No description available.

No description available.

No description available.

No description available.

The total mineral ion concentration of Rooibos Tea was determined using ICP-OES. Significant concentrations of Na, K, Mg, Ca, P were found, and trace levels of Al, Fe, Mo, Sr, Zn, Ba, Cu and Pb detected. Protocatechuic acid, aspalathin and rutin were identified in Rooibos tea infusions analysed with HPLC. Analysis of tea samples by Ion Chromatography showed the presence of Cr and S042- ions. Rooibos Tea liquor had a pH of 4.6 once equilibrium had been reached. Partition coefficients (1.0 - 1.4 mm sieving fraction) for Na+, K+, Mg2+, protocatechuic acid, aspalathin, rutin, S042- and Cl were determined for infusions at 80 C using a graphical and a successive extraction method. A total mineral content method was also used to determine the partition coefficients for the mineral ions. The Na+, K+, Mg2+,SO42-, H2P04- (as P) and Cl ions as well as protocatechuic acid, aspalathin and rutin all displayed first order behavior, allowing the determination of infusion rate constants. The particle size effect was investigated at 80 C. All the mineral ions showed an increase in infusion rate constant with decreasing particle size, protocatechuic acid and aspalathin showed no trend, while the rutin infusion rate constant was independent of particle size. Calcium uptake by the leaf was observed, this was more pronounced with the smaller particle sizes. Infusion rate constants and hence diffusion coefficients were determined for the nine species for temperatures ranging from 45 to 90 C. These diffusion coefficients for the mineral ions were compared with those for the respective species in aqueous media to give hindrance factors, which were of the order of 102. Except for Cl, all hindrance factors increased with an increase in temperature. The infusion rate constants for all the species at the various temperatures were fitted to an Arrhenius equation and activation energies of infusion determined. The values were lower than those predicted theoretically. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998

No abstract available. / Thesis (M.Sc.)-University of Natal, Durban, 1991.

No abstract available. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1996.

This thesis presents results from investigations of secondary metabolites from marine organisms. The first part pursued the isolation of new compounds from soft bodied marine organisms, the study of aqueous extracts from the different algae and soft bodied marine organisms permitted the selection of one extract from the red alga <i>Laurencia </i>sp., from which six new sesquiterpenes cyclic ethers were isolated. The investigation of the sponge <i>Stylotella aurantium </i>collected from Fijian waters, resulted in isolation of seven previously reported pyrrole alkaloids. The second part focused on the exploration of three novel actinomycete microbes isolated from Mariana Trench sediment, collected at depth 10,898 m (Challenger Deep; 11°19’911’’ N; 142°12’372’’E) for the production of bioactive compounds. Seven novel phenazine alkaloids, dermacozines (A-I), were isolated from the fermentation broth of two Mariana Trench microbes <i>Dermacoccus abyssi</i> strain MT1.1 and <i>Dermacoccus </i>strain MT1.2. The investigated cytotoxic activity against leukaemia cell line (K562) showed that dermacozine F and G have moderate activity with IC_50s of 9 and 7 <i>μ</i>M, respectively, while the highest radical scavenger activity was observed with dermacozine C with an IC₅₀ value of 21 <i>μ</i>M. Investigation of <i>Micromonspora</i> sp. isolated from Mariana Trench sediment led to the isolation of six compounds including: one unusual depeptide and the known deferoxamine together with four known diketopiprazines. Finally, the last part of work focused on the investigation of molecular basis of cold temperature and high pressure adapted growth in extremophilic microbes such as <i>Photobacterium profundum sp.</i> The overall aim of this project was to understand more about the high pressure and cold-adapted growth of two novel <i>P. profundum</i> strains SS9R (Piezophile) and 3TCK (Piezosensitive) by studying the surface of polysaccharides which play an important role in the cold-adapted growth of <i>P. profundum</i> <i>SS9.</i>

A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree of Master of Science. / An outline of reported synthetic routes to the Lupine alkaloids, epilamprolobine [2] and lamprolobine [3] and a review of the use of vinylogous amides and urethanes as precursors for the synthesis of alkaloids are presented in Chapter 1. This is followed by a presentation of our strategy for synthesis of the two Lupine alkaloids. Vinylogous cyanamide intermediate 1- (3-hydroxypropyl) -2- cyanomethylenepiperidine [68] plays a key role in this strategy, since exploitation of its ambident nucleophilicity forms the central theme of this project, The successful route to the intermediate [68] involved the preliminary preparation of the tertiary thiolactam, 1-(2- ethoxycarbonylethyl)piperidine-2-thione [83][ by thiation of the secondary lactam 2-piperidinone [72] and conjugate addition at nitrogen with ethyl acrylate in a Michael reaction. Sulphur extrusion of the salt made from [83] and bromoacetonitrile and subsequent reduction of the ester group provided the pivotal vinylogous cyanamide intermediate. A number; of alternative routes based on 5- bromopentanoic acid [80], 1-allyl-2-piperidinone [73] and thiolactams [84J and [105] were unsuccessful. Cyclisation of the intermediate [68] was achieved by an intramolecular c-alkylative ring closure via the corresponding tosylate [l16] to forln an unsaturated functionalised quinolizidine [69]. Stereoselective carboncarbon double bond reduction and nitrile reduction resulted in the synthesis of two quinolizidines. lupinamine [11] and epilupinamine [112]. Further transformations led to the formation of the derivatives, N-acetyllupinamine [113] and N-acetylepilupinamine [114], and also to the target alkaloids, epilamprolcbine [2] and lamprolobine [3]. / Andrew Chakane 2018

Typescript. Bibliography: leaves 51-61.