Previous studies have found similarities in medicinal plant use between geographic regions and cultures at different spatial scales. Furthermore, it has been shown that phylogeny constrains plant use and some lineages are richer in medicinal plants than others. This thesis investigates evolutionary and cross-cultural patterns in medicinal plant use using taxonomic and phylogenetic tools at different scales of human cultural proximity, plant phylogenetic relatedness and space. Between the ethnomedicinal floras of Nepal, the Cape of South Africa and New Zealand the most prominent plant families of plant use are recorded and compared, revealing some cases of common use across the three regions. Using comprehensive phylogenetic trees of the floras from the three regions, it is revealed that plants used in traditional medicine in all three regions come from significantly similar lineages. This finding is exploited to examine whether phylogenetic tools can predict medicinal plant use in one region from the medicinal plants used in another, demonstrating positive results. Medicinal plant use is also compared between 12 comparatively closely related ethnic groups in Nepal. In general more similar medicinal floras are found between ethnic groups that live in similar environments, rather than those with close cultural relationships. This result suggests that experimentation, rather than conservatism rules ethnobotany as humans migrate to new regions and come into contact with different cultures and floras, revealing the dynamic character of ethnomedicine. Finally, the ethnomedicinal uses of the pantropical genus Pterocarpus (Leguminosae) are recorded and the phylogenetic relationships within the genus are reconstructed. The combined study of taxonomic, phylogenetic, biogeographic and ethnobotanical information provides new insights into cross-cultural patterns in plant use, and phylogenetic tools for the discovery of new plant medicines are developed and tested. Overall, the use of explicit phylogenetic tools in this thesis confirms that plant use is significantly phylogenetically clustered. This finding is recovered at the family, genus and species level.

Thesis (M.Sc. (Microbiology)) --University of Limpopo, 2015 / Five plant species: Ziziphus mucronata, Senna italica, Lantana camara, Ricinus communis and Lippia javanica, were selected for this study based on their use in traditional medicine. In preliminary screening, crude extracts were prepared using hexane, dichloromethane (dcm), acetone and methanol. Phytochemical profiles on Thin Layer Chromatography plates of the extracts were obtained by developing the plates in mobile phases of varying polarity. Tests for compounds such as tannins, flavonoids, alkaloids, phlobatannins, terpenes, steroids, cardiac glycosides and saponins were carried out. Antibacterial activity of the extracts was carried out using microdilution assay for Minimum Inhibitory Concentration and bioautography against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Enterococcus faecalis. Antioxidant activity of the extracts was performed using the 2, 2, diphenyl-1-picrylhydrazyl (DPPH) assay. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay and Phagoburst test were used to investigate the toxic effects and anti-inflammatory activity of the extracts on mouse Raw 264.7 macrophage cells, respectively. The presence of phytochemicals was observed on the chromatograms after the plates were sprayed with vanillin sulphuric acid reagent. The dcm extracts of the plants showed antibacterial activity against the selected bacterial species on the bioautograms. Senna italica and Z. mucronata showed the most activity bands on the bioautograms. Lippia javanica had the lowest MIC average of 0.56 mg/ml. Antioxidant activity was observed in the extracts of L. javanica and R. communis. The extracts promoted proliferation of the mouse macrophage cells Raw 264.7 at concentrations ranging from 0.31 mg/ml and 0.08 mg/ml. Senna italica leaves were selected for isolation of antibacterial compounds. The isolated compound was analysed on 1H and 13C nuclear magnetic resonance (NMR) and Mass Spectrometry (MS) for structural analysis. The structure could not be elucidated due to impurities in the compound but the tentative structure is a branched chain alkane with at least one ether linkage per repeating unit. Therefore the study shows that there are plant components with biological activities against wound infecting bacteria and a single lead compound was identified. / the National Research Foundation

Thesis (M.Sc. (Biochemistry )) --University of Limpopo, 2007 / Refer to document / Medical Research Council (MRC), National Research Foundation (NRF) and University of Limpopo

Thesis (M.Sc. (Biochemistry)) --University of Limpopo, 2011 / Dicerocaryum senecioides is a crawling herb that is found growing mostly in sandy areas of southern and south-eastern Africa and its small, hairy leaves have been used over the years as food, shampoo, and for treatment of various ailments. In this study, the dichloromethane (D2) fraction was prepared from a crude methanol extract of D. senecoides leaves, and its effect on the proliferation of RAW 264.7 murine macrophages was investigated. Treatment of the macrophages with the extract resulted in a dose- and time-dependent decrease in cell viability as determined by the MTT assay and real time cell analysis. Cytotoxicity of the D2 fraction on the macrophages was demonstrated to be due to apoptosis by staining the cells with DAPI nucleic acid stain. Anti-inflammatory activity of D2 fraction on RAW cells was determined by evaluating intracellular ROS production by the DCFH-DA fluorescent assay. Cells treated with the D2 fraction and stimulated with PMA were found to have a lower fluorescence intensity compared to untreated, stimulated cells; thus mimicking the response observed in the resting cells. The percentage fluorescence in untreated, stimulated cells doubled, while no significant change was observed in the D2-treated cells. The effect of the D2 fraction on iNOS activity was also assessed. The fraction reduced the NO synthesised by iNOS in cells treated with the D2 fraction and stimulated with LPS dose-dependently. The D2 fraction was further fractionated by semi-preparative HPLC; and thin layer chromatography was used to analyse phytocompounds of the 96 HPLC sub-fractions as well as to screen these sub-fractions for anti-oxidative activity. Sub-fractions 1-7 and 33-39 showed an intensely pronounced DPPH-scavenging compound and this scavenging ability was confirmed by a quantitative DPPH assay that provided parallel results. The reducing potential of the sub-fractions was assessed by evaluating their Fe3+-reducing ability through the FRAP assay. Sub-fractions 1-7 and 33-39 displayed remarkable reducing potential. Taken together with the DPPH-scavenging activity, these findings suggest that HPLC sub-fractions 1-7 and 33-39 possess a compound(s) with impressive antioxidant activity. These findings merit the D2 fraction as an extract that can be used to control chronic inflammation as it does not only inhibit free radical production, but also scavenges excessive ROS and has the ability to induce apoptosis in the macrophages responsible for dysregulated production of the free radicals. The extract also has commendable chemoprotective and chemotherapeutic potential as it demonstrated pro-apoptotic activity along with prevention of excess free-radical production. / National Research Foundation and the University of Limpopo Research Office