The project focused on the isolation, characterization and synthesis of secondary metabolites of Gunnera perpensa L. (Gunneraceae), a South African medicinal plant used by many South African women to induce or augment labour and as an antenatal medication to tone the uterus. From the methanol extracts of the rhizomes we have isolated the compounds Z-venusol, methyl lespedezate, 4-6>-/?-D-glucopyranosyl-3,3',4'-tri-0- methylellagic acid and punicallagin. Structural elucidation of the compounds was performed using NMR spectroscopy. The presence of ellagic acid derivatives and hydrolysable tannins have not previously been reported from the family Gunneraceae. The study also focuses on the development of an HPLC analytical method to fingerprint the crude extracts of G perpensa. This method was used to determine the chemical composition of the rhizomes of the G. perpensa collected in different parts of South Africa. It is clear from the HPLC study that the rhizomes contain large concentrations of the hydrolysable tannin punicalagin and the second most abundant metabolite was Z-venusol. However, it was observed from plants collected in different regions that the ratio between punicalagin and Z-venusol differs substantially in the different extracts. An ellagic acid derivative isolated from G. perpensa contains a biaryl structure derived from gallic acid. The synthesis described in this thesis focused on reaction methods to access unsymmetrical biaryls and two synthetic routes were investigated - one that relies on the Ullmann reaction and the second that uses the Heck coupling reaction. Success of this coupling reaction towards the formation of ellagic acid derivatives was accomplished by the Heck coupling reaction method. One of the most important considerations towards the synthesis was the manipulation of hydroxyl groups of gallic acid by selective protection reactions that provide entry to the aforementioned preparation of unsymmetrical ellagic acid derivatives. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

Previous studies have shown that: (1) plant defensive compounds may have medicinal properties; and (2) defensive compounds present in aposematic insects are often sequestered from their host-plant(s). This study addresses whether aposematic insects can be used as guides to detect plants containing medicinally-active compounds. First, ten tropical medicinally-active plants and ten non-active plants, selected using previous ICBG bioassay results, were observed regularly to determine their insect populations. Aposematic insects were found more frequently on active than non-active plants ( X2=8.167, P=0.01). Second, three aposematic insects feeding on Tithonia diversifolia were examined chemically to determine the fate of the plant's pharmaceutically-active compounds. They were not found to sequester or excrete these compounds. Therefore, using aposematic insects could increase the likelihood of finding plants with medicinally-active compounds; however, these insects may not necessarily utilize these compounds for defensive purposes. The underlying basis for this significant association between aposematic insects and medicinally-active plants requires further investigation.

Thesis (M.S.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 86-102). / vii, 102 leaves, bound ill. 29 cm

Thesis (PhD) -- University of South Australia, 1999

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.

Thesis (PhD.(Pharmacology)--Faculty of Health Sciences)-University of Pretoria, 2006. / Includes bibliographical references.

Thesis (PhD (Medical Plant Science)--University of Pretoria, 2007. / Summary in English. Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 169-194) Also available in print.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 179-212) Also available in print.

Thesis (M.S.)--University of Wisconsin, 1926. / Includes bibliographical references (p. 32-42) and index.