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A dissertation submitted In fulfilment of the degree Doctor of Philosophy (Chemistry) In the Faculty of Science School of Chemistry University of the Witwatersrand. Johannesburg 2015. / According to the World Health Organization (WHO), cancer is a leading cause of death worldwide and has accounted for 7.6 million deaths (13% of all deaths) in 2008. The number of effective drugs available has been reduced by chemo resistant malignant tumors. Similarly, bacterial infections are one of the world’s most pressing public health problem. The major challenge in anti-bacterial treatment is due to the development of bacteria strains that are resistant to antibiotics. Each year more than 11 million people die from major infections such as MDR tuberculosis. In 2013, 9 million people fell ill with TB and 1.5 million died from the disease (WHO). Therefore there is a need for novel therapeutic alternatives such as the discovery of new anti-cancer and anti-bacterial agents. Benzofurans have attracted much attention due to their broad spectrum of pharmacological activities such as anti-cancer and anti-bacterial activities and one classical example is usnic acid. Most of the published synthesis of the benzofuran moiety involved the formation of annellated furan ring by intramolecular cyclisation of benzene, and these procedures involved a multi-step, rigorous reaction conditions and expensive catalyst. This research investigated the novel synthesis of benzofurans through the application of biocatalysis, where the reactions involved the use of the oxidative enzyme laccase to generate carbon-carbon bonds, carbon-oxygen and carbonnitrogen bonds between aromatic compounds. The substrates used were o-diols from catechols 1, p-quinone 2 from naphthoquinones and naphthohydroquinone 3, which, when activated by the enzyme action, could be reacted with 1,3-diketones 4, 5 or coumarins 6 (Figure 1). The aim of synthesising different classes of compounds was to vary the functional groups and to increase the number of rings, so as to possibly increase the biological activities.

Dissertation submitted for the qualification Master of Science in Molecular and Cell biology (full time) University of Witwatersrand 01 February 2016 / Ambergris is a large lump excreted by whales, when exposed to sunlight, air and sea water, it oxidatively decomposed through inorganic reactions to form different compounds including (-) ambrafuran. (-) Ambrafuran is a highly fragrant compound and it is considered to be a stronger perfume ingredient than other constituents in ambergris. It is used as a fixative agent to stabilize perfumes by reducing the rate of evaporation of volatile substances. A two-step process for production of (-) ambrafuran starting from sclareol was developed at CSIR for an industrial partner, Teubes cc. The current commercial production of (-) ambrafuran entails a chemical process consisting of at least 8 steps and require very harsh chemicals and elevated temperatures. In the current study, relevant technologies for the optimization of a process for commercial production of (-) ambrafuran were investigated. The project objective has been to optimize fermentation conditions on laboratory scale for the conversion of sclareol to an intermediate diol using the microorganism Hyphozyma roseoniger and to subsequently test different zeolites for conversion of diol to (-) ambrafuran. Production of ambradiol was achieved in potato dextrose broth media in 13 days compared to a patented method which took 16 days. The method was also scaled-up in a 2 L fermentation bioreactor and the yield of 93% was achieved after 24 hours of reaction. Following the initial use of the zeolite CBV320, two new zeolites (CFG-1 and ZD0614) were identified which have the potential to convert ambradiol to (-) ambrafuran without undergoing an activation process. Zeolite CFG-1 have been recognized to be highly effective for converting the intermediate ambradiol to the resulting (-) ambrafuran. One of the greatest outcomes of this research project is that the amount of zeolite required per substrate has been reduced from between 1:6 and 1:9 to 1:2. The substrate concentration has been increased from 5 mg/mL to 100 mg/mL which also resulted in the reduction of the volume of solvent required for the cyclodehydration step. The study allowed for scale-up and following further optimisation on larger scale should result in a process on commercial scale.

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Graduation date: 1999

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (M. Sc.)--University of Hong Kong, 1968. / Typewritten.

Thesis (M.S.)--University of North Carolina at Wilmington, 2003. / Includes bibliographical references (leaves : [90]-91).