From the dichloromethane-methanol (1:1) extract of the seed pods of Derris trifoliata, a new flavanone derivative (S)-lupinifolin 4´-methyl ether was isolated. In addition, the known flavonoids lupinifolin and rotenone were identified. The structures were determined on the basis of spectroscopic evidence. Lupinfolin showed moderate in vitro antiplasmodial activity against the D6 (chloroquine-sensitive) and W2 (chloroquineresistant) strains of Plasmodium falciparum. The different parts of this plant showed larvicidal activities against Aedes aegypti and rotenoids were identified as the active principles.

The focus of the present work is on the empirical characterization and modeling of ignition trends of ternary blends of three distinct hydrocarbon classes, namely a methyl ester (C9H18O2), a linear alkane (n-C9H20), and a cycloalkane (MCH). Numerous surrogate biofuel formulations have been proposed in the literature, yet specific blending of these species has not been studied. Moreover, the effects of blending biofuel compounds with conventional hydrocarbons are not widely studied and a further point is the lack of studies paying specific attention to the effects of fuel variation within a given blended biofuel. To this end, a statistical Design of Experiments L9 array, comprised of 4 parameters (%MO, %MCH, pressure, and equivalence ratio) with 3 levels of variation, constructed in order to systematically study the effects of relative fuel concentrations within the ternary blend enabled variations in fuel concentration for methyl octanoate and MCH of 10% - 30% and 20% - 40%, respectively. Variation in pressure of 1 atm, 5 atm, and 10 atm and in equivalence ratio of 0.5, 1.0, and 2.0 were used, respectively. The fuel-volume percentage of n-nonane varied from 30% - 70%. In total, 10 ternary blends were studied. Ignition delay times for the ternary blends and for the three constituents were obtained by monitoring excited-state OH or CH transitions, A2Epsilon+ -> X2Pi or A2Delta -> X2Pi, respectively, behind reflected shock waves using a heated shock tube facility. Dilute conditions of 99% Ar (vol.) were maintained in all shock tube experiments with the exception of a separate series of n-nonane and MCH experiments under stoichiometric conditions which used 4% oxygen (corresponding to ~ 95% Ar dilution). Temperatures behind reflected shock waves were varied over the range 1243 < T (K) < 1672. From over 450 shock tube experiments, empirical ignition delay time correlations were constructed for all three pure fuels and a master correlation equation for the blended fuels. Ignition experiments conducted on the pure fuels at 1.5 atm indicated the following ignition delay time order, from shortest to longest: methyl octanoate < n-nonane < MCH. With increased pressure to 10 atm (nominal) the order remained, in general, consistent. Under fuel-lean conditions, ignition trends between methyl octanoate and n-nonane exhibited overlap at temperatures below 1350 K, below which the trends diverged with methyl octanoate having shorter ignition delay times. Similar behavior was observed under fuel-rich conditions, yet with the overlap occurring above 1450 K. Stoichiometric ignition trends did not display overlapping behavior under either 1.5 atm or 10 atm pressure. Laminar flame speed measurements were performed at 1 atm and an initial temperature of 443 K on the pure fuel constituents. Additional flame speed measurements of MCH were conducted at 403 K to compare with literature values and were shown to agree strongly with experiments conducted in a constant-volume apparatus. The experiments conducted herein, for the first time, measure laminar flame speeds methyl octanoate. A detailed chemical kinetics mechanism was compiled from three independent, well-validated models for the constituent fuels, where the sub-mechanisms for methyl octanoate and MCH were extracted for integration into a base n-nonane model. The compiled mechanism in the present study (4785 reactions and 1082 species) enables modeling of oxidation processes of the ternary fuel blends of interest. Calculations were performed using the compiled model relative to the base models to assess the impact of utilizing different base chemistry sets. In general, results were reproduced well relative to base models for both n-nonane and MCH, however results for methyl octanoate from both the compiled model and the base model are in disagreement with the results measured herein. Ignition delay times of the fuel blends are well-predicted for several conditions, specifically for blends at lean/high-pressure and stoichiometric/high-pressure conditions, however are not accurately modeled at fuel-rich, high-pressure conditions.

The Baltic Sea was earlier identified as a highly polluted brackish water body and still is. The high concentrations of polychlorinated biphenyls (PCBs), p,p’-DDT and related compounds led to severe effects on several species in the Baltic region. However, the situation has improved significantly since the 1970’s resulting in lower exposures to a range of pollutants and healthier wildlife populations. Independent of this positive trend there are still new chemicals leaking into the Baltic Sea environment. The objective of this thesis is to improve the knowledge of sulfone containing compounds and pollutant metabolites in wildlife, with special interest in bis(4-chlorophenyl) sulfone (BCPS) distribution, temporal trend and exposure levels, and the methylsulfonyl-PCBs (MeSO2-PCBs). The latter are of particular interest for chiral MeSO2-PCBs. BCPS is used for the production of high temperature polymers and was detected as an environmental contaminant ten years ago. PCBs, p,p’-DDT and related compounds are still of scientific interest. BCPS is biomagnified and especially in the bird guillemot which has levels of up to 2000 ng BCPS/g fat compared to the grey seal with concentrations of about 60 ng/g fat. The seal levels are similar to the herring, the prey of the bird and seal, with concentrations of 30 ng BCPS/g fat. The guillemot concentration of BCPS has been similar over the last 30 years with a minimal, but significant, annual decline of 1.6%. The reason for the slow decline is not yet understood. Also MeSO2-PCBs and 3-MeSO2-DDE show a small decrease over time in guillemot egg (3 and 9%, respectively), which is less then for the parent compounds. This shows that the sulfone metabolites are more persistent than their precursors in the guillemot. Furthermore, all these sulfone containing compounds showed a specific retention to liver comparing different tissues in grey seal. The atropisomers of the chiral MeSO2-PCB were analysed in both the guillemot and the grey seal and showed to occur in a skewed relationship. This is particularly pronounced in seals where one atropisomer of each chiral congener is very dominating. The dominating atropisomers have been identified with an absolute R configuration, in both grey seal and guillemot. An enantioselective metabolism was indicated to occur when experimentally tested by CB-132 in rat. This thesis is stressing the high specificity in wildlife for one atropisomer in the pair of chiral PCB methyl sulfones being PCB metabolites, and the high BCPS concentrations in guillemot hatching in the Baltic proper.

This thesis is based on three inter-related studies: the first part deals with the microbial consortium, the identification of microbes and their volatiles, the second part deals with the study of bio-chemical control methods of two conifer pests; the pine weevil Hylobius abietis (L.) and the root rot fungi Heterobasidion spp., and the third part describes the production of styrene by a fungus using forest waste.The large pine weevil (Hylobius abietis L.) is an economically important pest insect of conifers in reforestation areas of Europe and Asia. The female weevils protect their eggs from feeding conspecifics by adding frass (mixture of weevil feces and chewed bark) along with the eggs. In order to understand the mechanism behind frass deposition at the egg laying site and to find repellents/antifeedants for pine weevils, microbes were isolated from the aseptically collected pine weevil frass. Microbial produced volatile organic compounds (VOCs) were collected by solid phase micro extraction and analyzed by GC-MS after cultivating them on weevil frass broth. The major VOCs were tested against pine weevils using a multi-choice olfactometer. Ewingella sp., Mucor racemosus, Penicillium solitum, P. expansum, Ophiostoma piceae, O. pluriannulatum, Debaryomyces hansenii and Candida sequanensis were identified as abundant microbes. Styrene, 6-protoilludene, 1-octene-3-ol, 3-methylanisole, methyl salicylate, 2-methoxyphenol and 2-methoxy-4-vinylphenol were the VOCs of persistently isolated microbes. In behavioral bioassay, methyl salicylate, 3-methylanisole and styrene significantly reduced the attraction of pine weevils to their host plant volatiles. Heterobasidion spp. are severe pathogenic fungi of conifers that cause root and butt rot in plants. Bacterial isolates were tested for the antagonistic activity against fungi on potato dextrose agar. Bacillus subtilis strains significantly inhibited the growth of H. annosum and H. parviporum. Styrene is an industrial chemical used for making polymeric products, currently produced from fossil fuel. A strain of Penicillium expansum isolated from pine weevil frass was investigated for the production of styrene using forest waste. Grated pine stem bark and mature oak bark supplemented with yeast extract produced greater amounts of styrene compared to potato dextrose broth. / <p>QC 20130507</p>

Les protéines à " Methyl-CpG-binding domain " (MBD) jouent un rôle important dans l'interprétationde la méthylation de l'ADN conduisant à la répression transcriptionnelle via le recrutement decomplexes remodelant la chromatine. Dans les cancers, MBD2 jouerait un rôle essentiel dans la perted'expression des gènes hyperméthylés. Ainsi, MBD2 serait une cible potentielle pour rétablir, enpartie au moins, leur expression. Caractériser, à l'échelle du génome, la distribution de MBD2 et sesconséquences sur la répression transcriptionnelle au cours de la cancérogenèse est donc une étapeincontournable. (1) L'impact sur l'expression génique de l'inhibition de MBD2 par interférence àl'ARN, a été étudié en utilisant des puces, dans des cellules normales MRC5. La perte de MBD2n'induit pas de surexpression génique globale et la densité en CpG des promoteurs méthylés sembleêtre une composante importante dans la force de répression par MBD2. (2) Les profils de méthylationde l'ADN, de liaisons de MBD2 et de l'ARN polymérase II dans les cellules HeLa ont été analysés parChIP-on-chip avec des puces promoteurs. Ces mêmes approches couplées à l'analyse de l'acétylationdes histones H3 ont été réalisées dans un modèle cellulaire syngénique de progression tumoralemammaire humain. Dans les modèles étudiés, une forte proportion de gènes silencieux et méthylés estliée par MBD2. Les comparaisons entre cellules immortalisées et transformées ne montrent pas dechangements majeurs de la méthylation de l'ADN ou de la répression transcriptionnelle, par contreune redistribution de MBD2 parmi ces sites est observée, suggérant une redondance entre les protéinesliant l'ADN méthylé.

The Angiotensin II Type 1 (AT1) receptor is the main receptor responsible for the effects of the renin-angiotensin system, and its expression pattern is altered in several diseases. [11C]Methyl-Losartan has been developed based on the clinically used AT1 receptor antagonist Losartan. The aim of this work is to characterize the pharmacokinetics, repeatability and reliability of measurements, binding specificity and selectivity of [11C]Methyl-Losartan in rats using in vivo small animal positron emission tomography (PET) imaging, ex vivo biodistribution and in vitro autoradiography methods. Also, we aim to measure the presence of metabolites in the kidney and plasma using high-performance liquid chromatography. We have demonstrated in vivo that [11C]Methyl-Losartan is taken up in the AT1 receptor-rich kidneys and that it is displaceable by selective AT1 receptor antagonists. Using ex vivo biodistribution, we have confirmed these results and demonstrated that [11C]Methyl-Losartan binds selectively to the AT1 receptor over the AT2, Mas and β-adrenergic receptors. In vitro autoradiography results confirmed these renal binding selectivity studies. [11C]Methyl-Losartan was also shown to have one and two C-11 labeled metabolites in the plasma and kidneys, respectively. In conclusion, [11C]Methyl-Losartan is a promising agent for studying the AT1 receptor in rat models with normal and altered AT1 receptor expression using small animal PET imaging.

Cardiac hypertrophy is a compensatory response to increased work load or stress on the heart, but over time can lead to heart failure and death. The molecular mechanisms underlying this disease are still not completely understood, however the Rho/Rho kinase pathway has been shown to play a role. N-[11C]-methyl-hydroxyfasudil, a PET radiotracer, binds to active Rho kinase and could be a possible tracer for hypertrophy. Hypertrophy was induced in vitro using the β-adrenergic receptor agonist isoproterenol to evaluate optimal Rho kinase activity. Rho kinase activity data was correlated to N-[11C]-methyl-hydroxyfasudil binding. Cardiac hypertrophy was verified with an increase in nuclear size (1.74 fold) and cell size (~2 fold), activation of hypertrophic signalling pathways, and increased Rho kinase activity (1.64 fold). This correlated to a 10.3% increase in N-[11C]-methyl-hydroxyfasudil binding. This data suggests that N-[11C]-methyl-hydroxyfasudil may be useful as a radiotracer for detecting cardiac hypertrophy and merits further in vivo investigation.

<p>The production of biodiesel (methyl esters) from vegetable oils represents analternative means of producing liquid fuels from biomass, and one which is growing rapidly in commercial importance and relevance due to increase in petroleum prices and the environmental advantages the process offers. Commercially, biodiesel is produced from vegetable oils, as well as from waste cooking oils and animal fats. These oils are typically composed of C14-C20 fatty acid triglycerides. In order to produce a fuel that is suitable for use in diesel engines, these triglycerides are usually converted into the respective mono alkyl esters by base-catalyzed transesterification with short chain alcohol, usually methanol. In the first part of this study, the transesterification reactions of three different vegetable oils / sunflower (SFO), soybean (SBO) and waste cooking oil (WCO) with methanol was studied using potassium hydroxide as catalyst in a conventional batch process. The production of biodiesel from waste cooking oil was also studied via continuous operation systems (employing the use of low frequency ultrasonic technology and the jet loop reactor). The characterisation of the feedstock used and the methyl ester products were determined by different analytical techniques such as gas chromatography (GC), high performance liquid chromatography (HPLC) and thin layer chromatography (TLC). The effects of different reaction parameters (catalyst amount, methanol to oil ratio, reaction temperature, reaction time) on methyl ester/FAME yield were studied and the optimum reaction conditions of the different process systems were determined. The optimum reaction conditions for production of methyl esters via the batch process with the fresh oil samples (SFO and SBO) were established as follows: a reaction time of 60 min at 60 &ordm / C with a methanol: oil ratio of 6:1 and 1.0 KOH % wt/wt of oil / while the optimum reaction conditions for the used oil (WCO) was observed at a reaction time of 90 min at 60 &ordm / C, methanol: oil ratio of 6:1 and 1.5% KOH wt/wt of oil. The optimum reaction conditions for the transesterification of the WCO via ultrasound technology applied in a continuous system in this study were: a reaction time of 30 min, 30 &ordm / C, 6:1 methanol/oil ratio and a 0.75 wt% (KOH) catalyst concentration. The ultrasound assisted transesterification reactions performed at optimum conditions on the different oil samples led to higher yields of methyl esters (96.8, 98.32 and 97.65 % for WCO, SFO and SBO respectively) compared to methyl esters yields (90, 95 and 96 % for WCO, SFO and SBO respectively) obtained when using conventional batch procedures. A considerable increase in yields of the methyl esters in the ultrasound assisted reaction process were obtained at room temperature, in a remarkably short time span (completed in 30 min) and with a lower amount of catalyst (0.75 wt % KOH) while the results from the continuous jet loop process system showed even better results, at an optimum reaction condition of 25 min of reaction, a methanol: oil ratio of 4:1 and a catalyst amount of 0.5 wt%. This new jet loop process allowed an added advantage of intense agitation for an efficient separation and adequate purification of the methyl esters phase at a reduced time of 30 min. The use of homogeneous catalysts in conventional processes poses many disadvantages / heterogeneous catalysts on the other hand are attractive on the basis that their use could enable the biodiesel production to be more readily performed as a continuous process resulting in low production costs. Consequently, a solid base catalyst (KNO3/FA) prepared from fly ash (obtained from Arnot coal power station, South Africa) and a new zeolite, FA/Na-X synthesized from the same fly ash were used as solid base catalysts in the transesterification reactions in the conversion of a variety of oil feedstock with methanol to methyl esters. Since fly ash is a waste product generated from the combustion of coal for power generation, its utilization in this manner would allow for its beneficiation (as a catalytic support material and raw material for zeolite synthesis) in an environmentally friendly way aimed at making the transesterification process reasonably viable. Arnot fly ash (AFA) was loaded with potassium (using potassium nitrate as precursor) via a wet impregnation method while the synthesized zeolite FA/Na-X was ion exchanged with potassium (using potassium acetate as precursor) to obtain the KNO3/FA and FA/K-X catalysts respectively. Several analytical techniques were applied for characterization purposes. The results of the XRD and XRF showed that the AFA predominantly contained some mineral phases such as quartz, mullite, calcite and lime. The high concentration of CaO in AFA was apparent to be beneficial for the use of fresh fly ash as a support material in the heterogeneous catalysed transesterification reactions. XRD characterisation of KNO3/FA results indicated that the structure of KNO3/FA gradually changed with the increase in KNO3 loading. The catalyst function was retained until the loading of KNO3 was over 10 %. IR spectra showed that the KNO3 was decomposed to K2O on the fly ash support during preparation at a calcination temperature of 500 &ordm / C. The CO2-TPD of the KNO3/FA catalysts showed that two basic catalytic sites were generated which were responsible for high catalytic abilities observed in the transesterification reactions of sunflower oil to methyl esters. On the other hand, XRD results for the as- received zeolite synthesized from AFA showed typical diffraction peaks of zeolite NaX. SEM images of the FA /NaX showed nano platelets unique morphology different from well known pyramidal octahedral shaped crystal formation of faujasite zeolites and the morphology of the FA /KX zeolite did not show any significant difference after ion exchange. The fly ash derived zeolite NaX (FA /NaX) exhibited a high surface area of 320 m2/g. The application of the KNO3/FA catalysts in the conversion reactions to produce methyl esters (biodiesel) via transesterification reactions revealed methyl ester yield of 87.5 % with 10 wt% KNO3 at optimum reaction conditions of methanol: oil ratio of 15:1, 5 h reaction time, catalyst amount of 15 g and reaction temperature 160 &deg / C, while with the use of the zeolite FA/K-X catalyst, a FAME yield of 83.53 % was obtained for 8 h using the ion exchanged Arnot fly ash zeolite NaX catalyst (FA/KX) at reaction conditions of methanol: oil ratio of 6:1, catalyst amount of 3 % wt/wt of oil and reaction temperature of 65 &ordm / C. Several studies have been carried out on the production of biodiesel using different heterogeneous catalysts but this study has been able to uniquely demonstrate the utilization of South African Class F AFA both as a catalyst support and as a raw material for zeolite synthesis / these catalyst materials subsequently applied sucessfully as solid base catalysts in the production of biodiesel.</p>

MosA is a protein found in <i>Sinorhizobium meliloti</i> L5-30 and has been suggested to be responsible for the biosynthesis of the rhizopine 3-O-methyl-scyllo-inosamine (3-MSI) from scyllo-inosamine (SI). However, we have shown MosA is a dihydrodipicolinate synthase (DHDPS) catalyzing the condensation of pyruvate with aspartate-β-semialdehyde (ASA). Since the DHDPS reaction occurs through a Schiff base aldol-type mechanism it was proposed that MosA could be an O-methyltransferase utilizing 2-oxo-butyrate (2-OB) as a novel methyl donor. This interesting yet unlikely possibility would explain MosA's role in the biosynthesis of 3-MSI without ignoring its similarity to DHDPS. Alternatively, MosA may have two catalytic domains one of which possesses a novel binding motif for S-Adenosyl methionine (SAM) to account for methyltransfer activity. In vitro demonstration of MosAs methyltransferase activity is required to resolve this apparent contradiction.<p>This dissertation describes the chemical synthesis of the rhizopines, investigation into whether MosA has a direct role in rhizopine biosynthesis and the thermodynamic characterization of compounds interacting with MosA as observed by isothermal titration calorimetry. <p>Initial investigation into MosAs methyltransferase activity began with 2-OBs interaction with the enzyme. Inhibition experiments determined 2-OB is a competitive inhibitor with respect to pyruvate of the DHDPS reaction of MosA. Furthermore, protein mass spectrometry of MosA in the presence of 2-OB and sodium borohydride indicated that a Schiff base enzyme intermediate was indeed being formed providing evidence that the proposed mechanism may exist. However, neither of the rhizopines had any effect on the DHDPS activity and HPLC assays determined that no 3-MSI was being produced by MosA in the presence of SI and 2-OB. Furthermore, HPLC assays failed to detect methyl transfer activity by MosA utilizing the SAM as a methyl donor. <p>Isothermal titration calorimetry provided thermodynamic characterization of the pyruvate and 2-OB Schiff base intermediates formed with MosA. In addition, ITC provided insight into the nature and thermodynamics of (S)-lysines inhibition of MosA. ITC failed to detect any interactions between the rhizopines or SAM with MosA. These results indicate that MosA is only a DHDPS and does not catalyze the formation of 3-MSI from SI as hypothesized in the literature.

Mesoporous silica materials containing microporous cavities provided by covalently bound ¦Â-cyclodextrin (CD ICS) were synthesized by co-condensation of a ¦Â-CD functionalized triethoxy silane (CD ICL) with tetraethyl orthosilicate (TEOS) by using neutral amine surfactants as structure directing agents (SDA). CD ICL was prepared by reacting ¦Â-CD with 3-isocyanatopropyltriethoxysilane. IR spectroscopy of CD ICL showed complete disappearance of isocyanato group at 2270 cm-1. 1H NMR results indicate an average of four isocyanate linkers covalently attached to random hydroxyl substituents of each molecule of ¦Â-CD. <p> Nine different CD ICS materials were synthesized using dodecylamine, tetradecylamine or hexadecylamine with ¦Â-CD (2, 4, and 6 mol %) with respect to TEOS. The incorporation of ¦Â-CD within the mesoporous framework was supported by IR, Raman, MALDI TOF MS, solid state 13C NMR CP-MAS and TGA results. Small angle X-ray diffraction results showed a peak at 2¦È ¡Ö 2.20, supporting the presence of an ordered silica mesostructure framework. For materials with same CD loading, the surface area and pore volume doubled as the surfactant from dodecylamine to hexadecylamine. However, as the CD loading increased from 2% to 6%, the surface area decreases by a factor of ~ 1.5. <p>MALDI TOF mass spectrometry showed two peaks at m/z 1157 a.m.u. and 1173 a.m.u. for [¦Â-CD + Na]+ and [¦Â-CD + K]+ respectively due to desorption of ¦Â-CD from the walls of the silica matrix. The 13C NMR CP MAS results showed 13C signals in the region ¦Ä=60-110 ppm due to the nuclei of ¦Â-CD. CD ICS materials were found to be effective as a sorbent in both gas and aqueous phases, respectively. The sorption capacity (mmol/g) of p-nitrophenol increased from 61% to 84% with an increase of CD loading from 2% to 6% and as the alkyl chain length of the SDA increases from dodecylamine to hexadecylamine. The adsorption isotherm of CH3Cl in the gas phase and that of p-nitrophenol in the aqueous phase at ambient temperature adopts a multilayer model of adsorption.