Ph.D. / The complexity of Combretaceae and lack of information on phylogenetic relationships within the family led me to explore relationships between and within genera of Combretaceae by means of combined analyses of plastid (rbcL, psaA-ycf3 spacer, and psbA-trnH spacer) and nuclear ribosomal ITS sequences for all but three of the 17 genera in Combretaceae. The current classification of the family into two subfamilies, Strephonematoideae and Combretoideae, is corroborated. Within Combretoideae, division into two tribes, Laguncularieae and Combreteae, is strongly supported. Within Combreteae subtribe Terminaliinae relationships between genera are largely unresolved. Terminalia is not supported as monophyletic, and two groups were identified, one containing mainly African species and another of mostly Asian species. Pteleopsis, Buchenavia and Anogeissus are embedded within Terminalia, and I suggest that all genera of Terminialiinae with the exception of Conocarpus should be included into an expanded Terminalia. Within subtribe Combretinae, a clade formed by the two monotypic genera Guiera and Calycopteris is sister to the rest of the subtribe. Within Combretinae, groupings are consistent with recent results based on morphological data. Combretum is currently divided into three subgenera: Apethalanthum, Cacoucia and Combretum. The two last were included in this study and supported as monophyletic. Meiostemon is sister to subgenus Combretum, and Quisqualis is embedded within subgenus Cacoucia. I recommend that subgenus Combretum should be expanded to include Meiostemon and subgenus Cacoucia to include Quisqualis. The sectional classification within Combretum proposed in earlier morphological studies is confirmed except for the exclusion of Combretum imberbe from section Hypocrateropsis into a separate and monotypic section and the inclusion of Combretum zeyheri (section Spathulipetala) within section Macrostigmatea. In order to accommodate Combretum imberbe a new section is suggested which is formally described in Maurin et al. (2010). The reinstatement of previously recognised sections Grandiflora and Trichopetala, both of which had been sunk into subgenus Cacoucia section Poivrea, is also suggested. In this study two new species from South Africa are presented: Combretum nwambiyana O.Maurin, M.Jordaan & A.E.van Wyk and Combretum stylesii Maurin, Jordaan & A.E.van Wyk. The formal description of these two new species will be done in regular journals. Divergence time estimates using a Bayesian MCMC approach implemented in BEAST suggested a crown date for Combretaceae around 82.6 mya with the two subtribes Combretinae and Terminaliinae splitting at the end of the Late Cretaceous during a period marked by a number of mass extinctions both in plants and animals. The Miocene and Pliocene are characterised by constant speciation with many clades within Combretaceae succesfully adapting to savanna vegetation and diversifying within it.

MSc (Botany) / Department of Botany / See the attached abstract below

MSc (Microbiology) / Department of Microbiology / Background: The medicinal value of plants lies in some chemical substances that produce a definite physiological action in the human body. The secondary metabolites help the plants to survive hash conditions and could be used by humans as supplements of their health, as foods additives or for medicinal purposes. This bioactive compounds are not always beneficial to human beings, and some of this plants bioactive compounds can be toxic or genotoxic to human cells. This study used several methods to evaluate of phytochemical constituents and mutagenic properties of Coccinia rehmanni and Jatropha zeyheri plant extracts. Methodology: Methanol was used for extraction of the bioactive compounds from the two selected plants, filtered with Whatman filter paper and evaporated with rotary evaporator. The extracts were fractionated using open column chromatography. Chemical and TLC methods were used to determine phytochemicals of the study plants extracts and fractions. The plants extracts and fractions were tested against Vero cell lines in order to evaluate cytotoxicity and genotoxicity of the plants. NucRed and LTR Hoechst 33342 dyes were used for cytotoxicity and genotoxicity respectively. For the evaluation of cytotoxicity and genotoxicity Quantification of live and dead cells for the screening assay was performed using the ImageXpress Micro XLS Widefield Microscope and acquired images analyses using the MetaXpress software and Multi-Wavelength Cell Scoring Application Module. Antimutagenicity of plants extracts was observed using PARP universal colorimetric assay kit. Acquired data was transferred to an EXCEL spreadsheet and data was analyzed. Results and discussion: C. rehmanni (12.03%) yielded more extract than J. Zeyheri (8.20%). the two plants had different compound composition and were in different stages of maturity. The study revealed the domination of Terpenoids, Cardiac glycosides, Phenolic and tannis. With an exception of two fraction fractions all the fractions was found to be toxic to an extent were genotoxicity of such fraction could not be concluded. The reason for such extreme toxicity could be due to the influence of the retained alcohol during rotary evaporation. xvi | P a g e Conclusion: this study provides and add to existing knowledge on the phytochemicals mutagenicity and anti-mutagenicity of C. rehmanni and J. Zeyheri medicinal plants. The study serves as scientific proof that extensive use of this plant in traditional medicine for treatment of various ailments may lead to some irreversible damages. / NRF