Polycyclic Polyprenylated Acylphloroglucinols (PPAPs) are a vast family of natural products, which includes more than 200 members. They contain a stunningly complex molecular architecture which in most cases includes a bicyclo[3.3.1]nonane core. PPAPs have been of interest to the scientific community for their intricate structure, their powerful aid in treating many ailments and large portfolio of biological activities. More particularly, they have been of synthetic interest since 1999 with the first report of an approach to these complicated cores by Nicolaou. Herein, we present the first total synthesis of papuaforin A, papuaforin B, papuaforin C, hyperforin and the formal synthesis of nemorosone following a report by Simpkins and co-workers. We relied on a gold(I)-catalyzed carbocyclization for the construction of the core of this family of natural products. Ginkgolides are isolated from the ginko tree, Ginkgo biloba, a living fossil with records of its existence dating back 280 million years. For centuries, the plant and its extracts have been used extensively for their beneficial properties, especially in China, Japan and India. For example, extract Egb761, one of the most potent fraction, generates over $500 million a year alone. The ginkgolides possess a truly unique compact diterpene framework of six 5-membered rings with a high content oxygen. Eleven oxygens can be found in ginkgolide C for a core containing only 23 carbons. The ginkgolides also include a very unique feature: a tert-butyl group located on the most convoluted ring system: the B ring. Few groups have found success in limning a synthetic route to ginkgolides. Corey’s group was the first to achieve the total synthesis of ginkgolide B in 1987. He was also able to complete ginkgolide A a year later. Crimmins and co-workers also achieved the total synthesis of ginkgolide B a decade later in 1999. Herein, we present our new approach toward ginkgolides through a newly developed methodology for the α-allylation of ketones and the creation of highly hindered contiguous quaternary centers. The synthesis is still at an early stage but a synthetic pathway giving access to the ring B with all the key moieties has been extensively investigated.

Understanding the electronic structure and dynamics of cyclic organic molecules is becoming increasingly the subject of investigations from different perspectives due to their unique chemical and physical properties. Since they are largely involved in the biochemistry of living organisms, studies on this class of compounds are also valuable to understand biologically relevant complex systems. Compared to other techniques, high-order harmonic generation (HHG) has been increasingly considered as a powerful spectroscopic tool with Angstrom spatial and attosecond temporal resolutions. This thesis demonstrates that high-order harmonic spectroscopy is capable of providing structural and dynamical information on the electronic systems of representative cyclic organic molecules comprising randomly oriented five-membered or six-membered rings. The first part of this thesis shows that the HHG from these molecules is sensitive to their aromatic character, which results from the de-localized pi electrons, and can potentially be a useful qualitative measure of aromaticity. We show that the advantage of utilizing HHG in this direction stems from the result that only pi molecular orbitals, associated with aromatcity, are responsible for the HHG emission in aromatic systems. The capability of HHG to distinguish cyclic isomers is demonstrated in the case of xylene molecules. Supported by numerical calculations, differences in the isomers are attributed to both tunnel ionization and photorecombination, the first and last steps of HHG. These results enable further HHG-based time-resolved studies of the dynamics associated with isomeric effects that these molecules exhibit. The present work also challenges the well-established prediction that strong field ionization from a molecular orbital is suppressed along nodal planes, where the electron density is zero. In fact, our study shows that considerable tunnel ionization in some cyclic molecules can occur near or along nodal planes. This unusual ionization is reported to have its signature on the quantitative and qualitative dependence of harmonic yield on laser ellipticity. The high symmetry displayed by the cyclic molecule, 1,4 cyclohexadiene, is shown to leave its imprints on the HHG in the form of structural interferences even if the target is randomly oriented. Two-color HHG from this molecule also indicates that hole dynamics could be involved in the generation process. A general study on high harmonic spectroscopy of the Cooper minimum in molecules is also reported. The presence of this minimum could affect the interpretation of harmonics spectra in any molecule containing S or Cl atoms. The molecular environment is shown to influence the position of this spectral modulation.

Cette étude se situe dans le contexte industriel de l’utilisation de superplastifiants pour la réalisation de bétons haute performance. Pour mieux comprendre le mode d’action des molécules fluidifiantes nous avons utilisé un système modèle constitué de suspensions de particules de carbonate de calcium l’une commerciale et constituée de microparticules et l’autre synthétisée au LPMC et constituée de nanoparticules. L’étude a porté sur cinq molécules organiques : quatre de type polyméthacrylates greffés polyoxyéthylène (PCP) avec des longueurs de greffons différentes et un diphosphonate polyoxyéthylène : OPTIMA100. La caractérisation des grandeurs pertinentes des fluidifiants comme leurs complexations vis-à-vis des ions ; leurs degré d’ionisation, leurs tailles, leurs affinités avec le solvant ou encore leurs capacités d’adsorption sur les surfaces a été effectuée. D’importantes différences d’efficacité de ces fluidifiants vis-à-vis de la rhéologie et de la sédimentation des deux types de suspension ont été mises en évidence. Ces différences de comportements on été interprétées grâce à la caractérisation effectuée sur les fluidifiants et à la modélisation des forces interparticulaires. / This study deals with the industrial context where the superplasticizers are used to manufacture the high performance cements. To better understand the action mode of plasticizing molecules, we used a model system which consists of calcium carbonate particles suspensions: in one hand, commercial microparticles suspension, and in the other hand, self synthesized nanoparticles suspensions. The study focuses on the use of five organic plasticizers: four types of polymethacrylates grafted polyoxyethylene (PCP) with different lengths of grafts, and a diphosphonate polyoxyethylene (OPTIMA100).Characterization of the plasticizers relevant parameters such as their complextation with the ions, their ionization degree, their size, their affinity with the solvent and their adsorption ability on the particles surfaces was performed. Significant differences in the effectiveness of these thinners regarding to the rheology and sedimentation of the two types of suspension were identified. These discrepancies in the behavior were interpreted by means of; the characterization performed on the thinners, and modeling of interparticle forces.

Cette thèse s’inscrit dans une thématique de recherche visant à synthétiser des moléculesamphiphiles présentant des propriétés bioactives, pouvant être mises à profit dans diversesapplications biomédicales ou encore dans le domaine de l’agrochimie. Les molécules amphiphilessont alors les propres actrices de leur formulation de par leurs propriétés d’auto-association et debioactivité (concept dit « d’économie moléculaire »). Dans ce contexte, la première partie de cetravail a été consacrée à la synthèse de molécules amphiphiles modèles dérivées de D-glucose etde N-acétyl-D-glucosamine. La voie de synthèse choisie pour les obtenir a été une aminationréductrice régiosélective à partir de chaînes alkylamine de différentes longueurs (6, 12 et 16atomes de carbone). Leur caractérisation a été réalisée par RMN et spectrométrie de masse. Ladeuxième partie de ce travail a été orientée vers l’étude du comportement auto-associatif desmolécules à base de D-glucose en solution aqueuse, seules, ou en mélange avec un phospholipidemodèle. Une organisation à différentes échelles de taille a été mise en évidence par les techniquesde diffusion de la lumière, microscopie électronique en transmission et grâce à la modélisation dedonnées expérimentales obtenues en diffusion des rayons X aux petits angles. / This work is part of a research program on the synthesis of amphiphilic molecules havingbioactive properties, which could be used in biomedical applications or in agrochemistry.Amphiphilic molecules could be the own actor of their formulation because of the dual propertyof bioactivity and self-assembly. In this context, the first part of this work concerns the synthesisof model amphiphilic molecules derived from D-glucose and N-acetyl-D-glucosamine. The chosenway to synthesize these molecules was a regioselective reductive amination from alkylaminechains of different lengths (6, 12 and 16 carbon atoms). Compounds were characterized by NMRand Mass Spectrometry. The second part of this work was oriented towards the study of the selfassemblyproperties of molecules derived from D-glucose in an aqueous solution, alone, or mixedwith a model phospholipid. An organization with different sizes was shown with severaltechniques: light diffusion, transmission electronic microscopy, and thanks to the establishment ofa model from experimental small-angle X-ray scattering data. When the amphiphilic moleculewith 12 atoms of carbon on this hydrocarbonated chain is studied alone in a solution, ellipsoidalmicelles seem to be present, mixed with bigger aggregates (~100 nm). However, when this sameamphiphilic molecule is used in a mix with a model phospholipid, a size diminution of theassembly was observed with the increase of amphiphilic molecules in the formulations.

Force field methods are used to investigate the properties of a wide variety of chemical systems on a routine basis. The expression for the electrostatic energy typically does not take into account the anisotropic nature of the atomic electron distribution or the dependence of that distribution on the system geometry. This has been suggested as a cause of the failure of force field methods to reliably predict the behaviour of chemical systems. A method for incorporation of anisotropy and polarisation is described in this work. Anisotropy is modelled by the inclusion of multipole moments centred at atoms whose values are determined by application of the methods of Quantum Chemical Topology. Polarisation, the dependence of the electron distribution on system geometry, is modelled by training machine learning models to predict atomic multipole moments from knowledge of the nuclear positions of a system. The resulting electrostatic method can be implemented for any chemical system. An application to progressively more complex systems is reported, including small organic molecules and larger molecules of biological importance. The accuracy of the method is rigorously assessed by comparison of its predictions to exact interaction energy values. A procedure for generating transferable atomic multipole moment models is defined and tested. The electrostatic method can be combined with the empirical expressions used in force field calculations to describe total system energies by fitting parameters against ab initio conformational energies. Derivatives of the energy are given and the resulting multipolar polarisable force field can be used to perform geometry optimisation calculations. Future applications to conformational searching and problems requiring dynamic descriptions of a system are feasible.

We present the results of a program to map the Sh2-235 molecular cloud complex in the CO and (CO)-C-13 J = 2 - 1 transitions using the Heinrich Hertz Submillimeter Telescope. The map resolution is 38 '' (FWHM), with an rms noise of 0.12K brightness temperature, for a velocity resolution of 0.34 km s(-1). With the same telescope, we also mapped the CO J = 3 - 2 line at a frequency of 345 GHz, using a 64 beam focal plane array of heterodyne mixers, achieving a typical rms noise of 0.5 K brightness temperature with a velocity resolution of 0.23 km s(-1). The three spectral line data cubes are available for download. Much of the cloud appears to be slightly sub-thermally excited in the J = 3 level, except for in the vicinity of the warmest and highest column density areas, which are currently forming stars. Using the CO and (CO)-C-13. J = 2 - 1 lines, we employ an LTE model to derive the gas column density over the entire mapped region. Examining a 125 pc(2). region centered on the most active star formation in the vicinity of Sh2-235, we find that the young stellar object surface density scales as approximately the 1.6-power of the gas column density. The area distribution function of the gas is a steeply declining exponential function of gas column density. Comparison of the morphology of ionized and molecular gas suggests that the cloud is being substantially disrupted by expansion of the H II regions, which may be triggering current star formation.

Two aluminum spherical mirrors with radii of 203.2 mm and radii of curvature also of 203.2 mm have been used to construct a tunable Fabry-Perót type resonator operational at frequencies as low as 500 MHz. The resonator has been incorporated into a pulsed nozzle, Fourier transform, Balle-Flygare spectrometer. The spectrometer is of use in recording low J transitions of large asymmetric molecules where the spectra are often greatly simplified compared to higher frequency regions. The resonators use is illustrated by recording the rotational spectra of bromobenzene and iodobenzene. In related experiments, using similar equipment, the pure rotational spectra of four isotopomers of SrS and all three naturally occurring isotopomers of the actinide-containing compound thorium monoxide have been recorded between 6 and 26 GHz. The data have been thoroughly analyzed to produce information pertaining to bond lengths and electronic structures.

Most studies on innate immunity in ticks have focused on the antimicrobial peptides from hemolymph, such as defensins and lysozyme, while less is known about bacterial recognition molecules, or antimicrobial mechanisms in other tissues. The current study attempted to identify novel antimicrobial mechanisms, with a focus on bacterial recognition by hemolymph proteins and antimicrobial activity in salivary gland extracts. Using bacteria as affinity beads, two high molecular mass molecules (Protein X and Protein Y) have been identified in tick hemolymph. These proteins are thought to interact with the bacterial surface via ionic interactions. Tandem mass spectrometry analysis followed by de novo sequencing indicated that these proteins are novel as no homologs could be identified from sequence databases. In an attempt to clone Protein X, using a degenerate primer obtained from a de novo sequence, an unrelated hemocyte protein was identified. This protein, named savicalin, was shown to belong to the lipocalin family based on bioinformatical analysis. Transcriptional profiling indicated that savicalin is found in hemocytes, midgut and ovaries, but not in the salivary glands. To date, this is the first tick lipocalin not derived from salivary glands. Interestingly, up-regulation of its mRNA transcript in response to bacterial challenge suggests that this protein could be involved in antimicrobial activity. Up-regulation after feeding also suggests a role in the post-feeding development of the tick. Two different approaches were used to purify the Gram-positive antibacterial activity from salivary gland extracts. The first attempt entailed a two-step separation approach. Tricine SDS-PAGE of the active fraction showed 3 components (~20, ~10 and ~7 kDa). BLAST searches using the N-terminal sequences of the latter proteins identified the ~20 kDa protein as savignin, while the other two proteins could not be matched. The second strategy included an ultrafiltration step (10 kDa cut-off) and MS-analysis of the active fraction in this case indicated the presence of various components with molecular masses ranging from 0.99 – 7.182 kDa, with 12 predominant components ranging from 0.99 - 4.448 kDa. Further tandem mass spectrometry analysis of the active fraction revealed the presence of three tick actin-derived fragments. This is of interest as actin fragments have been implicated in innate immunity of other invertebrates. In this study, synthetic peptides corresponding to one of the detected tick actin fragments as well as actin5C (detected in Drosophila hemolymph) were found not to inhibit the growth of Bacillus subtilis when tested up to a concentration of 100 ìg/ml. It is envisaged that future studies of immunoprotective molecules of the tick, O. savignyi, may contribute to the development of novel anti-infective agents and potential targets for anti-tick vaccine design. / Thesis (PhD)--University of Pretoria, 2011. / Biochemistry / unrestricted

Please read the abstract in the section 00front of this document / Thesis (PhD (Geneeskundige Immunologie))--University of Pretoria, 2005. / Pharmacology / unrestricted

Orientadores: Fernando Ferreira Costa, Nicola Conran / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-07T10:27:56Z (GMT). No. of bitstreams: 1 Gambero_Sheley_M.pdf: 2005109 bytes, checksum: faec483bdfe41c20b920e16808d8eb59 (MD5) Previous issue date: 2006 / Resumo: A anemia falciforme é um distúrbio genético da hemoglobina causado por uma mutação de ponto produzindo hemoglobina S (HbS) que quando desoxigenada causa, entre outros sintomas, eventos vaso-oclusivos. Um dos mecanismos indicados como causador da vaso-oclusão é a adesão de hemácias falciformes ao endotélio dos vasos. Eritrócitos falciformes e normais aderem ao endotélio vascular utilizando moléculas de adesão como, CD 36 e integrina VLA-4, entre outras moléculas de adesão. Hidroxiuréia (HU) é um agente quimioterápico que diminui a freqüência de crises vaso-oclusivas, síndrome torácica aguda e necessidade de transfusão. Longos tratamentos com HU levam a uma redução global das proteínas de superficie dos neutrófilos, monócitos e linfócitos, além de aumentar os níveis de Hemoglobina fetal (Hb F), que inibe a polimerização da célula falciforme desoxigenada. O NO é um importante vaso-dilatador responsável por inúmeros efeitos benéficos durante as crises vaso-oclusivas. Estudos demonstram que o NO pode diminuir a expressão endotelial de moléculas de adesão, mas estudos diretos sobre os níveis de expressão dessas moléculas em anemia falciforme na presença de NO não tem sido encontrados na literatura. Deste modo objetivamos neste trabalho, analisar a expressão, gênica e protéica, e a função das moléculas de adesão VLA-4 (CD49d ou cadeia a. e CD29 ou cadeia 13) e CD 36 em células vermelhas de pacientes com anemia falciforme com e sem terapia com HU e os efeitos do tratamento in vitro com HU e agentes doadores de NO na adesão dessas células. Analisando a adesão das células vermelhas normais e de pacientes com e sem terapia com HU confirmamos que as células vermelhas de pacientes falciformes são mais aderentes que as células vermelhas normais e que a terapia com HU provoca uma diminuição dessa aderência. A citometria de fluxo comprovou a maior presença de células CD36+ e CD49d+ além de maior índice de expressão dessas moléculas nos pacientes falciformes em relação ao controle e a diminuição da expressão e positividade dessas moléculas em células de pacientes em terapia com HU quando comparadas com pacientes sem terapia. Adicionalmente, a análise por Real Time PCR demonstrou que a expressão gênica de CD36, CD49d e CD29 em reticulócitos falciformes é significativamente menor em pacientes em terapia com HU quando comparado com pacientes que não recebem essa terapia. Em resumo, nossos resultados sugerem que: as propriedades adesivas à fibronectina (FN) são aumentadas em células SS e que estas propriedades diminuem nos pacientes que tomam a terapia de HU; a terapia com HU diminui a expressão protéica e a positividade, das células vermelhas falciformes, hemácias e células jovens, para os receptores CD36 e CD49d; e a expressão gêniea das moléculas de adesão CD36 e CD49d em reticulócitos de pacientes com anemia falciforme que recebem terapia com HU é diminuída em relação ao grupo de pacientes falciformes que não recebem essa terapia / Abstract: Sickle cell vaso-occlusion constitutes a complex process involving interactions between SS red blood cells (RBC), endothelial cells, leukocytes, platelets, coagula tive factors and plasma proteins. Propagation ofthe vaso-occlusive process in sickle cell anemia (SCA) is a complex process involving the adhesion of SS red cells and reticulocytes to the vascular endothelium. The effect of hydroxyurea therapy (HUT) on the adhesive properties of sickle red cells and the expression of adhesion molecule genes by erythroid cells of SCA individuals is not yet fully understood. The expressions of the CD36 gene and the VLA-4 integrin subunit genes, CD49d (a-subunit) and CD29 (J3-subunit), were compared in the reticulocytes of steady-state SCA patients and patients on HUT using Real-Time PCR Basal adhesion of red cells ftom these subjects was also compared using static adhesion assays, as was surface protein expression, using flow cytometry. Basal sickle red cell adhesion to fibronectin was significantly greater than that of normal cells (P<O.OI); in contrast, HUT significantly decreased (P<O.OI) red cell adhesion to levels similar to those of control cells and this decrease could not be justified solely by alterations in reticulocyte numbers in this population. Accordingly, flow cytometry demonstrated that HUT significantly decreased CD36 and CD49d surface expression (P<O.Ol) and, importantly, significant reductions in the expressions of the CD36, CD49d and CD29 genes were seen (P<O.O5) in the reticulocytes of SCA patients on HU. Taken together, data support the hypothesis that HUT reduces the adhesive properties of sickle cells and that this decrease appears to be mediated, at least in part, by a decrease in the gene and, consequently, surface protein expression of adhesion molecules such as VLA-4 and CD36 / Mestrado / Patologia Clinica / Mestre em Ciências Médicas