traditional use as an anti-inflammatory. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.
12

Screening and phytochemical characterization of a South African herbal concoction for anti-HIV-1 activity

Hlatshwayo, Vincent Nkosinathi January 2017 (has links)
A dissertation submitted to the Faculty of Science under the School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master in Science. Johannesburg, June 2017. / In South Africa, the anti-HIV-1 activity of various indigenous plants has not been studied extensively. Most of the phytochemical screening work has focused on anti-cancer activity with less attention given to infectious diseases. A large proportion of South Africans (70-80%) still rely on traditional medicines for treatment of various ailments. And, therefore, there is a need to evaluate and validate the effectiveness of the traditional medicines. The aim of this study was to identify, screen, phytochemically characterize and isolate bioactive compounds from a South African herbal extract that exhibit the best anti-HIV-1 activity. Three extracts were prepared: an ethanol extract, a dereplicated ethanol extract and an aqueous extract from a herbal concoction comprised of a mixture of six plants. These herbal concoctions were investigated for anti-HIV-1 subtype C activity. Phytochemical profiling of the ethanol- and dereplicated ethanol- extracts from the herbal concoctions showed the presence of intermediate polar compounds (flavonoids, alkaloids, sugars and terpenes) for both extracts, while the aqueous extract contained predominantly highly polar compounds. Anti-HIV-1 screening of the three extracts showed that the ethanol and dereplicated ethanol herbal- extracts had the best anti-reverse transcriptase activity. The ethanol extract had mean IC50 values of 56.53, 53.96 and 55.39 μg/ml against MJ4, Du179 and CM9 HIV-1 subtypes C isolates, respectively. The dereplicated ethanol extract had mean IC50 values of 51.87, 47.56 and 52.81 μg/ml against MJ4, Du179 and CM9 HIV-1 isolates, respectively. The aqueous extract was inactive against HIV-1 activity. Moreover, both the ethanol- and dereplicated ethanol- extracts showed activity against HIV neutralization. The ethanol- and dereplicated ethanol- extracts had mean IC50 values of 36.33 and 32.06 μg/ml, respectively. Furthermore, they also potently neutralized Vesicular stomatitis virus (VSV) yielding mean IC50 values of 24.91 and 20.82 μg/ml for ethanol- and dereplicated ethanol- extracts, respectively. All extracts were inactive against Murine leukemia virus (MLV). The isolation and phytochemical characterization of the bioactive compound(s) was done by utilizing various chromatographic and spectroscopic methods. Four homoisoflavanoids were isolated and tested for anti-HIV-1 subtype C activity. Three compounds (1, 3a and 3b) were inactive while compound 2 was found to be bioactive against HIV-1 reverse transcriptase (RT) and yielded mean IC50 values of 7.23 ± 1.88, 12.83 ± 0.41 & 12.81 ± 0.10 μg/ml for MJ4, CM9 and Du179 HIV-1 subtype C isolates, respectively. Compound 2 had a mean CC50 value of 23.08 ± 0.1981 μg/ml against HEK293T cells. Overall, the data suggested that ethanol- and dereplicated ethanol- herbal extracts possess direct and indirect anti-HIV-1 activity. They possess a cocktail of phytochemicals that can inhibit HIV-1 RT, HIV-1 entry. Furthermore, these extracts possess phytochemicals that can lower the activation of inflammatory responses during an infection and, hence, reduction in the number new cells infected during the course of HIV-1 infection. Moreover, they possess phytochemicals that have antioxidant activity which, in relation to HIV infection, results in a boosted immune system response in order to ward off the virus. / MT 2017
13

Quantitative and qualitative optimization of antimicrobial bioactive constituents of Helichrysum cymosum using hydroponics technology

Matanzima, Yonela January 2014 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Horticulture in the Faculty of Applied Sciences at the Cape Peninsula University of Technology / The high demand for medicinal plants has favoured over-exploitation of wild plants. The search for alternative and sustainable methods of medicinal plant cultivation is imperative and desirable. Biotechnological approaches particularly hydroponic technology has the potential for large scale plant cultivation and production of secondary metabolites. The current study aims at optimizing the production of antimicrobial secondary metabolites by an indigenous South African medicinal plant species (Helichrysum cymosum) through hydroponics N and K fertilization. In Chapter 1, the conceptual framework and justifications of the study are presented. In Chapter 2 the research objective was to discern the optimal potassium (K) supplement level for H. cymosum by evaluating the effects of different hydroponic K levels on growth, K-leaf content, and anti-Fusarium oxysporum f.sp.glycines (Ascomycota: Hypocreales) and total activities. Six weeks old seedlings of H. cymosum were treated with varied concentrations of K in the form of potassium chloride, potassium nitrate and monopotassium phosphate (58.75, 117.5, 235 and 470 ppm). These concentrations were based on a modification of Hoagland’s hydroponic nutrient formula. Plants were maintained under greenhouse conditions and growth parameters (plant height and number of leaves) were recorded weekly. At 8 weeks post treatment, plants were harvested and fresh weights were recorded and tissue nutrient content analysed. Sub-samples of the aerial parts of plants grown in the different treatments were air dried, extracted with acetone and tested against F. oxysporum. Plants exposed to 235 ppm K showed a marked increase in leaf number, plant height and fresh weight. Overall there was no significant difference (P > 0.05) among the treatments with respect to tissue nutrient content; K ranged from 3.56 ± 0.198 to 4.67 ± 0.29 %. The acetone extraction yield increased with increasing K fertilization: 58.75 ppm (16.67 ± 2.35 mg), 117.5 ppm (22.5 ± 4.79 mg), 235 ppm (210 ± 38.5 mg) but dropped to 40 ± 4.08 mg at 470 ppm K. Results from the anti-F. oxysporum bioassay showed that 58.75 and 235 ppm K treatments produced the most bioactive acetone extracts; MIC values of 0.49 and 0.645 mg/l, respectively. Acetone extracts obtained from plants exposed to 235 ppm K yielded the highest total activity, comparatively (P < 0.05). In conclusion, the optimum nutrient K level for growing H. cymosum hydroponically was 235 ppm. Chapter 3 focused on another important macro nutrient N and the objective was to determine the optimum nutrient requirements for growing the medicinal plant, Helichrysum cymosum (L.) (Asteraceae), hydroponically. Experiments were conducted to assess the effects of varied nitrogen (N) concentrations supplied as nitrate and ammonium on growth, tissue nutrient content, antimicrobial and total activities of acetone extracts of aerial parts. Treatments were based on a modified Hoagland’s nutrient formula. Six week old rooted cuttings were treated with 52.5 ppm, 105 ppm, 210 ppm and 420 ppm of N. Leaf number and stem height (cm) were recorded at weekly intervals and leaf analysis conducted. The effects of N treatments on plant growth parameters varied significantly among treatments; 52.5 ppm of N yielded the tallest plants (height) [19.4 ± 0.7 cm], while 105 ppm N yielded the maximum leaf number (68.1 ± 6.2) as well as maximum fresh weight of aerial parts was obtained with 105 ppm (15.12 ± 1.68 g). Nitrogen content of plant tissue ranged between 0.53 ± 0.03 and 4.74 ± 0.29% (d, f, 3, 12; f=14; P ≤ 0.002) depending on treatments. Powdered aerial parts (5 g) of H. cymosum obtained from the different N treatments were extracted with 100 ml of acetone. N treatment significantly affected the yield of crude extracts, which ranged from 87.5 ± 15.5 (52.5 ppm) to 230 ± 23.5 mg (105 ppm). Acetone extracts of plants that were exposed to varied N treatments were screened for anti-Fusarium oxysporum activity using minimum inhibitory concentration (MIC) method. The MIC value (0.073 ± 0.014 mg/ml) obtained with acetone extracts of plants exposed to 52.5 ppm N was significantly lower compared to the MICs of the other N treatments (105 [0.47 ± 0 and 0.705 ± 0.135 mg/ml], 210 [0.234 and 0.47 mg/ml] and 420 ppm [0.29 ± 0.101 mg/ml]) at 24 and 48 hours respectively. However, the total activities of extracts obtained among the four N treatments, which ranged from 0.062 ± 0.02 to 0.26 ± 0.06 ml/g was not statistically different at 24 or 48 hours (P > 0.05). LC-MS analysis of acetone extracts of H. cymosum plants obtained from the four treatments hinted that known anti-microbial agents such as apigenin, quercetin, kaempferol, helihumulone and quinic acids were present in the extracts and the quantity of helihumulone increased with increased nutrient N level. These results suggest that H. cymosum may be cultivated hydroponically and that the antimicrobial activity and/or the phytochemical profile of the crude acetone extracts is affected by nutrient nitrogen levels. Hydroponic cultivation of plants may be able to alleviate to an extent the pressure on wild medicinal plants.
14

Nxopaxopo wa rhijistara leri tirhisiwaka hi tin'anga to hambanahambana ta xintu na swikhedzakhedza leswi tirhisiwaka eka vutshunguri bya tona : Maendlelo ya soxiyolingwisitiki

Jivindhava, Hasani Morris January 2012 (has links)
Thesis (M.A. (African Languages)) --University of Limpopo, 2012 / Refer to the document
15

Sociological perceptions of harvesting, husbandry and sustainable utilization of redundant second-hatched chicks of wild hornbills, eagles and owls at Makuleke Community and the surrounding villages

Makatu, Shumani Elsie January 2000 (has links)
Thesis (M. A. (Sociology)) -- University of the North, 2000 / Refer to the document / NRF (National Research Foundation)
16

The role of traditional healers in the fight against HIV/AIDS : the case study of Tembisa Township, South Africa.

Nkungwana, Siyasanga. January 2005 (has links)
South Africa has a high HIV/AIDS prevalence. Due to the unavailability of antiretroviral drugs and South African’s trust in traditional healers for health problems, traditional healers are involved in treating HIV/AIDS. This dissertation outlines traditional healers’ role in HIV/AIDS in Tembisa, a township situated in the East Rand section of Johannesburg. People living with HIV/AIDS, traditional healers and health care workers were interviewed. The dissertation also confirms the high prevalence of HIV/AIDS in Tembisa.. According to the dissertation, a reasonable highest number of People Living with HIV/AIDS (PLWAS) 8 out of 10 consulted Traditional healers to seek treatment of HIV/AIDS Opportunistic infections, although three out of eight indicated that consulting traditional healers was not necessarily their own choice. Two PLWAS do not believe in traditional healers and have never consulted them. Five PLWAS’s view was that Traditional healers can treat opportunistic infections effectively and they indicated their own health bear evidence to such claims. The study had shown that, although traditional healers have shown good rapport with their clients, and have earned positive respect due to their involvement in HIV/AIDS prevention and treatment in their communities, there are also challenges with regards to their work that calls for urgent attention. For an example, a highest number of Traditional healers did misrepresent diseases related to sexual intercourse, and also they could not recognize the symptoms of HIV/AIDS. They also hardly gave all biomedical perspective of transmission of HIV/AIDS without being probed. Both the group that believed in traditional healers and those that do not, as well as Biomedicine indicated that using traditional healers alone without biomedicine is not a realistic option.due to their training that is not homogenous and their profession that is rarely regulated. All the participants interviewed were in support of the strong collaboration between traditional healers and Biomedicine. / Thesis (M.A.)-University of KwaZulu-Natal, Durban, 2005.
17

Traditional healers' perceptions of the integration of their practices. into the South African national health system.

Melato, Seleme Revelation. January 2000 (has links)
This study was aimed at identifying and exploring the perceptions of traditional healers particularly izangoma and izinyanga, on the integration of their practices into the South African National Health System. The main reason behind this research was to establish the position of traditional healers as well as to study their opinions on the issue of integration. The paucity of previous research studies on the 'perceptions of traditional healers on the integration of their practice-s into the national health care system, was the main motivation behind this study. Participants were drawn from the Pietermaritzburg area and selection was based on purposeful sampling. The data of the study was collected by means of semi-structured interviews, which employed open- ended questions. This study was conceptualized within the African world-view and cosmology. The interactive model design by Maxwell (1996) was employed in the design of this study. According to this model the purpose, conceptual context, research questions and methods as well as issues of validity and reliability, are all essential for the coherence of any qualitative study. The ethical considerations of this study were mainly around the issue of informed consent, and this was negotiated and discussed with the participants until they could understand the process of consent. The results of the study reflect the fact that traditional healers are positive about the process of integration. However, the participants were in favol of integration as a process of collaboration and co-operation as opposed to total integration, which was perceived as a process in which one system w0ll-Id dominate and oppress the other. The participants in this study perceive themselves as equal to their western counterparts because oftheir training and ability to treat "spiritual illnesses". Further, they view their role as that of providing alternative healing as well as acting as a medium between people and their ancestors. Education and negotiations were identified as the possible solutions to most problems in the process of integration. The findings of this study further reveal that there is mistrust and suspicion about western healers form traditional healers. As a result of this, improved collaboration between traditional and modem health care systems seems to be the only process, which could benefit all the people of the country. / Thesis (M.A.)-University of Natal, Pietermaritzburg, 2000.
18

Medicinal properties and growth of Merwilla natalensis.

Sparg, Shane Gordon. January 2003 (has links)
Merwilla natalensis (Planchon) Speta is ranked as one of the most commonly sold medicinal plants at most of the informal medicinal plant markets found throughout South Africa. The increasing demand for medicinal plants has resulted in over-exploitation of many of the wild populations. Overharvesting has resulted in M. natalensis being declared vulnerable. Although this species is so popular, and reports state that the bulbs are used for a variety of ailments, very little is known about its pharmacological activity or phytochemical composition. Extracts were made from mature M. natalensis bulbs using hexane, dichloromethane, methanol and water. These extracts were screened for antibacterial, anticancer, anti-inflammatory, antischistosomal and anthelmintic activity. Antibacterial activity was evaluated using the minimal inhibitory concentration (MIC) assay. Methanol extracts displayed good antibacterial activity against both Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Klebsiella pneumoniae) bacteria. Anti-inflammatory activity was evaluated using the COX-1 and COX-2 bioassays. Dichloromethane extracts displayed the highest inhibitory activity against both COX-1 and -2 enzymes. (80% and 91% inhibition respectively) Very good activity was displayed against the free-living nematode Caenorhabditis elegans and the schistosomula worms of Schistosoma haematobium using microdilution techniques. Anticancer activity was evaluated using the biochemical induction assay (BIA) in which DNA-damaging properties are tested for. No activity was found using this assay, however, these results do not prove that M. natalensis does not have other anticancer properties. The phytochemical investigation of mature M. natalensis plants showed the bulbs to contain both saponins and bufadienolides. One of the bufadienolides had the same Rf value as proscillaridin A. Cytotoxicity tests reveal M. natalensis to be extremely cytotoxic, yet the bulbs are commonly sold at traditional medicine markets around South Africa. This cytotoxicity may be accredited to the presence of saponins within the bulbs. No alkaloids or tannins were detected in the bulbs. With the growing population in South Africa, there is an increasing demand for traditional medicines. This increasing demand is placing tremendous strain on natural populations growing in the wild. However, as the demand cannot continue to be met other sources are needed. Tissue cultured plants have been grown at two different regions of South Africa. These plants have been grown under different conditions to determine the optimal ones needed to grow M. natalensis as a commercial crop on small-scale farms. Plantlets taken directly from tissue culture were acclimatized successfully for cultivation by means of simple and cost effective methods. Cultivated plants were harvested on a six-monthly basis for a period of two years. Field cultivation produced bulbs of almost marketable size (±300g fresh weight) after 24 months. Bulb size was not dependent on additional fertilizer or irrigation. No significant differences (p<_0.05) were shown in the average dry weights of bulbs grown under different treatments (control, fertilizer without irrigation, fertilizer with irrigation). Leaf senescence and dormancy of young plants were prevented with irrigation. Flowering occurred after 24 months, with the irrigation and fertilizer plot having the most flowering plants. TLC fingerprinting revealed differences in the chemical composition of the bulbs harvested at different stages of growth. Noticeable differences were found between bulbs cultivated at the different growing sites. Pharmacological screenings were done of the harvested bulbs to investigate the effect of age (time of harvest) and growing conditions on antibacterial, anti-inflammatory and anthelmintic activity. Methanol extracts were screened against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Klebsiella pneumoniae) bacteria. Variations in activity were found. The time of harvest had a significant effect (p<_0.05) on biological activity, with the younger plants being more active. Antibacterial activity decreased with an increase in plants age. Methanol extracts were also screened for anthelmintic activity against Caenorhabditis elegans. Activity was found to increase with plant maturity. Irrigation was found to increase activity at the low rainfall (Fort Hare) site. Bulbs harvested from the irrigation treatment had significantly higher anthelmintic activity (p<_0.05) than bulbs harvested from treatments without irrigation. Dichloromethane extracts from bulbs grown at both sites had high anti-inflammatory activity. There were no significant differences (p<_0.05) in the activity of bulbs harvested from the different treatment plots. The time of harvest had an effect on the inhibition of prostaglandin synthesis by COX-1 enzymes. This study provides not only scientific verification for the use of M. natalensis to some extent as a medicinal plant, but also important data needed to successfully cultivate this species as a crop for small-scale farming. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2003.
19

Negotiating healing : the professionalisation of traditional healers in KwaZulu-Natal between 1985 and 2003.

Devenish, Annie. January 2003 (has links)
No abstract available. / Thesis (M.Dev.Studies)-University of Natal, Durban, 2003.
20

Healing at the margins: discourses of culture and illness in psychiatrists', psychologists' and indigenous healers' talk about collaboration

Yen, Jeffery January 2000 (has links)
This dissertation explores discourses about culture and illness in the talk of mental health professionals and indigenous healers. It represents an attempt to situate the issue of indigenous healing in South Africa within a particular strand of critical discourse analytic research. In the context of current deliberations on the value, or otherwise, of indigenous healing in a changing health and specifically mental health system, the talk of both mental health practitioners and indigenous healers as they conceptualise “disorder”, and discuss possibilities for collaboration, is chosen as a specific focus for this study. Disputes over what constitutes “disorder” both within mental health, and between mental health and indigenous healing are an important site in which the negotiation of power relations between mental health professionals and indigenous healers is played out. The results of this study suggest that despite the construction of cogent commendations for the inclusion of indigenous healing in mental health, it remains largely marginalised within talk about mental health practice. While this study reproduces to some extent the marginalisation of indigenous healing discourse, it also examines some of the discursive practices and methodological difficulties implicated in its marginalisation. However, in the context of “cultural pride strategies” associated with talk about an African Renaissance, indigenous healing may also function as a site of assertion of African power and resistance in its construction as an essentially African enterprise. At the same time, it may achieve disciplinary effects consonant with cultural pride strategies, in constructing afflictions in terms of neglect of, or disloyalty to cultural tradition. These results are discussed in terms of the methodological difficulties associated with interviewing and discourse analysis of translated texts, which contributes to difficulties with articulating indigenous healing discourse in a way that challenges the dominant psychiatric discourses implicated in its marginalisation within mental health. It concludes with recommendations for future research which addresses indigenous healing discourse in its own terms, and examines its operation as a disciplinary apparatus in South African society.

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