This diploma thesis is focused on determination of aggregation behavior of selected phospholipids (lecithin; 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine) in water and on the effect of native hyaluronan addition of various molecular weights and concentrations on this behavior. The behavior has been investigated with fluorescence spectroscopy using pyrene and perylene as fluorescence probes being able to penetrate into hydrophobic cavities of formed aggregates. Critical aggregation concentration and the concentration at which lecithin begins to aggregate have been determined. Regarding 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine, it was possible to determine only the beginning of aggregation value. The values of this parameter for lecithin and for 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine correspond in the order. It has been investigated, that the addition of native hyaluronan has only in some systems slight effect on the aggregate behavior of selected phospholipids.

The diploma thesis deals with cellular membrane model preparation on microfluidic devices. It summarizes means of microfluidic device fabrication, phospholipid bilayer formation mechanisms, optimization techniques and characterization methods of those systems. It focuses on free-standing planar lipid bilayers which are easily accessible by a number of different characterization methods and at the same time exhibit good stability and variability. The aim of this work is to design and prepare a microfluidic chip on which a planar lipid bilayer can be prepared. It therefore presents microfluidic device prepared by soft lithography of PDMS adapted for model membrane formation by self-assembly of phospholipids at the interface of aqueous and organic phases created by the architecture of the microfluidic device. Formation of the model membrane was visualized by optical microscopy and fluorescence-lifetime imaging microscopy.

Plasma membranes are essential to both the structure and function of mammalian cells. The first unifying paradigm of membrane structure, the Fluid Mosaic Model, is no longer considered adequate to describe the many non-homogeneous lipid structures that have been observed in both natural and model membranes over the past approximately thirty years. The field of membrane biophysics now appreciates that the complex mixture of different lipid species found in natural membranes produces a range of dynamic, laterally segregated, non-homogeneous structures which exist on time scales ranging from microseconds to minutes. When sphingomyelin (SM), POPC and cholesterol are all present in a bilayer there is wide range of compositional ratios where the bilayer consists of a coexistence between two fluid phases designated liquid ordered (lo) and liquid disordered (ld). The lo phase is cholesterol-rich phase characterized by relatively high molecular order and slow rotational and translational motion, while the ld phase generally has low molecular order and relatively rapid rotational and translational motion. The driving force for the formation of these two phases is the ability of cholesterol to form favorable van der Waals contacts with the two saturated acyl chains on PSM and the one saturated acyl chain on POPC. The ternary system is an important model system for examining the physical properties and functional implications of co-existing lo and ld phases. However, it does not include one of the most significant compositional variables found in many important mammalian membranes. Membranes in the nervous system contain high concentrations of the highly polyunsaturated fatty acid docosahexaenoic acid (DHA), which contains 22 carbons and 6 double bonds. A wide range of experimental evidence shows that DHA-containing phospholipids are important for optimal performance of a number of membrane signaling systems and membrane protein functions. The goal of this study is to determine how addition of a DHA-containing phospholipid, PDPC alters the biologically important lo and ld co-existence region.

Phospholipids, such as phosphatidylserine (PS) have been shown to work synergistically with tocopherols to extend the shelf life of oil-in-water emulsions. However, the high cost of PS prevents it from being used as a food additive. This work investigated the potential use of a high PS enzyme-modified lecithin to be used along with α-tocopherol to extend the lag phase of oil-in-water emulsions stabilized using Tween 20. Phospholipase D from Streptomyces sp. and L-serine were used to modify lecithin to increase PS concentration. Enzyme activity was optimized as a function of pH and temperature using a high PC soybean lecithin. The high PS modified lecithin was examined for its ability to enhance the activity of α-tocopherol in Tween 20-stabilized oil-in-water emulsions. The modification was also performed in high PC sunflower lecithin and egg lecithin which were later analyzed for their efficiency in controlling lipid oxidation. α-Tocopherol (3.0 µmol/kg emulsion) alone increased the lag phase of hydroperoxide and hexanal lag phases by 3 and 4 days compared to the control. Authentic PS (15.0 µmol/kg emulsion) increased hydroperoxide and hexanal lag phases by 1 and 3 days, respectively, whereas high PS soy lecithin increased hydroperoxide and hexanal lag phases by 3 and 4 days, respectively. The addition of high PS sunflower and egg lecithin did not have any considerable effects on lag phases compared to the control. Authentic PS (15.0 µmol/kg emulsion) and a-tocopherol (3.0 µmol/kg emulsion) decreased lipid oxidation by increasing the hydroperoxide and hexanal lag phase to 6 and 9 days. The combination of phospholipase D modified high PS lecithins (15.0 µmol/kg emulsion) and a-tocopherol (3.0 µmol/kg emulsion) were able to synergistically increase the antioxidant activity of a-tocopherol increasing the hydroperoxide and hexanal lag phase by 6 and 9 days for soy, 5 days, and 7 days for sunflower and 4 and 6 days for egg lecithin, respectively. This resulted in synergistic antioxidant activity (interaction index > 1.0) except for a-tocopherol and high PS Egg lecithin which showed an additive effect. This research shows that the combination of enzyme-modified high PS lecithin and α-tocopherol could be an effective and commercially viable clean label antioxidant strategy to control lipid oxidation in emulsions.

No description available.

Ferroptosis, an oxidative cell death mechanism, is driven by iron-dependent lipid peroxidation. Despite being generally associated with lipid peroxidation that overwhelms endogenous repair systems, ferroptosis mechanisms and regulators in various pathological contexts remain elusive. Identifying novel modulators of the ferroptosis pathway is essential for cell-death marker development and drug discovery to target this process. Small molecule drugs and dietary intervention of metabolites and lipids can modulate ferroptosis sensitivity in diverse disease contexts. In this thesis, I investigated lipid metabolism involving ferroptosis in cancer models and an infectious lung disease model. I dissected the different roles of PUFA-containing phospholipids in dietary modulation of ferroptosis and discovered a specific phospholipid class, phosphatidylcholine with diacyl-polyunsaturated fatty acid tails (PC-PUFA2; diacyl-PUFA-PC) that promote ferroptosis. Exogenous PC-PUFA2 or free PUFA enriches PC-PUFA2 abundance in cancer cells and accounts for the ferroptosis-sensitizing effects. I also discovered the accumulation of PC-PUFA2 in the mitochondria, which disrupts mitochondrial redox homeostasis and initiates lipid peroxidation in the endoplasmic reticulum. These findings unveil the essential roles of diacyl-PUFA phospholipids during ferroptosis. Utilizing biomarkers of ferroptosis, I studied the pathogenic mechanism of COVID-19-associated pulmonary diseases. Elevated ferroptosis markers including transferrin receptor 1 and lipid peroxidation products were detected in human COVID-19 lung autopsies. Dysregulation in lipid profile, including a significant decrease in PUFA phospholipids and accumulation of lysophospholipids, further suggests dysregulation of lipid metabolism and ferroptosis that may contribute to inflammation and acute lung injury in COVID-19 lungs. Iron metabolism is affected in the COVID-19 lung and is associated with ferroptosis activation. We further discovered a strong correlation of ferroptosis markers with lung injury severity in a COVID-19 model using Syrian hamsters. These findings provide the fundament for targeting ferroptosis as a novel therapeutic and diagnostic strategy for various diseases.

Enzymatic and lipid transfer reactions involved in reverse cholesterol transport were studied in HDL deficient plasma systems. Fasting plasma samples were obtained from control and cholesterol fed guinea pigs as well as from a fish eye disease patient and were used to localize the enzyme LCAT among plasma lipoproteins (VLDL, LDL, and HDL). In both guinea pig and fish eye disease patient plasma, the LCAT activity was found in association with the HDL type particles. Cholesterol feeding in guinea pigs altered the properties of lipoprotein substrates for LCAT resulting in some changes, specifically: 1) decreased fractional rate of plasma cholesterol esterification and, 2) lower transfer of free cholesterol (FC) and esterified cholesterol (CE) within the lipoprotein fractions.

No description available.

En termes d’économie d’énergie, la réduction de trainée revêt un intérêt indéniable. Dans certains cas, ce phénomène obtenu grâce à l’ajout dans le milieu de faibles quantités d’additifs peut atteindre une réduction du frottement à la paroi, en régime turbulent, allant jusqu’à 80% comparé au fluide seul. On le retrouve dans divers domaines d’applications telles quele transport des hydrocarbures et dans les circuits d’eau de chauffage et de refroidissement.Trois systèmes qui ont la capacité de s’autoorganiser en milieux aqueux ou organique ont été étudiés dans le but de vérifier leur possible aptitude à réduire le frottement hydrodynamique.On s’est intéressé à un polysavon (80C12) composé d’un squelette polystyrène auquel sont liées des amines tertiaires portant des chaines alkyles de 12 carbones. Ce composé forme des micelles dans l’eau dont la forme cylindrique a été mise en évidence par diffusion de la lumière et Cryo-MET. L’étude du transfert de masse sur une électrode à disque tournant et les résultats rhéologiques ont mis en évidence le caractère viscoélastique qui est responsable duphénomène de réduction de frottement hydrodynamique recherché.Des études rhéologiques réalisés sur les systèmes lécithine/décane et ionomère/toluène ont permis de mettre en évidence le caractère viscoélastique des associations anisotropes de ces composés. / In terms of energy saving, drag reduction hasan undeniable interest. In some cases drag reduction with additives can reach 80% compared to pure solvent. This phenomenon has applications in many fields suchas transportation of hydrocarbons and cooling and heating systems. Three systems which have the capacity to selforganizein aqueous or organic media have been studied in order to check their possible ability to reduce hydrodynamic friction.We worked on a polysoap (80C12) based on polystyrene skeleton to which tertiary amines bearing alkyls chains of 12 carbons. This compound formsmicelles in water whose cylindrical shape has been demonstrated by light scattering and Cryo-TEM. The studies of the mass transfer on a rotating disk electrode and the rheological results have showed for the 80C12solutions several characteristics attributed to the dragreducing additives.Rheological studies on the systems lecithin/decane and ionomers/toluene, highlight the viscoelastic properties of the anisotropic associations of these compounds.

Submitted by Biblioteca da Faculdade de Farmácia (bff@ndc.uff.br) on 2018-01-24T13:57:53Z No. of bitstreams: 1 FRANCINE ALBERNAZ LOBO.pdf: 10489347 bytes, checksum: 0848175c51939f10b98f3dde92fdd2be (MD5) / Made available in DSpace on 2018-01-24T13:57:53Z (GMT). No. of bitstreams: 1 FRANCINE ALBERNAZ LOBO.pdf: 10489347 bytes, checksum: 0848175c51939f10b98f3dde92fdd2be (MD5) / Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A secagem por foam mat drying foi utilizada como método de desidratação para a polpa de manga da variedade Tommy Atkins. O desenho experimental do tipo Composto Central Rotacional (DCCR) foi elaborado com o intuito de avaliar os efeitos da concentração de lecitina de soja e carboximetilcelulose (CMC) utilizados como agentes estabilizadores de espuma (0 – 1,50 g / 100 g), e diferentes valores de temperatura (53 – 87 °C) sobre as concentrações de compostos bioativos (fenólicos, carotenoides e vitamina C), capacidade antioxidante e os parâmetros de cor na polpa de manga. O estudo permitiu a identificação dos principais compostos antioxidantes na polpa de manga, incluindo a mangiferina, que podem ser utilizados como ingredientes na produção de alimentos funcionais com o objetivo de melhorar suas propriedades nutricionais e antioxidantes. A concentração de lecitina de soja e os valores de temperatura apresentaram efeito significativo negativo (p < 0,05) sobre o conteúdo de fenóis totais, capacidade antioxidante e vitamina C, enquanto a concentração de CMC mostrou efeito positivo (p < 0,05) para o somatório de fenólicos e capacidade antioxidante. No entanto, a análise estatística não indicou efeito significativo (p > 0,05) sobre o conteúdo de carotenoides totais e dos parâmetros de cor. O aumento da concentração total de compostos fenólicos e carotenoides em manga seca contribuiu para maior capacidade antioxidante da polpa de manga após o processo de foam mat drying. O estudo concluiu que a temperatura de secagem em 80 °C e a concentração de CMC e lecitina de soja de 0,30 g / 100 g são bons parâmetros de operação para maior concentração de compostos fenólicos e carotenoides e capacidade antioxidante. Posteriormente, produtos foram formulados com a polpa seca nesta condição, e submetidos à análise sensorial, utilizando-se testes de escala hedônica e triangular e intenção de compra. Todas os produtos com a polpa de manga desidratada por foam mat drying apresentaram índice de aceitação maior de 44 %. A adição da polpa de manga desidratada nas formulações da mousse e refresco demonstraram o potencial uso para o desenvolvimento de alimento rico em substâncias fenólicas e carotenoides, agregando propriedades benéficas ao alimento / Foam mat drying was used as dehydration method for Tommy Atkins mango pulp. The effects of soy lecithin and carboxymethylcellulose (CMC) concentrations used as foam stabilizers (0 – 1,50 g/100 g) and temperature values (53 – 87 °C) on levels of bioactive compounds (phenolics, carotenoids and vitamin C), antioxidant capacity and the colour measured in mango pulp were evaluated and optimized according to a multilevel factorial design (DCCR). The present study allowed the identification of the main antioxidant compounds in mango pulp such as mangiferin that can be utilized for the production of valueadded ingredients for various food applications to enhance their nutritional and antioxidant properties. Soy lecithin concentration and T had a negative effect (p < 0,05) on the phenolic content, antioxidant capacity and vitamin C, while CMC concentration had a positive effect (p < 0,05) for phenolic content and antioxidant capacity on the evaluated responses. However, the statistical analysis indicated no significant effect of variables studied (p > 0,05) on the total carotenoid and color parameters. The increasing of the total phenolics and carotenoids content observed for dried mango contributed for higher antioxidant capacity of mango pulp after foam mat drying process. This study concluded that drying temperature of 80 °C and concentration of CMC and soy lecithin of 0,30 g / 100 g are good operating parameters for increased content phenolic and carotenoids compounds and antioxidant capacity. After that, products formulated with the dried pulp in this condition were submitted at the sensory analysis, using hedonic scale and triangular testing and purchase intent. All products formulated with the dried mango pulp by foam mat drying showed higher acceptance (rate 44 %). Addition of dried mango pulp in the mousse and refresh formulation demonstrates the potential of using on the development of food rich in phenolic and carotenoids substances, adding to food product beneficial properties