3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Development of pressurised hot water extraction (PHWE) for essential components from Moringa Oleifera and Ovalifolia leaves(2015-02-06) Matshediso, Phatsimo GimamahUnable to load abstract.Item A study of the elemental analysis and the effect of the pressurised hot water extraction method (PHWE) on the antibacterial activity of Moringa oleifera and Moringa ovalifolia plant parts(2015-01-30) Makita, Charlene SampuHeavy metal pollution is an increasing phenomenon and contamination of these heavy metals has detrimental effects on the environment and humans. The concentrations of metals in the soil, leaves, stem bark and flowers of Moringa ovalifolia sampled from Okahandja, Okaukuejo, Halali and Tsumeb in Namibia were investigated. Acid digestion of all samples was performed utilising the microwave technique. Determination of elements from the extracts were analysed by inductively coupled plasma - optical emission spectroscopy (ICP-OES). No lethal amounts of heavy metals were found in the soil, leaves, stem bark and flowers of Moringa ovalifolia. The results from Moringa ovalifolia was compared to spinach from another similar study. On average, Moringa leaves contained more or less similar amounts of Zn (29.4 mg kg-1) and Cr (13.2 mg kg-1) but higher higher amounts of Fe (263.8 mg kg-1) concentrations than spinach, with values of Zn (30.0 mg kg-1), Cr (20.0 mg kg-1) and Fe (190 mg kg-1) from a previous study. In this study, selected statistical methods such as correlation analysis and principal component analysis were used to identify the origin of these metals in the soil, leaves and stem bark collected from the Moringa farm, national parks and the road side in Namibia. From the correlation analysis, it was found that Co, Mg, Cr and Mg pairs were highly significant to each other. The principal component analysis revealed that heavy metals gave 53.41% of the total variance in factor 1. Sources of Mg and Ni could be from vehicle emissions. Factor 2 revealed As, Co, Al, and Si contributing to a total variance of 25.15% Co suggesting that the metals present could be as a result of geologic sources. This iii study proves that statistical analysis may provide a scientific foundation for the observation of heavy metal accumulation in samples. Pressurised hot water extraction (PHWE) was used for the extraction of bioactive compounds from the leaves and stem bark of Moringa ovalifolia and Moringa oleifera samples. The aim of the study was to assess the effect of temperature and extraction process of the Moringa extracts on Staphylococcus aureus (S. areus), Enterococcus faecalis (E. faecelis) and Pseudomonas aeruginosa (P. aeruginosa). The antibacterial activities of the extracts at varying temperatures were evaluated using the disk diffusion method where the zones of inhibition were recorded. ANOVA, which was calculated at a significance level of 0.05, was used to analyse the data. Antimicrobial activity of the stem bark extracts and leaf extracts from different sites extracted at 25˚C and 80˚C showed significant difference. As temperature increased, a decrease in inhibition was observed for stem bark extracts from different sites tested again S. areus, E. faecelis and P. aeruginosa. When the PHWE stem bark extracts collected in Tsumeb, were compared with ethanol and cold water extractions, the PHWE had more activity than other two methods. This proves that PHWE may be used as a novel extraction to get essential compounds from indigenous plant materials.Item South African Grade 9 teachers' and learners' knowledge about medicinal plants and their attitudes towards its integration into the science curriculum(2014-08-01) Muza, BlessingsThe integration of indigenous knowledge into the mainstream science curriculum has been advocated for by science educators around the world. The Revised National Curriculum Statements (RNCS) for Grades R-9 (Natural Sciences) clearly advocates for the incorporation of indigenous knowledge into the science curriculum. They stipulate that learners must learn science within the context of their historical, societal and cultural knowledge and values. It is important that learners should understand other systems of knowledge, such as indigenous knowledge systems (IKS). The underlying assumption is that teachers can help learners integrate science and indigenous knowledge but in order to do that, they too must have adequate knowledge and understanding regarding the two thought systems. The challenge is that some teachers are not well informed about the varying indigenous knowledge that typifies the multi-cultural situation in South African classrooms as they have been schooled in western science The study aimed at eliciting learners‟ and teachers‟ knowledge about traditional medicinal plants and their attitudes towards integration of that knowledge into the science curriculum. This was with a view to exploring any differences or similarities between the views of teachers and learners. A case study was carried out at a secondary school in Meadowlands, Soweto. A sample of 36 Grade 9 learners and 10 teachers of Natural sciences was selected using the convenience sampling technique. Structured pictorial questionnaire was used to collect data from both teachers and learners. Field notes were taken during a class debate on the effectiveness of traditional medicines versus western medicines. Unstructured follow up interviews (5 learners- group interview and 3 teachers-individual) were performed on selected participants to probe further their responses to the questionnaire. A ROSE1 type questionnaire was used as a follow up when learners were in grade 10 (2013). Analysis of the findings showed that a majority of learners and teachers that participated in this research have opposing attitudes regarding the need to integrate knowledge about traditional medicinal plants into the science curriculum. The 1ROSE-Relevance Of Science Education, a questionnaire distributed in many countries by Prof Svein Sjøberg, ILS, University of Oslo, Norway. learners in this study had generally more knowledge that the teachers about traditional medicinal plants. The majority of learners are willing to learn about indigenous knowledge (IK). Nine teachers out of ten in this study were generally less enthusiastic about teaching about traditional medicinal plants. In light of the findings it is recommended that teachers need to have in-house training in so far as the methodological aspects of integrating components IK into the science curriculum relate. This may go a long way in limiting conceptual conflicts amongst the learners.