Dissertations / Theses on the topic 'Antioxydant properties'
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Portes, Elise. "Synthèse et études de tétrahydrocurcuminoïdes : propriétés photochimiques et antioxydantes : applications à la préservation de matériaux d'origine naturelle." Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13695/document.
Full textA large variety of curcuminoids Cs and tetrahydrocurcuminoids THCs was synthesized and their antioxidant properties were studied in detail by the radical DPPH° method. For the first time, it was shown that the higher antioxidant properties of THCs compared to their counterparts’ curcuminoids are due to the presence of benzylic hydrogen atoms in THCs. The association of THCs with a biopolymer chitosan, allowed the preparation of films presenting antioxidant and antibacterial properties. Interactions between THCs and chitosan were evidenced by UV-visible absorption spectroscopy. THCs and more particularly tetrahydrocurcumin inhibited development of Fusarium proliferatum fungi in cereals, and limited the production of associated mycotoxins
Pons, Olivier. "Infusions de thés et santé : Dyslipidémie ˸ protocole d'étude du thé Hao Ling® chez des sujets atteints d'hypercholestérolémie. : Effet hypolipémiant de Camellia sinensis (Hao Ling® Tea) chez des sujets atteints d'hypercholestérolémie non traités par statine : protocole d'étude pour un essai randomisé, en double aveugle, contrôlé par placebo." Electronic Thesis or Diss., Toulon, 2023. http://www.theses.fr/2023TOUL1001.
Full textLipotropic effects of antioxidant molecules of tea (Camellia sinensis) on the most common chronic liver disease in industrialized countries because being strongly associated with the development related dyslipidaemia. To date, the mechanisms of pathology remain poorly defined and available therapeutic means have moderate efficacy. Epidemiological studies have reported a beneficial effect of tea consumption in the fight against liver disorders and cardiovascular risk factors such as dyslipidaemia. However, the mechanisms by which a blend of green tea, oolong tea and Pu-erh tea, Hao Ling tea, reduces fatty liver and dyslipidaemia remain unknown. Therefore, the objective of this thesis was to evaluate the effects and mechanisms of action of Hao Ling tea on cholesterol and dyslipidaemia, through two approaches, one on cellular model and the other on animal model. Our results show that Hao Ling tea reduces the hepatic lipogenesis in vitro and in vivo and thus attenuates steatosis induced by a high fat-high sucrose diet in a rat model. We observed that this tea improves the blood lipid profile by increasing plasma HDL levels. We were also able to highlight that tea owns antioxidant and hepato-protective properties to counteract an inducer of oxidative stress in vitro and to decrease lipid peroxidation in vivo. Finally, we have shown that the oxidative stress per se resulted in an accumulation of intracellular lipid in isolated hepatocytes and that the tea, due to its antioxidant properties, prevented this phenomenon. The Hao Ling tea is a good nutritional approach in preventing Cholestérol and to maintain LDL/HDL ratio
Asteian, Alice. "Synthèse et applications biologiques de nouveaux dérivés flavonoïques à caractère antioxydant : impact sur le stress oxydant au cours de l'ischémie / reperfusion myocardique chez le rat normal et diabétique." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10123.
Full textFlavonoids are natural polyphenolic compounds, and epidemiological and pharmacological studies have shown that flavonoids intake is associated with many beneficial effects. An important example is the 3’,4’-dihydroxyflavonol (DiOHF) which showed interesting therapeutic properties in vitro so it could be considered as an important lead compound to the treatment of cardiovascular diseases. However is poor water solubility prevents it use as a drug. Starting from this model we have synthesized a series of new flavones functionalized by a hydrophilic group in order to increase water solubility. To obtain these derivatives we have set up a fast, simple and clean method without formation of by-products, using micro-waves irradiation to optimize yield and to decrease reaction time. Our second purpose was to investigate the antioxidant activity of the synthesized compounds by undergoing several assays. The most promising compounds were tested in biological studies, in vitro and in vivo. The results showed a significant enhancement of the post-ischemic mechanical function recovery in vivo and in vitro. Another purpose was to designed new flavonols linked to selected antidiabetic moieties already used in the treatment of insulinoresistance. It was shown that these new compounds retain the antioxidant properties of the parent flavonols, and can be of interest in the development of new diabete 2 treatments
Rosselin, Marie. "Design of amphiphilic nitrones with improved spin-trapping and antioxidant properties." Thesis, Avignon, 2014. http://www.theses.fr/2014AVIG0258/document.
Full textOxidative stress is defined as an unbalance between the production of free radicals and the antioxidant defenses. The oxidative stress state has been associated with several pathologies such as neurodegenerative and cardiovascular diseases or cancers. To prevent oxidative stress-mediated damage, the use of synthetic antioxidants is attractive as it allows to tune their physico-chemical properties as well as their cellular targeting specificity. Of particular interest is the linear alpha-phenyl-N-tert-butylnitrone (PBN) which exhibits pharmacological activity against radical-mediated pathophysiological conditions and has been widely used as analytical reagent for the identification of radical species by the spin-trapping method coupled to electron paramagnetic resonance (EPR) spectroscopy. In this thesis report, we first tried to improve the intrinsic antioxidant properties of PBN by grafting various substituents either onto the aromatic ring or the N-tert-butyl-group of the nitronyl function. The physico-chemical and biological properties of the compounds were then determined. With optimized nitrone derivatives in hand, the second part of this project consisted in improving the bioactivity and bioavailability of our nitrone agents using amphiphilic carriers or specific targeting ligands
Wahyuni, Nelly. "Absorption and luminescence properties of beta-carotene with antioxidant and modified kaolinite and its application in OLED." Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0133/document.
Full textEnergy crises, especially fossil fuel-based energy, lead to increased use of new energy and renewable energy. In addition, research is also directed towards more efficient energy use through the development of energy storage materials such as batteries, and the use of energy-efficient materials. An OLED (organic light-emitting diode) is a light-emitting diode (LED) and is known for their high potential in a display, signage, and lighting applications. Carotenoids constitute an important class of linear -conjugated molecules that exhibit a high degree of electronic delocalization and ultrafast dynamic. The dye that is used as a photosensitizer plays an important role in the operation of DSSCs or other bifunctional material. In this research, we studied the photostability of the carotenoid compound (-carotene and fucoxanthin) using natural antioxidant and modified kaolinite. In this work, the carotenoid stability by the carotenoid compound/antioxidant binary is studied for the first time. Photostability of -carotene can be enhanced by antioxidant and modified kaolinite. Photoprotection efficiency of -carotene by curcumin was higher than fucoxanthin. Modified kaolinite decreased photodegradation of - carotene by shielded and protected from direct UV irradiation. Antioxidant fucoxanthin and curcumin decreased the electrochemical gap of the binary material. The electrochemical gap of carotene/curcumin is -1.61 eV, carotene/fucoxanthin is -1.75 eV compare to the only -carotene - 2.04 eV. Fucoxanthin can keep the first oxidation stage of -carotene. Therefore at the binary compound, electron was still reversible, but not for curcumin. Fucoxanthin in OLED devices NPD/Fx/ETL reduced significanly the EQE (%) almost 80% in Alq3 and 76% in BAlq. OLED device: NPD(50nm)/Fx(1nm)/Alq3(85nm) yielded an effeciency quantum external yield, EQE = 0.12% and CIE (0.4160, 0.5302). Fabrication OLED using -carotene as HTL and curcumin as EL layer resulted yellow color , EQE = 0.02%, with the composition MoO3(15nm)/NPD(40nm)/Car(10nm)/ Cur(15nm)/Alq3(70nm)/Ca(100nm). For application of - carotene in OLED device, its perfomance can be improved by using curcumin at the fabrication
El, Monfalouti Hanae. "Contribution à la détermination des propriétés photo-protectrices et anti-oxydantes des dérives de l’arganier : études chimiques et physiologiques." Thesis, Reims, 2013. http://www.theses.fr/2013REIMS027/document.
Full textArgan oil is traditionally used in Morocco as an ointment to cure some skin pathlogies or is ingested to prevent cardiovascular diseases. Its content in unsaturated fatty acids is high as is its content in polyphenols, tocopherols, sterols, squalene and triterpenic alcohols.The aim of this thesis was to increase the value of argan oil and derivatives. Our work focuses on phytochemistry and pharmacology.Concerning the phytochemical aspect, 11 polyphenols were identified and quantified by LC-ESI-SM. Their anti-oxidant activity has been evaluated as a function of kernel roasting time. Volatils obtained by microextraction were also quantified using CPG-SM.In a second section, photoprotective and anti-oxidant properties of argan oil were studied. Blood vitamine E level was determined in post menopausal women after 8 weeks of daily consumption of 25 ml of argan. Olive oil was given as a blank. Photoproptective properties of argan oil were evidenced in vitro using UV-C and Thymidylyl-(3',5') thymidine as DNA model. Preliminary results indicate a good photoproective activity even when argan oil is diluted (1/10) in parafin oil
Palierse, Estelle. "Development of a hybrid coating associating biomimetic hydroxyapatite and natural antibiotics with antibacterial properties." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS316.
Full textThis thesis aims to develop a hybrid coating based on biomimetic hydroxyapatite and natural antibacterial molecules, with the goal to add antibacterial properties and enhance the osseointegration of titanium (Ti6Al4V) implants. Four natural biologically active molecules (BAMs) were tested, rosmarinic acid, chlorogenic acid, baicalin and baicalein. To understand the interaction between those molecules and hydroxyapatite, we present here three complementary studies: in solution with calcium ion, with hydroxyapatite nanoparticles and with biomimetic hydroxyapatite coatings on titanium alloy. The complexation between BAMs and calcium ion in solution is highly pH-dependent. When incorporated within hydroxyapatite nanoparticles or coatings during synthesis, BAMs inhibit the formation of the mineral phase. On the contrary, they can be efficiently adsorbed on pre-synthesized particles. Finally, we present the biological properties of hydroxyapatite nanoparticles and coatings with adsorbed baicalein. Hybrid nanoparticles are potent antioxidant agents, but they do not exhibit any antibacterial activity, whereas hybrid coatings have a significant effect on the bacterial growth of Staphylococcus epidermidis CIP 105.777. This work originality stands on the use of natural antibacterial molecules, but we highlight the difficulty to handle them, due to their poor solubility and stability in physiological pH, which should be considered for further use in biomedical applications
Anouar, El Hassane. "Theoretical investigations of the antioxidant, optical and electronic properties of polyphenols." Limoges, 2011. https://aurore.unilim.fr/theses/nxfile/default/5d3ffe0f-e39c-4a6a-87dc-9ea626b004de/blobholder:0/2011LIMO330A.pdf.
Full textThe present PhD deals with the antioxidant activity and the capacity to absorb UV/visible light of polyphenols. Density functional theory (DFT) and time-dependent DFT (TD-DFT), respectively give an accurate description of the experimental data. In the first section, the structure-antioxidant activity of different series of polyphenols have been established, highlighting the importance of thermodynamic descriptors including bond dissociation enthalpies (BDE), π-electron conjugation, H-bonds, double BDE (BDED) and number of OH groups. In the second section, the excited states and the allowed electronic transitions are accurately evaluated. The number and position of the OH groups, the number of double bonds and the solvent influence the energy of the transitions. Thus, TD-DFT allows for an understanding of the structural parameters which are responsible for the variation of colours in fruits and flowers
Deyrieux, Charlotte. "Identification, characterisation and application of plant extracts with combined antioxidant and antimicrobial properties." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTG070.
Full textOxidation and microbial growth are the major parameters causing the deterioration of food products, including pet food. These degradations affect the nutritional and sensory qualities of the products and may lead to health issues. In this context, various ways of prevention are available to limit these phenomena. Among them, the promotion of plant extracts for food is a major challenge for research and industry. Their use as natural preservatives could be an attractive alternative to synthetic antioxidants or antimicrobials that suffer from lower consumer acceptance.Through this study we have identified and characterized the performance of fifteen plant extracts from an antioxidant and antimicrobial point of view. After a molecular characterization of the extracts, their antioxidant capacity was measured as well as their antimicrobial property on three Salmonella strains. The establishment of a selection procedure was made. Finally, the extracts presenting the most interesting characteristics were tested on a real food matrix: kibbles
Abdou, Bouba Armand. "Contribution à l’étude du développement d’un aliment fonctionnel à base d’épices du Cameroun : caractérisation physico-chimique et fonctionnelle." Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL006N/document.
Full textIncreasing evidences from current research point to the fact that certain disease conditions can be prevented through the consumption of antioxidant rich foods. The present work was carried out to evaluate the antioxidant potentials of twenty Cameroonian spices commonly used in some Cameroonian cuisine. The nutritional properties of spices, the in vitro antioxidant potential of their methanolic extracts as well as the in vivo antioxidant potential of the methanolic extracts of some selected samples were determined. The antioxidant activity brought about by N’ N-diphenyl-N’-picrylhydrazyl (DPPH), «trolox antioxidant equivalent capacity» (TEAC) and the total reduction power (PRT) methods have revealed that Z. leprieurii and D. glomerata presented the highest activities. The extracts of the two spices were used to prepare a mixture whose effect was tested on male rats with induced inflammation. The results obtained indicate that the individual spices and their mixture at 100 mg/kg and 150 mg/kg present an important anti-inflammatory activity comparable to that of commercial anti-inflammatory like indomethacin, dexamethasone and celecoxib. The variation of malondialdehyde content (a lipidic oxidant marquer) revealed the in vivo antioxidant action of extracts, thus demonstrating their potential for the development of functional foods with anti-stress effect
Biler, Michal. "Molecular insights in tracking optical properties and antioxidant activities of polyphenols." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0001/document.
Full textPolyphenols are abundantly found in many fruit, vegetables, beverages, etc. and they possess many potential health benefits. Computational methods were thoroughly used through this thesis to rationalize, describe and predict physical chemical properties of flavonolignans and pyranoanthocyanins. Here, we aim at an understanding of polyphenol biological actions at a molecular level. All outcomes from the theoretical computations were discussed with respect to experimental data. The properties related to antioxidant activity of flavonolignans were investigated by density functional theory (DFT) methods. The pH dependence of ultraviolet/visible (UV/Vis) absorption properties of flavonolignans and pyranoanthocyanins were evaluated by time dependent (TD-) DFT methods, and noncovalent interactions were investigated within dispersion-corrected DFT methods. A short overview is also given on interaction of such compounds with biomolecules. Chapter 6 presents yet not published results of several noncovalent pigment: copigment systems. This part of the results serves as a good starting point to search for ‘the best copigment’
Warchal, Andrzej. "Study of the influence of additives (antioxidants) on the thermomechanical properties of carbon-bonded refractory composites." Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0050.
Full textAlumina-carbon refractories are widely used in the continuous casting of steel. They are responsible for the steel flow control and its protection against oxidation. However, to improve their own oxidation resistance, several additives such as carbides, metals, low melting point compounds and glass frits are added as antioxidants. In this study, the influence of these additives, as well as firing conditions, on the properties related to the thermal shock resistance of carbon-bonded refractories was studied. Model materials, having simplified composition compared to the real industrial ones, were investigated tofacilitate the comprehension of interactions between different constituents of the composite. Behavior of both cured (before firing) and fired materials was studied. The first part of the study proved that antioxidants may modify the properties of the refractory through different mechanisms: crystallization of the carbon bond (B4C), microcracks healing (anhydrous borax and glass frit) and formation of new phases (Al-Si). However, since the metallic additives are the most widely used antioxidants in Vesuvius' products, the second part of the study was focused on their (Al-Si, Al-Mg and Al) impact on the key properties influencing the thermal shock resistance. What is more, the impact of firing conditions (temperature and atmosphere) was also investigated. It was proved that all metallic antioxidants react with other constituents to form new phases which both rigidify the refractory and increase its value of the coefficient of thermal expansion. Unfortunately, such behavior results in worsening of the thermal shock resistance. Moreover, it turned out that the firing atmosphere has a negligible influence on the additives reactivity and thus the final properties of the refractory. Thus, firing temperature is the parameter that has the most important impact on the refractory evolution. All the obtained results facilitate the choice of antioxidants and firing condition to obtain desired properties of the refractory
Kareb, Ourdia. "Development of new dairy ingredient with prebiotic and antioxidant properties through the electro-activation processing of sweet cheese whey." Doctoral thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/28249.
Full textThe goal of this project was to develop the electro-activation technology as innovative approach for an integral valorization of whey constituents. This by-product is rich in valuable components with promising biological and functional properties. The first step of this work aimed to determine the optimal conditions of lactulose production using whey as a source of lactose and a yield of 35% was obtained with high purity under temperatures of 0, 10 and 25°C and short reaction time (≅ 40 minutes). Moreover, the proteomic analysis revealed the hydrolysis of whey proteins and simultaneous formation of Maillard reaction products with high antioxidant properties. The second step aimed to elucidate the antioxidant mechanisms that governed the Maillard-reacted-whey protein hydrolysates (MRPs-whey) and to characterize their structures. The antioxidant effect was ascribed to a multiple properties and could be used as both primary and secondary antioxidants. The molecular structure of the MRPs-whey was characterized to be Schiff base compounds. Additionally, multifunctional bioactive peptides, with biological properties were also identified. In the third step, the efficacy of electro-activated whey (EA-whey) as a combined prebiotic and antioxidant component on the growth of tested probiotic bacteria was demonstrated. The EA-whey was comparatively a better bifidogenic factor than lactulose. Additionally, EA-whey was found to elicit a protective effect on L. johnsonii La-1 during its growth in the presence of oxygen. This effect may be related, in part, to the ability of EA-whey to scavenge hydrogen peroxide metabolites and prevent its accumulation in the growth medium. FTIR spectra showed that EA-whey prevented the cell membrane lipids oxidation by limiting the change in the structural order of fatty acids. Overall, EA-whey as a prebiotic supplement possessing antioxidant capacity has great potential for application not only in the dairy industry but also as a functional food ingredient with potent bioactivities and functionalities.
Denagbe, Wilfried. "Lipides et polysaccharides extraits du fruit du palmier Acrocomia aculeata (moucaya) : Structures, propriétés antioxydantes, émulsifiantes et formation de nano-vecteurs." Electronic Thesis or Diss., Guyane, 2023. http://www.theses.fr/2023YANE0006.
Full textAcrocomia aculeata (« moucaya », French Guiana creole) is a palm native to French Guiana and the Amazon. Although its fruits are rich in lipids (0.1 to 83% of fresh matter for the mesocarp fruit) and carbohydrates (6 to 98% of fresh matter for them esocarp fruit), only lipi ds are valued as source of biofuels (biodiesel and biokerosene) in the Amazon sub region, due to a lack of knowledge about thechemical nature of carbohydrates. In FrenchGuiana, the fruit is not subject to any valorizationand its antioxidant capacities remain poorly known.To overcome this situation, this thesis work focuses on the extraction, physico chemical and structural characterization of the lipids and carbohydrates (mono --, di --, oligo and polysaccharides) constitutive of the fruit. An evaluation of their antioxidant oremulsifying properties, was also considered. Ourexperiments showed that fruit mesocarps contain 717% oil compared to rich fresh mesocarp, with a chemical composition dominated by oleic (54 62%) and palmitic (23 29%) acids, in line with literature results (53 78 and 11 30% respectively). Regarding carbohydrates, this work identified for the first time the presence of original glucomannanoligo and polysaccharides (fraction F2, 11 22% offresh mesocarp) with remarkable e mulsifyingproperties observed in the case of oligomers (waterin olive oil system (25/75, v v ) at 1% w/v; stability >6 months). In terms of antioxidant activity, the fruit showed no note worthy properties. This preliminary work paves the way for future in vestigations aimed at developing applications for these new glucomannans in the cosmetics, food, and pharmaceutical industries
Petrocchi, Consuelo. "Synthèse de nouvelles nitrones ß-phosphorylées (PPNs) dérivées de la PBN et leurs analogues vectorisés pour le ciblage mitochondrial : évaluation par RPE et mesure de l'activité antioxydante et vasorelaxante dans un modèle d'endothélium aortique." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4739/document.
Full textNitrones are diamagnetic compounds commonly used as probes to monitor biological free radical formation by the spin trapping (ST)/electron paramagnetic resonance coupling (EPR). In addition the growing interest in the therapeutic potential of α-phenyl-N-tert-butylnitrone (PBN) derivatives led researchers to develop analogs having improved protective properties and bioavailability. Among these, PPNs are β-phosphorylated analogues of PBN which form more persistent spin adducts than PBN toward oxygen-centered radicals. In this context we have synthesized twenty new hybrid PPNs having their aromatic ring substituted either by groups which can bring electronic and steric effects to the nitrone function or mimic natural antioxidant moieties. We evaluated the antioxidant properties of the new PPNs with a series of specific assays and we used ESR to study PPNs properties in ST toward a wide array of biologically-relevant free radicals, and their intrinsic nitric oxide releasing properties. The most promising compounds were than tested as vasorelaxant and antioxidant free radicals detectors in rat aortic rings. Protection by PPNs was assessed by measuring vascular response preservation and biochemical indices in aortic tissue. The second purpose dealt with the synthesis of new mitochondrial targeted PPNs with the aim to reach the primary biological source of endogenous production of free radicals. Using EPR we have assessed their ability to scavenge alkyl and alkoxy free radicals in vitro which allowed us to envisage a potential use of this probe against lipid peroxidation at mitochondrial level
Lanthier, Caroline. "Conception, synthèse et évaluation de nouveaux composés à dualité d'action agoniste des récepteurs 5-HT4 et antioxydante, d'intérêt thérapeutique pléiotrope dans la maladie d'Alzheimer Novel multi target-directed ligands targeting 5-HT 4 receptors with in cellulo antioxidant properties as promising leads in Alzheimer's disease Novel potent Benzisoxazoles targeting 5-HT4 receptors with in cellulo antioxidant properties as promising leads for Alzheimer disease." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMC415.
Full textAlzheimer’s disease (AD) is a neurodegenerative disorder characterized by memory loss and cognitive decline. Although the physiopathology of AD is not entirely known at the time, some molecular causes were identified such as the ß-amyloid peptides aggregation, tau-dependent neurofibrillary tangles, as well as oxidative stress and neuroinflammation. Currently, treatments available for patients are mainly acetylcholinesterase (AChE) inhibitors, which only have symptomatic benefits and do not cure AD. The medical need is thus strong in AD population.In this context, the concept of Multi-Target Directed Ligands (MTDLs) was applied to design a drug active toward several therapeutic targets. The envisaged MTDL should be able in first hand, to limit the development of ß-amyloid plaques by activating 5HT4R and in another hand to reduce the oxidative stress that plays a central role in the disease’s physiopathology.To that end, different series of compounds were designed, synthesized and evaluated for their in vitro/in vivo properties regarding their agonist activity on 5-HT4R and antioxidant properties. It led to the discovery of innovative molecules with potential promising neuroprotective properties
Cesari, Laëtitia. "Extraction de composés phénoliques à partir d’une bio-huile de lignine." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0148/document.
Full textThe lignocellulosic biomass is mostly composed of cellulose, hemicellulose and lignin. Upon thermal conversion of lignin, a bio-oil rich in phenolic compounds is obtained. These latter are then generally recovered through several liquid-liquid extraction involving aqueous and organic solvents. In this work we investigated, by a multi-scale study, the feasibility and the efficiency of the ionic liquid [Choline][NTf2] for the extraction of these phenolic compounds by liquid-liquid extraction. Indeed, such a solvent could improve the extraction efficiency and at the same time, reduce the toxicity and the cost of the classic organic solvents. Quantum calculations were performed in order to better understand the interaction governing the key systems of these extractions. The structures of the phenolic compounds in their isolated forms and in contact with solvents show that the conformations are stabilized by the presence of hydrogen bonds. More, the determination of the interaction energies indicates that the [Choline][NTf2] ionic liquid is efficient for the extraction of phenolic compounds present in aqueous solution. Furthermore, the study of phase diagrams of binary systems {water-phenolic compound} and ternary systems {water-phenolic compound-[Choline][NTf2]} show that the extraction of these compounds is also possible at a macroscopic scale. Then, the NRTL parameters coming from these experiments allowed the simulation of the extraction of three compounds mostly present in the bio-oils, namely phenol, guaiacol and syringol, as so at low cost. Finally, the extraction of these compounds from bio-oil obtained from lignin fast pyrolysis was also particularly efficient with the [Choline][NTf2] ionic liquid. Therefore, this multi-scale study demonstrated that [Choline][NTf2] is an excellent solvent for the recovery of phenolic compounds. Lastly, the study of the antioxidant properties testify the added-value of these compounds, especially through their reducing power and their radical scavenging capacity
Azofeifa, Gabriela. "Study of the health promoting properties of the tropical highland blackberry (Rubus adenotrichos) and the impact of digestion and pasteurization processes." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2013. http://tel.archives-ouvertes.fr/tel-01002531.
Full textVignault, Adeline. "Tanins œnologiques : caractéristiques, propriétés et fonctionnalités. Impact sur la qualité des vins." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0263.
Full textThe use of oenological tannins is a common practice worldwide in winemaking. However, up to date this use, is only authorized by the OIV to facilitate wines and must clarification. Nevertheless, oenological tannins are used for several reasons, explaining the existence of diverse tannins on the market. For all these reasons, OIV has begun few years ago to create a working group in order to conduct a large study on oenological tannins. Thus, the aim of this research was to carry out an exhaustive study to determine firstly the chemical composition and the richness in tannins of the oenological tannins. Secondly, their potential functionalities were studied, focusing on their antioxidant activity, their ability to stabilize and improve wine color and finally, their antioxidasic activity. Concerning chemical composition, the principal tannins monomers, dimers, trimers and tetramers were identified and quantified by HPLC-MS and LC-QTOF. The abundance in tannins was estimated by different methods: TPI, Bate-Smith, Methyl-cellulose, Folin-Ciocalteu, OIV official method and phloroglucinolisis. The antioxidant capacity was measured 5 methods (ABTS, CUPRAC, DPPH, FRAP and ORAC) meanwhile the oxygen consumption was measured using a non-invasive method based on luminescence. Antioxidasic property, was achieved by measuring first the laccase activity in winemaking, then by determined inhibition type and finally by laccase characterization precipitation by electrophoresis SDS-PAGE. The oenological tannins ability to stabilize the color was determined by their bathochromic and hyperchromic effect and by the calculation of the copigmentation index. Their color stabilization effect was evaluated during several days, different ethanol content and pH level. The results confirm that oenological tannins and specifically, ellagitannins, really protect wine against oxidation either because they exert antioxidant capacity and/or they consume directly oxygen. Moreover, oenological tannins can improve and stabilize red wines color acting as copigments, with gallotannins being the most efficient ones. In addition, oenological tannins, particularly grapes tannins, can be a new tool to inhibit the laccases produced by B. cinerea. As a fruit of these results, the OIV resolutions OENO-TECHNO 17-612 and OENO-TECHNO 17-613, just accepted, proposed to include two new functionalities of tannins uses in musts and wines:• Contribute to the antioxidant protection of must and wine components• Promote the expression, stabilization and preservation of color