In pharmaceutical R & D, drug stereochemistry, and consequently the rotation of enantiomers, is very important. Because they act as chiral selectors in vivo, biomacromolecules have been extensively used as chiral selectors for the liquid chromatographic (LC) resolution of enantiomers and more latterly have also been employed in the newer separative technique, capillary electrophoresis (CE). However, at the outset of this research programme, this had generally been restricted to common easily accessible biomacromolecules such as plasma-binding proteins. It was clear that it be would be useful therefore to adapt LC and CE in such a way as would allow the use of a much wider range of biomacromolecules. Accordingly the general aim of this study was to develop LC and CE protocols involving biomacromolecules that would give rise to minimum consumption of the biomacromolecule. To study biomacromolecules in free solution CE, a number of experimental variables had to be established for both optimum chiral discrimination and for investigating biomacromolecule-ligand interactions. The typical and widely used biomacromolecule for chiral discrimination, bovine serum albumin (BSA) was used to study the variables of pH from pH 5.4 to 8.4, concentration of BSA form 0 to 60 mM and concentration of organic modifiers in the range 0 – 20 % v/v for chiral selectivity. This involved an investigation into some unusual artefacts such as ghost peaks and stepped baselines, but ultimately the outcome was a successful free solution CE protocol suitable for the rapid evaluation of chiral discrimination of other biomacromolecules. The conditions were: run buffer (30 mM protein, 67 mM phosphate (pH 7.4) – methanol (97.5 : 2.5, v/v)), capillary CElect p150, 40 cm (35 cm to detector) x 50 mm i.d., temperature of ambient or 25 °C and an applied voltage of 10 kV. The ability of other biomacromolecules, such as human serum albumin (HSA), lactoferrin and protamine, to resolve enantiomers was studied using this protocol including looking at the effect of the addition of modifiers to the buffer such as metal ions like manganese and zinc, competing ligands, e.g. warfarin and ibuprofen, and b-cyclodextrin. As well as using CE, miniaturisation of LC was also studied in view of the success of biomacromolecule-affinity chiral LC. Two different, but similar, microbore LC protocols were employed, i.e. using the protein in free solution or as a pseudo stationary phase. For the former, a Lichrosorb DIOL stationary phase, based on hydroxyl groups immobilised on silica, was chosen in order to minimise the adsorption of protein to the stationary phase. Using this protocol it was demonstrated that free solution microbore LC could be easily be carried out, therefore used to evaluate chiral discrimination and that the use of the system to study in vivo interactions was feasible. The creation of a biomacromolecule pseudo stationary phase, as opposed to conventional chiral stationary phases where the protein is permanently bonded to the stationary phases, involves the biomacromolecule being adsorbed within the pores of the stationary phase. In this way the overall biomacromolecule structure should not be grossly distorted. Three stationary phases were evaluated, viz wide-pore Nucleosil silica, Nucleosil C8 and Lichrosorb DIOL, for optimum biomacromolecule loading and minimal biomacromolecule leakage when mobile phase was pumped through the column. The Nucleosil silica with adsorbed BSA proved the most successful, e.g. a of 3.6 and 4.0 for tryptophan and kynurenine respectively, and robust of the stationary phases with respect to demonstrating the chiral discrimination potential for this system. All the miniaturised systems evaluated were successful, to a greater or lesser degree, for the demonstration of chiral selectivity of biomacromolecules. While CE was better for minimisation of the consumption of the biomacromolecule, it was also important that the biomacromolecule LC systems could be operated in reduced dimensions since these systems have perhaps greater potential for exhibiting enantioselectivity and are more appropriate for the ever increasing need for the study of the interaction of ligands with the biomacromolecule in its ‘natural’ form. With the knowledge gained from this research programme it will now be possible to more easily carry out such studies with much smaller amounts of biomacromolecule, and, accordingly be able to work with biomacromolecules which hitherto it has not been possible to study because of limited availability. While some of the protocols have now been superseded by recent developments the system developed still has potential. The use of such small scale systems offers the potential to study chiral selectivity and drug-biomacromolecule binding of rare or expensive biomacromolecules.

Hydrophilic matrix tablets present a convenient method for oral modified drug delivery. The performance of such dosage forms is affected by multiple factors, amongst which the influence of tablet shape and structural properties have been partially investigated in previous literature. This work focused on investigating the influence of changing tablet properties on the in-vitro behaviour of hydrophilic matrix tablets, in particular, the influence of tablet face curvature on the hydration and drug release behaviour of round and elongated Xanthan Gum tablets containing the two model drugs Orphenadrine Citrate and Orphenadrine Hydrochloride. The influences of tablet overall porosity and of the formulation used on tablet behaviour were also investigated, in addition to the investigation of any interactions between the influences of tablet and formulation variables. Initially the properties of the powders incorporated into the various formulations used were characterised. The physical properties of the dry tablets were then investigated in terms of tablet tensile strength and Abstract 2 structural properties. The hydration behaviour of the various tablets was investigated quantitatively using live in-situ swelling studies and qualitatively using rheological and calorimetric methods. Finally the process of drug and polymer dissolution from the tablets was investigated. The results of the work indicated that tablet face curvature had a significant influence on the physical properties of the dry tablets as well as on the hydration and dissolution patterns associated with the hydrated tablets. The influence of tablet overall porosity was profound on the properties of the dry tablets but became rather minor upon tablet hydration. The type of formulation had a major influence on the properties of dry tablets. Moreover, ionic interactions between the two drugs and Xanthan Gum had a significant influence on the properties of hydrated tablets. Thus, tablet face curvature, porosity of the tablets and physicochemical properties of the drugs need to be considered when formulating a hydrophilic matrix tablet.

The project started with studying the unique characteristics of the zwitterionic drug (norfloxacin), considered as an example of very slightly water soluble drug. The study focused on the effects of its chemical structure on its interaction with surfactants (PEG200 and Synperonic TM PE/L-61) in liquisolid systems and, consequently, on its release into water dissolution medium. The next stage was an approach to solve the problems of the dissolution, compressibility and flowability of norfloxacin liquisolid formulations through adding water as a liquid binder to make wet granulated liquisolid formulations. The water in the liquisolid formulations works as a liquid binder to the carrier and coating particles, creating a wider space inside their structure, which allows the amount of the liquid vehicle (PEG200 and Synperonic TM PE/L-61) to increase inside the formulations. This feature reflects positively on the flowability (decreasing the angle of the slide), compressibility (increasing the load factor) and the dissolution behaviour of norfloxacin (increasing drug release to more than 20%). Another liquid binder (PVP) was used in the wet granulations and a comparison was made between PVP solutions, water and classical liquisolid formulations in terms of dissolutions, flowability, compressibility, DSC thermographs and FTIR spectra. The successful application of wet granulation techniques with liquisolid formulations was tested with a very hydrophobic drug (cinnarizine). Due to its hydrophobicity, traditional mixing of surfactants and the drug particles did not improve its dissolution in water medium, although the solubility was relatively high. ii The methodology was again applied to investigate how the dissolution of cinnarizine altered with several different types of surfactants. The results lead to a change from traditional mixing to a self-nano emulsifying drug delivery system (SNEDD). Optimization to select a suitable oil (Capmul® MCM EP), surfactant (Kolliphor® RH40) and co-surfactant (PEG400) was found to depend initially on the solubility of cinnarizine. Further optimisation identified the relative percentages (66.6:16.6:16.6 for oil, surfactant and co-surfactant, respectively) and the drug concentration required for the SNEDD (6.0% w/w) was found to depend on the mixture experimental design, using dissolution trends as an indicator. Finally, the selected SNEDD system was converted to a liquisolid system using the water granulation technique to make tablets with acceptable compressibility and flowability. Due to the negative effect of coating material (Cab-O-Sil® M-5P) on the dissolution behaviour, a new method was developed to determine the compressibility load factor using a central composite design and response surface methodology. The predicted model was validated and the accuracy was over 95%, allowing it to be used for preparation of the SNEDDs. The new preparations were compared to tablets from the commercial sources. The new formulations show significant enhancement in the percentage of the drug releases in distilled water dissolution medium.

Caveolae, 50-75nm invaginations of the plasma membrane (PM), were originally described by the late Nobel Prize-winning cell biologist George Palade (1). They are a subset of membrane lipid rafts (MLR), microdomains of the plasmalemma highly enriched in cholesterol and glycosphingolipids. Caveolins (Cav-1, Cav-2 and Cav-3) are scaffolding and cholesterol binding proteins that localise to the inner leaflet of the PM within caveolae and insert via palmitoylated cysteine residues. Caveolins (Cavs) interact with and bind many signalling transduction proteins, such as G-protein-coupled receptor (GPCR) signalling components, and also serve to modulate the cytoskeleton via tethering to actin and/or microtubules. By acting within the MLR domain, Cavs drive pro-survival pathways (p-Src, p-Akt, p-ERK), leading to protective phenotypes. I have shown Cav-1KO mice have a neurodegenerative phenotype, whilst also demonstrating viral driven increased expression of Cav-1 enhances dendritic growth in neurons. Cav-3 can increase protective or anti-apoptotic signalling events in the heart. Cav-3 overexpressing mice have increased morphological caveolae quantitated with my TEM images and have enhanced protection from injury. Cav-3KO mice, with disrupted mitochondrial and sarcomeric ultrastructure analysed by me, are at significant risk of cardiomyopathies, revealing a critical role for Cavs in protection. Using multiple and complementary techniques, new cellular functions, beyond the previously described role as protein scaffolds in signalling networks, have been uncovered for Cavs isoforms. I have discovered increased numbers of caveolae following virus-mediated transfection, preconditioning (protective) protocols and some pathological states. In contrast, I have found decreased caveolae and other pathologies associated with reduced Cavs expression. Localisation of Cavs in non-canonical cellular domains, such as mitochondria and cytoskeletal fractions, established by my LM, TEM and cell fractionation analyses, have led to the hypothesis that Cavs are critical cellular regulators. And as such, represent an attractive pharmacological target for diseases with diverse aetiologies, including cardiomyopathies, neurodegenerative diseases, diabetes and inflammation.

Organocatalysis has rapidly expanded in the last decade to encompass a wide variety of small organic molecules that are capable of either activating substrates or transforming them into more reactive forms. The aim of this study was to develop novel chiral organocatalysts based on the tetrahydroisoquinoline backbone and evaluate them on asymmetric reactions. Three organocatalytic modes of activation have been investigated for C-C bond forming asymmetric reactions. In chapter 2, for the first time organocatalysts bearing a secondary nitrogen within a cyclohexane ring were evaluated in the asymmetric Diels–Alder reaction. These catalysts were tested over a range of dienes and dienophiles and displayed promising chemical conversions of up to 100 % with up to 64 % ee when triflic acid was employed as the cocatalyst. Density functional theory computational studies and 2D NMR spectroscopy were used to determine the structure of the intermediate iminium ion formed between the most efficient catalyst and cinnamaldehyde. Chapter 3 includes a series of novel tetrahydroisoquinoline chiral N-oxide organocatalysts and their evaluation in the asymmetric allylation reaction of aromatic and α-β-unsaturated aldehydes with allyltrichlorosilane. The chiral homoallyl products were obtained with good chemical efficiency (up to 93 % yield) and high enantioselectivity (up to 91 % ee) under mild reaction conditions (23 °C). Chapter 4 is the simple and practical microwave-assisted synthesis of new tetrahydroisquinoline guanidine organocatalysts and their evaluation in the asymmetric Michael addition reaction of malonates and β-ketoesters with nitro-olefins. In addition, a novel microwave assisted procedure of introducing the guanidine unit onto amino amide derivatives is reported. The chiral products were obtained with quantitative chemical efficiency (up to 99 % yield) and excellent enantioselectivity (up to 97 % ee). Chapter 5 is a collection of all X-ray crystal structures that were published from novel compounds synthesized pertaining to Chapters 2-4, it contains 15 published crystal structures while Chapters 3-4 contain 3 other X-ray crystal structures. It should be noted that with the exception of the introduction and Chapter 4 (submitted for publication), the remaining chapters of this thesis have been published in international peer reviewed journals. In the next section (DECLARATION 2 – PUBLICATIONS) a precise description of my contribution to each of the publications/chapters is provided. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2012.

The use of plant materials for the treatment of various diseases is very common in African countries. As traditional medicine used by the rural people does not always have a proper scientific basis, research programmes have to be undertaken to evaluate their therapeutic efficacy and safety. In traditional African medicine various Bulbine species are used to treat a number of conditions including sexually transmitted diseases, wound infections, dysentery and urinary tract infections. The Bulbine species belong to the family Asphodelaceae. There are over fifty South African Bulbine species and they are mostly herbs. Their leaves are evergreen and succulent in appearance. Bulbine species have thick fleshy tuberous roots, are easy to grow, are able to withstand drought and heat and are able to grow in poor soil. There is very little documented information on the antimicrobial activity and chemical properties of the Bulbine species. Therefore research programmes of this nature have to be undertaken. Various Bulbine species, viz., B. natalensis Bak, B. frutescens Willd (yellow flowers), B. narcissifalia Salm Dyck, B. abyssinica A Rich and B. frutescens Willd (orange flowers) were collected. The plants were washed with tap water, air dried and separated into the different components. Each component was cut into small pieces and immersed in methanol: dichloromethane (1:1, v/v) for extraction. The organic solvent was decanted from the plant material and evaporated under reduced pressure. The resultant crude extracts were stored in glass vials in the freezer. In addition, the roots, stems and leaves of B. natalensis and B. frutescens (yellow flowers) were extracted aqueously. The crude organic and aqueous were subjected to various tests to evaluate their antimicrobial and cytotoxic potential. To evaluate their antibacterial activities, the Disk Diffusion and Bore Well Methods were employed. The crude extracts were tested against various pathogens implicated in wound and urinary tract infections and dysentery. In these experiments the Disk Diffusion Method produced better results than the Bore Well Method. The crude organic and aqueous extracts were found to be effective against many of the bacteria used in this study including K. pneumoniae, S. aureus, S. typhi and S. flexneri which are considered to be troublesome pathogens. The TLC bioassay was employed to evaluate the antifungal potential of the various crude extracts against Aspergillus and Penicillium and the Disk Diffusion and Bore Well methods were used to evaluate the antifungal potential of C. albicans. The Bulbine species displayed no antifungal activity against Penicillium and limited antifungal activity against Aspergillus. The two method used to evaluate the antifungal activity of. C albicans was chosen because C. albicans grows in a similar manner to bacteria on solid and liquid culture media. Only the root extracts of the two B. frutescens varieties were inhibitory to C. albicans. The Brine Shrimp Bioassay was used to ascertain the cytotoxic potential of the crude extracts. The majority of the extracts were cytotoxic at the most concentrated dilution (i.e., dilution 1) but not cytotoxic at the lower dilutions. The only extracts that were not cytotoxic at the most concentrated dilution were the organic extract of the root of B. frutescens (yellow flowers), the organic extract of the root of B. narcissifolia and the organic extract of the leaf of B. abyssinica. TLC and column chromatography was carried out to evaluate the chemical composition of the Bulbine species. The TLC indicate that this technique could be a valuable tool in identifying the different species in the genus Bulbine. Column chromatogram was carried out on the extract which displayed a significant amount of antibacterial activity against the bacteria used in this study. The stem extract of B. natalensis was chosen for further analysis. The stem extract was fractitioned into different fractions but unfortunately none of the chemical component could be identified. According to the results obtained in this study, there is considerable scope for further studies of this genus. / Thesis (M.Med.Sc.)-University of Durban-Westville, 2000.

Thesis (M. Med. Sc.)-University of KwaZulu-Natal, 2006.

Abstract not available. / Thesis (M.Med.Sc.)-University of KwaZulu-Natal, 2008.

Extracts of Hypoxis hemerocallidea corm (African potato) are commonly used by some traditional health practitioners in KwaZulu-Natal Province of South Africa for an array of human ailments. This study was, therefore, undertaken to investigate the GIT spasmolytic, bronchospasmolytic, uterolytic and vasa deferentia relaxant effects of Hypoxis hemerocallidea corm aqueous extract. Respectively, these effects were determined on both naive and spasmogenevoked contractions of the guinea-pig and rat isolated ileum, trachea, uterine horns and the vas deferens in vitro. Healthy, young adult, male and female Dunkin-Hartley guinea-pigs (300-400g) and Wistar rats (250-350g) were used in this study. The isolated tissues were prepared and mounted in Ugo Basile organ-baths under normal physiological conditions. After an equilibration period of 30-45 minutes, the isolated smooth tissue segments were challenged with graded concentrations of Hypoxis hemerocallidea corm aqueous extract, and/or reference drugs. Changes in tension developed by the muscle preparations (relaxations and contractions) were recorded isometrically by means of Ugo Basile's force-displacement transducers and pen-writing 'Gemini' recorders. Relatively low to high concentrations of Hypoxis hemerocallidea corm aqueous extract (APE, 25-400 mg/ml) produced dose-dependent and significant (p<0.05) relaxations of the guinea-pig ileum, and the uterine horns taken from non-pregnant rats, as well as on spasmogenprovoked contractions of stilboesterol-primed, oestrogen-dominated, non-pregnant rats in a concentration-related manner. Potassium chloride (40 mM)-induced contractions of uterine horns, ACh (0.1-3.2 ug/ml)-induced increases in the amplitude of contractions of the guinea-pig ileum, as well as noradrenaline (0.2-1.6 ug/ml)-induced increases in the amplitude of contractions of the male rat isolated vasa diferentia, were significantly (p<0.05-0.001) reduced or abolished by bathapplied APE (25-400 mg/ml). Relatively low to high concentrations of the extract (25-400 mg/ml) caused concentration-dependent increases in the relaxations of the guinea-pig isolated tracheal smooth muscles. Inhibitions of ACh (0.1-3.2 ug/ml)-induced contractions of the guineapig isolated ileum probably suggests possession of antidiarrhoeal activity of APE. Results of this study show pronounced relaxant effects of Hypoxis hemerocallidea corm aqueous extract on guinea-pig vas deferens. The study also lends pharmacological credence to the folkloric, ethnomedical uses of APE as a natural antenatal remedy for threatening abortions, as an antidiarrhoeal remedy, and as a bronchorelaxant. The precise mechanisms of APE action on the smooth muscles could not be established in the present study. However, the uterolytic action of the corm's extract is unlikely to be mediated via ^-adrenoceptor stimulation, but probably mediated through a non-specific spasmolytic mechanism. / Thesis (M.Pharm.)-University of KwaZulu-Natal, 2009.

Abstract not available. / Thesis (M.Med.Sc.-Pharm.)-University of KwaZulu-Natal, 2006.