In this work high resolution crystals were produced of full length human eIF4E complexed to m7GTP and the 4E-BP1 motif peptide. The interactions of eIF4E with the cap structure were also analysed by mass spectrometry, revealing a requirement of eIF4E for a guanine monophosphates derivative with a positive delocalised charge on the m7G string. Potential inhibitors for screening were either isolated using virtual screening techniques or synthesised to produce a series of cap mimicking molecules containing a positive delocalised charge. Mass spectrometry identified a series of N7 substituted CMP derivatives that bound to eIF4E in the gas-phase. These compounds were then used in co-crystallisation trials with full length human eIF4E complexed with a 4E-BP1 motif peptide. The co-crystal structures of eIF4E with N7 benzyl derivatives revealed a flipping of the tryptophan 102 to accommodate the bulky N7 group and the expulsion of two structured waters. It also showed that if a para-fluoro group is located on the benzyl modification, then interactions also occur with structured water and an arginine, which explains its increased binding to eIF4E. The flipping of the tryptophan reveals the inherent flexibility in the cap-binding site. The structural information, revealing that the cap-binding site of eIF4E undergoes a conformational change in binding N7 derivatives of GMP with large bulky groups, provides us with valuable insight that can be used in future drug design efforts. The mass spectrometry assay coupled with a clear structure activity relationship, developed on the basis of various “cap-like” ligands studied in the work, gives an excellent starting point for the development of cap-analogue mimics for anti-cancer therapeutics.

This thesis describes the application of lipase mediated kinetic resolutions in the synthesis of two biologically active and pharmaceutically important compounds :- Bufuralol has activity as a beta-blocker and recently it has become useful in metabolism studies as a substrate for a specific cytochrome P450 enzyme. Chapter three details how bufuralol, formerly marketed as a racemate, can be conveniently prepared in optically enriched form with a lipase resolution of a precursor as the key step. Methadone is currently used worldwide as a treatment in the maintenance of patients with addictions to opiates. It is mainly administered as a racemic mixture although the activity of the drug is due to the levorotatory isomer only. Levo-methadone can be efficiently prepared by employing a lipase in the resolution of 1-dimethylamino-2-propanol which is an inexpensive starting material for the synthesis of methadone. This is described in chapter four. Since both isomers of 1-dimethylamino-2-propanol are isolated from the resolution dextro-methadone may also be prepared and although it shows little or no activity itself, dextro-methadone may be converted in two steps to levo-α-acetylmethadol which is used in the U.S. as a longer acting alternative to methadone.

Cyclophilins are regarded as potential drug targets for the treatment of several diseases such as AIDS and malaria. In the present study, the binding of a series of Xaa-Pro dipeptide ligands to human cyclophilin A (CypA) or <i>C. elegans</i> cyclophilin 3 (Cyp3) has been studied using enzymatic activity assays and crystal soaking experiments. The binding energies and dissociation constant (<i>K</i>_d) values of the dipeptide ligands are found to be essentially identical in the crystal and in solution. Three Xaa-Pro/Cyp complex crystal structures were determined in order to calculate their <i>K</i>_d values. A set of 9 known CypA-ligand complex structures were used for docking and scoring performance evaluation, which was carried out by our in-house virtual screening suite LIDAEUS. The results indicate that with appropriate parameterisation LIDAEUS is competent in predicting correct poses. Docking and scoring parameters used in screening for novel CypA ligands with LIDAEUS were optimised during the re-docking experiments. A composite <i>S_screening </i>score which involved the high weighted PIP (Pose Interactions Profiles) score combined with the low weighted energy score enabled us to identify hits for the target protein from a larch chemical database (ZINC database subset 3.2 million compounds). A post-screening filtering was performed by searching for conserved interactions found in tight binding ligands. This enabled us to select 14 compounds for protein-ligand testing. Six novel CypA ligands were identified by PPIase activity assays and isothermal titration calorimetry competition assays (<i>K</i>_dto CypA in a range of 1-120 μM).

Literature methods for the synthesis of benzyl 6-oxo-penicillanate have been studied, it was apparent that some of these reports contained conflicting information with regards to reaction conditions and yields. The same methodology was also used to synthesise the cephalosporin analogue <i>t</i>.butyl7-oxocephalosporanate. The reactions of these compounds with various trimethylsilyl amides and with the Wittig reagent 5'triphenylphosphoranylidenecyclohexanespiro-2'-(1',3'dioxolan)-4'-one have been investigated. The potential for attaching penicillin and cephalosporin nuclei to polymer supports, and thereby utilising the well developed methodology of solid phase peptide synthesis in the field of the discovery of novel β-lactam compounds, has been investigated. Difficulties were encountered when attempting to remove the β-lactams from the resin, however both penicillin and cephalosporin compounds were recovered, in low yield, having had the 6β-(7β-) amino protecting group changed whilst attached to the resin.

The neglected diseases of African sleeping sickness, Chagas’ disease, and leishmaniasis are caused by the protozoan trypanosomatid parasites <i>Trypanosoma </i>and <i>Leishmania,</i> and are major world-wide causes of disease and death. There is a compelling need for the development of new drug treatments because existing treatments are inadequate due to high levels of toxicity and growing drug resistance within the parasites. Glycolysis is an attractive target because many of the trypanosomatid glycolytic enzymes are sequestered within the glycosome, giving them unique regulatory properties. Trypanosomatid pyruvate kinase (PYK) is particularly attractive because, although a cytosolic enzyme, is allosterically regulated by fructose-2,6-bisphosphate whilst the allosteric PYK in mammalians is regulated by fructose-1,6-bisphosophate. X-ray crystallography has been used in this study to solve three structures of pyruvate kinase from <i>Leishmania mexicana</i> in order to determine the mechanism of allosteric activation of PYK. Knowledge of the conformational changes that PYK undergoes during enzyme activation showed that the best place for the design of inhibitors of PYK from <i>L. mexicana</i> is the effector site and the surrounding area. This study has used a structure-based approach to drug design, encompassing virtual screening and combinatorial chemistry to identify novel inhibitors of PYK from <i>L. mexicana</i>. The most potent inhibitor of PYK from <i>L. mexicana</i> was MN92, synthesised through combinatorial chemistry, which had an IC₅₀ of 71μM and a <i>K</i>_iPEP of 45μM. This compound is believed to bind to the PYK effector site and is suitable for further studies of ligand optimisation.

A series of platinum(II) aminophosphine complexes has been prepared and their interactions with nucleotides studied, such complexes are potential anticancer agents combining cytotoxic phosphines with features of platinum am(m)ine drugs. Ligands of the form Ph₂P(CH₂)₃NRR’ have been prepared, where R and R’ are alkyl groups of varying steric bulk. On complexation with platinum the ligands form six-membered chelate rings bound via P and N and the extent of chelation has been shown to be controlled by the bulk of the substituents. Chelate formation is also pH dependent with low pH favouring a ring-operated structure due to protonation of the amine group. All the complexes formed were fully characterised by the use of ³¹P NMR and X-ray crystallography. Nucleotides are ideal model compounds for studying the interactions of platinum complexes with DNA, the target for platinum drugs <i>in vivo</i>. The aminophosphine complexes prepared were reacted with four different nucleotides and their binding analysed by ¹H NMR. Binding was most prominent to the nucleotides guanosine and thymidine. The complexes can bind two guanosine per Pt to form monofunctional adducts but with the other nucleotides only monofunctional binding was observed. The formation of these bound adducts was confirmed by electrospray ionisation mass spectrometry. The pH dependence of thymidine binding was investigated since binding occurs through the endocyclic N3 site which has a high pK_a of ca. 10. Although the extent of binding of the complexes decreased at low pH, the thymidine remained fully bound over an usually wide pH range 4-12. For the less sterically hindered complexes binding also decreased at low pH due to competition from chelate ring-closing reactions. Competition reactions were carried out with the complexes and all four nucleotides together to determine the selectivity of binding by capillary electrophoresis. Surprisingly thymidine binding was as prevalent as guanosine, this is in contrast to Pt-am(m)ine anticancer complexes which have a much higher affinity for the purine bases than pyrimidines.

In this thesis the biological activity and aqueous solution chemistry of half-sandwich Os¹¹ arene complexes of the type [(η⁶-arene)Os(XY)C1] is explored, and it is demonstrated that these properties can be tuned by careful choice of XY chelating ligand (N,N-, O,O- and N,O-chelates) to achieve cancer cytotoxicity comparable to carboplatin. The osmium complexes containing N,N-chelates hydrolyse more slowly than their ruthenium analogues and the p<i>K</i>_a of the resulting water is more acidic. Efforts to increase the rates of hydrolysis and the resulting p<i>K</i>_a led to replacement of the neutral N,N-chelating ligand by an anionic O,O-chelate. This was successful in that hydrolysis is more rapid and the p<i>K</i>_a of the coordinated water has increased by ca 0.8 units. However, these complexes are deactivated by formation of the inert and thermodynamically stable hydroxo-bridged dimers. Attempts to tune the stability of complexes containing XY = O,O-chelate, by replacing the 6-membered O,O-chelate with 5-membered analogues, was partially successful for the development of active complexes, but was unsuccessful in preventing hydroxo-bridged dimer formation. Within the class of N,N- and N,O-chelated complexes the choice of donor group is important. Replacing amine N-donor groups with the Π-acceptor pyridine, reduced both the rate of hydrolysis and p<i>K</i>_a or coordinated water, and increased the overall stability of the complex. This was especially the case for complexes containing N,O-chelates, which displayed aqueous chemistry in between that of the parent compounds containing neutral N,N-or anionic O,O-chelates. Within this group of osmium arene complexes, [(η⁶-arene)Os(N,O)C1], active cytotoxic complexes were obtained, and the first X-ray crystal structures of osmium bound to either G or A nucleobases is reported. This work shows that a wide range of reactivity can be obtained for complexes of the form [(η⁶-arene)Os(XY)C1]ⁿ⁺ by careful choice of the XY chelating ligand, and this knowledge has allowed complexes with cancer cell cytotoxicity to be designed.

The removal or killing of microorganisms on surfaces is of concern in the health care setting, food preparation areas and general work environment. The use of TiO2 photosterilisation has been proposed as an alternative to chemical disinfection of surfaces as a means to reduce the need for increasingly concentrated and aggressive chemicals necessary to kill disinfectant-resistant organisms. The objective of this research was to evaluate the ability of photocatalytic oxidation to reduce bacterial and viral contaminants on surfaces coated with TiOa and Ag-TiC^, TiO2-Ag, Cu-TiC^, TiO2-Cu. There are no British Standards that cover evaluation of such surfaces. A method for evaluation of photocatalytic surfaces was therefore developed from BS EN 13697:2001 and used to evaluate the activities of a variety of catalytic surfaces coated with TiO2, Ag and Cu and multi-layers of Ag-TiO2,TiO2-Ag, Cu-TiO2,TiO2-Cu. The antimicrobial activities were found to be dependent on the nature of the coating. Highest killing activities were obtained with Ag and Cu alone but combinations of Ag or Cu with TiO2were more active than TiO2 alone and also retained some self- cleaning activity. The results showed that the developed method was adaptable for determination of the antimicrobial activity of coatings with a wide range of activities producing 100% killing of Escherichia coll in times from 3 min up to 4 h. The results showed that it was possible to produce self cleaning self disinfecting surfaces and that surfaces with TiO2 on top, although having reduced activity compared to Ag or Cu, were durable and may have applications in the prevention of transmission of infections on surfaces in a wide range of applications.

This thesis reports on the formulation, characterisation and in-vitro release characteristics of oil-in-water microemulsions containing egg or soya lecithin, ethanol, isopropyl myristate and water. The use of lecithin as a surfactant in the formulation of pharmaceutical microemulsions has been discussed. The various techniques used for particle size determination and the application of microemulsions in drug delivery have been reviewed. Oil-in-water microemulsion regions were detected for systems containing egg or soya lecithin/isopropyl myristate/ethanol/water with continuous phases of 80%, 70% or 60% w/w aqueous ethanol. No microemulsion region could be detected for systems containing 50% w/w ethanol solution. The effect of ethanol content on the size of the microemulsion region has been discussed. Static and dynamic light scattering measurements have been carried out on microemulsions prepared with egg or soya lecithin. The droplet radius has been determined by analysis of the static light scattering data using the Percus- Yevick hard sphere model. There was a decrease in droplet radius with an increase in lecithin content within the microemulsion region. An increase in droplet radius with an increase in oil content and also with a decrease in ethanol content of the aqueous phase has been noted. No significant difference in results obtained for microemulsions prepared with egg or soya lecithin has been detected. A correction for hard sphere interactions was applied to the dynamic light scattering data. The variation of droplet size with changes in the formulation determined by analysis of the results from dynamic light scattering was similar to that from static light scattering. However, there was poor correlation between droplet radii obtained from these two techniques for identical formulations with the radii obtained from dynamic light scattering being generally lower. The effect of various formulation parameters, such as droplet size, oil, lecithin or ethanol content on the release of two model drugs (methylene 'violet (Bernthsen) and methylene blue) from microemulsions prepared with soya lecithin has been examined. In-vitro release has been studied by examining diffusion of the model drugs across a hydrophilic cellulose membrane separating the microemulsions from a receptor solution of aqueous ethanol. The results have been related to the partition coefficients of the dyes between isopropyl myristate and aqueous ethanol and the release of the dyes from aqueous ethanol solutions. An increase in the rate of release of both dyes from the microemulsions of soya lecithin/ isopropyl myristate/ethanol/water with a decrease in lecithin content has been noted. An increase in oil content and hence droplet size has been found to cause an increase in the rate of release of methylene violet (Bernthsen). The release rate of methylene blue increased with increase of oil content up to 20% oil but decreased with further increase of oil content due to the instability of these microemulsions under the experimental conditions. The release rate of both dyes was found to decrease as the lecithin content of the micro emulsions increased. Release of methylene violet (Bernthsen) decreased as the ethanol content increased, however the trend was reversed for the release of methylene blue. Viscosity studies showed Newtonian flow behaviour for all the micro emulsion formulations used for drug release studies. An increase in viscosity with an increase in oil or lecithin content or a decrease in ethanol content was noted.

The subject matter of this thesis is concerned with investigations into the synthesis of tricyclic heteropine systems. In particular Lewis acid-catalysed and carbanion-induced cyclisation reactions of suitably substituted isothiocyanate and carbodiimide derivatives were investigated for the synthesis of dibenzoxazepines, pyridobenxoxazepines, dibenzothiazepines, dibenzodiazepines and benzonapthoxazepines. These studies were also expanded to investigate the synthesis of benzoxazepinodibenzoxazepines and benzoxazepinobenzonapthoxazepines via the double-cyclisation of the appropriate bis-isothiocyanate derivatives. The description of the results obtained in these studies is preceded by a review on the use of tricyclic heteropine derivatives as chemotherapeutic agents in the areas of schizophrenia and Alzheimer's disease. The synthetic strategies currently available for the synthesis of tricyclic heteropines are also included in this review. It highlights the need for a flexible, widely applicable route to this class of compound and how the present studies could address this problem. The syntheses of the appropriate 2-isothiocyanatodiphenyl ether derivatives were readily accomplished, and in most cases their subsequent reaction with a Lewis acid catalyst resulted in the formation of the desired tricyclic heteropine. These compounds were also synthesised in high yield via a carbanion-induced cyclisation involving reaction of appropriate halogen derivatives with butyl lithium, the first examples of intramolecular carbanion addition to a heterocumulene. The attempted transition metal-mediated and radical -induced cyclisation of the isothiocyanate precursors, however, proved unsuccessful, with no formation of the desired tricyclic heteropine-system. The attempted functionalisation of the tricyclic heteropines, via thiomethylation of the thiolactam moiety and subsequent displacement of the thiomethyl-group, proved unsuccessful.