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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Physico-chemical characterization of African traditional cosmetics produced by the Ovahimba tribes of Northern Namibia

Molefe, Ontibile January 2015 (has links)
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2015. / Ovahimba people from Kunene region, northern Namibia, are known for covering their bodies with red ochre mixed with clarified butterfat, traditionally known as otjize to give them a distinct red appearance. Ochre refers to a clay-like earth pigment which contains some form of iron-containing mineral. A mixture of traditional herbs with clarified butterfat, otjizumba, is also applied around the necks as a perfume. This study was prompted by ethnographic interviews amongst the Ovahimba people which revealed functional uses of the traditional cosmetics, specifically the red ochre-derived cosmetic, as a mosquito repellent. Several analytical techniques were used to determine the presence of mosquito repellent compounds in the red ochre- derived cosmetic and the aromatic plant derived-cosmetic. GC-MS was used to identify the presence of compounds which have previously been found to have mosquito repellent capabilities. GC-MS analysis identified mostly oxygenated compounds which include ketones (2-dodecanone, 2-nanonone, 2-undecanone and 2-tridecanone), aldehydes (heptanal and nonanal) and carboxylic acids (hexanoic acid and heptanoic acid) in dichloromethane extracts of otjize and mostly hydrocarbons (o-cymene, α-pinene, limonene, and squalene) and less oxygenated compounds (terpinen-4-ol and α-campholenal) in plant derived cosmetic extracts. The chemical composition of the cosmetics was also analyzed using FTIR. FTIR analysis for organics in both cosmetics showed presence of vibrational motions including O-H, C=O, C-H, C=C and C-C which affirmed the presence of organic functional groups including aldehydes, ketones, esters, alkenes and alkanes. Peak patterns observed using GC-FID showed that the mixture of red ochre and clarified butterfat released higher quantities of volatiles than when individual samples were analyzed. Mineralogical composition of red ochre was determined by PXRD, supported by FTIR which revealed as significant amount of hematite (Fe2O3), the primary mineral responsible for the red hue of the ochre. Other major minerals including quartz (SiO2), kaolinite (Al2(Si2O5)(OH)4, calcites (CaCO3) and chalconatronite(Na2Cu(CO3)2.3H2O) were found to be present in the ochre powder. Elemental analysis of the ochre determined using EDXRF and ICP-OES supported mineralogical composition as iii Ovahimba red ochre exhibited high content of iron (Fe) and silicon (Si) and a significant amount of aluminum (Al), calcium (Ca) and copper (Cu). Based on % weight, presence of transition metals in red ochre powder identified using ICP-OES was observed in the descending order; Fe> V> Cu> Au> Ti> Zr. Based on the analysis carried out in this study, it is suggested that red ochre provides catalytic role, due to its diverse metal content especially the presence of transition metals including Fe and Cu, which might be influencing the production of secondary products during autoxidation of fatty acids present in otjize, specifically ketones and aldehydes. It was also concluded that the composition of clarified butterfat could be attributed to the release of mosquito repellent compounds in the red ochre derived cosmetic because when animal fat (kudufat) was used as an organic binder, the mixture did not release any of the identified possible mosquito repellent compounds. Keywords: Aldehydes, autoxidation, clarified butterfat, fatty acids, ketones, mosquito repellents, and red ochre
232

Rate Enhancement Of The Catalytic Hydrogenation Of An Unsaturated Ketone By Ultrasonic Irradiation

Mahishi, Shreesha 08 1900 (has links)
The aim of the work was to develop an understanding of the phenomenon of rate enhancement observed when a heterogeneous catalytic reaction system is irradiated by ultrasound. The system under investigation was the catalytic hydrogenation of an a, B - unsaturated ketone, using zinc dust and aqueous nickel chloride as a source of hydrogen. When a slurry of zinc particles and aqueous nickel chloride is stirred or sonicated, nickel deposits in the form of patches on the surface of the zinc particles and simultaneously, zinc dissolves into the solution in the form of zinc ions, a process called pitting corrosion. Hydrogen atoms are formed when hydrogen ions diffuse from the bulk, adsorb onto the nickel surface and take up electrons generated by the dissolution of zinc. Once the atoms are formed on the surface, the atoms combine to form hydrogen molecules, which desorb in the form of hydrogen gas. When ketone is added to this slurry, the hydrogen atom formed on the surface of nickel is used as the source of hydrogen for the hydrogenation reaction. In these processes, nickel serves as catalyst. The ketone first has to diffuse to the bulk, adsorb onto the surface of nickel and undergo reduction by the hydrogen atoms to form the product. The product then has to desorb from the surface and diffuse into the bulk, in order to create vacant sites on the nickel surface for the adsorption of more ketone. Experiments dealing with measurements of hydrogen evolution rates pointed out that hydrogen is not a limiting reactant, since evolution was sustained for long periods of time. The evolution rates versus time data revealed that the nature of the plots for both, the stirred and sonicated systems were similar. These facts lead us to infer that the basic mechanism of nickel deposition, pitting corrosion, etc. was similar for the two cases. To study the hydrogenation reaction, experiments were first conducted keeping the nickel catalyst surface area constant. The results of these experiments showed that the hydrogenation reaction can be explained by a first order mechanism. Changing the speed of the stirrer did not effect the rate of the reaction; hence it was inferred that the reaction was not external mass transfer controlled. It was also seen that there was an no significant difference in reaction rates between the stirred and sonicated systems. Hence we conclude that sonication does not effect any process involved in the actual process of hydrogenation, i.e., adsorption, desorption, surface reaction, etc., do not get effected. It was concluded that the observed rate enhancements of similar compounds in the same system occur only when nickel catalyst is being continuously formed. This is possible only if irradiation with ultrasound enhances the rate of formation of the surface area of the nickel deposit. To study this phenomena, experiments were conducted with continuous formation of nickel catalyst. These experiments were conducted in three ways - stirring with zinc dust, sonication with zinc dust and stirring with presonicated zinc dust. For the first two kinds of experiments, the rates were low, increased to a maximum value and then decreased, but the nature of the third kind of experiments were different. The initial rates were very high as compared to either of the other two kinds of experiments but the rate rapidly reduces and becomes comparable to the rates obtained by stirring with zinc dust. We conclude that sonication creates many active sites on the surface of the zinc particles in the form of crystal defects, which are perhaps necessary for the deposition of nickel. When presonicated zinc particles are used, there are large numbers of these sites and these get consumed rapidly when stirred with aqueous nickel chloride solution. In this work, we do not deal with this case. In the case of sonication with zinc dust, these active sites are continuously created and are consumed by nickel deposition. For the stirred system, these sites are quite small to start with and new ones are not generated since there is no irradiation by ultrasound. Hence, the rates in the latter case are low for both nickel deposition and the hydrogenation reaction. In the model, it was assumed that the rate of increase of surface area of nickel, characterized by a specific rate term k z, was proportional to the amount of nickel in the bulk and also to the amount of free zinc surface area available. Similarly, nickel which deposits on previously deposited nickel (characterized by another specific rate constant, kn) was proportional to the amount of nickel in the bulk, the nickel area already deposited and also the free zinc surface area available. The model is in excellent agreement with the experimental data obtained. The model predicted higher values of kn and kz for the sonicated system, indicating that the rate of deposition of nickel is much higher in this case than for the stirred system. Moreover, the model also predicts that the deposit in the case of a sonicated system is thinner and flatter, since it was seen that the surface area created for the same amount of nickel deposited was much higher in this case than the stirred system.
233

The effects of a novel substrate on exercise energetics in elite athletes

Cox, Peter John January 2013 (has links)
The physiological ketosis of starvation makes sound evolutionary sense, as ketone bodies have several thermodynamic advantages over other nutritional substrates, in addition to their actions to conserve protein and glucose stores. Utilising the body’s metabolic responses to ketosis by delivering a novel nutritional source of ketone bodies, the work in this thesis explored the metabolic effects of ketosis on physical performance in humans. First, the pharmacokinetics and dosing requirements for ketone containing drink preparations were characterised in a population of athletes and healthy controls (n = 45). Using endurance exercise as a model of physiologic stress, the functional impact of ketosis during sustained high intensity effort was investigated in high performance athletes (n = 22). It was shown that nutritional ketosis improved performance in 18/22 athletes, who set 14 new best performances during 30 min of rowing. Furthermore, when ketones and glucose were delivered together, cycling performance was improved by 2% (n = 8) following 1.5 hours of fatiguing effort, compared with optimal carbohydrate intake. Blood D-β-hydroxybutyrate reached 3-5 mM following ketone drinks, equivalent to several days of total fasting, but rapidly decreased during exercise. It was found that higher physical workloads correlated with larger decreases in plasma ketone concentration (n = 8), consistent with their oxidation as respiratory fuels. Nutritional ketosis significantly altered fuel metabolism during exercise in elite athletes (n = 10), decreasing peripheral lipolysis, skeletal muscle glycolytic intermediates, blood lactate, and branched chain amino acid release. In conclusion this work suggests a new hierarchy of substrate preference during physical stress, whereby mimicking the physiology of starvation, the energetic consequences of oxidising ketones may significantly enhance athletic performance. The extrapolation of these findings may have therapeutic implications for patient populations where energetic demands are high, and deleterious switches in substrate selection occur.
234

Development of HIV-1 Protease Inhibitors and Palladium-Catalyzed Synthesis of Aryl Ketones and N-Allylbenzamides

Axelsson, Linda January 2014 (has links)
The use of palladium-catalyzed reactions to introduce new carbon-carbon bonds is a fundamental synthetic strategy that has been widely embraced due to its high chemo- and regioselectivity and functional group tolerance. In this context, Pd(0)-catalyzed aminocarbonylations using Mo(CO)6 instead of toxic and gaseous CO and with allylamine as the nucleophile were investigated. The aminocarbonylated product dominated over the Mizoroki-Heck product, and (hetero)aryl iodides, bromides and chlorides gave N-allylbenzamides in good yields. In this thesis improvements to an existing protocol for the Pd(II)-catalyzed synthesis of aryl ketones from five benzoic acids and a variety of nitriles are also presented. Addition of TFA improved the yields and employing THF as solvent enabled the use of solid nitriles, and the aryl ketones were isolated in good yields. The pandemic of HIV infection is one of the greatest public health issues of our time and approximately 35.3 million people worldwide are living with HIV. There are currently many drugs on the market targeting various parts of the viral reproduction cycle, but the problems of resistance warrant the search for new drugs. HIV-1 protease makes the virus mature into infectious particles. In this thesis a new type of HIV-1 protease inhibitor (PI) is presented, based on two of the PIs on the market, atazanavir and indinavir, but it has a tertiary alcohol, as well as a two-carbon tether between the quaternary carbon and the hydrazide β-nitrogen. A total of 25 new inhibitors were designed, synthesized and biologically evaluated, the best compound had an EC50 value of 3 nM. Based on this series a project aimed at synthesizing macrocycles spanning the P1-P3 area was initiated. Macrocycles often tend to have an improved affinity and metabolic profile compared to their linear analogs. Introduction of a handle in the para position of the P1 benzyl group proved difficult, despite efforts to synthesize intermediates containing either a bromo-, hydroxy-, methoxy-, silyl-group protected hydroxy- or an alkyne-group. The lactone intermediate was abandoned in favor of an alternative synthetic route and initial studies were found to be promising. This new approach requires further investigation before the target macrocycles can be synthesized.
235

INVESTIGATIONS INTO RARE 3-COORDINATE PALLADIUM COMPLEXES AND NEW APPLICATIONS OF COPPER IN COUPLING REACTIONS

2012 October 1900 (has links)
In this thesis, the paper is divided into 2 parts, each corresponding to 2 individual projects. We started with looking into the synthesis of 3-coordinate palladium complexes incorporating a nacnac ligated system for academic interest. We utilized [{2,6-iPr2Ph)2nacnac}PdCl]2 as the precursor into synthesizing these 3-coordinate palladium complexes. Through many failed attempts of manipulating different substrates, we were able to synthesize a 4-coordinate [{(2,6-iPr2Ph)2nacnacPdCl}(NH2Ph)]. The second project deals with the application of dibromobis(1,1'-dibenzyl-3,3'-methylenediimidazolin-2,2'-diylidene)dicopper(I) complex to catalysis. We decided to focus our attentions specifically on carbonyl reduction of ketones being that hydrosilations with copper catalysts have only been recently looked at. The dibromobis(1,1'-dibenzyl-3,3'-methylenediimidazolin-2,2'-diylidene)dicopper(I) complex proved to be very effective at hydrosilations of a wide variety of ketones at high temperatures. We further investigated the scope of the dibromobis(1,1'-dibenzyl-3,3'-methylenediimidazolin-2,2'-diylidene)dicopper(I) catalyst by testing it on the arylation and alkylation of imidazole. The arylation of imidazole showed little to no conversion, whereas the alkylation proved to be quite active for both alkyl bromides and chlorides. We also looked at the attempts in synthesizing bulkier analogues of dibromobis(1,1'-dibenzyl-3,3'-methylenediimidazolin-2,2'-diylidene)dicopper(I) by varying the benzyl groups to 2,6-diisopropylphenyl and mesityl groups. However, results show that there were difficulties in coordinating these bulkier ligands onto copper. Optimization of complexing bulkier ligands onto copper needs to be conducted before one can proceed onto further reactions.
236

Étude de la stimulation cétogénique chez l’adulte en bonne santé : impact sur le métabolisme énergétique cérébral / Study of a ketogenic stimulation in healthy adults : effect of ketosis on brain energy metabolism

Courchesne-Loyer, Alexandre January 2016 (has links)
Le cerveau humain est un organe très métaboliquement actif. Cet énorme besoin énergétique l’expose à un risque accru de détérioration causée par un dérèglement de ce métabolisme. Dans la phase précoce de la maladie d’Alzheimer, un hypométabolisme cérébral du glucose est observé. Cette carence énergétique serait à l’origine des détériorations observée lors du développement de cette maladie. Le cerveau a accès à une autre source endogène d’énergie : les cétones. Les cétones sont particulièrement importantes pour le cerveau puisqu’il ne possède pas la capacité d’utiliser les acides gras comme source énergétique à l’instar des autres organes. Les cétones sont issues de la β-oxydation hépatique des acides gras. Ils sont produits en situation de jeûne lorsque les niveaux circulants de glucose et d’insuline sont bas. Les cétones se sont déjà montré efficaces dans le traitement de divers troubles neurologiques comme l’épilepsie. Par contre, outre les diètes cétogènes et le jeûne prolongé, il n’existe pas de traitement efficace pour maintenir une cétonémie modérée chez l’adulte. Le métabolisme énergétique cérébral en situation de cétose modérée reste encore mal compris dans cette population. Les travaux de cette thèse se sont donc concentrés à étudier la possibilité d’une combinaison d’approche nutritionnelle et pharmacologique afin de stimuler la cétogenèse chez l’adulte. Ils ont aussi exploré les changements de métabolisme cérébral chez l’adulte durant une cétose modérée. L’objectif de la première étude était d’étudier le potentiel du bezafibrate à stimuler la cétogenèse induite par une supplémentation en triglycérides de moyennes chaînes (MCT). Cette première étude a démontré que le bezafibrate avait peu d’effet sur la stimulation de la cétogenèse induite par les MCT et que le facteur limitant dans cette stimulation était donc la disponibilité des substrats et non la capacité cétogène des cellules hépatiques. L’objectif de la seconde étude était d’étudier les changements de capture des cétones et du glucose au cerveau durant un état de cétose modérée chez l’adulte. Les résultats de cette deuxième étude ont montré que la capture des cétones au cerveau est directement proportionnelle à leur concentration plasmatique. Cette étude a aussi démontré que la capture cérébrale des cétones était directement reliée à leur concentration plasmatique alors que la capture cérébrale du glucose est modulée par les besoins énergétiques du cerveau. Une stimulation cétogénique chez des personnes atteintes de déclin cognitif pourrait donc aider à rétablir la balance énergétique et ralentir l’apparition des symptômes chez ces personnes mais cet effet devra être étudié dans une étude ultérieure. / Abstract : The human brain is the most metabolically active organ of the body. This high need for energy exposes it to an increase risk in case of hypometabolism. Such a glucose hypometabolism is seen during the early stages of Alzheimer’s disease. This factor is believed to be one of the cause of the disease. Ketones are the main alternate substrate for the human brain. Ketones are particularly important since, unlike other organs, the brain can not use fatty acids as alternative fuel. Ketones are mainly produce through β-oxidation of fatty acid by the liver. This happens mainly during fasting when circulating levels of glucose and insulin are low. Studies have shown that ketones can have a therapeutic effect in a variety of neurological diseases, mainly epilepsy and Alzheimer’s disease. Nevertheless, apart from ketogenic diet and prolonged fasting, there is currently no effective ways to induce and maintain moderate ketosis in adults. Brain energy metabolism under moderate ketosis remains also misunderstood in this population. This thesis aimed look at the effect of a combination of a pharmacological treatment and a nutritional supplementation to induce moderate sustain ketosis in adults. It also studied the effect of a moderate ketosis on brain energy metabolism in adults. The aim of the first study was to study the effect of a pharmacological treatment, bezafibrate, on the potentiation of the ketogenic effect induced by a medium-chain triglycerides (MCT) supplementation. The results of this study that bezafibrate had little effect on the ketosis induced by a MCT supplementation and, therefore, that the limiting factor in human ketosis was not the liver cells capacity to produce ketones but the availability of substrates for ketogenesis. The aim of the second study was to study the impact of a nutritional moderate ketosis on brain glucose and ketone uptake. The results of this study showed a direct correlation between brain ketone uptake and plasma ketone concentrations. This study also showed that brain ketone uptake is regulated by blood ketone concentration whereas brain glucose uptake is regulated by the brain energy needs. Further studies should then look if such a moderate ketosis induced in cognitively impaired patients could re-equilibrate the energy balance in the brain and then slow the apparition of clinical symptoms in this population.
237

Reações de contração de anel promovidas por sais de tálio (III) / Ring contraction reactions promoted by thallium(III) salts

Silva Junior, Luiz Fernando da 04 March 1999 (has links)
Esta tese apresenta um estudo sobre a contração de anel de olefinas e cetonas cíclicas promovida por sais de tálio(III). A reação de uma série de cicloexanonas e cis e trans-2-decalonas com TTN em CH2Cl2 levou aos correspondentes produtos de contração em rendimentos muito bons, desde que não houvesse um grupo metila em α-carbonila. A reação de 3- e 4-alquilcicloexanonas, bem como de trans-2-decalonas, ocorreu com alto grau de seletividade. As diastereosseletividades observadas estão de acordo com o mecanismo proposto por McKillop. O sistema indânico, resultante da contração de um dos anéis do sistema bicíclico[4.4.0], foi construído de três maneiras diferentes. A reação de 1-tetralonas com TTN/K-10 em pentano forneceu 1-indanocarboxilatos de metila em rendimentos razoáveis, enquanto que o tratamento de 1,2-diidronaftalenos com TTN em MeOH levou aos correspondentes produtos de contração em bons rendimentos, quando não havia grupos alquílicos ligados à dupla ligação. Finalmente, a reação de dois álcoois homoalílicos, contendo a dupla ligação endocíclica, com TTN em uma mistura 1:1 de AcOH e H2O, levou às correspondentes 1-(2,3-diidro-1H-1-indanil)-3-hidroxi-1- propanonas em rendimentos excelentes. / This thesis presents studies toward the ring contraction of ketones and olefins promoted by thallium(III) The reaction of alkylcyclohexanones and cis and trans-2-decalones with TTN in CH2Cl2 led to the corresponding ring contraction products in very good yields, providing there is no methyl group at α-carbonyl position. The reaction of 3- and 4-alkylcyclohexanones, as well as trans-2-decalones, occurred with high degree of selectivity. The observed diastereoselectivities agree with the McKillop\'s mechanism. The indan ring system was constructed by three different protocols. The reaction of 1-tetralones with TTN/K-10 in pentane afforded methyl 1-indanecarboxylates in reasonable yields, while treatment of 1,2-dihydronaphathlenes with TTN in MeOH furnished the corresponding ring contraction products in good yields, as long as there is no alkyl group at the double bond. Finally, the reaction of two homoallylic alcohols, bearing an endocyclic double bond, with TTN in a 1:1 mixture of AcOH and H2O, led to 1-(2,3-dihydro-1H-1-indenyl)-3-hydroxypropan-1-ones in excellent yields.
238

Efficacy of Diet Therapies in the Treatment of Neurological and Neurodegenerative Diseases

Mantis, John G. January 2010 (has links)
Thesis advisor: Thomas N. Seyfried / Epilepsy is a prevalent disabling chronic and socially isolating neurological disorder that involves recurrent abnormal discharges of neurons. Despite seizures afflicting about 10% of people worldwide, antiepileptic drugs (AEDs) are largely unable to manage seizures in many persons with epilepsy. As an alternative to AEDs, dietary therapies possess a broad therapeutic potential in both humans and animals models of various neurological and neurodegenerative disease etiologies. My research focus was to identify the therapeutic efficacy and potential mechanism(s) of action of calorie restriction (CR) and the ketogenic diet (KD) in both the epileptic EL mouse model and the Mecp2<super>308/y<super/> mouse model of Rett syndrome. My findings indicate that both the KD and CR can reduce seizure susceptibility in EL mice, a natural model for multifactorial idiopathic generalized epilepsy. CR and circulating glucose and ketone levels significantly influence the therapeutic efficacy of the KD. A concurrent reduction in circulating plasma glucose levels and elevation in circulating plasma &beta-hydroxybutyrate levels was predicted to associate with the anticonvulsant effect of these diets in EL mice. For the first time, I was able to show that a KD fed in unrestricted amount is able to reduce seizure threshold in EL mice. Interestingly, supplementation of calories in the form of carbohydrate in the water of calorie-restricted EL mice results in a diminished anticonvulsant efficacy of the KD. In my effort to elucidate the neuroprotective mechanism(s) associated with these changes in metabolite availability, I started investigating the complex alterations occurring in multiple integrated neural and metabolic processes. Furthermore, I showed that a restricted KD diet improves aspects of the behavioral abnormalities seen in Rett mice, in particular with respect to anxiety. Finally, for the first time, I provide a standardized protocol for the implementation of diet therapies in the management of an array of neurological and neurodegenerative diseases, which ultimately may help elucidate the complex neuroprotective mechanism(s) of CR and the KD. This research overall has provided a new understanding in the therapeutic efficacy of diets in epilepsy and Rett Syndrome. / Thesis (PhD) — Boston College, 2010. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Biology.
239

Biorredução de cetonas por espécies vegetais / Bioreduction of ketones by plant species

Rocha, Erica Oliveira 15 December 2011 (has links)
O trabalho abrange o estudo de biorreduções de cetonas por espécies vegetais, empregando-se homogenatos de células de tecidos de plantas já desenvolvidas (folhas) ou culturas de células de Rauwolfia sellowii e Cereus peruvianus em suspensão. Dentre os objetivos principais do trabalho estão: reduzir cetonas-modelo por culturas de células vegetais, avaliando a eficiência e estereosseletividade do processo. Desenvolver um procedimento de triagem por enzimas vegetais solúveis entre diversas espécies obtidas no campus \"Armando Salles de Oliveira\", através da manipulação de variáveis que sabidamente alteram a atividade enzimática. Este tipo de preparação enzimática é utilizado no estudo de rotas biossintéticas, mas o emprego de homogenatos de células vegetais na triagem por novos biocatalisadores é inovador, tendo sido demonstrado seu potencial como ferramenta na seleção de enzimas vegetais para a biotransformação de xenobióticos. A metodologia é simples e confiável, possibilitando o estudo de biotransformações por enzimas diferentes daquelas expressas em culturas de células e oferecendo maior garantia de que a atividade enzimática observada é originária da espécie vegetal em estudo, e não de microorganismos endofíticos, que podem atuar nas biotransformações em que se utilizam partes de plantas desenvolvidas como biocatalisador / The work focuses on the study of the bioreduction of ketones by plant species, using homogenates of already developed plant tissues cells (leaves) or of Rauwolfia sellowii and Cereus peruvianus cell cultures suspensions. Among the main objectives of the study are the evaluation of the efficiency and stereoselectivity of the ketone-reduction process in plant cell cultures. It was employed a screening procedure for soluble enzymes from different plant species found on campus \"Armando Salles de Oliveira\", through the manipulation of variables known to be related to the enzyme activity. This type of enzyme preparation has been already reported in studies of biosynthetic routes, but the use of homogenates of plant cells to the screening for new biocatalysts is innovative. In this work we could demonstrate the potential of this approach as a tool in the selection of plant enzymes for the biotransformation of xenobiotics. The methodology is simple and reliable, allows the study of biotransformations by enzymes different from those expressed in cultured cells, and provides greater assurance that the enzymatic activity observed originated in plant species under study, rather than in endophytic microorganisms, which can act in biotransformations that employ parts of developed plants as biocatalyst.
240

Bond activation and supramolecular chemistry with iridium(III) porphyrins.

January 2007 (has links)
Song, Xu. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 92-96). / Abstracts in English and Chinese. / Table of Contents --- p.i / Acknowledgements --- p.iii / Abbreviations --- p.iv / Abstract --- p.v / Chapter Part I --- Carbon-Carbon Bonds Activation (CCA) of Ketones by Iridium(III) Porphyrins / Chapter Chapter 1 --- General Introduction / Chapter 1.1 --- Carbon-Carbon Bonds Activation by Transition Metals --- p.1 / Chapter 1.2 --- Thermodynamic and Kinetic Considerations in CCA --- p.1 / Chapter 1.3 --- C-C Bonds Activation by Low Valent Transition Metal Complexes --- p.3 / Chapter 1.3.1 --- CCA in Strained System --- p.3 / Chapter 1.3.2 --- CCA Driven by Aromatization --- p.6 / Chapter 1.3.3 --- Chelation Assisted CCA --- p.8 / Chapter 1.4 --- C-C Bonds Activation by High Valent Transition Metal Complexes --- p.11 / Chapter 1.5 --- Previous Mechanistic Studies on CCA by High Valent Transition Metal Complexes --- p.14 / Chapter 1.6 --- Objective of the Work --- p.16 / Chapter Chapter 2 --- Carbon-Carbon Bonds Activation (CCA) of Ketones by Iridium(III) Porphyrins / Chapter 2.1 --- Introduction --- p.17 / Chapter 2.2 --- CCA of Aromatic Ketones with Iridium(III) Porphyrins --- p.17 / Chapter 2.2.1 --- CCA of Aromatic Ketones with Ir(III) Porphyrin Chloride --- p.17 / Chapter 2.2.2 --- CCA of Aromatic Ketones with Ir(III) Porphyrin Methyl --- p.20 / Chapter 2.2.3 --- Steric Effect on CCA with Ir(III) Porphyrins --- p.21 / Chapter 2.3 --- CCA of Aliphatic Ketones with Iridium(III) Porphyrins --- p.21 / Chapter 2.3.1 --- CCA of Unstrained Aliphatic Ketones with Ir(III) Porphyrins --- p.21 / Chapter 2.3.2 --- CCA of Cyclic Aliphatic Ketones with Ir(III) Porphyrins --- p.22 / Chapter 2.4 --- Summary --- p.23 / Chapter Chapter 3 --- Preliminary Mechanistic Studies of Carbon-Carbon Bonds Activation (CCA) / Chapter 3.1 --- Proposed Mechanism of CCA with Ir(III) Porphyrin Chloride --- p.24 / Chapter 3.2 --- Proposed Mechanism of CCA with Ir(III) Porphyrin Methyl --- p.27 / Chapter 3.3 --- Determination of CCA co-product in situ --- p.30 / Chapter 3.4 --- Summary --- p.31 / Experimental Section --- p.33 / References --- p.44 / List of Spectra I --- p.48 / Chapter Part II --- Supramolecular Chemistry of C6o with Ir(III) Porphyrin Methyl / Chapter Chapter 1 --- General Introduction / Chapter 1.1 --- Supramolecular Interactions --- p.62 / Chapter 1.2 --- Introduction of C6o --- p.67 / Chapter 1.3 --- Supramolecular Interactions between C6o and Metalloporphyrins --- p.70 / Chapter 1.3.1 --- Discovery of Supramolecular Interactions between C6o And Metalloporphyrins --- p.70 / Chapter 1.3.2 --- Development of C6o-Metalloporphyrin Supramolecular Structure and Application --- p.71 / Chapter 1.3.3 --- Investigation on C6o-Metalloporphyrin Bonding Nature --- p.73 / Chapter 1.4 --- Objective of the Work --- p.76 / Chapter Chapter 2 --- Supramolecular Interaction between C60 and Ir(III) Porphyrin Methyl / Chapter 2.1 --- Synthesis of C60-Ir(ttp)Me Complexes --- p.77 / Chapter 2.2 --- X-ray Structure Analysis of C60-Ir(ttp)Me Complexes --- p.78 / Chapter 2.3 --- 1H NMR Analysis of C60-Ir(ttp)Me Complexes --- p.83 / Chapter 2.4 --- 13C NMR Analysis of C60-Ir(ttp)Me Complexes --- p.84 / Chapter 2.5 --- Binding Constant of C60-Ir(ttp)Me Complexes Using UV-Vis Analysis --- p.85 / Chapter 2.6 --- Summary --- p.87 / Experimental Section --- p.88 / References --- p.92 / Appendix --- p.97 / List of Spectra II --- p.101 / Reprint of OM Paper --- p.112 / Supporting Information for Organometallics Paper --- p.118

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