The work contained in this thesis is split into two sections. Each section covers a different biological pathway, its current importance as a potential drug target, and the syntheses towards a selection of natural products and analogues relevant to the pathway. In Section A, the novel approach towards a new class of n-formyl amides is described. Furthermore, this new methodology is used to generate the imide intermediate A1. This imide is now considered a key intermediate in our synthesis of natural products CJ-15,801, Pantothenate, and the first generation of analogues based on CJ-15,801. This section also covers the potential scope for n-formyl imides in chemical synthesis in general. Section B describes two novel approaches towards non-mevalonate pathway (MEP) intermediates and inhibitors. The synthesis towards a previously unpublished 2,2-dimethyl MEP analogue, is described alongside the attempted generation MEP. The methodology described herein shows the use of Neighbouring Group Participation in intramolecular opening of epoxides, and how this can be applied to the generation of analogues. Above all, the aim of this thesis is to open up new synthetic strategies towards potential inhibitors for individual biosynthetic pathways.

An understanding of the criteria governing lymphatic absorption of drugs from the gastrointestinal tract may lead to selective uptake of drugs via this route. Lymphatic absorption may have potential advantages over the portal absorption of drugs; first pass elimination may be avoided as the drug reaches the systemic circulation before it reaches the liver, the absorption of some poorly absorbed drugs may be improved and it may provide a means of targeting anticancer agents directly to the lymphatics. In the present study, the lymphatic uptake of a series of retinoids was investigated after oral administration. The most important factors which were found to affect lymphatic absorption were, the chemical nature of the compound and the nature of the oily vehicle in which the retinoid was administered. It was found that the greater the lipophilicity of the retinoid, (as defined by the logarithm of its octanol : water partition coefficient, log. P), the greater was its lymphatic absorption. Temarotene, Ro 15-0778, (log. P = 8.7) exhibited a maximum dose adjusted lymphatic absorption rate of 4100 ng/h compared with the less lipophilic Ro 04-3780 (log. P = 6.8) which showed a maximum rate of only 150 ng/h. The oily vehicle in which the retinoid was orally administered strongly influenced the rate of absorption via the lymphatic route. Ro 04-3780 demonstrated a 150 fold difference between the selected oils giving the maximum and the minimum lymphatic absorption rate. The best oils in this role appeared to be those in which the retinoid showed the least solubility. Mesenteric lymph flow rate was also shown to vary depending upon the oil. Basal lymph flow rate in the fasted rat, after dosing with saline, was 1.6 m1/h/kg. Cottonseed oil and soyabean oil promoted an increase in this flow rate to greater than 3.0 ml/h/kg (p < 0.01) when orally administered with Ro 04-3780. Conversely, linoleic acid suppressed the mean lymph flow rate to 0.8 ml/h/kg (p < 0.01) after oral administration with Ro 04-3780. Lymph turbidity was evaluated as an indication of chylomicron formation and transport in the lymph. Since the chylomicron is the particle in which dietary fats enter the lymphatic system, it was thought that lipophilic drugs, which are soluble in dietary lipid, may be carried into the lymphatic system via this pathway. The mixed long chain fatty tri-acyl glycerol oils, cotton seed oil, soyabean oil and peanut oil, when orally dosed to rats, produced the most turbid lymph (25 - 48 times greater than the turbidity produced after an oral dose of saline). These type of oil also promoted the highest lymphatic uptake rate for the retinoids. Other oils including, oleic acid, linoleic acid and MTS (a Miglyol S12 based self-emulsifying oil system), demonstrated much wider ranging extents of lymphatic absorption, but produced lymph with similar but lower turbidity (10 - 12 times greater than the turbidity produced after an oral dose of saline). A self-emulsifying oil system was developed for use in the oral administration of a retinoid. This system (MTS), produced a stable emulsion with a particle size of 500 nm after gentle mixing with an aqueous solvent and contained 80% Miglyol 812 and 20 % surfactants. MTS increased both the lymphatic and portal absorption rates for Ro 15-0778 by three fold compared with Miglyol S12 alone, improving the overall bioavailability but without selective promotion of lymphatic uptake. The effect of feeding, prior to orally dosing with an oil (linoleic acid) containing Ro 10-9359, was to suppress greatly the portal absorption rate of the retinoid from 310 ng/h to less than 25 ng/h. A number of factors, which were believed to be important in the lymphatic absorption of the retinoids, have been investigated here, using the rat as an animal model. The data obtained in this work suggest that lymphatic absorption is a very complex process and the factors which govern this absorptive pathway vary depending upon the nature of the drug being studied and the nature of the orally dosed vehicle.

Lavender (Lavandula angustifolia) is a popular treatment for stress and mild anxiety. Currently, there are few reliable investigations of its efficacy because cognitive and associative effects of odours can confound pharmacological effects. Some of these problems can be overcome by testing the effects of odours in animals, and by using orally-administered lavender in sealed capsules in human participants. In addition, a criticism of current studies is that most employ short-term administration of lavender, even though humans most often use lavender over longer time-periods. There are two parts to this thesis. The first part addressed two questions; whether lavender odour exhibits anxiolytic effects in animal models of anxiety, and whether chronically administered lavender is more effective than acutely administered lavender. The second part addressed the question of whether, in a randomised double-blind placebo-controlled trial, orally-administered lavender exhibits anxiolytic effects in humans. This thesis makes three significant contributions: First, these studies provided a validation of the gerbil elevated plus-maze model of anxiety in both male and female gerbils, a model that has only previously been validated in female gerbils (Varty et al., 2002). Second, the studies on gerbils have shown that both lavender and rose essential oils have anxiolytic effects, which, rather than dissipating following acute odour administration (Cooke & Ernst, 2000), potentiate over time. Lavender’s effects were particularly apparent in female gerbils on measures related to risk-assessment, a behaviour that has been related to the human anxiety trait of worry (Blanchard, Blanchard, Griebel, & Nutt, 2008). Third, lavender had a clear dose response effect in reducing baseline anxiety in humans when tested acutely via oral administration, although there were no effects when more severe anxiety was induced. The route of administration and the fact that iv lavender had dose response effects indicate that lavender’s effects are not caused by psychological qualities of the odour, but are more likely to be due to direct pharmacological effects. Again, and comparable to results in gerbils, lavender’s anxiolytic effects in human females were more noticeable, particularly during the anxiety task and in the recovery phase of the study. In summary, prolonged exposure to lavender odour relieved anxiety in a validated animal model of anxiety, and orally-administered lavender alleviated mild anxiety in humans. In both cases, results were more prevalent in females.

Liposomes have established roles in drug delivery and cell membrane studies. Amongst other applications; they can also be used as analytical reagents, particularly in immunoassays. Liposomal immunoassays have potential advantages over alternatives; including sensitivity, speed, simplicity and relative reagent stability. The aim of these studies was to develop and evaluate novel examples of these assays. When liposomes entrapped the dye, Sulphorhodamine B, a shift in its maximum absorption wavelength compared to free dye was observed. This was attributed to dimerization of the dye at high concentrations. If the liposomes were disrupted, the released dye was diluted into the external buffer, and the dye's absorption spectrum reverted to that of free dye. After optimization of dye entrapment, immunoassays were developed using these liposomes. Albumin-coated liposomes were used in a model assay to measure serum albumin. This assay employed complement-mediated immunolysis, commonly used in liposomal immunoassays. The liposomes were lysed by anti-albumin and complement, and this could be competitively inhibited by serum albumin. To improve sensitivity, Fab' anti-albumin liposomes were prepared. These enabled measurement of urinary albumin by a complement-mediated immunoassay, but using a sandwich technique. Anti-albumin (intact) liposomes were shown to precipitate on gentle centrifugation after reaction with albumin. They were applied as a solid phase reagent in an heterogeneous immunoassay, using radioimmunoassay for urinary microalbumin as a model assay. Liposomes containing Sulphorhodamine B were also used in a more novel assay; for serum anticardiolipin antibodies. Cardiolipin-containing liposomes were prepared. These were lysable using magnesium ions. Anticardiolipin antibodies (IgG) were found to augment this lysis, enabling their estimation. Similar imprecision and acceptable correlation with a commercial enzyme-linked immunosorbent assay (ELISA) were obtained. The findings demonstrate Sulphorhodamine B release can be used as a marker in homogeneous colorimetric liposomal immunoassays; both in model assays and in potentially more useful clinical biochemistry applications.

Effects of anxiolytic compounds of diverse chemical classes (chlordiazepoxide, buspirone, ritanserin, propranolol and BRL46470) on the behaviour of mice were examined in several animal models of anxiety. These models included social interaction by male mice in the animal's home cage and an unfamiliar neutral cage, the light/dark box and responsiveness of the mice to calls from predatory and non-predatory birds. Effects of anxiolytics were also examined in mice in the timid female paradigm, and on the behaviour of marmosets when confronted with their unfamiliar conspecifics. Effects of anxiolytics in mice were compared with those of quinpirole, given at anxiogenic dose levels. The results showed that during social interaction, anxiolytic compounds released behaviour of animals that normally was suppressed by social and environmental constraints. In male mice, anxiolytics also increased exploratory digging and in some cases enhanced aggression. Quinpirole, however, in these models, decreased their social investigation, non-social activities as well as locomotor activities while increasing their flight behaviour. In the present studies, the light/dark box model was found to be sensitive to chlordiazepoxide and several other anxiolytics after acute administration. Effects of three classical antidepressants (imipramine, phenelzine, mianserin) on social interaction in male mice were also screened, using similar ethological techniques. It was found that the effects of antidepressants following different time courses were different from the effects of anxiolytics. When given acutely, antidepressants induced a range of diverse changes to behaviour which included anxiogenic-like effects, such as decrease of aggressive behaviour and social investigation. After subchronic administration, antidepressants exhibited anxiolytic-like effects in that they increased social investigation and sometimes increased aggression. Enhancement of exploratory digging was found only by subchronic administration of one of the antidepressants tested. Commonalities in the behavioural effects induced by anxiolytics and antidepressants when given by long-term administration indicate that they may be acting at common pathways in the central nervous system. They may act to suppress functioning of the behavioural inhibition system and also influence the hippocampal-5-HT defence reactions. The dissimilarities of behavioural effects produced by anxiolytics and antidepressants suggest that these drugs may alter defensive responding via different neurochemical routes

The use of rhIL-2 to augment antitumour immunity was seen as having great potential for the treatment of neoplasia, but the efficacy of immunotherapy has remained poor despite encouraging experimental data. A reason for this could be active immunosuppression by the tumour mediated by the secretion of suppressor factors. Suramin is a polyanionic drug which blocks and inhibits a range of growth factors and cytokines. This project investigates the potential of suramin to act as an adjunct to rhIL-2 based immunotherapy by acting as a blockade to suppressor factors. In vitro studies showed that rhIL-2 generation of LAK cells resulted in an increase in expression of activation associated antigens, a proliferation of cytotoxic T cells and natural killer cells and augmentation of cytolytic activity. These parameters could be suppressed by factors released from the colorectal cell line LoVo, but co-culture with suramin reversed the suppression in cells isolated from normal individuals. A suramin induced fall in the percentage of cells expressing CD4 was shown to be due to CD4 modulation and not the apoptotic death of CD4+ve cells. CD4 modulation could be reversed by the removal of suramin and could be influenced by tyrosine kinase inhibitors, though direct tyrosine phosphorylation of CD4 did not occur. The CBHlCBi Hooded rat was used as an in vivo model to study the potential of suramin and rhIL-2 in controlling induced liver metastasis from the syngeneic HSN sarcoma cell line. A toxicology study showed suramin side effects to include a reduction in total body weight gain and an increase in lymph node and spleen weights. Enlargement of kidneys and reduction in liver size were also seen. Haematologically, a suramin induced basophilia and thrombocytopenia were recorded as well as a rhIL-2 induced eosinophilia. In vivo CD4 modulation was also seen. Finally a combined suramin and rhIL-2 therapy regimen was found to be more effective than either agent alone in reducing both hepatic tumour mass and numbers after the induction of metastases in these animals. It was concluded that suramin can be used as an adjunct to rhIL-2 based immunotherapy.

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The use of Mitomycin C in the treatment of a wide range of neoplastic conditions is discussed. The mechanism of action of mitomycin anticancer antibiotics under reductive activation conditions using either enzymes, sodium dithionite, catalytic hydrogenation or chromium (Il) perchlorate is examined, as is the alkylation of DNA. An intramolecular [3+2] cycloaddition strategy has been employed to synthesise the pyrrolo[I,2-aJ]indole nucleus for a wide range of cyclopropamitosenes, whereas the key step in the synthesis of pyrrolo[I ,2-a]indoles without the cyclopropane ring was a modified Wittig reaction. From the onset of the work it was important to investigate the role of the 7 -methoxy group. Hence a variety of cyclopropamitosenes or related pyrrolo[I,2-a]indoles were subjected to C-7 exchange reactions with either (i) other alkoxides or (ii) cyclic / acyclic amines. In this way, structural modification at C-7 can be related to the biological results. Biological and electrochemical data were recorded for the cyclopropamitosenes and related pyrrolo[I,2-a]indoles and correlated with their structures.