Dissertations / Theses: 'Conversion of fatty acids'

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Hussein, Nahed Mohamed. "Nutritional studies of long chain conversion of dietary polyunsaturated fatty acids." Thesis, University of Surrey, 2003. http://epubs.surrey.ac.uk/844191/.

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Growing evidence suggests that dietary n-3 very long chain polyunsaturated fatty acids (eicosapentaenoic acid; EPA and docosahexaenoic acid; DHA) reduce the risk of coronary heart disease and stroke, alpha-linolenic acid (alpha-LNA) is the natural precursor of EPA and DHA and is an abundant and accessible source of dietary n-3 PUFA that can be further elongated and unsaturated in vivo. The overall aim of the project is to examine the conversion of alpha-LNA to its long chain metabolite, most importantly DHA. This aim was accomplished by a combination of a human dietary intervention study to assess accumulation of EPA and DHA from dietary alpha-LNA, and 13C-tracer studies of alpha-LNA & linoleic acid (LA) conversion to their long-chain metabolites. The dietary intervention trial was a 12-week parallel design in men expressing an atherogenic lipoprotein phenotype, a common source of lipid-mediated coronary heart disease risk. Diets were enriched with 18 g of alpha-LNA as flaxseed oil (n=21), with a high LA oil (n=17), or with fish-oil (6g/d n=19) as a positive control group. Thus the intention was to provide an increased intake of alpha-LNA with a low ratio of n-6 to n-3 PUFA (1:1 or less), minimizing competition between alpha-LNA and the abundant LA and, in theory, increasing the conversion of alpha-LNA to LC n-3 PUFA. The results from the dietary intervention indicate that, dietary alpha-LNA as flaxseed oil can increase n-3 membrane fatty acid contents, through a 3-fold increase in alpha-LNA (p <0.001)) and 2.5 fold increase in EPA (p<0.001) at week-12, decreasing in n-6:n-3 ratio (p =0.001), but not changing DHA level. In contrast the fish oil diet increased both EPA and DHA. Dietary alpha-LNA had 7% of the efficacy of preformed EPA from fish oil to increase membrane EPA levels. Subjects on the 13C tracer study were a sub-group of the intervention study, studied after 12-weeks on the high alpha-LNA (n=6) or high n-6 (n=5) diets. Subjects were given an oral mixture of 400 mg each of uniformly 13C labelled alpha-LNA and LA in a milk shake after an overnight fast. 13C enrichment was measured in fatty acids isolated from plasma at 1,2,3,7,10 and 14 days after the dose. Of the dose appearing in the plasma 35-45% was converted to EPA with no dietary effects. Some conversion to DHA did occur especially in the high n-6 group (3.9% of dose) compared with the flaxseed-oil group (mean value 0.8% of the dose; p < 0.05). In the single subject studied on the fish-oil diet there was a much lower conversion rate compared to the flaxseed-oil diet. The variability between subjects for percent conversion to DHA ranged from zero to 6.2% of the dose appearing in plasma. Taken together these results clearly establish the effectiveness of dietary alpha-LNA as a method of increasing the concentration of EPA, but not DHA, in membrane phospholipids, with up to 7% of the efficacy of preformed EPA. The increase in the EPA: AA ratio (eicosapentanoic: arachidonic acid) in membrane phospholipids with dietary alpha-LNA is likely to reduce the overall inflammatory environment with beneficial effects for long-term health.

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Portolesi, Roxanne, and roxanne portolesi@flinders edu au. "Fatty acid metabolism in HepG2 cells: Limitations in the accumulation of docosahexaenoic acid in cell membranes." Flinders University. Medicine, 2007. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20070802.103146.

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The current dietary recommendations for optimal health are designed to increase our intake of two bioactive omega-3 (n-3) fatty acids, eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), abundant naturally in fatty fish such as salmon. Health authorities recommend that the general population consume two to three fatty fish meals per week (1) for optimal health and for the prevention of cardiovascular disease. However, some modern Western societies consume only modest amounts of fish and seafood (2;3). Land based vegetable oils may provide an alternative to meet these needs. Linseed and canola oils are rich in alpha-linolenic acid (ALA, 18:3n-3) (4). ALA can be converted endogenously to EPA and DHA and suggests that increasing the dietary intake of ALA may increase the conversion and accumulation of DHA in tissues and plasma. However, elevated dietary intakes of ALA in animals and humans results in an increased level of EPA in tissues yet there is little or no change in the level of DHA (5-7). The current consensus is that the synthesis of DHA from ALA in humans is limited yet the mechanisms involved in regulating the accumulation of DHA in tissues are poorly understood. The reputed rate-limiting enzyme in the conversion of fatty acids is delta 6 desaturase (D6D). ALA is a substrate for D6D and undergoes a series of desaturation and elongation reactions to yield n-3 long chain polyunsaturated fatty acids (LCPUFA). The final step in the synthesis of DHA from ALA involves translocation of its immediate fatty acid precursor, 24:6n-3 from the endoplasmic reticulum to the peroxisome to be partially beta-oxidised to yield DHA. The involvement of multiple enzymes in the desaturation-elongation pathway, and the integration of other pathways, such as phospholipid biosynthesis, suggests there are various steps that may regulate the accumulation of DHA in cell membranes. This thesis aimed to examine the possible regulatory steps in the conversion of fatty acids to LCPUFA, particularly in the synthesis of DHA from n-3 fatty acid precursors. The human hepatoma cell line, HepG2, was used as an in vitro cell system to examine the accumulation of individual fatty acids and their metabolites in isolation from other competing fatty acid substrates. The accumulation of linoleic acid (LA, 18:2n-6) and ALA in HepG2 cell phospholipids following supplementation with increasing concentrations of each respective fatty acid correlated with that described in vivo, as was the accumulation of their conversion products. The accumulation of DHA in cells supplemented with ALA reached a plateau at concentrations above 5 micro g/ml and paralleled the accumulation of 24:6n-3 in cell phospholipids, suggesting that the delta 6 desaturation of 24:6n-3 was prevented by increasing concentrations of ALA, thereby limiting the accumulation of DHA. The accumulation of DHA in cells supplemented with eicosapentaenoic acid (EPA, 20:5n-3) or docosapentaenoic acid (DPA, 22:5n-3) was significantly greater than the level of DHA that accumulated in cells supplemented with ALA. However, regardless of substrate, the level of DHA in cell membranes reached a plateau at substrate concentrations above 5 micro g/ml. This thesis further aimed to examine the effect of fatty acid supplementation on the mRNA expression of D6D in HepG2 cells. The expression and activity of D6D mRNA is subject to nutritional and hormonal regulation. The mRNA expression of D6D in HepG2 cells following supplementation with oleic acid (OA, 18:1n-9), LA, ALA, arachidonic acid (AA, 20:4n-6) or EPA was examined by real time RT PCR. The expression of D6D mRNA was reduced by up to 50% in cells supplemented with OA, LA, ALA , AA or EPA compared with control cells and suggests that fatty acids modulate the expression of the key enzyme involved in the conversion of fatty acids. The effect of fatty acid co-supplementation on the fatty acid composition of HepG2 cell phospholipids was also examined in an attempt to gain insights into the role of D6D and the enzymes involved in peroxisomal beta-oxidation on the accumulation of DHA from n-3 fatty acid precursors. The reduction in the accumulation of DHA in cells co-supplemented with DPA and docosatetraenoic acid (DTA, 22:4n-6) was greater than in cells co-supplemented with DPA and LA, suggesting that peroxisomal beta-oxidation may have a greater role in determining the accumulation of DHA from DPA than the activity of D6D. Further investigation should be directed towards understanding the role that peroxisomal beta-oxidation may play in the synthesis of DHA from precursor fatty acids. The fatty acid composition of cell membranes in vivo is a result of several physiological processes including dietary intake, phospholipids biosynthesis and fatty acid conversion as well as catabolic processes. This thesis demonstrates that a greater understanding of the regulation of the conversion of fatty acids will help to define dietary approaches that enhance the synthesis of n-3 LCPUFA from n-3 fatty acid precursors to lead to improved outcomes for health.

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Pietrzyk, Julian Darius. "Use of microbial consortia for conversion of biomass pyrolysis liquids into value-added products." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31562.

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Lignocellulosic biomasses are considered promising feedstocks for the next generation of biofuels and chemicals; however, the recalcitrance of lignocellulose remains a barrier to its utilisation over conventional sources. Pyrolysis is the heating of biomass to several hundred degrees Celsius in the absence of oxygen, which can thermally depolymerise lignocellulose. Products of pyrolysis are a solid biochar, liquid bio-oil and syngas. Biochar has roles in both carbon sequestration and soil amendment however bio-oil has no defined use, despite a high concentration of fermentable sugars. Bio-oil is a complex organic microemulsion with a host of biocatalyst inhibitors that makes its microbial degradation a challenge. In this work, the use of aerobic cultures using microbial communities isolated from natural environments saw limited potential; however, the use of anaerobic digestion (AD) successfully generated a higher volume of biogas from reactors with bio-oil than controls. Biogas yield test reactors were set up with anaerobic digestate from a wastewater treatment plant as the substrate for degradation and conversion of bio-oils. Next-generation 16S rRNA gene sequencing was utilised to characterise the communities in the reactors while the ultrahigh resolution mass spectrometry technique of Fourier transform ion cyclotron resonance (FT-ICR) was used for characterisation of the chemical changes occurring during AD. Both sets of high-resolution data were additionally combined for multivariate analysis and modelling of the microbial genera that correlated best with the changes in digestate chemistry. This represents a novel analysis method for the microbial degradation of complex organic products. Bio-oil from common lignocellulosic feedstock was the most easily degradable by the AD communities, with significant inhibition observed when bio-oils from anaerobic digestate and macroalgae were used. Additionally it was found that the inclusion of biochars that were pre-incubated in anaerobic digestate prior to use in AD were capable of significantly reducing the lag time observed for biogas production in bio-oil-supplemented reactors. The addition of biochars that were not pre-incubated had no effect on biogas production. Specific inhibition of methanogenesis was also capable of causing the digestates to accumulate volatile fatty acids (VFAs) as a product of greater value than biogas. Scale-up experiments will be required to confirm the precise practicalities of the addition of bio-oil to AD as well as to establish the potential for isolation and purification of VFAs.

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Santos, Dantas Tatiane Regina dos [Verfasser], and Uwe [Akademischer Betreuer] Schröder. "Electroorganic Synthesis for the Conversion of Fatty Acids and Levulinic Acid into Chemicals and Alternative Fuels / Tatiane Regina dos Santos Dantas ; Betreuer: Uwe Schröder." Braunschweig : Technische Universität Braunschweig, 2017. http://d-nb.info/1175817562/34.

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Facchin, Andrea. "New path for thermochemical-biological conversion with a power-to-material approach." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23117/.

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I sistemi termochimico-biologici si basano su due proprietà: la capacità dei processi termochimici di dissociare le macromolecole della biomassa producendo composti a basso peso molecolare, e l’abilità dei batteri di convertire substrati anche complessi in sostanze chimiche di valore. Questa tesi ha sviluppato un nuovo approccio metodologico per approfondire la possibilità di un accoppiamento diretto tra pirolisi e digestione anaerobica, allo scopo di produrre acidi grassi volatili (VFA), sinergicamente con l’utilizzo di idrogeno come fonte rinnovabile per aumentare il valore del prodotto finale. In primo luogo, è stata fatta un'ampia caratterizzazione del rendimento di COD e della composizione chimica dei prodotti di pirolisi che ha rivelato come più del 50% del COD della biomassa di partenza sia convogliato in sostanze chimiche biodisponibili. In secondo luogo, sono stati sviluppati tre reattori anaerobici a gocciolamento con diversi materiali di riempimento, incluso il biochar. I prodotti di pirolisi sono stati successivamente fermentati con e senza idrogeno, per valutarne, in via preliminare, la possibile conversione in VFA. I risultati suggeriscono che il biochar ha agito come promotore per la biotrasformazione dei prodotti di pirolisi in VFA, producendo una conversione del 35% rispetto al COD in input, mentre l'idrogeno ha dimostrato la capacità di stabilizzare le rese di VFA a catena lunga.

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Chen, Xi. "Functional food-related bioactive compounds: effect of sorghum phenolics on cancer cells in vivo and conversion of short- to long-chain omega-3 polyunsaturated fatty acids in duck liver in vivo." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/38244.

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Doctor of Philosophy
Department of Human Nutrition
Weiqun Wang
Many functional food related bioactive compounds have been discovered and draw the attention of scientists. This dissertation focused on sorghum phenolic compounds and omega-3 polyunsaturated fatty acids. Study 1: phenolic agents in plant foods have been associated with chronic disease prevention, especially cancer. However, a direct evidence and the underlying mechanisms are mostly unknown. This study selected 13 sorghum accessions and was aim to investigate: (1) the effect of extracted sorghum phenolics on inhibiting cancer cell growth using hepatocarcinoma HepG2 and colorectal adenocarcinoma Caco-2 cell lines; (2) and the underlying mechanisms regarding cytotoxicity, cell cycle interruption, and apoptosis induction. Treatment of HepG2 and Caco-2 cells with the extracted phenolics at 0-200 M GAE (Gallic acid equivalent) up to 72 hrs resulted in a dose- and time-dependent reduction in cell number. The underlying mechanism of cell growth inhibition was examined by flow cytometry, significant inverse correlations were observed between the decreased cell number and increased cell cycle arrest at G2/M or induced apoptosis cells in both HepG2 and Caco-2 cells. The cytotoxic assay showed that the sorghum phenolic extracts were non-toxic. Although it was less sensitive, a similar inhibitory impact and underlying mechanisms were found in Caco-2 cells. These results indicated for the 1st time that a direct inhibition of either HepG2 or Caco-2 cell growth by phenolic extracts from13 selected sorghum accessions was due to cytostatic and apoptotic but not cytotoxic mechanisms. In addition, these findings suggested that sorghum be a valuable functional food by providing sustainable phenolics for potential cancer prevention. Study 2: omega-3 polyunsaturated fatty acids (ω-3 PUFAs) especially long-chain ω-3 PUFAs, have been associated with potential health benefits in chronic disease prevention. However, the conversion rate from short- to long-chain ω-3 PUFAs is limited in human body. This study was aim to assess the modification of fatty acid profiles as well as investigate the conversion of short- to long-chain ω-3 PUFAs in the liver of Shan Partridge duck after feeding various dietary fats. The experimental diets substituted the basal diet by 2% of flaxseed oil, rapeseed oil, beef tallow, or fish oil, respectively. As expected, the total ω-3 fatty acids and the ratio of total ω-3/ ω-6 significantly increased in both flaxseed and fish oil groups when compared with the control diet. No significant change of total saturated fatty acids or ω-3 fatty acids was found in both rapeseed and beef tallow groups. Short-chain ω-3 α-linolenic acid (ALA) in flaxseed oil-fed group was efficiently converted to long-chain ω-3 docosahexaenoic acid (DHA) in the duck liver. This study showed the fatty acid profiling in the duck liver after various dietary fat consumption, provided insight into a dose response change of ω-3 fatty acids, indicated an efficient conversion of short- to long-chain ω-3 fatty acid, and suggested alternative long-chain ω-3 fatty acid-enriched duck products for human health benefits. In conclusion, the two studies in this dissertation provided a fundamental understanding of anti-cancer activity by sorghum phenolic extracts and the conversion of short- to long-chain ω-3 PUFAs in duck liver, contribute to a long term goal of promoting sorghum and duck as sustainable phenolic and ω-3 PUFAs sources as well as healthy food products for human beings.

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Ghandour, Rayane. "Effet des acides gras polyinsaturés sur la conversion des adipocytes blancs en adipocytes brites." Thesis, Nice, 2016. http://www.theses.fr/2016NICE4010/document.

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Il existe deux populations d’adipocytes thermogéniques, les adipocytes bruns du tissu adipeux bruns et les adipocytes ‘’brites’’ qui apparaissent au sein du tissu adipeux blanc. Récemment, la caractérisation d’adipocytes bruns et brites fonctionnels chez l’homme adulte a permis d’envisager de nouvelles approches nutritionnelles et thérapeutiques pour traiter l’obésité. Mon projet de thèse a porté sur l’étude des effets des acides gras polyinsaturés ω6 et ω3 d’origine alimentaire sur la conversion des adipocytes blancs en brites, d’abord chez l’homme in vitro puis chez les rongeurs in vivo. Nous avons pu ainsi démontrer que l'acide arachidonique ω6 à l’origine de nombreux métabolites oxygénés, exerce 1) un effet inhibiteur sur la formation des adipocytes brites grâce aux prostaglandines E2 et F2α, et 2) un effet inducteur via la prostacycline. En effet, celle-ci active la conversion des adipocytes blancs en brites par une voie impliquant le récepteur membranaire IP et les récepteurs nucléaires PPARs. En nous basant sur les recommandations nutritionnelles actuelles chez l’Homme, qui ont pris en considération l’insuffisance de l’apport en acides garsω3 par rapport à l’excès des ω6, nous avons pu montrer chez la souris qu’une supplémentation en acides gras ω3 dans le régime alimentaire était capable d’inhiber l’effet néfaste des acides gras ω6 et d’activer le tissu adipeux brun. Nos résultats démontrent l’importance de la biodisponibilité de l’acide arachidonique dans la biologie du tissu adipeux et permettent de renforcer l’idée que le rééquilibrage du ratio ω6/ω3 est un outil de choix dans la prévention du surpoids et de l’obésité et les maladies métaboliques associées
There are two types of thermogenic adipocytes able to use fatty acids and glucose to produce heat. We distinguish brown adipocytes from the brown adipose tissue and ‘’brite’’ adipocytes which occur into the white adipose tissue. Recently, the characterization of functional brown and brite adipocytes in adult humans has led to the consideration of their use to treat obesity by increasing energy expenditure. My thesis project was to study the effect of dietary polyunsaturated fatty acids, on the conversion of white into brite adipocytes, in vitro and in vivo, in humans and rodents respectively. We demonstrated that arachidonic acid ω6, precursor of prostaglandins, has 1) an inhibitory effect on the recruitment of brite adipocytes via prostaglandins E2 and F2α and 2) an activatory effect via prostacyclin. In fact, prostacyclin induces the conversion of white into brite adipocytes through the IP receptor and the PPARs signaling pathways. Based on human present nutritional recommendations, we demonstrated that a supplementation of ω3 fatty acids in mice diet was able to inhibit the negative effect of ω6 fatty acids and activate brown adipose tissue. Our data highlights the importance of arachidonic acid bioavailability on the biology of adipose tissue and reinforce the idea that an equilibrate ω6/ω3 ratio is a tool that can be used to prevent overweight obesity and associated metabolic disorders

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Faneca, Vera Lúcia Almeida. "Caracterização de fosfolípidos, incluindo plasmalogénios, em bivalves da costa portuguesa." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2016. http://hdl.handle.net/10400.5/13056.

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Dissertação de Mestrado em Segurança Alimentar
Apesar da existência de alguns estudos que envolvem a caracterização lipídica de bivalves, não se conhece a existência de trabalhos que envolvam os bivalves da Costa Portuguesa, nomeadamente no que diz respeito à caracterização lipídica de plasmalogénios. Os plasmalogénios são fosfolípidos presentes nas membranas celulares que parecem ter relevância no estado de saúde e/ou doença nos humanos, dado as suas funções biológicas. O objetivo deste trabalho consistiu na caracterização e determinação do perfil lipídico (ácidos gordos e dimetilacetais), em especial de plasmalogénios, de vários bivalves da Costa Portuguesa: ameijoa japonesa (Ruditapes phillippinarum), lambujinha (Scrobicularia plana), berbigão (Cerastoderma spp.), mexilhão (Mytillus spp.), ostra (Crassostera spp.) e longueirão (Ensis spp.). Também pretendeu verificar se estes bivalves seriam uma boa fonte alimentar de plasmalogénios. Além disto, também se determinou fatores de conversão lipídicos para as diferentes frações lipídicas dos bivalves em estudo. Os resultados deste trabalho demonstraram que a composição em ácidos gordos dos plasmalogénios é variável entre os bivalves estudados, mas em todos eles houve pontos consistentes, nomeadamente a frequência do C16:0 e C18:0 nos ácidos gordos saturados, bem como a de EPA e DHA e o total de ácidos gordos NMI nos ácidos gordos polinsaturados. Relativamente aos dimetilacetais, o mais frequente foi o 18:0. Através da aplicação dos fatores de conversão lipídicos determinados, conseguiu-se determinar o teor de plasmalogénios existentes em 100g de bivalve, verificando-se que o mexilhão foi o bivalve que apresentou maior conteúdo em plasmalogénios (58,6 mg/100g). Contudo, os bivalves estudados mostraram que não são ricos em plasmalogénios.
ABSTRACT - Phospholipids characterization, including plasmalogens, in bivalves of the Portuguese Coast - Despite the existence of research involving the lipid characterization of bivalves, there are no concerning bivalves of the Portuguese Coast, particularly regarding the lipid characterization of plasmalogens. Plasmalogens are phospholipids existing in cell membranes, which seem to be relevant to human's health and sickness due to their biological functions. The goal of this study is to characterize and determine the lipid profile (fatty acids and dimethylacetals, especially plasmalogens) of several bivalves of the Portuguese Coast, namely Japanese carpet shell (Ruditapes phillippinarum), peppery furrow shell (Scrobicularia plana), cockle (Cerastoderma spp.), mussel (Mytillus spp.), oyster (Crassostera spp.) and razor shell (Ensis spp.). This work also intends to verify if they are a good nutritional source of plasmalogens. Furthermore, the lipid conversion factors for the different lipid fractions of bivalves were also determined under this research. The results showed that the composition of fatty acids of the plasmalogens are variable amongst the researched bivalves. However, all of them had consistent points, namely the frequency of C16:0 and C18:0 in saturated fatty acids as well as EPA and DHA and a total NMI fatty acids in polyunsaturated fatty acids. Regarding dimethylacetals, the most common was 18:0. Through the application of the determined lipid conversion factors, it was possible to quantify the plasmalogens content in 100g of bivalves. The mussels revealed to have the highest content of plasmalogens (58,6 mg/100g). Nevertheless, this work showed that the researched bivalves are not rich in plasmalogens.
N/A

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Matzen-Fredel, Anna. "Immobilisation of metathesis catalysts on mesoporous materials for the conversion of bio sourced fatty compounds." Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10174.

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Alors que les ressources fossiles décroissent, le concept de bio-raffinerie est une approche très attrayante pour la production de produits chimiques à partir de ressources renouvelables. Dans ce contexte, les dérivés d’acides gras insaturés, obtenus par hydrolyse de triglycérides issus de végétaux, sont une catégorie importante de substrats. Leur conversion en composés à haute valeur ajoutée est un objectif majeur qui peut être atteint grâce à la catalyse, et plus particulièrement grâce à la métathèse des alcènes. De plus, dans un esprit de meilleure séparation entre produits et catalyseurs, et pour des questions de recyclage, l’emploi de catalyseurs hétérogènes est de grand intérêt. L’hétérogénéisation de catalyseurs commerciaux à base de ruthénium a été entreprise. Les matériaux hybrides ont été préparés en deux étapes: après une cationisation à l’aide de sels d’argent, les espèces organométalliques ont été immobilisées par échange ionique dans les aluminosilicates mésoporeuses de type MCM-41. Ces nouveaux catalyseurs ont été caractérisés par RMN du solide, IR, DRX, BET, analyse élémentaire et ATG. Ils ont été employés avec succès dans différentes réactions de métathèse impliquant le substrat-type, l’oléate de méthyle. Les réactions étudiées sont l’homométathèse, l’éthénolyse et la métathèse croisée avec des oléfines fonctionnalisées issues des acides acrylique et crotonique. Bien que le recyclage n’ait pas été couronné de succès, les catalyseurs supportés permettent de réaliser toutes ces réactions, ce qui représente dans certains cas le premier exemple de telles transformations par catalyse hétérogène avec des activités et sélectivités élevées
As fossil resources constantly decrease, the concept of bio-refinery is a most attractive approach to generate chemicals from renewable resources. In this context, unsaturated fatty acids derived from the hydrolysis of crops extracted-triglycerides are a major class of substrates. These must be converted to high added-value derivatives: catalytic transformations can play a key role in this, by converting such compounds into other functionalized derivatives. A most attractive reaction to meet this challenge is olefin metathesis. Based on product/catalyst separation and catalyst recycling issues, use of heterogeneous catalysts is of high interest.We thus prepared heterogenized commercial ruthenium catalysts. The hybrid materials were prepared in a two-step procedure: after silver salt-mediated cationization, the organometallic species were immobilized by ion exchange on mesoporous aluminosilicates of the MCM-41 family. The novel catalysts were characterized by solid-state NMR, IR, XRD, BET, elemental analysis and TGA. They were successfully applied in several metathesis reactions involving the archetypic methyl oleate, a C18 unsaturated ester, with different grades of purity. The probed reactions were self-metathesis, ethenolysis and cross-metathesis with functionalized olefins derived from acrylic and crotonic acids. Though recycling was not completely successful, the supported catalysts were able to efficiently catalyze all these transformations, providing in some instances the first heterogeneously examples of such reactions with high activity and selectivity

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Beligon, Vanessa. "Valorisation d'acides gras volatils issus de fermentation anaérobie par la production de lipides microbiens, précurseurs de biodiesel." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22687/document.

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Une part importante de la production mondiale de vecteurs énergétiques et de produits chimiques provient de la raffinerie de combustibles fossiles. En raison de l'augmentation du prix du pétrole et de son impact environnemental, la recherche de solutions alternatives, écologiques et économiques constitue l’un des enjeux de notre siècle. Le remplacement du pétrole par de la biomasse en tant que matière première pour la production de carburants et de produits chimiques constitue la force motrice dans le développement de complexes de bioraffinerie.Cette étude fait partie d’un projet de bioraffinerie visant la valorisation de biomasse lignocellulosique par la production d’hydrogène et de lipides microbiens précurseurs de biodiesel. Ce travail se concentre en particulier sur l’étape de production de biomasse et de lipides par la levure oléagineuse Cryptococcus curvatus à partir d’acides gras volatils (AGVs) synthétisés au cours de la fermentation anaérobie productrice d’hydrogène. Les cultures ont dans un premier temps été réalisées à partir d’un substrat modèle, l’acétate, en fed-batch et en continu. La détermination de l’influence de différents paramètres opératoires sur la production de biomasse et de lipides à partir d’acétate a permis de mettre au point des cultures en fed-batch dont les cinétiques, les productivités et les rendements finaux étaient compétitifs avec ceux rapportés dans la littérature pour des cultures sur substrats simples. Un modèle de croissance et de production de lipides a été construit à partir de ces données afin de prédire le comportement de la souche lors de cultures continues, permettant d’obtenir des productivités en lipides et en biomasse élevées. Enfin, des cultures ont été menées à partir d’AGVs issus de surnageant de fermentation anaérobie. Les résultats ont confirmé la croissance de ces levures sur ce substrat particulier et la production de lipides dont la composition en acides gras estérifiés était compatible avec une utilisation comme biodiesel
A great part of the global production of energy vectors and chemicals comes from fossil fuels refinery. Because of the increase in oil price and their environmental impacts, the search for alternative, ecological and economic solutions is a current challenge. The replacement of oil with biomass as raw material for the production of fuels and chemicals is the driving force for the development of biorefinery complexes.This study is part of a project aiming at the biorefinery of lignocellulosic biomass for hydrogen and microbial lipids as biodiesel precursors. This work focuses on the biomass and lipids production step by the oleaginous yeast Cryptococcus curvatus using volatile fatty acids (VFAs) as carbon sources, which are synthesized during the anaerobic fermentation step. Yeast cultures have initially been realized using a model substrate, acetate, and fed-batch and continuous modes. The determination of the influence of different operating parameters on the biomass and lipids production led to the development of fed-batch cultures which kinetics, productivities and yields were competitive with those reported in the literature for cultures on simple substrates. A growth and lipid production model was built from these data to predict the behavior of the strain during continuous cultures and to obtain high lipid and biomass productivities. Finally, cultures were conducted using VFAs from anaerobic fermentation supernatant. The results confirmed the growth of these yeasts on this particular substrate and the production of lipids which composition was compatible with use as biodiesel

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Johnson, Michael Ben. "Microalgal Biodiesel Production through a Novel Attached Culture System and Conversion Parameters." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/32034.

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Due to a number of factors, the biodiesel industry in the United States is surging in growth. Traditionally, oil seed crops such as soybean are used as the feedstock to create biodiesel. However, the crop production can no longer safely keep up with the demand for the growing biodiesel industry. Using algae as a feedstock has been considered for a number of years, but it has always had limitations. These limitations were mainly due to the production methods used to grow and harvest the algae, rather than the reaction methods of creating the biodiesel, which are the same as when using traditional crops. Algae is a promising alternative to other crops for a number of reasons: it can be grown on non arable land, is not a food crop, and produces much more oil than other crops. In this project, we propose a novel attached growth method to produce the algae while recycling dairy farm wastewater using the microalga Chlorella sp. The first part of the study provided a feasibility study as the attachment of the alga onto the supporting substrate as well as determining the pretreatment options necessary for the alga to grow on wastewater. The results showed that wastewater filtered through cheesecloth to remove large particles was feasible for production of Chlorella sp, with pure wastewater producing the highest biomass yield. Most importantly, the attached culture system largely exceeded suspended culture systems as a potentially feasible and practical method to produce microalgae. The algae grew quickly and were able to produce more than 3.2 g/m2-day with lipid contents of about 9% dry weight, while treating dairy farm wastewater and removing upwards of 90% of the total phosphorus and 79% of the nitrogen contained within the wastewater. Once the â proof-of-conceptâ work was completed, we investigated the effects of repeat harvests and intervals on the biomass and lipid production of the microalgae. The alga, once established, was harvested every 6, 10, or 15 days, with the remaining algae on the substrate material functioning as inoculums for repeated growth. Using this method, a single alga colony produced biomass and lipids for well over six months time in a laboratory setting. The second part of this study investigated another aspect of biodiesel production from algae. Rather than focus solely on biomass production, we looked into biodiesel creation methods as well. Biodiesel is created through a chemical reaction known as transesterification, alcoholysis, or commonly, methylation, when methanol is the alcohol used. There are several different transesterification methods. By simplifying the reaction conditions and examining the effects in terms of maximum fatty acid methyl esters (FAME) produced, we were able to determine that a direct transesterification with chloroform solvent was more effective than the traditional extraction-transesterification method first popularized by Bligh & Dyer in 1959 and widely used. This synergistic research helps to create a more complete picture of where algal biodiesel research and development is going in the future.
Master of Science

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Machado, Junior Francisco Roberto da Silva. "Conversão por via biotecnológica de glicerina residual em biomassa de leveduras como fonte de proteínas e lipídios." reponame:Repositório Institucional da FURG, 2010. http://repositorio.furg.br/handle/1/2924.

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Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia e Ciência de Alimentos, Escola de Química e Alimentos, 2010.
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A crescente demanda de energia em tempos de diminuição no fornecimento de combustível fóssil tem atraído a atenção para a busca por fontes alternativas, que venham a substituir o uso do petróleo, do carvão e do gás natural. Neste contexto, o biodiesel produzido a partir de óleos vegetais aparece como uma alternativa para substituição ao óleo diesel. Esta possibilidade de utilização de combustíveis de origem agrícola vem apresentando um potencial promissor no mundo inteiro, sendo um mercado que cresce aceleradamente devido à sua enorme contribuição ao meio ambiente, com a redução qualitativa e quantitativa dos níveis de poluição ambiental, principalmente nos grandes centros urbanos, e também servindo como fonte estratégica de energia renovável em substituição ao óleo diesel e outros derivados do petróleo. A produção de biodiesel a partir dos óleos vegetais fornece um sistema bifásico, sendo uma fase não polar de ésteres de ácidos graxos e outra mais densa constituída por glicerina e outros componentes residuais do processo. Considerando que na produção de biodiesel há geração de aproximadamente 10% de glicerina, com a mistura constituída de 5% de biodiesel ao diesel (B5) estimativas apontam, em 2013, uma geração de cerca de 150 mil toneladas por ano de glicerina. Uma vez que os mercados tradicionais de glicerina não conseguirão absorver esta oferta de produto neste cenário, este trabalho vem contribuir em inovações tecnológicas relacionadas ao aproveitamento da glicerina, mais especificamente na conversão por via biotecnológica da glicerina gerada na síntese de biodiesel em biomassa de interesse comercial, como fonte de nutrientes. Os efeitos da composição do meio de preparo de inóculo e da temperatura de incubação sobre o crescimento da levedura Yarrowia lipolytica NRRL YB – 423, cultivada em meio à base de glicerina residual, foram estudados em incubadora rotatória, verificando-se que a temperatura de 25°C e utilizando um meio de inóculo com mesma composição do meio de produção foram mais adequados ao crescimento microbiano, atingindo uma concentração de biomassa de 17,7 g.L-1. Em biorreator de bancada, um planejamento fatorial para avaliar a aeração e agitação (22 ensaios mais 3 pontos centrais) foi realizado. Os ensaios indicaram agitação de 200 rpm e aeração de 1 vvm como a melhor condição de cultivo, atingindo 19,14 g.L-1 de concentração de biomassa máxima média, conteúdo protéico médio de 13,55% e teor lipídico de 7,87%. Nestas condições, o cultivo em biorreator de bancada, em relação ao cultivo em frascos agitados, levou a incrementos significativos na biomassa máxima, velocidade específica máxima de crescimento celular e produtividade, respectivamente de 1,22, 1,53 e 2,36 vezes. Com base na determinação do perfil de ácidos graxos e aminoácidos, a biomassa mostrou-se fonte promissora de ácidos graxos essenciais, em particular o ácido linoléico (49,16%) e aminoácidos essenciais como isoleucina, valina, treonina e lisina, que apresentaram escores químicos superiores ao padrão FAO/WHO, respectivamente 1,42, 1,42, 1,30 e 1,17. Portanto a biomassa mostrou-se promissora para utilização como fonte de nutrientes, em particular para alimentação animal.
The crescent demand of energy in times of decreasing in the supply of fossil fuel has been attracting the attention for the search for alternative sources, which will come to substitute the use of the petroleum, coal and natural gas. In this context, the vegetable oils appear as an alternative for substitution to the diesel oil. This possibility of using fuels from agricultural sources has shown a promising potential in the whole world, with a market that is growing rapidly because of its enormous contribution to the environment, with the qualitative and quantitative reduction of the levels of environmental pollution, mainly in the great urban centers, and also serving as strategic source of renewable energy in substitution to the diesel oil and others derived of the petroleum. The production of biodiesel from vegetable oils provides a biphasic system, being a non-polar phase of esters of fatty acids and other more dense consisting of glycerin and other waste components of the process. Considering that in the biodiesel production there is a generation of approximately 10% of glycerin, with the mixture consisting of 5% of biodiesel to diesel (B5) estimates indicate, in 2013, the generation of 150,000 tons per year. Since the traditional markets of glycerin can not absorb this additional supply of product on this scene, this work will contribute in technological innovations related to the use of glycerin, more specifically in the biotechnology conversion of glycerin generated in the synthesis of biodiesel in biomass of commercial interest, as source of nutrients. The effects of temperature and inoculum medium composition on the performance of yeast Yarrowia lipolytica NRRL YB – 423, growing on a glycerin-based medium, were studied in shaken flasks, verifying that the temperature of 25°C and the inoculum medium with the same composition of production medium were the most appropriate conditions for microorganism growth, reaching a biomass concentration of 17.7 g.L-1. In the bioreactor bench scale, a factorial design involving two variables (22 assays plus three central points) was performed, where the studied variables were agitation and aeration. The assays showed agitation of 200 rpm and aeration of 1 vvm as the best culture conditions, reaching a concentration of 19.14 g.L-1 of biomass with protein content of 13.55% and lipid content of 7.88 %. In these conditions, the cultivation in the bioreactor, in relation to the shaken flasks cultivation, leaded to significant increases in the maximum biomass concentration, maximum specific growth rate and productivity, respectively 1.22, 1.53 and 2.36 times. Based on the fatty acid and aminoacid profiles, the biomass showed to be a promising source of essential fatty acids, in particular linoleic acid (49.16%), and essential aminoacids such as isoleucine, valine, threonine and lysine, which presented chemical scores superior than FAO/WHO standard, respectively 1.42, 1.42, 1.30 and 1.17.Therefore biomass showed to be promise for use as a source of nutrients, particularly for animal feed.

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Mukumbo, Felicitas Esnart. "Effect of dietary inclusion of Moringa oleifera Lam leaf meal on feed conversion efficiency, meat quality, fatty acid composition, shelf life and consumer health-related perceptions of pork." Thesis, University of Fort Hare, 2013. http://hdl.handle.net/10353/d1016071.

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The objective of the study was to determine the feed conversion efficiency (FCE), carcass characteristics, physico-chemical quality, fatty acid (FA) composition and shelf life of pork from pigs fed diets containing either 0% (T1), 2.5% (T2), 5% (T3) or 7.5% (T4) Moringa oleifera leaf meal (MOLM). Consumer health-related perceptions on pork and fatty acids were also investigated. Twenty four crossbred Large White x Landrace pigs of both sexes at 18 weeks of age and initially weighing 71.6 kg on average were housed individually and had ad libitum access to one of the four dietary treatments for a period of six weeks. Average daily feed intake (ADFI) and average daily gain (ADG) and feed conversion ratios (FCR) were calculated as an indication of FCE and pigs were slaughtered at an average live weight of 99.6 kg. Carcass traits such as back fat thickness (BFT), carcass temperatures and pH readings taken 45 minutes and 24 hours (pH45 and pHu) post mortem were recorded. M. longissimus thoracis et lumborum (LTL) samples were taken from each carcass for the determination of lightness (L*), redness (a*), yellowness (b*), thawing loss percentage (TL%), cooking loss percentage (CL%), Warner Bratzler Shear Force (WBSF), shelf life and FA composition. Furthermore a survey was conducted amongst 80 University of Fort Hare Students to determine their health-related perceptions on pork and fatty acids as well as their pork consumption frequency using questionnaires. The FCE of pigs fed on 0-5% MOLM (T1, T2 and T3) diets did not differ significantly, but the FCE of pigs fed 7.5% MOLM (T4) was significantly (p<0.05) reduced. No significant relationship was reported between inclusion of MOLM carcass characteristics and physico-chemical pork quality. There was however a significant improvement (p<0.05) in the shelf life of the pork from MOLM fed pigs in terms of colour and odour during 10 days of refrigerated storage (at 3±1°C). There was a significant (p<0.05) reduction in the total intramuscular fat (IMF) content and the saturated fatty acid (SFA) C18:0 (stearic acid) content and an overall non-significant (p>0.05) increase in the poly unsaturated fatty acid (PUFA) content of pork from MOLM fed pigs. The possible reason for this is that the feeding of MOLM was commenced when the pigs were at an advanced age and weight. The survey revealed that the majority of interviewed students consume fresh (39.7%) and processed (32.4%) pork two to three times a week, perceive pork to be generally healthy (70%) and the second most healthy meat type (39.5%). While the majority (55.4%) were aware of the health implications of FAs they did not know which FA classes pose more of a health risk (51.3%). In conclusion2.5% and 5% of MOLM in finisher pig feed did not negatively affect FCE, carcass characteristics or physico-chemical meat quality; significantly improved pork shelf life and reduced total IMF and SFA content of pork but 7.5% MOLM negatively affected FCE; and the majority of students perceive pork to be the second most healthy type of meat and are generally aware of the health implications of FAs.

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14

Lloyd, Davidson A. "The effect of forest to pasture conversion on soil biological diversity and function." Diss., Lincoln University, 2008. http://hdl.handle.net/10182/711.

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Recent declines in returns from primary forest products in New Zealand and projected increases in world food prices have led to the land-use conversion from plantation forest to pastoral farming in many lowland areas. After decades of forest cover the soils are in many cases less than adequate for pastoral farming, as they are acidic, with toxic levels of exchangeable aluminum, and contain low levels of available nitrogen (N), very high carbon (C):N ratio, and are devoid of earthworms and structural integrity. Overcoming the major site limitations of low soil pH and available N was a major priority and a field experiment was established in April 2005 to determine the impact of various rates of lime and N in relation to pasture establishment and production. Concerns about the short and long-term effects of these inputs on biological soil quality gave rise to the present study. The effects of land-use change and establishment inputs were assessed by comparison of selected treatment plots with two adjacent reference sites (long-term pasture and a 60–year Pinus radiata forest) on the same soil type. The effects of lime and N on soil biological quality were investigated under field and controlled environment conditions by determination of: microbial community structure (phospholipid fatty acids - PLFA), microbial biomass (total PLFA), and microbial activity (dehydrogenase activity). Soil physical (percentage water-stable aggregates) and chemical (pH, and total C and N) properties were also determined. Similarly, the effects of earthworm addition on soil biological properties were explored in a short-term glasshouse pot experiment. The role of earthworms as indicators of soil biological quality in the field was assumed by nematodes and these were assessed in field trial plots and the reference sites mentioned above. Land-use change and applications of lime and N contributed to changing the microbial community structure determined by principal component analysis of transformed PLFA data. However, the effect of lime was more pronounced in the field, while N contributed most to changing microbial community structure in the glasshouse. Mean microbial activity in the field increased from 4 µg dwt/hr without lime to 16 and 21 µg dwt/hr where lime was applied at 5 and 10 tons/hectare (t/ha), respectively. Mean microbial activity in the field was markedly higher (7-fold) than in the glasshouse at similar rates of lime. Lime application also increased soil moisture retention in the field, mean gravimetric soil moisture increased from 0.33 in control plots to 0.38 and 0.39 in plots treated with 5 and 10 t/ha lime, respectively. Lime application was associated with greater soil aggregate stability. Soils from test plots treated with 5 and 10 tons/ha lime had 45-50% water-stable aggregates compared to 34% in treatments without lime. After 16 weeks in pots, earthworm treatments increased mean plant dry matter (DM)/pot by at least 19% above the control. The increase was attributed primarily to greater N mineralization in the presence of earthworms. For the duration of the trial the earthworm species tested (Apporectodea caliginosa and Lumbricus rubellus, individually or combined) did not affect any of the measured soil microbial properties. However, the survival rate of A. caliginosa was 83% compared to 25% for L. rubellus. The control not receiving any lime or N and plots treated with 10t/ha lime and 200 kgN/ha had similar nematodes species composition, comprising 40% each of bacterial and fungal feeding nematodes. They differed markedly from the reference sites as the forest soil was dominated by plant associated species (38%) and the long-term pasture had 44% plant parasitic nematodes. Accordingly, the soil food web condition inferred from nematode faunal analysis characterized all test plots as basal, stressed and depleted, while the forest soil was categorized as highly structured and fungal dominated. The findings of this thesis demonstrated that land-use change from forest to pasture can have significant impacts on soil biological properties, earthworms can contribute to pasture productivity even in the short term, and nematode faunal analysis is a robust and reliable indicator of soil biological quality.

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Huws, Enlli Haf. "Novel bio-active fatty acids." Thesis, Bangor University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.568810.

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New methods were developed to produce thiolated analogues of Mycobacteria components. Thiolated tuberculostearic acid, (S)-18-mercapto-l O-methyloctadecanoic acid, was firstly produced in seven steps in an overall yield of 7.6 %. This was followed by the first synthesis of a thiolated simple mycolic acid, the disulfide, ((2R,2' R,3R,3' R)- 2,2' - (disulfanediylbis(tetradecane-14, I-diyl))bis(3-hydroxyhenicosanoic acid, in 11 steps in an overall yield of 2.6 %. The first synthesis of a thiolated u-rnethyl-zrcns-cyclopropane methoxy mycolic acid was also achieved using the newly developed methods with the thiol introduced at two different positions within the molecule. (S,S,S,R,S,R,2R,2R')-26-26'- Disulfanediylbis(2-((R)-I-hydroxy-19-((1 S,2R)-2-((2S, 19S,20S)-19-methoxy-20- methyloctatriacontan-2-yl)cyclopropyl)nonadecyl)hexacosanoic acid, which includes the thiolated disulfide at the end of the a-alkyl chain, was synthesised in 18 steps from synthetically prepared starting materials in an overall yield of2.6 %. (S)-2-((S)-I-Hydroxy- 19-((1R,2S)-2-((2R, 19R,20R)-19-methoxy-20-methyloctatriacontan-2- yl)cyclopropyl)nonadecyl)-N-(2-((2-((R)-2-((R)-I-hydroxy-19-((IS,2R)-2-((2S, 19S,20S)- 19-methoxy- 20-methyloctatria-contan- 2- yl)cyclopropyl)nonadecyl)hexacosanamido )ethyl)disulfanyl)ethyl)hexacosan-amide, which contais a thiolated linker on the carboxylic acid, was synthesised in two steps from the free synthetic mycolic acid in an overall yield of 8.7 %. The different methods attempted for the formation of the thiolated analogues are discussed. To attempt to maximise the inhibitory effect of sterculic acid against Plasmodium falciparum /19 desaturase, which is essential for parasite growth, analogues of sterculic acid were designed and synthesised. 7-(2-0ctyl-cycloprop-l-enyl)-heptanoic acid methyl ester and 9-(2-octyl-cycloprop-l-enyl)-nonanoic acid methyl ester which contain one more and one less carbon atoms than sterculic acid in their chain lengths respectively were both synthesised in five steps in overall yields of 8 % and 4.6 % respectively. (±)-8-Methoxy-8- (2-octyl-cycloprop-l-enyl)-octanoic acid methyl ester was subsequently synthesised in three steps in an overall yield of 36 % whilst (±)-8-hydroxy-8-(2-octyl-cycloprop-l-enyl)- octanoic acid methyl ester was also synthesised in three steps in an overall yield of 25 %. In four steps both (± )-8-(tert-butyldimethylsilyloxy)-8-(2-octyl-cycloprop-l-enyl)-octanoic iii acid methyl ester and (±)-8-acetoxy-8-(2-octyl-cycloprop-I-enyl)-octanoic acid methyl ester were synthesised in an overall yield of 22.7 % and 34.9 % respectively. The inhibitory effects of these analogues were investigated.

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Pararasa, Chathyan. "Fatty acids, monocytes and ageing." Thesis, Aston University, 2013. http://publications.aston.ac.uk/20894/.

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Elevated free fatty acids (FFA) are a feature of ageing and a risk factor for metabolic disorders such as cardiovascular disease (CVD) and type-2 diabetes (T2D). Elevated FFA contribute to insulin resistance, production of inflammatory cytokines and expression of adhesion molecules on immune cells and endothelial cells, risk factors for CVD and T2D. Molecular mechanisms of FFA effects on monocyte function and how FFA phenotype is affected by healthy ageing remain poorly understood. This thesis evaluated the effects of the two major FFA in plasma, oleate and palmitate on monocyte viability, cell surface antigen expression, and inflammatory activation in THP-1 monocytes. Palmitate but not oleate increased cell surface expression of CD11b and CD36 after 24h, independent of mitochondrial superoxide, but dependent on de novo synthesis of ceramides. LPS-mediated cytokine production in THP-1 monocytes was enhanced and decreased following incubation with palmitate and oleate respectively. In a model of monocyte-macrophage differentiation, palmitate induced a pro-inflammatory macrophage phenotype which required de novo ceramide synthesis, whilst oleate reduced cytokine secretion, producing a macrophage with enhanced clearance apoptotic cells. Plasma fatty acid analysis in young and mid-life populations revealed age-related increases in both the SFA and MUFA classes, especially the medium and very long chain C14 and C24 fatty acids, which were accompanied by increases in the estimated activities of desaturase enzymes. Changes were independently correlated with increased PBMC CD11b, plasma TNF-a and insulin resistance. In conclusion, the pro-atherogenic phenotype, enhanced LPS responses in monocytes, and pro-inflammatory macrophage in the presence of palmitate but not oleate is reliant upon de novo ceramide synthesis. Age-related increases in inflammation, cell surface integrin expression are related to increases in both the MUFA and SFA fatty acids, which in part may be explained by altered de novo fatty acid synthesis.

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Syed, Rahmatullah M. S. K. "Synthesis and physical properties of C18 azido-oxygenated and N-heterocyclic fatty acid derivatives." Thesis, [Hong Kong : University of Hong Kong], 1991. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12964657.

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Kew, Samantha. "Fatty acids and the immune system : dose response studies with n-3 polyunsaturated fatty acids." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396188.

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Yu, Rong. "Metabolic interactions among amino acids, phospholipids and fatty acids." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45211.

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Cystic fibrosis (CF) is the most common life-shortening disorder among Caucasians. Excessive faecal bile acid loss, increased oxidant stress, reduced plasma choline, increased oxidant stress, reduced glutathione and alterations in essential fatty acids are well recognized in patients with CF. It is also well-known that diabetes perturbs the methionine-homocysteine cycle. However, experimental data linking loss of amino acids in CF or decreased glucose availability in experimental diabetes to altered phospholipids and fatty acid metabolism are lacking. In the liver, bile acids are conjugated with glycine or taurine prior to secretion, and glycine de novo synthesis begins with glucose. Thus, the objectives of this thesis are: 1) to determine if inducing faecal bile acid loss will alter the methionine-homocysteine, and choline-betaine cycle metabolites, phospholipids and phospholipids n-6 and n-3 fatty acids, and 2) to show that experimental diabetes, which decreases glucose availability, alters methionine-homocysteine and choline-betaine cycle metabolites, phospholipids and phospholipid fatty acids in rats. Studies to address the first objective demonstrated that inducing faecal bile acid malabsorption leads to fat malabsorption with increased faecal total lipids and phospholipid excretion. This increased excretion was accompanied by increased plasma betaine concentration, decreased plasma triacylglycerol concentration, increased plasma and liver S-adenosylhomocysteine (SAH) concentration, and changes in the fatty acid composition of hepatic phospholipids. Studies to address the second objective showed that experimental diabetes led to increased plasma betaine concentration, decreased homocysteine concentration, increased liver phosphatidylethanolamine, decreased phosphatidylcholine, changes in the fatty acid composition of hepatic phospholipids, and abundance of the enzyme choline dehydrogenase. Thus, experimental diabetes, which reduces intracellular glucose availability, alters methionine-homocysteine and choline-betaine cycle metabolites, phospholipids and fatty acids. In conclusion, metabolism of phospholipids, their fatty acids, and the amino acids involved in the methionine-homocysteine cycle are inter-related.

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Sieberg, Maureen A. "Heritability and development of the free fatty acids and acylglycerideconstituent fatty acids in Vernonia galamensis oil." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280501.

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Since the mid-1970's, there has been active research on the development of Vernonia galamensis (Cass.) Less. as a potential new oilseed crop. Vernolic acid (cis-12:13-epoxy-cis-9-octadecenoic acid) comprises 70--75% of vernonia oil and is chemically reactive, affording it a variety of industrial applications. A concern in the domestication of an oilseed crop is to establish a breeding program to improve oil quality traits. The objectives of this research were to (1) develop a rapid procedure for seed analyses; (2) determine the development of vernonia oil; and (3) estimate the narrow-sense heritability (h 2) of oil quality traits. Successful separation of free fatty acids (FFA) and acylglycerides from small vernonia seed samples was achieved using aminopropyl solid phase extraction columns. Acylglycerides were eluted with a mixture of chloroform and isopropanol, while FFA were eluted with a mixture of acetone and trifluoroacetic acid. Four breeding lines from a collection of Vernonia galamensis held at the US Water Conservation Laboratory in Phoenix, AZ were used for the oil development study and grown in field trails in Phoenix and Tucson, Arizona. Seeds were collected on nine different days after flowering over the course of seed maturation. Seed samples were analyzed for FFA, acylglyceride constituent fatty acids, total acylglycerides, and total oil. In each breeding line, FFA content changed significantly throughout the course of the measurement period, and synthesis of acylglycerides constituent fatty acids followed a previously described pathway proceeding from C16:0 to C18:0 to C18:1 to C18:2 to C18:1 epoxy. Vernolic acid increased late in the measurement period, while total acylglycerides and total oil increased steadily over the period. Mature vernonia seed exhibited substantial variation in the amount of FFA, acylglyceride constituent fatty acids, total acylglycerides, and total oil. Sixty-nine half-sib families were created to study the heritability of FFA, vernolic acid, acylglycerides, and total oil production. Mature capitula were collected and analyzed individually for oil constituents. Narrow sense heritability estimates for these four oil quality traits were: FFA = 33%, vernolic acid = 65%, acylglycerides = 47%, and total oil = 50%. The results indicate potential for progress in selection for these traits.

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21

Bradburn, David Michael. "Bile acids and short fatty acids in familial adenomatous polyposis." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308760.

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22

Zhang, Runhou 1963. "Manipulating fatty acids in sheep milk." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102236.

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Four studies were conducted to investigate some factors affecting milk fatty acid composition of dairy ewes. The first study was performed to determine the influence of freezing temperatures and storage time on ovine milk composition and cheese making. The other three experiments were conducted to examine the effects of dietary added fats with different profiles of fatty acids from canola, sunflower and flaxseeds on animal performance, nutrient utilization, milk yield and cheese making. The main emphasis was on fatty acid composition, particularly CLA and Omega-3 fatty acids, in milk and cheese. Results showed that: (1) feeding up to 8% of canola, sunflower and flaxseed had no adverse effects on dry matter intake and total tract digestibilities of dry matter, neutral detergent fiber, acid detergent fiber and crude protein, while the digestibilities of fatty acids and gross energy were increased with oilseed supplementation; (2) feeding flaxseed to lactating ewes up to 260g/ewe/d increased milk yield by up to 8.4%, and fat content by up to 14.3% without adversely affecting other milk components or cheese yield and composition; (3) Oilseed supplementation increased milk concentrations of long-chain and unsaturated fatty acids in the expenses of short-chain, medium-chain and saturated fatty acids. The concentrations of CLA and Omega-3 fatty acids were also increased by oilseed supplementation; (4) the manipulated fatty acids profiles can be reflected in cheese; (5) good quality cheese can be produced from ovine milk frozen at -15°C and -25°C for up to 6 months without influencing cheese content of fat and protein and fatty acid composition.
In conclusion, ovine milk with nutritionally healthy characteristics can be produced by feeding ewes diets with oilseeds, and freezing storage of milk for up to 6 months at -15°C or -25°C does not significantly affects milk composition including fatty acid composition. The characteristics of milk can be reflected in cheese.

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Beysen, Carine. "Metabolic effects of specific fatty acids." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249513.

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O'Keeffe, Majella. "New sources of polyunsaturated fatty acids." Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54727/.

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Two groups of essential fatty acids (n-6 and n-3) are needed in a healthy human diet. Current advice suggests an optimal ratio of about 4:1 for these polyunsaturated fatty acids (PUFAs) in the diet but in Western countries it is usually 10-20:1. The n-3 PUFAs are synthesized in photosynthetic organisms from where they move up the food chain. Fish in particular, are a rich source of twenty and twenty two carbon n-3 PUFAs which are particularly effective for humans. Fish oils have been shown to be beneficial in a variety of chronic inflammatory diseases. However, fish stocks arc under threat. Therefore, fish farming has increased recently and offers some opportunities for viable sources of n-3 PUFAs, especially since disposal of fish farm waste is expensive and environmentally problematic. In this project, we investigated trout ( Oncorhynchus mykiss) as a potential source of n-3 PUFAs. The lipid composition of different tissues was analysed by combinations of TLC and GLC. This work identified the differences between various individual tissues and pin-pointed those with high eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) content. Two possible industrial lipid extraction methods were compared with a standard laboratory procedure. These studies included a comparison of yields for offal which had been stored for various times. The rendering method, although not as efficient as the laboratory procedure (Garbus), was concluded to allow oil yield for nutraceutical development although tissues could not be stored for greater than two days without compromised quality. Finally, oil extracts from trout (containing 2.5% EPA and 10.5% DHA) were tested in a model system (bovine cartilage explants) as treatment for osteoarthritis. The trout oil preparation significantly reduced cytokine-induced glycosaminoglycan release indicating a protective action. However, it was not as effective as pure EPA or DHA. Moreover, the trout oil preparation was not able to reduce mRNA levels of inflammatory genes (e.g., COX-2, IL-6, ADAMTS-4, -5 and MMP-3) which were lowered by pure EPA or DHA supplementation. We conclude that trout waste is a viable source of n-3 PUFAs for nutraceutical development but that processing will probably be needed to produce a dietary supplement with potent anti inflammatory properties.

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Rogerson, Madeleine. "Interactions of phospholipids with fatty acids." Thesis, University of East Anglia, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398493.

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26

Glen, Anthony D. "Synthetic studies on cyclopropane fatty acids." Thesis, University of Newcastle Upon Tyne, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386040.

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Peacock, Lesley. "Isomeric fatty acids and platelet function." Thesis, University of Aberdeen, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253708.

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1. Cis unsaturated fatty acids were shown to inhibit porcine platelet aggregation in response to both collagen and thrombin. Fatty acids with a trans double bond had an anti-aggregatory effect on collagen-induced aggregation but this was significantly less than that observed with the cis equivalent and was diminished as the dose of agonist increased. Thrombin-induced platelet aggregation was unchanged or slightly potentiated by trans isomers. 2. Both the cis and trans isomeric acids inhibited collagen-induced TXB₂ production. The trans unsaturated fatty acids also inhibited TXB₂ production in response to thrombin, even though they did not inhibit thrombin induced platelet aggregation. 3. Unlike arachidonic acid, the cis and trans mono-unsaturated fatty acids were not rapidly incorporated into membrane phospholipids but modified platelet aggregation whilst in the free acid form. 4. Pre-incubation of platelets with either cis or trans delta 13, 18:1, selectivity inhibited the incorporation of radio-labelled arachidonic acid into membrane PS. 5. Cis and trans unsaturated delta 13, 18:1, inhibited the initial turnover of membrane PI in response to thrombin possibly by an inhibitory effect on PI-specific phospholipase C. After 5 minutes, however, the level of arachidonic acid released from both PI and PE was increased in the presence of the isomeric fatty acids. This may have been via a potentiation of the action of phospholipase A₂. 6. An increased release of arachidonic acid could result in the inhibition of aggregation if metabolised via the 12-lipoxygenase pathway, as the end products of this sytem have direct anti-aggregatory activity and inhibit the cyclo-oxygenase enzymes thus reducing TXA₂ synthesis. 7. Cis unsaturated fatty acids, which produce a greater level of membrane disruption than the trans, may lead to more efficient channelling of the released arachidonic acid in the direction of the lipoxygenase pathway, and thereby produce a greater inhibition of aggregation. The possibility remains that the cis isomers have another, as yet unidentified mechanism by which they inhibit platelet aggregation.

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Bonner, Shelagh Anne. "Immunomodulatory effects of dietary fatty acids." Thesis, University of Strathclyde, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366809.

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29

Wilson, Gillian Mary. "Fatty acids in human colonic mucosa." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316584.

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30

Smith, Benjamin. "Mineral mediated catalysis of fatty acids." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10611/.

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In order to reduce reliance on fossil oil, and it’s associated problems, there is a need to develop new platform chemicals, fuels and products, in a sustainable way, from biomass. In this thesis the catalytic upgrading of fatty acids, derived from the lipid fraction of biomass, through deoxygenation reactions is studied. Chapter 1 reviews the general area of catalytic upgrading of biomass into biofuels and bioproducts. The history and motivation for alternative sources of fuels and materials are introduced, followed by a summary of the reaction processes currently utilised for biofuels and bioproducts production. It is shown that the demand for alternative fuel sources initially led to the mass commercial production of ethanol, via fermentation of sugars, and biodiesel, through trans-esterification of lipids present in vegetable and algal oils. A selection of the catalysts and mechanisms for trans-esterification reactions is reviewed and, following an outline of the fuel properties and processes, an evaluation of “green diesel” production is given, whereby fatty acids are converted directly into hydrocarbons through decarboxylation reactions. This review culminates in an analysis of alternative conversion of fatty acids into long chain ketone bioproducts, namely ketonic decarboxylation, which details the catalysts and processes involved to date. Chapter 2 describes the analytical methods utilised in this thesis to investigate heterogeneous catalysis of biomass conversion, along with the relevant background theory and describes the type of data that can be obtained using the techniques. The techniques include powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, inductively coupled plasma optical emission spectroscopy, surface area analysis, Hammett basicity, elemental analysis, Fourier-transform infra-red spectroscopy and gas chromatography. Chapter 3 introduces a class of materials known as layered double hydroxides (LDHs) of general formula Mz+1–xM3+x (OH)2]q+(Xn–)q/n•yH2O. The ease with which these mixed oxide materials may be prepared offers significant scope for the variation of the metal cations; the M2+:M3+ ratio (denoted R-value); the counter anion(s); and crystal morphology. These LDHs consist of positively charged layers, with negatively charged counter-anions and water residing in the interlayer. A review of the commonly used synthesis methods for LDHs is given, along with the advantages and disadvantages associated with each method. Following this, the synthesis of the Mg-Al LDHs and their calcined counterparts, mixed metal oxides (MMOs) (for R-values 1-6) via a readily scalable co-precipitation (CoP) and a more environmentally-friendly co-hydration (CoH) route is described. A range of techniques, outlined in chapter 2, are utilised to study the LDH and MMO crystal and chemical structures, surface topography, surface area, pore volume and relative basicities. The crystal structures of two of the CoP-LDHs were refined to the 3R-polytype using DICVOL, however the other LDHs were not significantly ordered and could not be refined. Upon calcination from LDHs to MMOs, the interlayer counter-anions and water are lost, along with the layered structure, leading to a commensurate increase in surface area and pore volume. In chapter 4, investigations undertaken to deoxygenate stearic acid, a free fatty acid model biomass compound, are described. As a catalyst, 5 % Pd/C was used, adapting a method found in the literature. These reactions were undertaken at 230 °C, with decarboxylation of stearic acid producing straight-chain n-heptadecane at up to 58 % conversion by gas chromatography analysis. However, in this study, issues arose due to catalyst instability and an ensuing loss of catalyst activity was observed. In chapters 5 and 6, to increase catalyst stability and recyclability, while also reducing costs relative to the Pd/C catalyst used in chapter 4, (due to the use of precious metals), LDHs and their calcined derivatives, MMOs, were utilised for deoxygenation of the model stearic acid biomass. Thermal reactions of stearic acid controls, without catalyst, were not observed to occur, however, stearic acid conversions between 83-97 % at 250 °C were observed to occur with both LDH and MMO catalysts. However, unlike the Pd/C reaction, no decarboxylated product was evidenced and, instead, a waxy solid formed, which was subsequently analysed and found to be the ketonic decarboxylation product, stearone. A protocol was developed to separate the stearone from the catalyst. Gas chromatography analysis showed the LDH and MMO materials catalysed the conversion of stearic acid to a similar degree, allowing for the error within the extraction and analysis processes employed. The reasons for similarity in reactivity are discussed, and it is suggested that an intermediate state of catalyst is present in the reactor. Comparing synthesis methods, the CoH materials were as effective as their CoP counterparts, despite the presence of Mg(OH)2 secondary-phases. Within the LDH phases, an indication of catalytic dependence on pore size was also recorded, with the smaller pore-sized materials leading to lower conversions of stearic acid, resulting from the bulky size and required head alignment of the long-chain fatty acid molecules. In terms of control reactions, calcined MgO led to 90 % conversion of stearic acid to stearone, however very little reaction occurred with uncalcined MgO (0.5 %) and zero reaction with the acidic Al2O3 (both uncalcined and calcined). Hence activated MgO is also an effective catalyst for ketonic decarboxylation. Chapter 7 summarises the results and discussion given within this thesis, highlighting the milestones achieved such as the first ketonic decarboxylation reactions involving MMO catalysts and concluding that LDHs and MMOs catalyse the conversion of stearic acid via ketonic decarboxylation of free fatty acids to high value ketones, to a similar degree, within the associated errors. In addition the LDH synthesis method employed does not play a significant role in the degree of catalysis, resulting in the recommendation that the more environmentally-friendly co-hydration synthesis method should be employed for the catalyst involved in the conversion of stearic acid derived from biomass. The MMO catalysts were found to behave akin to the calcined MgO material during the ketonic decarboxylation of stearic acid, while the catalytic reactions involving LDH catalysts were potentially involving the interaction of their interlayer anions and cations. Finally, a summary of additional work for further developing this process is discussed.

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Barton, Louise Marie. "Polyunsaturated fatty acids and adrenal steroidogenesis." Thesis, Royal Veterinary College (University of London), 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519549.

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32

Qadir, Abdul. "The effects of endotoxaemia and omega-3 fatty acids on membrane fatty acids and cardiac G-proteins." Thesis, University of Aberdeen, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300911.

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Dietary manipulation was undertaken with the aim of influencing membrane composition and improving adrenergic dysfunction. The objective was to explore the effects of 5 days of continuous intra-duodenal feeding of diets containing n-3 PUFA on myocyte membrane phospholipids, contractility and G-protein. The control diet was omega-6 (n-6) PUFA from safflower oil. The animals were infused with either saline or endotoxin (1 mg/kg) in the last 24 hours. The diets resulted in incorporation of lipids with alteration in myocyte membrane lipid composition. The relative percentage of n-3 PUFA was increased in the fish oil group (22.61± 1.30, 20.46±1.35 for control and endotoxin) compared to safflower oil group (15.21±1.77, 14.16±0.56 for control and endotoxin). The mean inotropic response to isoprenaline was improved by feeding of n-3 PUFA enriched diets (0.175±0.027 for safflower oil endotoxin group vs 0.264±0.03 for safflower oil control, 0.261±0.064 for fish oil control and 0.275±0.073 for fish oil endotoxin group). The adenylyl cyclase activity on forskolin stimulation was not affected by diet or endotoxin (0.165±0.036, 0.176±0.058 for safflower control and endotoxin, and 0.163±0.036, 0.173±0.017 for fish oil control and endotoxin). The data on forskolin stimulation suggested distal contractile mechanisms were intact and that the defect in βAR signal was occurring at a site proximal to adenylyl cyclase. Sodium fluoride, a direct activator of G-proteins revealed a much greater degree of stimulation in the fish oil endotoxin group compared to the safflower oil endotoxin group (0.013±0.030 for safflower oil endotoxin, 0.053±0.015 for fish oil endotoxin and 0.055±0.022 for safflower oil control, 0.088±0.26 for fish oil control). The mean relative percentage of Gαo subunits was reduced in fish oil endotoxin group compared to safflower oil endotoxin group (16.65±3.01 for fish oil endotoxin, 25.37±1.29 for safflower oil endotoxin and 15.63±0.91 for safflower oil control, 13.06±2.70 for fish oil control). In summary, n-3 PUFA improve βAR transmembrane signal in endotoxaemia by favourably altering G-regulatory proteins possibly through membrane displacement of n-6 fatty acids.

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Baker, Nancy Carol. "The Associations Among Dietary Fatty Acids, Plasma Fatty Acids, and Clinical Markers in Postmenopausal Women with Diabetes." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253666943.

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34

Akpinar, Arzu. "Transformations of fatty acids in filamentous fungi." Thesis, University of Hull, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363270.

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35

Pinto, Eva. "Polyunsaturated fatty acids and immune cell functions." Thesis, University of Greenwich, 2007. http://gala.gre.ac.uk/6268/.

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In MS patients there was a significantly positive relationship between membrane AA and TGF-ß1 indicating that it is the individual long chain (LC) PUFA, i.e. AA that regulate the levels of TGF-ß1. Investigation of the effects of n-6 and n-3 PUFAs on normal healthy PBMC production of TGF-ß1 in vitro showed that PBMC in the presence of phytohaemaglutinin (PHA) supplemented with LA, dihyomo-?-linolenic (DGLA) and arachidonic acid (AA) significantly increase TGF-ß1 compared with non-supplemented PHA-stimulated PBMCs. In contrast, TGF-ß1 levels from PHA-stimulated PBMCs supplemented with a-linolenic (ALA), eicosapentaenoic (EPA) or docosahexaenoic acid (DHA) were significantly decreased suggesting that n-6 fatty acids (LA, DGLA and AA) increase in vitro TGF-ß1 production by PHA-stimulated PBMCs and, in contrast, n-3 fatty acids (ALA, EPA and DHA) decrease TGF-ß1 production. GLA-rich borage oil supplementation resulted in significantly decreased ex vivo monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1a (MIP-1a) and interleukin-8 (IL-8) production from PHA-or LPS-stimulated PBMC compared with baseline. It also significantly decreased cell surface expression of CD36+, CD54+ and CD62L+ on monocytes. In contrast, there was no association between LA-rich corn oil and these adhesion molecules and chemokines suggesting that GLA and/or its metabolites are affecting the chemokines and adhesion molecules studied. Overall, results of this study indicate that n-6 long chain PUFAs may have anti-inflammatory properties and might therefore be beneficial in multiple sclerosis, atherosclerosis and other inflammatory diseases.

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Abouzreba, Salem Ali. "Volatile fatty acids in the ambient atmosphere." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388115.

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Di, Nunzio Mattia <1980&gt. "N-3 fatty acids and cardiovascular prevention." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/2162/.

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In this study we elucidate the role of polyunsaturated fatty acids (PUFAs) in the prevention of cardiovascular diseases, focusing the attention on their role in the modulation of acyl composition of cell lipids and of gene expression. Regarding this latter mechanism, the effectiveness of PUFAs as activators of two transcriptional factors, SREBPs and PPARs, have been considered. Two different model system have been used: primary cultures of neonatal rat cardiomyocytes and an human hepatoma cell line (HepG2). Cells have been supplemented with different PUFAs at physiological concentration, and special attention has been devoted to the main n-3 PUFAs, EPA and DHA. PUFAs influence on global gene expression in cardiomyocytes has been evaluated using microarray technique. Furthermore, since it is not fully elucidated which transcription factors are involved in this modulation in the heart, expression and activation of the three different PPAR isoforms have been investigated. Hepatocytes have been used as experimental model system in the evaluation of PUFAs effect on SREBP activity. SREBPs are considered the main regulator of cholesterol and triglyceride synthesis, which occur mainly in the liver. In both experimental models the modification of cell lipid fatty acid composition subsequent to PUFAs supplementation has been evaluated, and related to the effects observed at molecular level. The global vision given by the obtained results may be important for addressing new researches and be useful to educators and policy makers in setting recommendations for reaching optimal health through good nutrition.

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Hartil, Kirsten. "Fatty acids, insulin sensitivity and skeletal muscle." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621348.

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39

Afonso, Marise da Costa Pereira. "Enzymatic biodiesel production from free fatty acids." Master's thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/3137.

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Mestrado em Materiais Derivados de Recursos Renováveis
O ácido oleico é um co-produto da refinação de óleos alimentares e é removido num passo antecedente à catalise alcalina na produção industrial de biodiesel. Este ácido gordo livre é uma fonte alternativa de biodiesel. Neste trabalho estudou-se a esterificação enzimática do acido oleico com metanol ou etanol. Definiu-se um planeamento experimental 22 para estudar a influência das variáveis razão molar álcool/ácido oleico(R) e concentração de enzima(E), as variáveis dependentes, na percentagem de conversão, a variável independente. As condições óptimas foram obtidas em R=6,32 e E=6,64% para o metanol (100% conversão), e R=4,87 e E=5,65 % para o etanol (95,5% de conversão). Estudou-se também a influência da temperatura na reacção para uma razão molar de 6 e uma concentração de enzima de 2%, numa gama de temperaturas entre 30 e 60ºC, para o metanol, e 70ºC, para o etanol. Foi constatado que a conversão aumenta monotonamente com o aumento da temperatura para o etanol. Para o metanol, o aumento da conversão com o aumento da temperatura apenas se verifica até aos 50ºC. A mesma enzima pode ser usada 10 vezes na esterificação enzimática do ácido oleico com etanol, sem perda significativa de actividade enzimática. ABSTRACT: Oleic acid is a co-product of oil refining and is removed in a step preceding the alkaline catalysis in industrial production of biodiesel. This free fatty acid is an alternative source of biodiesel. In this present work the enzymatic esterification of oleic acid with methanol or ethanol was studied. Was defined as an design of experiments 22 to study the influence of the alcohol / oleic acid molar ratio (R) and enzyme concentration (E), the dependent variables, in the percentage of conversion, the independent variable The optimal conditions obtained were R=6.32 and E=6.64% for methanol (100% conversion), and R=4.87 and E=5.65% for ethanol (95,5% of conversion. Was also studied the influence of temperature on the reaction to a molar ratio of 6 and an enzyme concentration of 2%, in a temperature range between 30 and 60 ° C for methanol, and 70 ° C for ethanol. It was found that the conversion increases monotonously with increasing temperature for ethanol. For methanol, the conversion increased with increasing temperature up to 50 º C. The same enzyme can be used 10 times in the enzymatic esterification of oleic acid with ethanol, without significant loss of enzyme activity.

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O'Shea, Karen Michelle. "Omega-3 Fatty Acids and Heart Failure." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1258128805.

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Wu, Zhiguo. "Ruminal synthesis and biohydrogenation of fatty acids /." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487683756125827.

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42

Hudson, Elizabeth A. "Polyunsaturated fatty acids in tumour-induced cachexia." Thesis, Aston University, 1993. http://publications.aston.ac.uk/12600/.

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A transplantable murine colon adenocarcinoma (MAC16) was utilised as a model of human cancer cachexia. This tumour has been found to produce extensive weight loss, characterised by depletion of host body protein and lipid stores at a small tumour burden. This weight loss has been found to be associated with production by the tumour of a lipolytic factor, activity of which was inhibited in vitro by the polyunsaturated fatty acid (PUFA) eicosapentaenoic acid (EPA). EPA has also been shown to possess anti-tumour and anti-cachectic activity in vivo, leading to the hypothesis that fatty acids mobilised by the lipolytic factor supply a growth requirement of the MAC16 tumour. In this study mobilisation and sequestration of fatty acids by the tumour was found to be non-specific, although a relationship between weight loss and arachidonic acid (AA) concentration was found in both tumour-bearing mice, and human cancer patients. The anti-tumour effect of EPA, which was found to be associated with an increase in cell loss, but not its anti-cachectic activity, was reversed by the administration of the PUFAs oleic acid (OA) and linoleic acid (LA). LA was also found to be capable of stimulating tumour growth. Inhibition of either the cyclooxygenase or lipoxygenase pathways was found to result in reduction of tumour growth, leading to the implication of one of the metabolites of LA or AA in tumour growth and cachexia. The ethyl ester of EPA was found to be inactive against the growth and cachexia of the MAC16 tumour, due to its retarded uptake compared with the free acid. The anti-proliferative agent 5-fluorouracil was found to cause tumour growth inhibition, and when given in combination with EPA, reduced the phase of tumour regrowth observed after 4 to 5 days of treatment with EPA.

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Wang, Qianyi. "Fatty Acids, Cardiovascular Diseases, and Diabetes Mellitus." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:14117764.

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Cardiovascular disease (CVD) is the number one cause for mortality and morbidity around the world. Meanwhile, diabetes mellitus (DM) has become an emerging epidemic, causing 1.5 million deaths in 2012, with 80% occurring in low- and middle-income countries. Substantial evidence has linked both lifestyle and metabolic risk factors to increased risk of CVD and death, with suboptimal diet being the single leading modifiable cause of poor health (Lim. SS, et al, Lancet 2012). Of 20 top individual causes of disease burden worldwide, 8 are related to poor nutrition, including suboptimal intakes of various dietary fatty acids. Although previous studies have found divergent health effects of different dietary fatty acids on health, gaps still exist in terms of the scientific knowledge (e.g. how individual circulating vs. dietary trans fatty acid subtypes affect health) and related disease burdens (e.g. national CHD mortality burdens attributable to suboptimal intakes of fatty acids). These gaps have motivated my dissertation researches. In chapter one and two, I investigated the prospective associations of five subtypes of plasma phospholipid trans fatty acid (TFA) levels with the risk of various disease endpoints, including total, CVD and non-CVD mortality, incident coronary heart disease (CHD) and DM. In chapter two, I also examined the prospective associations of total and subclasses dietary TFA with risk of DM. The analyses were conducted using the Cardiovascular Health Study, a community-based multicenter prospective cohort consisted of older Americans. The risks were estimated using the Cox proportional hazard model. The study in chapter three was a collaborative effort of the Nutrition and Chronic Diseases Expert Group as part of the 2010 Global Burden of Diseases, Injuries, and Risk Factors study. Using the comparative risk assessment framework, I comprehensively quantified the CHD mortality attributable to suboptimal intakes of saturated fat, omega-6 polyunsaturated fat, and TFA in 186 countries in 1990 and 2010, by age and sex groups. I also estimated the regional and country level trends of these attributable CHD burdens from 1990 to 2010. The findings of this study are relevant for informing regional and country level public health policy priorities.

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44

Lalia, Antigoni. "Omega-3 fatty acids to combat sarcopenia." Thesis, College of Medicine - Mayo Clinic, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10124986.

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Background: Age-related sarcopenia leads to frailty, physical disability and loss of independence. Although exercise is an effective strategy to counteract the prevailing loss of muscle mass, older adults exhibit blunted anabolic responses, and are often unable to adopt an active lifestyle due to comorbidities associated with aging. Long chain polyunsaturated fatty acids (n-3 PUFA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid, are non-pharmaceutical nutrients which have surfaced for their potential anabolic properties on skeletal muscle and may be particularly beneficial in the context of sarcopenia.

Objective: First, to determine if EPA and DHA increase muscle protein synthesis in older adults. Second, to determine if n-3 PUFA increase the anabolic response to an acute resistance exercise stimulus in older adults. Third, to assess if their effect is mediated through improved mitochondrial function, which is known to be impaired with aging.

Methods: Twelve old, sedentary, healthy women and men (65-85 years) were given 3.9 grams/day purified EPA/DHA for 4 months. 12 young adults (18-35 years) were included as a comparison group for baseline measurements. Muscle protein fractional synthesis rate (FSR) was measured before and after treatment for mixed muscle, and subcellular fractions of myofibrillar, mitochondrial and sarcoplasmic proteins. We infused a stable isotope tracer of [ring-¹³C₆] phenylalanine and monitored incorporation of the amino acid into muscle proteins, at the fasting, post absorptive state, and 16 hours following an acute bout of unaccustomed resistance exercise, using mass spectrometry. Muscle mitochondrial function was assessed ex vivo from skeletal muscle biopsies. Further mechanistic information was generated through large scale and individual mRNA gene expression, inflammatory markers, and protein phosphorylation signaling of the anabolic pathway.

Results: Protein synthesis was similar between age groups at baseline and post exercise, despite the robust decline in mRNA gene expression with aging. EPA/DHA supplementation increased total lean mass, and increased mitochondrial and sarcoplasmic FSR at baseline. Following acute exercise, mixed muscle and subcellular FSR did not change significantly, but participants were segregated into responders and non-responders. EPA/DHA further potentiated the anabolic response of mitochondrial FSR to levels greater than that in the young. There was no improvement in mitochondrial oxidative capacity and efficiency, but there was a significant decrease in ROS emissions.

Conclusion: In healthy older adults, EPA/DHA exhibited significant anabolic effect in baseline skeletal muscle mitochondrial and sarcoplasmic FSR, which was dissociated from mitochondrial oxidative capacity. The anabolic response to exercise was variable between responders and non-responders where some individuals presented with marked increase in mixed muscle and subcellular FSR. This observation sets the ground for identifying the phenotypic traits of the elderly who are likely to benefit from the therapeutic use of n-3 PUFA to combat sarcopenia of aging.

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Teran-Garcia, Margarita de Lourdes. "Functional mapping and characterization of the responsive region required for polyunsaturated fatty acid regulation in the rat fatty acid synthase gene." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3035987.

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46

Bakare, Oladapo. "Synthesis and properties of sulphur-containing long chain fatty acid derivatives." Thesis, [Hong Kong : University of Hong Kong], 1993. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13544561.

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47

Scorletti, Eleonora. "Effect of omega-3 fatty acids in non-alcoholic fatty liver disease." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/422265/.

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The first chapter (Introduction) of the thesis summarises the pathogenesis of NAFLD and its associated risk factors such as type 2 diabetes and cardiovascular disease. Moreover, it describes: a) the potential beneficial effects of long chain omega-3 fatty acid treatment [docosahexaenoic acid (DHA) plus eicosapentaenoic acid (EPA)] in NAFLD; b) the effect of genotypes patatin-like phospholipase domain-containing protein-3 (PNPLA3 I148M) and the transmembrane 6 superfamily member 2 protein (TM6SF2 E167K), on the level of DHA and EPA enrichment and end of study liver fat percentage after DHA+EPA treatment; and c) the effect of fatty acid desaturase (FADS) and Elongase (ELOVL) polymorphisms influencing omega-3 fatty acid metabolism. The second chapter describes the overall aim of this thesis. The aim of my research was to investigate in patients with NAFLD: a) the effect of long-chain omega-3 fatty acid treatment on liver fat percentage and liver fibrosis biomarkers; b) the effect of genotypes influencing NAFLD severity on treatment with DHA+EPA; and c) the effect of genotypes influencing omega-3 fatty acid metabolism in NAFLD. The third chapter describes in details the design and methods used in my research. Chapter four highlights my novel results from the WELCOME study. This chapter describes the baseline and end of study characteristics of the WELCOME study participants and shows the results of the DHA+EPA treatment on liver fat percentage and liver fibrosis biomarkers. This chapter also describes the association between DHA erythrocyte enrichment and decrease in liver fat percentage after DHA+EPA treatment. Chapter five illustrates the association between PNPLA3 I148M and DHA erythrocyte enrichment percentage and end of study liver fat percentage after DHA+EPA treatment. The chapter shows that PNPLA3 I148M was associated with higher end of study liver fat percentage and lower DHA tissue enrichment. Chapter six shows the negative association between FADS polymorphisms and omega-3 fatty acid metabolism in NAFLD. The chapter also shows that there was a gene-DHA+EPA interaction between the minor allele of the FADS1 rs174556 and Δ-5 desaturase activity after treatment with DHA+EPA. Finally, chapter seven, summarises my results in the context of current evidence and knowledge about the subject matter.

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Hauff, Simone [Verfasser]. "Methyl-Branched Fatty Acids and Chiral Anteiso-Fatty Acids in Neutral and Polar Lipids of Biological Samples / Simone Hauff." Aachen : Shaker, 2010. http://d-nb.info/108188570X/34.

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Chavez, Talavera Oscar Manuel. "Rôle des acides biliaires dans la physiopathologie de l'obésité, la résistance à l'insuline, le diabète de type 2, la stéatose hépatique non alcoolique et dans le contexte de la chirurgie bariatrique Bile Acid Control of Metabolism and Inflammation in Obesity, Type 2 Diabetes, Dyslipidemia, and Nonalcoholic Fatty Liver Disease Bile Acid Alterations in Nonalcoholic Fatty Liver Disease, Obesity, Insulin Resistance and Type 2 Diabetes: What Do the Human Studies Tell?” Bile acids associate with glucose metabolism, but do not predict conversion to diabetes Bile acid alterations are associated with insulin resistance, but not with NASH in obese subjects Roux-en-Y gastric bypass increases systemic but not portal bile acid concentrations by decreasing hepatic bile acid uptake in minipigs The functional relevance of bile acids in the improvement of HDL-mediated endothelial protection after bariatric surgery Metabolic effects of bile acid sequestration: impact on cardiovascular risk factors." Thesis, Lille, 2019. http://www.theses.fr/2019LILUS057.

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Abstract:

En plus de leur rôle dans la solubilisation des lipides alimentaires, les acides biliaires sont des molécules de signalisation régulant leur propre métabolisme, l'homéostasie du glucose et des lipides, la dépense énergétique, la fonction cardiovasculaire et l’inflammation, en modulant le Farnesoid X Receptor (FXR) et le Takeda G protein coupled Receptor 5 (TGR5). En effet, des modifications dans les concentrations des acides biliaires sont associées aux maladies métaboliques et ce sont des candidats pour participer à la pathophysiologie de ces maladies ou prédire leur progression.Dans la première partie de cette thèse nous avons étudié les modifications des acides biliaires dans le contexte de l'obésité, l'insulinorésistance, le diabète de type 2 et la stéatohépatite non alcoolique. Nous avons montré que les acides biliaires sont corrélés avec l’homéostasie du glucose chez l’Homme, mais qu’ils ne sont pas des prédicteurs de la bascule du prédiabète en diabète de type 2 dans un étude de cohorte.La deuxième partie de cette thèse est dédiée à l’étude des acides biliaires dans la chirurgie bariatrique. Nos résultats ont montré que la chirurgie bariatrique réduit la recapture hépatique des acides biliaires, provoquant leur augmentation dans la circulation systémique, et que ce n’est pas l’anse biliaire mais l’anse commune qui est responsable des modifications métaboliques après la chirurgie bariatrique chez le minipig. Ensuite, nous avons montré chez l’Homme que les acides biliaires liés aux lipoprotéines de haute densité (HDL) augmentent après la chirurgie bariatrique, et que cette augmentation est corrélée avec la restauration de leurs fonctions vaso-protectrices
In addition to their role in the solubilization of dietary lipids, bile acids are signaling molecules regulating their own metabolism, glucose and lipid homeostasis, energy expenditure, cardiovascular function and inflammation via the activation of the Farnesoid X Receptor (FXR) and the Takeda G protein coupled Receptor 5 (TGR5). Indeed, changes in bile acid concentrations are associated with metabolic diseases and therefore they are candidates to participate in the pathophysiology of these diseases or predict their progression.In the first part of this thesis, we studied bile acid changes in the context of obesity, insulin resistance, type 2 diabetes and non-alcoholic steatohepatitis. We demonstrated that bile acids are correlated with glucose homeostasis in humans, but that they are not predictors for the progression from prediabetes to type 2 diabetes in a longitudinal cohort study.In the second part of this thesis, we studied the bile acids in the context of bariatric surgery. Our results showed that bariatric surgery reduces the hepatic recapture of certain bile acids, causing them to increase in the systemic circulation. Additionally, we showed that it is not the bile limb but the common limb the one responsible for metabolic changes after bariatric surgery in the minipig. Finally, we showed in humans that bile acids linked to high-density lipoproteins (HDL) increase after bariatric surgery, and that this increase is correlated with the restoration of their vasoprotective functions

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富洵 and Xun Fu. "Lipase selectivity in reactions involving natural and synthetic fatty acids and fatty alcohols." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B3124015X.

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Dissertations / Theses on the topic 'Conversion of fatty acids'

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