A biomassa vegetal, seja como produto de interesse econômico ou do ponto de vista ecológico, é estritamente dependente do processo fotossintético. O advento das técnicas de biologia molecular e transformação genética de plantas trouxe boas perspectivas para a alteração do processo fotossintético, já que pouco foi conseguido com o melhoramento vegetal tradicional. Modificações genéticas nos LHCs (estruturas responsáveis pela captação e transferência da energia luminosa) mostram-se promissoras. Plantas transgênicas de tabaco (Nicotiana tabacum, L.) que expressam o gene quimérico Lhcb1*2 de ervilha têm sido estudadas por apresentarem uma série de alterações no metabolismo fotossintético, além de um ganho genético em relação à planta selvagem original. Vários autores observaram mudanças morfológicas, fisiológicas, bioquímicas e adaptativas que favorecem estas plantas em diversas condições de cultivo. Diversos experimentos foram realizados no intuito de melhor caracterizar as plantas transformadas com o gene Lhcb1*2 de ervilha. O potencial produtivo foi avaliado através da análise de crescimento e produção de massa seca. O metabolismo fotossintético foi analisado através de medidas de assimilação de CO2, fluorescência da clorofila a, metabólitos do ciclo de Calvin-Benson, glicólise e ciclo de Krebs, carboidratos (amido e sacarose) e aminoácidos. Os resultados obtidos mostram uma redução da taxa de fotorrespiração pelas plantas transgênicas. Esta redução promoveu o aumento do período de crescimento vegetativo e produção de biomassa, à semelhança do que ocorre em plantas cultivadas sob baixa pressão de oxigênio (5%) ou alto CO2. Entretanto, ao contrário do que ocorre nessas condições, a produção de sementes e o peso nas linhagens transgênicas não foram reduzidos. / Plant biomass, seen either from the economic or the ecological points of view, is highly dependent upon photosynthesys. The development of molecular biology and genetic engineering techniques brought great perspectives for the improvement of the photosynthetic process, since few progress had been achieved with traditional plant breeding. Genetic alteration of the LHCs (structures responsible for the capture and distribution of radiant energy) seems promising. Transgenic tobacco plants (Nicotiana tabacum, L.) over expressing the pea Lhcb1*2 gene have been studied. They present several alterations in the photosynthetic metabolism which lead to a genetic improvement of them in relation to the original plant. Many authors observed morphological, physiological, biochemical and adaptative changes which were benefical to these plants to diverse growing conditions. Several experiments were carried out in order to better characterize these transgenic tobacco lines. The potential for production was evaluated, via dry wight and growth rate. The photosynthetic metabolism was analyzed through CO2 assimilation, chlorophyll fluorescence, metabolites of the Calvin-Benson, glycolysis and Krebs cycles, carbohydrates (starch and sucrose) contents and amino acids. The results obtained show a reduction in photorespiration rate in the transgenic plants. Such reduction lead to on extension of the plant growing period and on enlargment of the biomass, similar to what occurs in plants growing under low O2 (5%) or high CO2 conditions. However, in contrast to what normally happens under these conditions, dry weight and seed production were not reduced in the transgenic lines.

The biodegradability and when functionalised biocompatibility of aliphatic polycarbonates (APCs) makes them an attractive class of materials for biomedical applications such as tissue engineering scaffolds and drug-delivery carriers. One route to accessing a wide-range of well-defined and functional APCs is the controlled ring-opening polymerisation (ROP) of cyclic carbonates. In turn, these would ideally be prepared by the direct coupling of CO2 with diols to give water as the only by-product. In this way, the combination of CO2 and sugar-derived diols draws upon two natural renewable building blocks for the construction of polycarbonates that are anticipated to show good biocompatibility properties. Chapter 2 develops a simple and mild alternative to the traditional use of phosgene derivatives for the synthesis of six-membered cyclic carbonates from 1,3-diols and CO2. DFT calculations highlighted the need to lower both the CO2-insertion and ring-closing kinetic barriers to cyclic carbonate formation. Organic superbase, 1,8- diazabicyclo[5.4.0]undec-7-ene (DBU) enabled the formation of carbonate species at 1 atm CO2 pressure whereas, the introduction of a leaving group strategy lowered the cyclisation barrier. Mechanistic considerations suggested a kinetic preference for ring- closing via a nucleophilic addition-elimination pathway rather than a SN2-like intramolecular cyclisation. Chapter 3 applies the procedure with CO2 to the preparation of a novel monomer from natural sugar, ᴅ-mannose. ROP was carried out via an organocatalytic approach and a preference for head-tail linkages in the polycarbonate backbone indicated by NMR spectroscopy and supported by DFT calculations. Chapter 4 utilises CO2 to invert the natural stereochemistry of sugars and create a thymidine-based monomer. The thermodynamic parameters of the ROP with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) catalyst are determined and the properties of the polycarbonates investigated to include preliminary cell attachment studies. Finally, chapter 5 details the synthesis of cyclic carbonates from 2- deoxy-ᴅ-ribose and the investigation into the different ROP behaviour of the α- and β- anomers. The ability to tune the polymer properties through copolymerisation with trimethylene carbonate (TMC) is also discussed.

Submitted by MAGNUN ANTONIO PENARIOL DA SILVA null (penariol@fca.unesp.br) on 2017-03-20T14:07:54Z No. of bitstreams: 1 TESE FINAL MAGNUN.pdf: 1184516 bytes, checksum: 33f0c41c91f8f4d05c677615ccd2d145 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2017-03-22T13:27:17Z (GMT) No. of bitstreams: 1 silva_map_dr_bot.pdf: 1184516 bytes, checksum: 33f0c41c91f8f4d05c677615ccd2d145 (MD5) / Made available in DSpace on 2017-03-22T13:27:17Z (GMT). No. of bitstreams: 1 silva_map_dr_bot.pdf: 1184516 bytes, checksum: 33f0c41c91f8f4d05c677615ccd2d145 (MD5) Previous issue date: 2016-10-06 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A cultura do crambe começou a ser estudada no Brasil por apresentar elevado teor de óleo nos grãos. A produção é totalmente mecanizada e de baixo custo por utilizar as ferramentas disponíveis para outras espécies. O crambe é uma cultura de inverno, então se torna também uma excelente opção para o cultivo em safrinha. No entanto a cultivar desenvolvida para a comercialização no país apresenta maturação irregular dos grãos, o que se torna um problema tanto para a colheita quanto para os processos pós-colheita, por não se haver uma época ideal para colheita mecanizada sem que ocorram perdas durante esta etapa, ou ainda durante a secagem e armazenamento. Diante do exposto, o objetivo do presente trabalho foi acompanhar o processo de secagem dos grãos de crambe, e ainda o período de 12 meses de armazenamento, relacionando esses processos com a dinâmica de formação de lipídeos dos grãos, os sistemas antioxidantes, o acúmulo de açúcares, lipídeos e proteínas ao longo do desenvolvimento, os estresses ocasionados pela secagem e a pigmentação durante o armazenamento. Para isso, um experimento foi instalado na área de produção da Fazenda Experimental Lageado, onde utilizou-se para semeadura sementes de crambe da cultivar FMS Brilhante (Fundação Mato Grosso do Sul), na qual o processo foi acompanhado semanalmente verificando os teores de água dos grãos (82, 74, 60, 40, 30, 20 e 10%) que foram submetidos à diferentes métodos de secagem (testemunha, natural, secagem em estufa à 30ºC e secagem em estufa à 40ºC). Para melhor entendimento dos dados obtidos este trabalho foi dividido em quatro capítulos. O primeiro capítulo trata-se de uma revisão de literatura a respeito dos processos de desenvolvimento, secagem e armazenamento de grãos de crambe. O segundo capítulo estudou a dinâmica de formação de lipídeos nestes grãos. No terceiro capítulo avaliou-se o acúmulo das principais reservas (proteínas, açúcares e lipídeos) e os danos oxidativos ocasionados pela secagem dos grãos. E no quarto o foco foi verificar se o tempo de armazenamento afeta as reservas, pigmentação e a atividade enzimática dos grãos. Conclui-se que a maior reserva encontrada em grãos de crambe são os lipídeos, seguido por açúcares e proteínas, os grãos de crambe apresentam maior acúmulo de lipídeos aos 49 dias após a floração, a secagem à 80 ºC provoca danos aos grãos e que os grãos de crambe começam aumentar o conteúdo de pigmentos à partir dos 6 meses de armazenamento. / The culture of crambe began to be studied in Brazil by a high oil content in grain. The production is fully mechanized and low cost to use the tools available for other species. It is a winter crop, then it also makes an excellent choice for growing in off-season. However cultivating developed for sale in the country is irregular grain maturity, which becomes a problem for both the harvest time to post-harvest processes, not be an ideal time for mechanized harvesting without incurring losses during this step or during drying and storage. Given the above, the objective of this study was to follow up the development process of crambe grain, and also the steps of drying and storage, linking these processes with the dynamics of grain lipid formation, antioxidant systems, the accumulation of sugars , lipids and proteins throughout the development of the stresses caused by drying and pigmentation during storage. For this, an experiment was conducted in the area of Fazenda Experimental Lageado. We used to cultivate the crambe sowing seeds FMS Brilhante (Fundação Mato Grosso do Sul), in which the process was monitored weekly by checking the water content of grains (82, 74, 60, 40, 30, 20 and 10%) which were subjected to different drying methods (control, natural drying oven at 30 ° C and dried at 40 ° C). For better understanding of the data from this study was divided into four chapters. The first chapter it is a literature review about the development processes, drying and crambe grain storage. The second chapter studied the dynamics of the formation of lipids in these grains. In the third chapter, we evaluated the accumulation of the main reserves (proteins, sugars and lipids) and the oxidative damage caused by the drying of the beans. And in the room the focus was to determine whether the storage time affects the reserves, pigmentation and the enzymatic activity of the grains. It follows that the largest reserve found in crambe grains are lipids, followed by sugars and proteins, crambe grains have higher accumulation of lipids at 49 days after flowering, drying at 80 ° C causes damage to the beans and that crambe grains begin to increase the content of pigments from 6 months of storage. / CNPq: 140263/2013-6

Os carboidratos presentes nos glicoconjugados apresentam alto grau de complexidade e diversidade estrutural, desempenhando um importante papel em diversos processos biológicos. As glucosidases, enzimas responsáveis pela clivagem de ligações O-glicosídicas em oligossacarídeos e glicoconjugados, participam de processos bioquímicos fundamentais do metabolismo e também estão envolvidas na biossíntese de glicoproteínas e glicoesfingolipídeos. Diversos inibidores de glucosidases de origem natural ou sintética têm sido descritos, como por exemplo: acarbose (1), miglitol (2), voglibose (3) e N-butil-desoxi-nojirimicina (4); sendo 1, 2 e 3 indicados para tratamento de diabetes mellitus tipo II e 4 para o controle da doença de Gaucher. Considerando a importância do planejamento e da síntese de novos inibidores de glucosidases, bem como a necessidade de obtenção de modelos tridimensionais para glucosidases, os objetivos deste trabalho foram: i) sintetizar carba-açúcares e pseudodissacarídeos potencialmente anti-glucosidase, ii) avaliar suas atividades inibitórias empregando a enzima ?-D-glucosidase de Saccharomyces cerevisiae e iii) aplicar técnicas de bioinformática e modelagem molecular na construção de um modelo estrutural 3D por homologia da sacarase intestinal de rato e realizar estudos de relação estrutura-atividade baseado no padrão farmacofórico calculado para os inibidores descritos. Neste sentido, a partir do precursor-chave (3/2,4)-2,3,4-tri-O-benzil-5-hidroxi-cicloexanona (12), obtido em 6 etapas, foram sintetizados diferentes carba-açúcares. Adicionalmente, reações de aminação redutiva, rearranjo alílico e \"click chemistry\" foram empregadas na síntese dos pseudodissacarídeos inéditos 3-(2,4-dibenziloxi-fenilamino)-2,4,6-tri-O-benzil-3-desoxi-?-D-glucopiranosídeo de metila (81), 1-(2\',3\',4\'-tri-O-benzil-5\'-oxo-cicloexanil)-4,6-di-O-acetil-2,3-didesoxi-hex-2-enopiranosídeo (89) e 2-{4-[(1H-1,2,3-triazol-4-il)metoxi]-2,4-di-O-benzil-fenila}-1,3,4,6-tetra-O-acetil-2-desoxi-?-D-glucopiranosídeo (99), respectivamente. O composto (3/2,4)-2,3,4,5-tetraidroxi-cicloexanona (46) foi submetido a estudos de inibição enzimática e apresentou moderada atividade de inibição da enzima ?-D-glucosidase. As simulações de docking com o modelo construído da sacarase de rato bem como a determinação do padrão farmacofórico forneceram novas informações estruturais sobre o sítio ativo desta enzima e do modo de ligação de diferentes inibidores. Portanto, as estratégias sintéticas, os estudos de cinética enzimática e de modelagem molecular realizados durante o trabalho resultaram em contribuições relevantes no que diz respeito à química de carboidratos, permitindo avaliar potenciais inibidores da enzima ?-glucosidase in silico, os quais poderão ser sintetizados e submetidos a novos ensaios enzimáticos. / Carbohydrates of glycoconjugates display high degree of complexity and structural diversity, playing a central role in biological processes. Glucosidases are enzymes that catalyze the cleavage of glycosidic bonds in oligosaccharides or glycoconjugates, being essentials in several metabolic pathways and in the biosynthesis of glycoproteins and glycosfingolipids. Several glucosidase inhibitors from natural and synthetic sources have been described, such as: acarbose (1), miglitol (2), voglibose (3) and N-butyl-desoxy-nojirimycin (4). Compounds 1, 2 and 3 are used in the treatment of type II diabetes mellitus and 4 for patients with Gaucher\'s disease. Concerning to the importance of the design and synthesis of new glucosidase inhibitors, as well as the need of 3D models for glucosidases, the aims of this work were: i) the synthesis of potentially anti-glucosidase carba-sugars and pseudodisaccharides, ii) the evaluation of its inhibitory activities by using ?-D-glucosidase from Saccharomyces cerevisiae and iii) the use of bioinformatics and molecular modeling techniques for creation of a 3D structural homology model of rat intestinal sucrase to accomplish the structure-activity relationships studies concerning to the pharmacophoric pattern of the reported inhibitors. Thus, starting with the key precursor 12, prepared in six steps, different carba-sugars were synthesized. Additionally, reductive amination reactions, allylic rearrangement and \"click chemistry\" were applied on the synthesis of novel pseudosaccharides 81, 89 and 99, respectively. Compound 46 was assayed for enzymatic inhibition and demonstrated reasonable activity for the inhibition of ?-D-glucosidase. Docking simulations by using the rat sucrase model and the determination of pharmacophoric pattern provided significant information concerning to the enzyme\'s active site and the inhibitor\'s binding pattern. Therefore, the synthetic strategies, enzymatic kinetic assays and molecular modeling studies performed in this work resulted in relevant contributions to the carbohydrate chemistry, making possible for our research group to evaluate potential ?-glucosidase inhibitors in silico, which can be synthesized and assayed for enzymatic activity in the future.

O objetivo do presente trabalho é a elucidação da estrutura cristalográfica da proteína N-acetilglicosamina 6-fosfato desacetilase (desacetilase) da bactéria Escherichia coli. A desacetilase é um tetrãmero de subunidades idênticas de 382 aminoácidos e massa molecular de 41 kDa. Esta é uma enzima da via de catabolismo de açúcares aminados e cataliza a conversão do N-acetilglicosamina 6-fosfato em glicosamina 6-fosfato. Nesta via a bactéria dedica cinco genes organizados em um regulon, o nagE-nagBACD, com propósitos de obtenção de energia e de reciclagem de componentes de parede celular. A reciclagem de componentes de parede celular é a via de maior atividade metabólica de E. coli, na qual aproximadamente 40% dos peptidoglicanos de parede celular são quebrados a cada geração, sendo o N-acetilglicosamina (GlcNAc) reutilizado para a síntese de novo de peptidoglicanos e lipopolissacarídeos de membrana externa. O GlcNAc exerce funções multi-regulatórias na via de catabolismo de aminoaçúcares e a desacetilase é o maior fator controlador da sua concentração intracelular. Foi demonstrado que a desacetilase é a enzima mais importante da via e que sem ela a E. coli não é capaz de reciclar o GlcNAc. A desacetilase é encontrada em outros organismos desempenhando funções igualmente importantes, estando relacionada à captura e o armazenamento de carboidratos em hepatócitos e células sinusiais de fígado de camundongo, à morfogênese e à diminuição da patogenicidade e da adesão da Candida albicans a tecidos endoteliais, chegando também a ser estudada para desenvolvimento de inibidores contra o parasita da malária o Plasmodzum falciparum. Neste trabalho foram descritos os procedimentos desde a subclonagem do gene codificador da desacetilase de E. coli até a interpretação da sua estrutura quaternária, incluindo a expressão, a purificação, a cristalização, a produção de cristas derivados de átomos pesados, a estimativa de fases e a construção e refinamento do modelo cristalográfico. A estrutura foi resolvida por espalhamento anômalo de iodo de baixa resolução (2,9 angstron), em comprimento de onda único, sendo refinada a resolução de 2,0 angstron. Na unidade assimétrica encontram-se dois monômeros relacionados por um eixo de ordem 2 não cristalográfico aproximadamente a 15° da direção do eixo cristalográfico c. A simetria do cristal aplicada à unidade assimétrica leva a formação de um tetrâmero cuja área da superfície de tetramerização é de 5.343 angstron2, correspondente a 18,4% da área do dímero. A área de superfície de acessibilidade da interface dimerização é de 1.053 angstron2, correspondente a 6,8 % da área do monômero. O monômero da desacetilase é constituído por dois domínios: o beta, um pequeno sanduíche beta; e o alfa, um pseudo barril (beta/alfa)8 comum aos membros da super família da Amidohidrolases. O domínio-beta é constituído por duas folhas beta mistas e uma hélice alfa. O domínio- alfa é constituído por 11 hélices alfa e por três folhas beta, uma paralela e as outras duas anti paralelas. No domínio- beta, oito das onze hélices alfa formam ligações cruzadas com as oito fitas da folha beta paralela para formar o \"barril\" onde encontra-se o sítio ativo. No sitio ativo foi observada a presença de um íon fosfato. Os resíduos do sítio ativo que participam da ligação ao fosfato são Gln59, Glu131, His195, His216 e Asp273, dos quais pelo menos uma histidina e um ácido aspártico têm se conservado em membros da super família das Amidohidrolases / The goal of the present work is to elucidate the crystallographic structure of the protein N-acetylglucosamine Bphosphate deacetylase (deacetylase) from Escherichia coli. The deacetylase is a tetramer of identical subunits with 382 aminoacids and molecular weight of 41 kDa. It is an euzyme of the amino sugar catabolism pathway and it catalyzes the conversion of the N-acetylglucosamine Gphosphate in to glucosamine 6-phosphate. In this pathway the bacteria dedicates five genes organized in the nagE-nagBACD regulon for purposes of cell wall component recycling and energy production. The cell wall component recycling is the major E. coli metabolic pathway in which aproximately 40% of the cellular wall peptidoglicans is broken in each generation. Its degradation product, the amino sugar N-acetylglucosamine (GlcNAC) is reused for the peptidoglican and for the lipopolysacharide de novo synthesis. The GlcNAC plays several regulatory roles in the amino sugar catabolism pathway and deacetylase is its major intra cellular concentration controlling factos. It was demonstrated that without the deacetylase, E. coli is uncapable of recycling the GlcNAc. The deacetylase plays important roles in the other organisms in which it has been found. It is related to the carbohydrate up-take and storage in hepatocytes and sinusoidal cells from rat liver and to the Candida albicans morphogenesis, pathogenicity and adherence to the endothelial tissues. Deacetylase has also been studied in the development of inhibitors against the malaria parasite Plasmodzum falciparum. This work describes all the approaches from the nagA subcloning to the crystallographic structure analysis, including deacetylase expression, purification, crystallization, heavy atoms derivatives production, phasing, model building and model refinement. The E. coli deacetylase structure was solved by Single Anomalous Dispersion using low resolution (2,0 angstron) iodine anomalous scattering. The structure was refined to 2,0 angstron resolution. The contends of the asymmetric unit is a dimer related by a non-crystallographic 2-fold symmetry axis about 15° from the crystallographic axis c. The crystallographic symmetry applied to the asymmetric unit produces a tetramer, whose the surface accessibility of the buried area is 5.343 angstron, corresponding to 18.4 % of the dimer total area. The dimer surface accessibility of the buried area is 1.053 angstron2, corresponding to 6.8 % of the monomer total area. The deacetylase monomer folds into two domains, a pseudo (beta/alfa)8 barrel enclosing the catalytic site of the enzyme and a small beta sandwich made up from secondary structure elements contributed by the N and C termini. The beta domain is composed of two mixt beta sheets and one alfa helice. The alfa domain is composed of 11 alfa helices and 3 beta sheets, one of them parallel and the other two anti parallel. In the alfa domain, 8 alfa helices are cross linked to 8 beta strands to form the pseudo barrel which encloses the active site. A phosphate ion was found into the catalytic site. The catalytic residues that bind the phosphate ion are Gln59, Glu131, Hisl95, His216 and Asp273, from which at least one histidine and one aspartic acid are conserved amongst the Amidrohydrolases super family members

This study was concerned with development of chromatographic methods suitable for determination of plant sugars. The resultant methodology was applied to the comprehensive study of plant carbohydrates as they vary during plant growth. Plant cell walls were isolated with boiling water followed by delignification with acid chlorite. The soluble portions were hydrolyzed with 2N sulfuric acid and the total sugars and individual monosaccharides were quantified using gas chromatography and colorimetry. The insoluble residues were hydrolyzed with 72% sulfuric acid followed by dilution with water to 2N and further hydrolysis. The effects of duration of delignification and acid hydrolysis were interpreted in terms of carbohydrate yield monitored colorimetrically and with gas chromatography. The rapid derivation of sugars was perfected using N-methyl-imidazole as an acetylation catalyst. This catalyst was also employed for the derivatization of lactonized aldonic acids, enabling the gas chromatographic quantitation of uronic acids. The growth of reed canarygrass was interpreted with empirical and non-empirical methodology. the empirical procedures provided little insightinto plant cell wall composition. The non-empirical methodology which included DMSO extraction and gas-liquid chromatography revealed the possible presence of a branched galactoarabinoxylan and a linear arabinoxylan in reed canarygrass hemicellulose. The presence of β-glucan was also confirmed using selective enzymatic hydrolysis. As the plants matured, the proportion of linear xylan increased. The occurence of galactose, mannose, fucose and rhamnose in cell wall extracts may be the result of acid catalyzed degradations and transformations of other cell wall sugars. The results revealed the value of chromatography as it is applied to interpretation of plant growth and composition. Gas-liquid chromatography was proposed as a tool for the evaluation of forage digestibility and forage quality.

1,2-Dioxines are a specific class of cyclic peroxide that are both prevalent in nature and important synthetic building blocks. To date, much of the chemistry involving 1,2-dioxines is concerned with cleavage of the weak peroxide bond, providing a convenient method for the incorporation of 1,4-oxygen functionality into molecules. Comparatively little attention has been directed towards transformations of the alkene unit contained within 1,2-dioxines, which is the focus of this thesis. The synthesis of a broad range of diversely functionalised 1,2-dioxines from commonly available starting materials is presented. Subsequently, the osmium catalysed dihydroxylation of 3,6-disubstituted 1,2-dioxines was investigated, furnishing novel peroxy diols in high yield and with excellent diastereoselectivity. The peroxy diols were then reduced, affording stereospecific tetraols and higher polyols, including the rare sugar allitol. In addition, homolytic ring-opening of the 1,2-dioxanes was examined, providing a new route to polyhydroxylated furanoses, highlighted by the synthesis of the natural keto-sugar psicose. Several 4-substituted 1,2-dioxines were also dihydroxylated, followed by reduction of the peroxide bond, providing a convenient route to branched erythritol derivatives, including the important plant sugar 2-C-methyl-erythritol. The cobalt catalysed ring-opening of the peroxy diols produced novel erythrose derivatives in high yield. In addition, the triphenylphosphine induced ring contraction of the peroxy diols is presented, which allowed for the synthesis of novel dihydroxylated tetrahydrofurans in excellent yield. Asymmetric dihydroxylation of the achiral 4-substituted 1,2-dioxines was explored, furnishing optically enriched peroxy diols with varying enantioselectivity depending on the substrate. The synthesis of novel alkyl and aryl branched erythrono-γ-lactones via oxidation of lactols derived from the acetonide protected peroxy diols is also documented. The utility of this sequence is illustrated by the preparation of potassium 2,3,4-trihydroxy-2-methylbutanoate, a leaf-closing substance of Leucaena leucocephalam. Additionally, γ-lactones were prepared from epoxy hydroxy ketones derived from epoxy-1,2-dioxanes, facilitated by a Baeyer-Villiger lactonisation protocol. The requirements and limitations of this procedure are discussed. The proposed and attempted synthesis of other lactones from 1,2-dioxines was also examined. Finally, several other general alkene transformations were investigated on 1,2- dioxines including: halo-hydrin formation, phenylselenyl chloride addition, aminohydroxylation, cyclopropanation, and aziridination, allowing for the preparation of several new classes of functionalised 1,2-dioxines. In summary, the work presented in this thesis establishes clear and efficient methodology towards several interesting and useful sugar-type core structures from modified 1,2-dioxines. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1313493 / Thesis (Ph.D) -- University of Adelaide, School of Chemistry and Physics, 2008

Sources of polar/water-soluble organic compounds conjunctly with apolar biomarkers were characterized in natural organic matter. This multi-biomarker approach was accomplished by a simple analytical method consisting of extraction with dichloromethane:methanol (2:1, v/v), silylation and analysis by gaschromatography- mass spectrometry (GC-MS). Polar and apolar biomarkers, derived mainly from higher plants and microorganisms, were used as tracers of processes occurring in the environmental compartments and registered in aerosol, soil and sediment samples. Sugars (monosaccharides, disaccharides, anhydrosugars and sugar alcohols) were utilized to trace seasonal variation inputs of biogenic organic carbon to aerosols over a pristine forest and the passage of a smoke plume from the long-range transport wildfire emissions. Sugars and fatty acid methyl esters were target compounds used to better understand the plant-microorganism dynamics in a ryegrass soil over a one-year period. Distributions and abundances of straight chain homologous series (n-alkanes, n-alkanols, n-alkanoic acids), cyclic components (e.g., diterpenoids, triterpenoids, steroids) and polar biomakers (e.g., sugars) were determined for sediment and smoke samples. In the first study, the transport and alterations of major terrestrial biomarkers were assessed for small rivers draining the northwestern US. In the latter, biomarkers and their thermal alteration derivatives were identified in smoke emissions from known temperate and semi-arid green vegetation to be applied as tracers of wildfires. This work demonstrated that a multi-biomarker tracer analysis is a useful tool for describing and understanding the biogeochemistry occurring in various environmental compartments. / Graduation date: 2006

No description available.

Sustainable waste treatment and lignin development strategies targeted for biorefineries will benefit industry, consumers, and the environment. This dissertation demonstrates the feasibility of a novel biochemical pathway capable of converting sugars and lignin sourced from biorefinery waste streams into microbial oils suitable for biodiesel, cosmetic, and biopharmaceutical applications. This biochemical pathway also presents interesting avenues for the commercial production of higher-value intermediate metabolites such as catechol, protocatechuate, pyruvate, and succinate. Alternatively, this dissertation also demonstrates a unique polymerization strategy for lignin that can be adopted towards the production of green polymeric biomaterials. Overall, these strategies jointly present intriguing routes for lignin valorization.