Дисертації з теми "Bioactifs"
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Bessières, Bernard. "Synthese asymetrique d'aminoacides cyclopropaniques bioactifs." Rennes 1, 1996. http://www.theses.fr/1996REN10028.
Mazeh, Sara. "Synthèse d'alcaloïdes bioactifs issus de batracien." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAV043.
Alkaloids are widely occurring compounds in nature. The increasing scope of pharmacological properties displayed by the alkaloids extracted from a neotropical frog Dendrobates pumilio has arouse an intense interest in their study, both from a synthetic and biological aspect. The interest toward the alkaloid (-)-205B has not been considered in our laboratory solely because of the challenged 8b-azaacenaphthylene ring structure, but also was inspired by the promising biological activity it might possess against neuronal disorders.An efficient and highly stereoselective synthetic strategy was developed for the synthesis of the alkaloid (-)-205B. This approach features three characteristic transformations for building up the tricyclic core and installing the main stereochemistry: a 2+2 cycloaddition, a vinylogous Mannich reaction and an aza-Prins cyclization. In tandem with this total synthesis, a novel methodology was developed focusing on the stereo-directed alkylation based on silicon-tethered chemistry that comes up as an efficient solution for a difficulty encountered within the earlier approach
Giribaldi, Julien. "Synthèse de peptides bioactifs inspirés des venins." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS124.
Natural extracts such as animal venoms are an important source of bioactive peptides for therapeutic purposes. Peptides derived from venoms currently used in medicine include Eptifibatide, an antiplatelet drug developed from echistatin, a toxin isolated from a viper, Ziconotide, a potent analgesic identified in the venom of a cone snail and Exenatide , a glucagon-like peptide 1 receptor agonist isolated from the saliva of the Gila monster and used for the treatment of type 2 diabetes. These disulfide-rich venom peptides exhibit a constrained three-dimensional structure and increased plasma stability compared to linear peptides. Conservation of prey / predator receptors with human receptors makes venom peptides a unique source of lead compounds for the design of pharmacological tools and therapeutic compounds. It is estimated that less than 1% of the venom peptides have been pharmacologically characterized. Thus, this project aims to explore the pharmacology of novel venom-isolated peptides using solid phase peptide synthesis based on Fmoc chemistry (Fmoc-SPPS) as well as oxidative and regioselective folding strategies to produce the correctly folded and biologically active peptide for subsequent characterization. While the first part of this project is dedicated to the synthesis of linear and disulfide-poor venom peptides, the second part will be dedicated to the synthesis of disulfide-rich peptides via oxidative and regioselective folding strategies. Finally, we will use proteomic approaches integrated with transcriptomic data for the identification of new sequences from venoms. Overall, this project provides a better understanding of the pharmacology of venom peptides and identifies leads for the development of new pharmacological tools and potential drug candidates
NSENDA, THOMAS. "Syntheses enantio- et diastereoselectives de composes bioactifs." Université Louis Pasteur (Strasbourg) (1971-2008), 1999. http://www.theses.fr/1999STR13117.
Laville, Rémi. "Alcaloïdes bioactifs isolés d'éponges marines Haplosclerida et Poecilosclerida." Nice, 2008. http://www.theses.fr/2008NICE4077.
Pardini, Richez Aurélie. "Elaboration et analyses structurales de verres bioactifs macroporeux." Valenciennes, 2007. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/9599a9ab-378c-4241-95d2-9b3b6d3d25df.
The work concerns the study of bioactive SiO2, CaO, Na2O and P2O5 glasses and presents three parts. In order to connect the structure and the bioactivity, a structural study of these glasses was carried out by 29Si and 31P NMR. The study allowed to show that the progressive phosphorus addition generates an increasingly important polymerization of the silicate network and modifies slightly the phosphate entities chemical nature. The second part relates the macroporous bioactive glass elaboration with controlled porosity by transposing the « Procédé d’élaboration de substituts osseux synthétiques d’architecture poreuse parfaitement maîtrisée » to 43. 65SiO2-22. 795CaO-30. 555Na2O-3P2O5 glass. However, the densification by heat treatment generates a partial crystallization of the glass. The 23Na NMR confirms the glass-ceramic formation. The third part relates to the in vitro bioactivity evaluation as well as preliminary cytocompatibility tests of for the initial glass and the corresponding glass-ceramic. The Infra Red analysis, made on the samples plunged in simulated body fluid (SBF), showed that the glass-ceramic is more bioactive than the glass: apatite was formed after 5h15 immersion for glass-ceramic against 10h15 for glass. The cytocompatibility tests put in evidence no cytotoxicity of the glass-ceramic. This study thus allowed to correlate the glasses structure to their bioactivity. From a very bioactive glass, it was also possible to elaborate a macroporous vitreous ceramic with controlled porosity and with better in vitro bioactivity results
Mascitti, Vincent. "Synthèse d'oligosaccharides bioactifs ; Synthèse totale de la (-)-doliculide /." [Montréal] : Université de Montréal, 2003. http://wwwlib.umi.com/cr/umontreal/fullcit?pNQ91921.
"Thèse présentée à la Faculté des études supérieures en vue de l'obtention du grade de Philosophiae Doctor (Ph.D.) en Chimie" Version électronique également disponible sur Internet.
Nzambe, Ta Keki Jean Kerim. "Elaboration de matériaux bioactifs à partir de fibres lignocellulosiques." Thesis, Limoges, 2015. http://www.theses.fr/2015LIMO0133/document.
Surface contamination by pathogens constitutes a major public health problem encountered in many areas such as hospitals, environment and food industry. This contamination consists in the adhesion of pathogenic or opportunistic bacteria that can attach to a biotic or abiotic surface and lead to the formation of biofilm. An effective way to fight against microbial contamination is the development of antibacterial surfaces, in order to prevent or reduce bacterial adhesion. Based on the expertise of the Laboratoire de Chimie des Substances Naturelles in the field of polysaccharides, we have undertaken the development of antibacterial materials by grafting through covalent bonds molecules presenting antibacterial properties onto lignocellulosic fibers (in this case Kraft pulp fibers). Triazoles are resistant to acid and basic hydrolysis, reductive and oxidative conditions. This moiety is also relatively resistant to metabolic degradation and is not posing particular toxicity problems. The study of the antibacterial effect has shown a bactericidal activity of the triclosan-Kraft pulp sheet against three strains frequently found in hospitals: Pseudomonas aeruginosa, Bacillus cereus and Escherichia coli. In the case of grafting photosensitizers, only the neutral porphyrin-Kraft pulp sheet material displayed a strong photobactericidal activity after irradiation
Lapointe, Verreault Camille. "Développement du motif sulfahydantoïne comme source de composés bioactifs." Thesis, Université Laval, 2014. http://www.theses.ulaval.ca/2014/30436/30436.pdf.
Riva-Grenouillat, Nathalie. "Synthèse d'analogues bioactifs de facteurs de nodulation des légumineuses." Paris 11, 2001. http://www.theses.fr/2001PA112237.
The process of nitrogen fixation by leguminous plants is initiated by the exchange of signal compounds: flavonoids secreted by the plant and nodulation factors (Nod factors) secreted by the bacterium. Nod factors consist in a short chitin oligosaccharidic backbone (typically tetra or pentameric) that is N-acylated at the non-reducing end by a fatty acid. Ln order to understand the role of the structural elements of the bacterial molecule (the nodulation factor) that are involved in the nodulation induction, we have prepared analogs able to trigger the organogenesis in the plant. The focus is on the symbiotic relationship between alfalfa or vetch and their specific rhizobia. The tetrameric backbone was produced by the appropriate E. Coli recombinant cells. The first type of analogs are lipo-chitooligosaccharides in which the fatty-acid is fixed on the sugar via an amine. The sulfated compounds were tested on alfalfa and proved to be still active in nodulation induction, suggesting that there is no cleavage of the fatty-acid during the recognition process. However a decrease of activity seems to prove the influence of the amide group in the recognition process. In a second time, we considered the synthesis of various analogs with modified lipid chains by a method using multi-component reactions such as Passerini and Ugi reactions. Preliminary experiments with glucosamine derivatives are very promising and extrapolation to the tetrameric compounds are in progress
Patel, Kirti. "Extraction de métabolites bioactifs d'éponges marines du Pacifique Sud." Paris, Muséum national d'histoire naturelle, 2010. http://www.theses.fr/2010MNHN0006.
The work described in this manuscript deals with the exhaustive isolation of marine metabolites from marine sponges collected from the coast of New Georgie in Solomon Islands. A total of 65 compounds were isolated from Petrosia (Petrosia) crassa, Amorphinopsis excavans and Stylissa carteri, out if which 10 new compounds were identified. Sarasinoside B4, a new product isolated from Amorphinopsis excavans is an epimer of sarasinoside B1. Stylissazoles A-I were isolated from Stylissa carteri. Stylissazoles A-E have kinase activites and belongs to a new subclass of pyrrole-2-aminoimidazoles dimers, which have exclusively N-C bond between the two monomers. This new subclass of molecules constitute additional mode of dimerization and add another dimension to the molecular diversity of pyrrole-2- aminoimidazoles. This research work allowed us to deepen our knowledge about pyrrole-2-aminoimidazoles and update the universal biogenetic pathway proposed previously for pyrrole-2-aminoimidazoles
Amokrane, Gana. "Influence du greffage covalent de polymères bioactifs, sous irradiations UV, sur des échafaudages en fibres PCL électrofilées : Caractérisation de surface, étude des propriétés mécaniques et évaluation de la réponse biologique." Thesis, Paris 13, 2019. http://www.theses.fr/2019PA131069.
Electrospinning, an electrostatic fiber fabrication technique has evinced more interest in recent years due to its versatility and potential for applications in diverse fields especially in tissue engineering. Polycaprolactone (PCL) polymer has been approved for biomedical application and offers excellent mechanical properties and slow biodegradation, making it an appropriate material for use as a scaffold for tissue engineering. Previous studies carried out in our laboratory have shown that the covalent direct grafting (“Grafting From” method) of bioactive polymers or copolymers allows to overcome the PCL hydrophobicity and can favor cell adhesion and differentiation onto scaffolds. Various PCL scaffolds with different microstructures were prepared by electrospinning. The grafting of bioactive polymers on PCL electrospun scaffolds was carried out using two “grafting from” techniques; (i) the thermal grafting for 1 or 3 hours which requires a surface activation by ozonation as reference and (ii) the UV grafting for 1 hour with or without surface activation. We compared these grafting techniques in terms of surface modification, effect of the grafting processes on the intrinsic PCL properties. In vitro assay experiments were carried out to observe the fibroblast cell behavior on various functionalized scaffolds exhibiting different degrees of surface hydrophilicity and compare them to each other as well as an ungrafted scaffold. The successful grafting of ionic polymers onto the grafted PCL scaffolds was demonstrated using surface characterization techniques. Possible changes in the intrinsic properties of PCL have been studied using mechanical characterization, size exclusion chromatography (SEC), and differential scanning calorimetry (DSC). Finally, the biodegradation at different time points of these scaffolds was evaluated in different environments. This study shows the elaboration of various PCL fiber scaffolds, their functionalization by the grafting of bioactive polymers and the appreciation of the mechanical and microstructural changes. The in vitro biological assays have shown the favorable effect of the grafted polymer on the cellular response and that, depending on the microstructure type of the scaffold, its surface functionalization by bioactive polymers and its surface hydrophilicity, different cell behaviors can be observed
Travert, Nathalie. "Métabolites pyrrole-2-aminoimidazoles marins bioactifs : réactivité et synthèse biomimétique." Paris 11, 2003. http://www.theses.fr/2003PA112120.
The work described in this manuscript is centered on the reactivity of pyrrole-2-aminoimidazole alcaloids isolated from marine sponges. This study is based on a biogenetic hypothesis which could explain the chemical pathways formation of most of this compounds, starting from very simple precursors like oroidine and dispacamide A. This family of compounds comprise linear and polycyclic structural groups. 2-Pyrrolecarboxylic acid, more or less brominated, and 2-aminoimidazole parts are the most important building blocks. The manuscript is divided into three studies: the study of N1-C and C3-C intramolecular cyclisations on pyrrole-aminoacids derivates allowed us to postulate a new synthetic scheme towards many polycyclic compounds belonging to this family. The study of dimeric pyrrole-proline or proline-proline systems and their biomimetic spontaneous transformations to dispacamide A and derivates. Biomechanistic analysis and the access to oroidine, hymenidine and clathrodine, using N-acyl-1,2-dihydropyridines. This general study allowed us to understand numbers of chemical mecanisms involved in the reactivity of pyrrole-2-aminoimidazole alcaloids
D'Almeida, Mélanie. "Synthèse et caractérisations physico-chimiques et biologiques de revêtements implantaires bioactifs." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10297/document.
In the past years, population requirement for dental care service increased. More precisely, replacement of missing tooth using dental implant is now a common intervention. As implant provides an artificial root, this procedure is permanent. The failure of the placement procedure is mainly due to an inflammatory disease: peri-implantitis. This disease leads to the death of bone tissues surrounding the dental implant. Today only curative solutions are available, and no implants can prevent bacterial development. It appears that preventing post-surgical complications by designing antibacterial implants is now a public health issue. To achieve this goal, we evaluate in this thesis different solutions to design bioactive implant coatings. We focused our work on coating of a model titanium surface by a bioactive polymer: chitosan. Polymer binding on the substrate is achieved by covalent link using a coupling agent. We described each step of the coating synthesis and characterized its biological properties using both surface chemistry analysis and cell biology techniques. We studied its behavior in an acid environment and analyzed its biological and antibacterial properties in vitro. Results of this work were used to select the bioactive coating with the best properties for the intended application, particularly due to its resistance in acidic condition and its antibacterial activity against common bacteria
Perron, Tommy. "Étude du potentiel bioactif de la Brasenia schreberi /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2006. http://theses.uqac.ca.
La p. de t. porte en outre: Mémoire présenté à l'Université du Québec à Chicoutimi comme exigence partielle de la maîtrise en ressources renouvelables. CaQCU Comprend des références bibliographiques. Document électronique également accessible en format PDF. CaQCU
Tounsi, Latifa. "Microalgue rouge du genre porphyridium : modélisation de la production de métabolites et application dans la production d'emballages actifs." Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2023. http://www.theses.fr/2023UCFA0144.
A microalga was isolated from the Tunisian coast in the Mahdia governorate and subsequently identified using morphological criteria as well as molecular biology techniques. The isolate was identified as belonging to the genus Porphyridium. In the 1st part, Porphyridium sp. and Porphyridium cruentum UTEX 161 were grown in 3 culture media to identify the optimal growth medium and enhance the production of metabolites. Results showed that Porphyridium could thrive in a wide range of media. The highest biomass production was achieved with the Pm medium (2 × 107 cells/mL) for Porphyridium sp. The highest pigment content (chlorophyll a = 0.678 ± 0.005 pg/cell, total carotenoids = 0.18 ± 0.003 pg/cell, B-phycoerythrin = 3.88 ± 0.003 pg/cell) and soluble proteins (14.58 ± 0.35 pg/cell) were observed with F/2 medium. Porphyridium sp. accumulated a higher amount of starch in the F/2 medium (0.69 ± 0.016%) and was on par with the Hemerick medium (0.62 ± 0.050%). The Hemerick medium showed the most promise in terms of lipid (2.23%) and EPS (5.41 ± 0.56) production. For Porphyridium cruentum, the F/2 medium was the best medium for growth (4.65 × 106 cells/mL) and production of pigments (chlorophyll a = 1.76 ± 0.007 pg/cell, total carotenoids = 0.48 ± 0.0022 pg/cell, B-phycoerythrin = 15.77 ± 0.6 pg/cell), starch (3.97 ± 0.22%) and proteins (34.36 ± 1.035 pg/cell). However, the Pm and Hemerick media proved to be the best for supporting the production of lipid (4.51 ± 0.45%) and EPS (14.19 ± 0.19 pg/cell),. In the 2nd part, bioactive films based on gelatin and sodium alginate were developed by incorporating an aqueous extract of B-phycoerythrin from Porphyridium cruentum at different concentrations (45, 67.5, and 90 μg/mL). The optimization process yielded a maximum B-phycoerythrin content of 4.16 ± 0.24% under the following conditions: NaCl = 17 g/L, MgCl2.6H2O = 2.6 g/L and K2HPO4 = 0 g/L. The B-phycoerythrin extract demonstrated antibacterial and antioxidant properties. The incorporation of B-phycoerythrin led to a significant increase in water swelling index and solubility, as well as a notable decrease in moisture content. Furthermore, when added to gelatin and sodium alginate films, the B-phycoerythrin extract improved the L*, a*, and ΔE* values. X-ray diffraction analysis revealed that the addition of B-phycoerythrin extract had a positive influence on the crystallinity of the developed films. The films incorporating the B-phycoerythrin extract exhibited a homogeneous structure with a slightly rough surface. The new films demonstrated complete biodegradability and promising antioxidant potential
Modjinou, Tina. "Valorisation de la biomasse pour l'élaboration de matériaux bioactifs sous irradiation." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1152/document.
The valorization of phenolic and terpene derivatives of biomass is perfectly in line with the current challenge of our societies that drives traditional chemistry to evolve towards a sustainable chemistry. Because of their unsaturated nature, terpenes are particularly interesting for synthesizing new materials by thiol-ene chemistry. At the same time, the phenolic derivatives can easily be modified to unsaturated synthons capable of reacting in these same reactions. Thus, a wide range of materials based on linalool and eugenol has been developed under UV irradiation. An approach by photochemistry has been selected since it fits perfectly within the framework of a chemistry more respectful of the environment. The beneficial effect of the oxygenated functions of linalol and phenolic functions of eugenol on antibacterial activity was demonstrated against two bacterial strains mainly responsible for the development of nosocomial diseases: S. aureus and E. coli. The incorporation of ZnO nanoparticles, carvacrol or tannic acid during the crosslinking reaction makes it possible to improve the antimicrobial properties significantly. The association with semi-crystalline biobased and biodegradable polyesters presents an interesting alternative to optimize the thermomechanical performance of the obtained materials.A second type of materials has been synthesized by photocrosslinking epoxidized phenolic derivatives such as resorcinol or eugenol. The photoinitiated cationic polymerization by opening of the ring enables the synthesis of materials whose mechanical properties are higher than the materials obtained by thiol-ene reaction and on the other hand to get rid of the thiol-based crosslinking agent. The synthesis of various monoepoxidized eugenol derivatives offers the advantage of being able to modulate the composition of the obtained materials which may contain phenol functions and / or unsaturations. The phenol groups are essential to the antibacterial activity and lead to the antioxidant properties. The possibility of introducing unsaturations allows a post-functionalization of the surface of the materials.Thus, a wide range of crosslinked, biosourced and bioactive materials whose properties vary from elastomer to thermosetting have been synthesized under irradiation
Kadri, Rana. "Nano-fonctionnalisation des hydrogels naturels bioactifs sous forme de matrice 3D." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0226/document.
Novel crosslinking methods to design 3D hydrogels consist on an innovative combination of various components in order to create 3D structure with optimal properties and functionalities. This blending technic can be carried out by mixing several polymers or/and incorporation of nanoparticles into the polymer network. The present work showed the advantages of interpenetrating polymer networks forms composed of alginate and GelMA and highlighted the effect of the incorporation of nanoliposomes on the physico-chemical properties of the hydrogels. It consisted primarily on a multiscale characterization of the hydrogels and then on the study of the possible interactions in the 3D structure. At first, the surface characterization of the composite hydrogels at different alginate concentrations, before and after the functionalization with soft nanoparticles, showed an improvement of the wetting properties and the surface energy. The mechanical properties of the hydrogels were determined by multiscale analysis using the atomic force microscopy (nanoscopic) and the rheometer (mesoscopic). These analysis took into account the various concentrations of alginateas well as the two different concentrations of the liposomes added in the 3D structure. The results showed the effectiveness of mixing the polymers and the influence of the nanoliposomes on the alginate coagulation due to an interaction between the soft nanoparticules and the coagulation agent (CaCl2). A morphological study of the hydrogels showed the possibility to control the size of the pores by the modification of concentration for each component of hydrogel or by functionalization the 3D structure. The physicochemical interactions were then studied thanks to the X-ray Photoelectron Spectroscopy, the Nuclear Magnetic Resonance Spectroscopy and the Fourier Transform Infrared spectroscopy
Fennouri, Aziz. "Analyse de molécules individuelles de glucides bioactifs confinées dans des nanopores." Thesis, Evry-Val d'Essonne, 2013. http://www.theses.fr/2013EVRY0037/document.
Glycosaminoglycans (GAGs) are bio-active polysaccharide expressed at the cell surface and in the extra-cellular matrix, which mediate cell-cell and cell-matrix interactions at the origin of a variety of physiological and pathological activities such as in embryonic development, cell growth, homeostasis, etc. Among all biopolymers, they offer the largest potential of information owing the incomparable variety of combinations and region-selective modifications of their building monosaccharides. The structural analysis of such complex carbohydrates is recognized as one of the most challenging task of glycosciences. New approaches based on single-molecule detection are currently arousing great interest in biology as it allows the direct observation and nano-manipulation of bio-molecules. Mainly applied to nucleic acids and proteins, these approaches have been not often used for the study of carbohydrates. We report here the detection of individual glycosaminoglycan oligosaccharides confined in aerolysin and α-hemolysin proteic nanopores. Our results show the capability of this new approach to discriminate hyaluronic acid (HA) oligosaccharides according to their polymerization degree based on the analysis of duration and frequency of the current blockades. This feature prompted us to apply this approach to the enzyme monitoring of the hyaluronidase-catalyzed depolymerization of HA and the determination of its kinetic parameters. Translocation has also been proved by mass spectrometry. Other oligosaccharides like heparin, dermatan sulfate and dextran sulfate, have also been studied, showing different characteristic “fingerprints”, due to structure and/or conformation differences
Schlumberger, Sébastien. "Etude d'agents bioactifs et de neurotoxines isolés à partir d'organismes marins." Paris, Muséum national d'histoire naturelle, 2009. http://www.theses.fr/2009MNHN0010.
The present work deals with the study of the pharmacological properties of bioactive agents, in particular neurotoxins, isolated from aquatic organisms and micro-organisms, to determine their functional alterations, molecular targets and mechanisms of action. Using electrophysiological techniques and micro-spectro-fluorometry confocal imaging, we have studied the activity of cyclic polyether toxins isolated from the dinoflagellate Gambierdiscus toxicus [the Caribbean ciguatoxin 1 (C-CTX-1), the Pacific ciguatoxin 4B (P-CTX-4B) and gambierol], and the activity of a peptide isolated from the venom of the piscivorous cone snail Conus consors (the µ-conopeptide CnIIIC), on myelinated axons, vertebrate skeletal neuromuscular preparations, mouse neuroblastoma and rat foetal chromaffin cells. The main results indicate that: (i) C-CTX-1, at nanomolar concentrations, induces asynchronous muscle contractions and depolarizes the muscle membrane. In addition, it increases spontaneous quantal acetylcholine (ACh) release, in a sustained manner until complete exhaustion of the transmitter stores. Furthermore, it increases transiently and blocks completely nerve-evoked quantal ACh release. Those effects are concomitant with an increase of nerve endings volume that could be reversed with hyper-osmolar D-mannitol. C-CTX-1 also increases nodal excitability and increases action potential duration. All together, results suggest that C-CTX-1 activates voltage gated Na+ channels (VGSC) and inhibits voltage gated K+ channels (VGPC). (ii) P-CTX-4B is the precursor of some Pacific ciguatoxins isolated from ciguateric fish. P-CTX-4B blocks Na+ and K+ currents without affecting their kinetics, with a higher affinity for the last one. It is 4 times more active on VGPC and 50 times less active on VGSC than P-CTX-1B. P-CTX-4B also modifies activation and inactivation voltage-sensitivity of VGSC. The local anaesthetic lidocaine affects in the same manner P-CTX-4B modified and unmodified Na+ currents. Those effects depend on both concentration and pre-pulse membrane potential. (iii) Gambierol is a VGPC inhibitor that increases isometric twitch tension in neuromuscular preparations stimulated through the motor nerve. Less twitch augmentation was observed in directly stimulated muscles, when comparing twitch tension-time integrals obtained by nerve stimulation. Gambierol slowed the rate of muscle action potential repolarization without affecting amplitude and overshoot, but triggered spontaneous and/or repetitive action potentials in skeletal muscle fibres. Further evidence is provided that gambierol at sub-micromolar concentrations blocks a fast inactivating outward K+ current that is responsible for action potential prolongation in Xenopus skeletal myocytes. It is suggested that gambierol through a selective action on VGPC prolongs the duration of action potentials, enhances the extent and time course of Ca2+ release from the sarcoplasmic reticulum, and increases twitch tension generation. (iv) Gambierol specifically inhibits VGPC without affecting calcium-dependent and ATP-sensitive K+ channels, and without affecting catecholamine release of foetal chromaffin cells in primary culture. At the neuromuscular junction, gambierol increases nerve terminal calcium levels after nerve stimulation and increases synchronous quantal ACh release, without affecting spontaneous quantal release. Gambierol reverses the effects of d-tubocurarine and of botulinium type-A toxin in vitro. In addition, gambierol increases delayed quantal ACh release. (v) µ-conopeptides are known to block VGSC. The µ-CnIIIC has been purified from Conus consors venom, and synthesized. It inhibits completely skeletal muscle contraction induced by nerve or muscle stimulation, as expected for this family of toxins. However, µ-CnIIIC also inhibits Na+ current in neuroblastoma cells, and in KEK-293 and Xenopus oocytes expressing muscle-type Nav1. 4 channels. µ-CnIIIC is about 10 times more potent to inhibit global action potentials in unmyelinated axon than in myelinated ones. Therefore, results show that µ-CnIIIC is active on both muscle-type and neuronal-type VGSC. All together, present results show the great diversity of mechanisms of action of neurotoxins isolated from aquatic organisms, and the interest in continuing their studies in order to understand their physio-pathological effects during intoxinations, as well as for developing new and original selective pharmacological agents and tools to study physiological processes
Kerzaon, Isabelle. "Métabolites bioactifs d'Ascomycètes marins : déréplication, isolement, identification et étude de production." Nantes, 2009. http://archive.bu.univ-nantes.fr/pollux/show.action?id=a66c6ee3-4831-448a-8421-65e29b1ec13d.
In the search for novel bioactive substances, marine-derived micromycetes are a promising source of novel compounds. Previous woks on fungi of regional shellfish farming areas have shown a wide diversity of fungal strains with more than 30 percent producing toxins or bioactive compounds. The present work presents the study of some of these Ascomycetes in order to search novel fungal bioactive substances and to estimate their ability to produce mycotoxins in marine conditions. The 42 extracts from cultures of 11 marine-derived Penicillium sp. Strains have been subjected to a screening for biological activities and dereplication by LC-UV/DAD and LC-MS/MS. This led to the selection of 10 neuroactive or cytotoxic extracts and to the identification of 38 metabolites. Bioguided fractionation of an extract of a P. Expansum strain led to the isolation and structural identification by NMR of communesin B as the neuroactive compound. Thorough analyses by LC-HRMS/MS led to identification of 14 other communesins including 10 new derivatives. Their structures were determined after development of a predictive model of fragmentation. Meanwhile, 15 marine and terrestrial strains of Aspergillus fumigatus were studied for their production of gliotoxin in the marine environment. The development of a bioassay for the detection and quantification of this mycotoxin has shown the influence of salinity on its excretion
Turcotte, Caroline, and Caroline Turcotte. "Régulation de l'inflammation par les lipides bioactifs : interactions biosynthétiques et fonctionnelles entre les endocannabinoïdes et les éicosanoïdes." Doctoral thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/37592.
Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2019-2020
Les maladies inflammatoires chroniques sont un fardeau de santé important à travers le monde. Les traitements actuellement disponibles soulagent la douleur et l’inflammation, mais leurs effets secondaires rendent leur utilisation à long terme risquée. À la lumière de cette problématique, la communauté scientifique s’intéresse au potentiel d’anti-inflammatoires naturels comme les endocannabinoïdes. Les endocannabinoïdes sont des lipides endogènes qui activent les récepteurs cannabinoïdes (CB1 et CB2). Ils régulent ainsi divers processus physiologiques tels l’appétit, l’adipogénèse et la nociception. Les deux endocannabinoïdes les mieux caractérisés, le 2-AG et l’AEA, peuvent également moduler l’inflammation en activant le récepteur CB2 à la surface des cellules immunitaires. Les souris déficientes pour le récepteur CB2 présentent un phénotype inflammatoire exacerbé, suggérant que ce récepteur est anti-inflammatoire. Cependant, le rôle des endocannabinoïdes dans l’inflammation est beaucoup plus complexe puisqu’ils peuvent être métabolisés en une grande variété de médiateurs lipidiques de l’inflammation. Leur voie de dégradation principale est leur hydrolyse en acide arachidonique (AA), qui sert de précurseur à la biosynthèse d’éicosanoïdes pro-inflammatoires comme le leucotriène B4 et la prostaglandine E2. Ils peuvent également être métabolisés directement par certaines enzymes impliquées dans la synthèse d’éicosanoïdes, pour générer des médiateurs comme les prostaglandines-glycérol (PG-G). Par conséquent, les endocannabinoïdes peuvent générer un profil unique d’effets pro- et anti-inflammatoires. Des stratégies thérapeutiques visant à bloquer l’hydrolyse des endocannabinoïdes pour amplifier leurs effets anti-inflammatoires ont été étudiées, mais une très grande proportion de cette recherche a été effectuée sur des animaux. Les façons dont les endocannabinoïdes sont synthétisés et dégradés par les leucocytes humains, ainsi les effets de leurs métabolites sur les fonctions de ces cellules, sont mal définis. Bien que les résultats obtenus dans des modèles animaux soient prometteurs, ces mécanismes doivent être mieux caractérisés chez l’humain avant qu’il ne soit envisageable de les manipuler afin de traiter les maladies inflammatoires. Le premier objectif de mon doctorat était de caractériser les voies de dégradation et de biosynthèse des endocannabinoïdes chez les leucocytes humains. Nous avons documenté l’expression de toutes les lipases hydrolysant le 2-AG, chez plusieurs types leucocytaires. Ces résultats ont souligné que chaque leucocyte exprime plusieurs 2-AG hydrolases et que les inhibiteurs sélectifs actuellement disponibles n’inhibent que partiellement l’hydrolyse du 2-AG chez ces cellules. Ces données ont également démontré que les leucocytes humains hydrolysent très efficacement le 2-AG, une découverte qui nous a permis de mettre en évidence une nouvelle voie de biosynthèse du 2-AG par les leucocytes. En présence d’inhibiteurs d’hydrolyse, les neutrophiles, éosinophiles et monocytes stimulés avec de l’AA ont produit des quantités de 2-AG environ 1000 fois supérieures aux niveaux rapportés dans la littérature. Ils ont également transformé d’autres acides gras polyinsaturés en leurs endocannabinoïdes-glycérol respectifs. Nous avons démontré que cette voie de biosynthèse est dépendante de la réacylation des acides gras dans les phospholipides membranaires, et que leur métabolisme subséquent en endocannabinoïdes implique possiblement l’acide lysophosphatidique comme intermédiaire. Cette étude est la première à rapporter une biosynthèse significative d’endocannabinoïdes par les leucocytes humains, et à démontrer que cette biosynthèse est indépendante de la voie classique de biosynthèse du 2-AG. Nous avions également pour objectif de caractériser l’impact du 2-AG et des PG-G sur les fonctions des leucocytes humains. Nous avons démontré qu’en présence d’IL-5, une cytokine impliquée dans l’inflammation éosinophilique présente dans l’asthme, le 2-AG induit une migration importante des éosinophiles. Cet effet du 2-AG requiert à la fois l’activation du récepteur CB2 et l’hydrolyse du 2-AG en AA pour produire des métabolites de la 15-lipoxygénase. Ceci souligne que l’hydrolyse du 2-AG permet la production de médiateurs causant des effets pro-inflammatoires et qu’il serait souhaitable de bloquer cette hydrolyse in vivo. Finalement, nous avons étudié l’effet de la PGE2-G sur les fonctions des neutrophiles et démontré qu’elle inhibe plusieurs fonctions effectrices de ces cellules. Cet effet inhibiteur nécessite l’hydrolyse de la PGE2-G en PGE2 par les neutrophiles, et l’activation du récepteur EP2 à leur surface. Nos travaux permettront de mieux comprendre la façon dont l’hydrolyse des endocannabinoïdes devrait être bloquée chez les humains, ainsi que tous les effets biologiques qui en découleront. Le but ultime est de développer de nouveaux traitements contre les maladies inflammatoires chroniques, qui maximiseront les effets analgésiques et anti-inflammatoires des endocannabinoïdes tout en limitant leurs effets néfastes.
Les maladies inflammatoires chroniques sont un fardeau de santé important à travers le monde. Les traitements actuellement disponibles soulagent la douleur et l’inflammation, mais leurs effets secondaires rendent leur utilisation à long terme risquée. À la lumière de cette problématique, la communauté scientifique s’intéresse au potentiel d’anti-inflammatoires naturels comme les endocannabinoïdes. Les endocannabinoïdes sont des lipides endogènes qui activent les récepteurs cannabinoïdes (CB1 et CB2). Ils régulent ainsi divers processus physiologiques tels l’appétit, l’adipogénèse et la nociception. Les deux endocannabinoïdes les mieux caractérisés, le 2-AG et l’AEA, peuvent également moduler l’inflammation en activant le récepteur CB2 à la surface des cellules immunitaires. Les souris déficientes pour le récepteur CB2 présentent un phénotype inflammatoire exacerbé, suggérant que ce récepteur est anti-inflammatoire. Cependant, le rôle des endocannabinoïdes dans l’inflammation est beaucoup plus complexe puisqu’ils peuvent être métabolisés en une grande variété de médiateurs lipidiques de l’inflammation. Leur voie de dégradation principale est leur hydrolyse en acide arachidonique (AA), qui sert de précurseur à la biosynthèse d’éicosanoïdes pro-inflammatoires comme le leucotriène B4 et la prostaglandine E2. Ils peuvent également être métabolisés directement par certaines enzymes impliquées dans la synthèse d’éicosanoïdes, pour générer des médiateurs comme les prostaglandines-glycérol (PG-G). Par conséquent, les endocannabinoïdes peuvent générer un profil unique d’effets pro- et anti-inflammatoires. Des stratégies thérapeutiques visant à bloquer l’hydrolyse des endocannabinoïdes pour amplifier leurs effets anti-inflammatoires ont été étudiées, mais une très grande proportion de cette recherche a été effectuée sur des animaux. Les façons dont les endocannabinoïdes sont synthétisés et dégradés par les leucocytes humains, ainsi les effets de leurs métabolites sur les fonctions de ces cellules, sont mal définis. Bien que les résultats obtenus dans des modèles animaux soient prometteurs, ces mécanismes doivent être mieux caractérisés chez l’humain avant qu’il ne soit envisageable de les manipuler afin de traiter les maladies inflammatoires. Le premier objectif de mon doctorat était de caractériser les voies de dégradation et de biosynthèse des endocannabinoïdes chez les leucocytes humains. Nous avons documenté l’expression de toutes les lipases hydrolysant le 2-AG, chez plusieurs types leucocytaires. Ces résultats ont souligné que chaque leucocyte exprime plusieurs 2-AG hydrolases et que les inhibiteurs sélectifs actuellement disponibles n’inhibent que partiellement l’hydrolyse du 2-AG chez ces cellules. Ces données ont également démontré que les leucocytes humains hydrolysent très efficacement le 2-AG, une découverte qui nous a permis de mettre en évidence une nouvelle voie de biosynthèse du 2-AG par les leucocytes. En présence d’inhibiteurs d’hydrolyse, les neutrophiles, éosinophiles et monocytes stimulés avec de l’AA ont produit des quantités de 2-AG environ 1000 fois supérieures aux niveaux rapportés dans la littérature. Ils ont également transformé d’autres acides gras polyinsaturés en leurs endocannabinoïdes-glycérol respectifs. Nous avons démontré que cette voie de biosynthèse est dépendante de la réacylation des acides gras dans les phospholipides membranaires, et que leur métabolisme subséquent en endocannabinoïdes implique possiblement l’acide lysophosphatidique comme intermédiaire. Cette étude est la première à rapporter une biosynthèse significative d’endocannabinoïdes par les leucocytes humains, et à démontrer que cette biosynthèse est indépendante de la voie classique de biosynthèse du 2-AG. Nous avions également pour objectif de caractériser l’impact du 2-AG et des PG-G sur les fonctions des leucocytes humains. Nous avons démontré qu’en présence d’IL-5, une cytokine impliquée dans l’inflammation éosinophilique présente dans l’asthme, le 2-AG induit une migration importante des éosinophiles. Cet effet du 2-AG requiert à la fois l’activation du récepteur CB2 et l’hydrolyse du 2-AG en AA pour produire des métabolites de la 15-lipoxygénase. Ceci souligne que l’hydrolyse du 2-AG permet la production de médiateurs causant des effets pro-inflammatoires et qu’il serait souhaitable de bloquer cette hydrolyse in vivo. Finalement, nous avons étudié l’effet de la PGE2-G sur les fonctions des neutrophiles et démontré qu’elle inhibe plusieurs fonctions effectrices de ces cellules. Cet effet inhibiteur nécessite l’hydrolyse de la PGE2-G en PGE2 par les neutrophiles, et l’activation du récepteur EP2 à leur surface. Nos travaux permettront de mieux comprendre la façon dont l’hydrolyse des endocannabinoïdes devrait être bloquée chez les humains, ainsi que tous les effets biologiques qui en découleront. Le but ultime est de développer de nouveaux traitements contre les maladies inflammatoires chroniques, qui maximiseront les effets analgésiques et anti-inflammatoires des endocannabinoïdes tout en limitant leurs effets néfastes.
Chronic inflammatory diseases are an important health burden worldwide. The currently available treatments alleviate pain and inflammation, but their numerous adverse effects make their long term use difficult. Therefore, the scientific community is studying the anti-inflammatory potential of mediators such as endocannabinoids. Endocannabinoids are endogenous lipids that activate the cannabinoid receptors, namely CB1 and CB2. In doing so, they regulate various physiological functions and cognitive processes functions such as appetite, adipogenesis and nociception. The two best-characterized endocannabinoids, 2-AG and AEA, also exert effects on immune cell functions, leading to the modulation of immunity and inflammation. They do so by activating the CB2 receptor, which is expressed in the periphery, notably on immune cells. Notably, it was shown that mice lacking the CB2 receptor display an exacerbated inflammatory phenotype, suggesting that CB2 activation by endocannabinoids is anti-inflammatory. However, the biological effects of endocannabinoids are far more complex, given that they can be metabolized into a wide variety of bioactive lipids. The main degradation pathway for 2-AG and AEA is their hydrolysis into arachidonic acid (AA), a fatty acid that acts a precursor for the biosynthesis of several pro-inflammatory eicosanoids such as leukotriene B4 and prostaglandin E2. They can also be directly metabolized by eicosanoid-biosynthetic enzymes, which generates mediators such as glyceryl-prostaglandins (PG-Gs). Therefore, endocannabinoids can generate an intriguing profile of pro- and anti-inflammatory effects, depending on the balance between their catabolic pathways and receptor activation. Therapeutic strategies aiming at blocking endocannabinoid hydrolysis to amplify their anti-inflammatory effects have been extensively studied. However, most of these studies were conducted in animals. Endocannabinoid metabolism by human leukocytes, as well as the effects of their metabolites on human leukocytes functions, are poorly defined. Although the data obtained from animal models is promising, these mechanisms must be characterized in humans before they can be manipulated to treat inflammatory diseases. Our first aim was to characterize endocannabinoid biosynthetic and hydrolytic pathways in human leukocytes. We documented the expression of several 2-AG hydrolases in human neutrophils, eosinophils, monocytes, lymphocytes and alveolar macrophages. The data we obtained underscored that each cell type expresses several 2-AG hydrolases, and that the selective inhibitors that are currently available only partially block 2-AG degradation by leukocytes. Our results also show that human leukocytes are experts at hydrolyzing 2-AG, a finding that allowed us to establish a novel 2-AG biosynthetic pathway in human leukocytes. In the presence of 2-AG hydrolysis inhibitors, neutrophils, eosinophils and monocytes stimulated with AA produced 2-AG in amounts ~ 1000 times greater than those previously reported. They also converted other polyunsaturated fatty acids into their glycerol-containing endocannabinoid counterparts. We showed that this endocannabinoid biosynthetic pathway depends on fatty acid reacylation into membrane phospholipids, and that their subsequent metabolism into endocannabinoid likely requires the production of a lysophosphatidic acid intermediate. This study is the first one to report a significant endocannabinoid synthesis by human leukocytes, and to show that this biosynthesis is independent from the classical 2-AG biosynthetic pathway. We also aimed to characterize the impact of 2-AG and PG-Gs on human leukocyte functions. We showed that in the presence of IL-5, a cytokine involved in the eosinophilic inflammation found in asthma, 2-AG induces eosinophil migration. This requires the activation of the CB2 receptor, as well as 2-AG hydrolysis into AA to produce 15-lipoxygenase metabolites. This underscores that 2-AG hydrolysis by eosinophils allows for the synthesis of mediators that have pro-inflammatory effects, and that blocking this hydrolysis in vivo may be beneficial. We also studied the biological effects of PGE2-G and found that it inhibits several effector functions of human neutrophils. This inhibitory effect requires PGE2-G hydrolysis into PGE2 by neutrophils, and the activation of the EP2 receptor on their surface. Our work will allow a better understanding of how endocannabinoid hydrolysis should be blocked in humans, and of the biological effects that will result from this inhibition. The goal is to develop new treatments against chronic inflammatory diseases, which will enhance the analgesic and anti-inflammatory effects of endocannabinoids while limiting their deleterious effects.
Chronic inflammatory diseases are an important health burden worldwide. The currently available treatments alleviate pain and inflammation, but their numerous adverse effects make their long term use difficult. Therefore, the scientific community is studying the anti-inflammatory potential of mediators such as endocannabinoids. Endocannabinoids are endogenous lipids that activate the cannabinoid receptors, namely CB1 and CB2. In doing so, they regulate various physiological functions and cognitive processes functions such as appetite, adipogenesis and nociception. The two best-characterized endocannabinoids, 2-AG and AEA, also exert effects on immune cell functions, leading to the modulation of immunity and inflammation. They do so by activating the CB2 receptor, which is expressed in the periphery, notably on immune cells. Notably, it was shown that mice lacking the CB2 receptor display an exacerbated inflammatory phenotype, suggesting that CB2 activation by endocannabinoids is anti-inflammatory. However, the biological effects of endocannabinoids are far more complex, given that they can be metabolized into a wide variety of bioactive lipids. The main degradation pathway for 2-AG and AEA is their hydrolysis into arachidonic acid (AA), a fatty acid that acts a precursor for the biosynthesis of several pro-inflammatory eicosanoids such as leukotriene B4 and prostaglandin E2. They can also be directly metabolized by eicosanoid-biosynthetic enzymes, which generates mediators such as glyceryl-prostaglandins (PG-Gs). Therefore, endocannabinoids can generate an intriguing profile of pro- and anti-inflammatory effects, depending on the balance between their catabolic pathways and receptor activation. Therapeutic strategies aiming at blocking endocannabinoid hydrolysis to amplify their anti-inflammatory effects have been extensively studied. However, most of these studies were conducted in animals. Endocannabinoid metabolism by human leukocytes, as well as the effects of their metabolites on human leukocytes functions, are poorly defined. Although the data obtained from animal models is promising, these mechanisms must be characterized in humans before they can be manipulated to treat inflammatory diseases. Our first aim was to characterize endocannabinoid biosynthetic and hydrolytic pathways in human leukocytes. We documented the expression of several 2-AG hydrolases in human neutrophils, eosinophils, monocytes, lymphocytes and alveolar macrophages. The data we obtained underscored that each cell type expresses several 2-AG hydrolases, and that the selective inhibitors that are currently available only partially block 2-AG degradation by leukocytes. Our results also show that human leukocytes are experts at hydrolyzing 2-AG, a finding that allowed us to establish a novel 2-AG biosynthetic pathway in human leukocytes. In the presence of 2-AG hydrolysis inhibitors, neutrophils, eosinophils and monocytes stimulated with AA produced 2-AG in amounts ~ 1000 times greater than those previously reported. They also converted other polyunsaturated fatty acids into their glycerol-containing endocannabinoid counterparts. We showed that this endocannabinoid biosynthetic pathway depends on fatty acid reacylation into membrane phospholipids, and that their subsequent metabolism into endocannabinoid likely requires the production of a lysophosphatidic acid intermediate. This study is the first one to report a significant endocannabinoid synthesis by human leukocytes, and to show that this biosynthesis is independent from the classical 2-AG biosynthetic pathway. We also aimed to characterize the impact of 2-AG and PG-Gs on human leukocyte functions. We showed that in the presence of IL-5, a cytokine involved in the eosinophilic inflammation found in asthma, 2-AG induces eosinophil migration. This requires the activation of the CB2 receptor, as well as 2-AG hydrolysis into AA to produce 15-lipoxygenase metabolites. This underscores that 2-AG hydrolysis by eosinophils allows for the synthesis of mediators that have pro-inflammatory effects, and that blocking this hydrolysis in vivo may be beneficial. We also studied the biological effects of PGE2-G and found that it inhibits several effector functions of human neutrophils. This inhibitory effect requires PGE2-G hydrolysis into PGE2 by neutrophils, and the activation of the EP2 receptor on their surface. Our work will allow a better understanding of how endocannabinoid hydrolysis should be blocked in humans, and of the biological effects that will result from this inhibition. The goal is to develop new treatments against chronic inflammatory diseases, which will enhance the analgesic and anti-inflammatory effects of endocannabinoids while limiting their deleterious effects.
Boissard, Christophe. "Etude de relations structure-activité de peptides bioactifs comprenant une pseudo-proline /." [S.l.] : [s.n.], 2002. http://library.epfl.ch/theses/?nr=2596.
Stevenin, Arnaud. "Symbiose mycorhizienne : développement de nouvelles méthodes pour la synthèse de glycoconjugues bioactifs." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00737492.
Lacombe, Marielle. "METHODES ELECTROCHIMIQUES POUR L'ANALYSE IN SITU DE COMPOSES BIOACTIFS EN MILIEU OCEANIQUE." Phd thesis, Université Paul Sabatier - Toulouse III, 2007. http://tel.archives-ouvertes.fr/tel-00256800.
Gholamifard, Shabnam. "Modélisation des écoulements diphasiques bioactifs dans les installations de stockage de déchets." Phd thesis, Université Paris-Est, 2009. http://tel.archives-ouvertes.fr/tel-00512102.
Przybylski, Cédric. "Développement de nouvelles méthodes d'analyse d'oligosaccharides anioniques bioactifs par spectrométrie de masse." Thesis, Evry-Val d'Essonne, 2014. http://www.theses.fr/2014EVRY0001.
The non-Covalent interactions between proteins and anionic polysaccharides such as glycosaminoglycans (GAGs) are involved in several physio-Pathological processes such as cell signalling and recognition, bacterial and viral infections or during cancer progression. One of the obstacles to get the molecular mechanisms involved during these interactions hold in the structural information deciphering within GAG's sequences. This task is delicate especially because of variable level of acetylations and sulfations, constituting important bottleneck in the research advances of the glycobiology field. To bypass these restrictions, accurate and innovative analytical methods such as mass spectrometry (MS) provide numerous advantages. During this Ph.D training, three original MS based approaches have been developed. The first dealt with the synthesis of new ionic liquid matrices, which both restrict desulfation process and favour the homogeneous deposits for UV-MALDI-TOF analysis. The second way used a soft recently introduced ionization method, desorption electrospray ionization (DESI) allowing direct analysis in ambient conditions of anionic oligosaccharides or under complexes with protein. Finally, the third involved the making of protein or saccharide chips for the analysis of protein / GAG complexes using the hyphenation of surpface plasmon resonance with MS (SPR-MS). Thos coupling allows real time monitoring protein / GAG complexes formation, their dissociation constant determination and the direct detection of protéic as wall as saccharidic ligands by UV-MALDI-TOF
Lacombe, Marielle. "Méthodes électrochimiques pour l'analyse in situ de composés bioactifs en milieu océanique." Toulouse 3, 2007. http://thesesups.ups-tlse.fr/119/.
The implementation of in situ autonomous observatories for biogeochemical studies in the open ocean water column and in deep-sea chemosynthetic environments is crucial for the understanding of these ecosystems. We focussed this study on silicate and sulphide, two key compounds of the marine food chain. A voltammetric method for sulphide measurements on silver electrode is presented, and a new method for quantitative determination based on the solubility difference between silver chloride and silver sulphide is proposed. A completely reagentless method for silicate measurements is developed using molybdate and protons produced during molybdenum oxidation. These analytical developments allowed us to validate a submersible potentiostat, first step toward a new sensor for in situ measurements. A Drake Passage water masses analysis is also performed using data collected during the Drake ANTIII/3 oceanographic cruise in 2006
Lefranc, Olivier. "Developpement de stents bioactifs par fixation permanente ou temporaire de dextranes fonctionnalisés." Paris 13, 2003. http://www.theses.fr/2003PA132015.
Nowadays, high rate of restenosis limits the use of the stents for the treatement of vascular stenosis. To enhance the stent biocompatibility, several drugs are associated with such device in order to limit the restenosis. Dextran derivatives, obtained from statistic substitution of some of the dextran hydroxyl groups have shown promising results in their effects onto the behaviour of vascular cells. These polysaccharides could consist in a way of traitment of the restenosis. Hence, the aim of this study consists on an immobilization of such a polysaccharide onto a stent surface. We investigate two ways of immobilization. On the one hand, the dextran derivative has been covalently grafted onto the metallic surface previously aminated in order to obtain a permanent immobilization. On the other hand, the stent coating has been achieve by using the dextran derivative associated with a collagen matrix to enhance the dextran derivative concentration onto the surface and release the molecule in the blood flow to prevent the restenosis above the stent. A physico-chemical characterization campaign and a biological evaluation planning have been studied. Modified surfaces have shown a good behaviour toward the restenosis elements. These results allowed an in-vivo implantation
Roger, Olivier. "Etude d'oligosaccharides bioactifs issus d'exopolysaccharides bactériens : obtention, caractérisation et relation structure/fonction." Paris 13, 2002. http://www.theses.fr/2002PA132032.
Unsual expolysaccharides 5EPS) produced by heterotrophic aerobic and mesophilic bacteria originating from hydrothermal vent, were reviewed as a new source of polysaccharidic structure determination of the EPS GY785, synthesized by Alteromonas infernus. A highly branched nonasaccharidic repetitive unnit was identified using chemical modifications and nuclear magnetic resonancespectroscopy. His 10 puissance 6 g/mol polysaccharide is composed of glucose, galactose, glucuronic acid, galacturonic acid, and ontaibns a single branched ramification and one sulphate group. .
Khoder, Hassan. "Effet de confinement de l’eau dans les verres bioactifs : relation structure propriétés." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0106.
The use of nanostructured mesoporous silica gels for the confinement of functional nano-objects or liquids is a very active area of research with potential applications in various fields. However, the confinement might affect the properties of these nanomaterials and thus their potential applications, depending both on the nature of the liquids used and on the properties of the host materials. In this context, bioactive glasses are porous systems in which physiological fluids are confined. These biomaterials are increasingly studied in view of their frequent application in orthopedic and reconstructive surgery. The biomedical applications of these bioactive glasses are mainly due to their high biocompatibility and high reactivity with the human physiological environment, since the reaction products obtained from these bioactive glasses and the physiological fluids lead to the deposition of a layer of crystalline bone-like carbonate calcium phosphate (Hydroxy-Carbonate Apatite) on their surface shortly after interaction. This hydroxyapatite layer allows the adhesion to the biological substrate, and hence to reconstruct damaged bones.Since these materials are intended to interact with body fluids, the understanding of the impact of confinement on the organization and diffusion of the encapsulated physiological fluids is crucial for improving their properties. Given that the physiological fluids are composed mainly of water, we have focused our investigations to study the structure and properties of water confined in bioactive glasses as model systems. In this thesis work, we propose to tackle this problem by specific experimental methods, primarily by total X-ray scattering coupled with pair distribution function (PDF) analysis. Complementary characterizations by differential scanning calorimetry (DSC) and atomistic simulations based on the Monte Carlo method are used to corroborate the structural models obtained from the PDF analysis. To better understand the impact of size reduction and the influence of host matrix textural properties on the structural and physical properties of confined liquids, we have applied our multi-scale approach to other model systems such as MCM-41, and SBA-15.The total X-ray scattering measurements have been performed as a function of temperature for the different studied nanomaterials while for the numerical simulations the Empirical Potential Structure Refinement (EPSR) code was used. The obtained results indicate a non-homogeneous structuring of the water confined within the silica nanopores. We have shown that the structural organization of confined liquids depends on pore size, water-loading ratio and the textural properties of the host nanomaterials. Furthermore, the partial pair distribution function analysis show that liquids confined in large pores, (pore diameter > 5 nm), have three phases. However, only one distorted phase was observed in the matrices with narrower pores
Vo, Duc Duy. "Design, synthèse et évaluation de l'activité biologique d'analogues de polyphénols biaryliques bioactifs." Rennes 1, 2011. http://www.theses.fr/2011REN1S076.
This thesis is a part of the medicinal chemistry programme developed in the laboratory. Our first goal is the research of new inhibitors of Bcl-2 protein, compounds which are apoptosis inducers for cancer cells. We have designed new carbo- and heterocyclic compounds – analogs of bioactive biarylic polyphenol (gossypol and Wang���s compound). Chapters 1, 2 and 3 describe synthetic and biological results obtained for this cancer part, where new hits have been discovered and first structure activity relationships have been established. The second goal is the synthesis of new small molecules with neurotrophic properties, ie able to induce neuronal cell growth. Such derivatives could be of use for treatment of neurodegenerative diseases such as Parkinson, Alzheimer, Huntington. Therefore, we have designed new carbo- and heterocyclic compounds, analogs of bioactive biarylic polyphenol (honokiol and magnolol). The results are described in chapter 4. A complete series of 24 honokiol analogs, as well as a first series of magnolol analogs have been prepared. First biological results in serie of honokiol analogs showed that our compounds were, at best, weakly active compared to honokiol
Dufour, Dominic. "Évaluation de l'activité biologique du Ledum groenlandicum Retzius /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2006. http://theses.uqac.ca.
La p. de t. porte en outre: Mémoire présenté à l'Université du Québec à Chicoutimi comme exigence partielle de la maîtrise en ressources renouvelables. CaQCU Bibliogr.: f. [68]-75. Document électronique également accessible en format PDF. CaQCU
Bérubé-Gagnon, Jérôme. "Isolation et identification de composés antibiotiques des écorces de Picea mariana /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2006. http://theses.uqac.ca.
La p. de t. porte en outre: Mémoire présenté à l'Université du Québec à Chicoutimi comme exigence partielle de la maîtrise en ressources renouvelables. CaQCU Bibliogr.: f. 59-66. Document électronique également accessible en format PDF. CaQCU
Reid, Alexandra. "Protection de composés bioactifs hydrosolubles et liposolubles par encapsulation dans une émulsion multiple." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27011/27011.pdf.
LOTY, CHRISTINE. "Stimulation in vitro de la chondrogenese et de l'osteogenese par des materiaux bioactifs." Paris 7, 2000. http://www.theses.fr/2000PA07GA03.
Auberger, Stéphane. "Tensio-bioactifs originaux de type béta-lactame ; Formulations d'émulsions végétales à visées industrielles." Nancy 1, 2000. http://www.theses.fr/2000NAN10084.
Lemée, Frédéric. "Composés polyioniques contraints bioactifs libres et supportés : accès à de nouveaux matériaux antibactériens." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0047/document.
Development of new materials with antibacterial properties is a major concern in medical and environmental world. It’s for that reason that, Merrifield and Wang commercial polymers were modified by grafting polycationic calixarenic sub-units inspired by laboratory work and designed to interact with negatively charged bacterial surface. Those calixarenes were modified on the lower part, in a controlled manner, by the incorporation of a functional spacer group leading to a targeted grafting of the polymer. We have, at first, evaluated several kinds of functionalities introduced on the calixarene, giving us the opportunity to graft them on the polymeric support. Like this, a reductive amination was chosen to anchor the Wang-benzaldehyde resin, whereas a pyridinium anchoring point was pointed out as a very good candidate for the grafting of calixarenes. The validation of this pyridinium anchoring point was checked by incorporation of a fluorescent probe (pyrene) and characterized by solid state fluorescence, by infrared spectroscopy, those two lasts analysis were applied for all the other grafted polymers grafted after that. Through a capture-release study in aqueous media of two carboxylic antibiotics (quinolone and ß–lactame kind), the pyridinium polymer model, without calixarène, showed his interest faced to Cholestyramine (Questran®) or Amberlite IRA-400, as an anion exchange resin and leading to depoluting/decontamination applications. Before antibacterial studies of thoses new materials, we wanted to find a way to quantify the material capacity to catch/hold bacteria. Capillary electrophoresis, rapid and sensitive analytical method, appeared as a perfect solution. Using E. coli model, synthesized polycationic resins were evaluated as sequestering agent in aqueous media. Results obtained prove the efficiency of some of them; capture was finally confirmed by confocal fluorescent microscopy. The number of bacteria fixed by material surface could be visually evaluated
Balde, Mamadou. "Etude physico-chimique et valorisation de composés bioactifs de Parinari macrophylla Sabine (Chrysobalanaceae)." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAF013/document.
Type 2 diabetes is often associated with oxidative stress that can lead to several metabolic complications. In Senegal, in addition to drug treatment, medicinal plants are still widely used in the treatment of this pathology. The aim of this work was to contribute to the enhancement of Senegalese biodiversity and more particularly to improve the phytochemical properties of Parinari macrophylla Sabine, traditionally used for the treatment of diabetes. For this, the total antiradical activity and at the molecular level of leaves and bark has been determined by the TEAC, ORAC and HPLC - ABTS-+ online methods. In addition, a phytochemical screening (precipitation reactions, CCM) was carried out and revealed several chemical groups of compounds such as flavonoids, tannins, terpenes, anthracenes, saponosides, cardiotonic heterosides and alkaloids. For the identification of active compounds, NMR and the molecular network approach (UHPLC-MS), identified chlorogenic acid, hyperoside, procyanidin B2 and other procyanidins. The in vitro study carried out on a RINm5F cellular model showed a low anti-radical activity of plant extracts against HX-XO-induced stress. However, the compounds identified in this study are known for their antioxidant and inhibitory effects on digestive enzymes responsible for glucose metabolism. This could justify the use of this plant in the treatment of type 2 diabetes by Senegalese traditional therapists
Mousavi, Mahta. "Isolement de métabolites secondaires & caractérisation de composés bioactifs issus de matrices végétales." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0269.
This study is divided into two parts, the first one is devoted to the implementation of a methodology to isolate secondary metabolites. The second describes the phytochemical properties of powders of vegetal material according to their particle size. In the first part, which is dedicated to the isolation of secondary metabolites by semi-preparative HPLC, setting up the isolation process for hederacoside C and α-hederin was performed using extracts of aerial parts of ivy (Hedera helix L.). The generalization of this isolation process applied to the extracts of aerial parts of st. john's wort (Hypericum perforatum L.) lead to successful isolation the hyperoside, which is one of the characteristic flavonoids of st. john's wort. The purpose of this second part is to validate the process of grinding and sieving plant material: CDS « Comminution and to control Diffraction Sieving » under industrial scale to product different granulometric classes of powders. For this purpose, the results of phytochemical analyses of granulometric classes of nine plants from the Lorraine Region obtained by CDS using an industrial pilot are compared with those obtained under laboratory scale. Selected plants are fennel (Foeniculum vulgare Mill.), white willow (Salix alba L.), st. john's wort (Hypericum perforatum L.), nettle (Urtica dioica L.), goldenrod (Solidago virgaurea L.), pilosella (Hieracium Pilosella Vaill.), dog rose (Rosa canina L.), devil's claw (Harpagophytum DC.) and ivy (Hedera helix L.). The evaluation of the antioxidant activity, as well as the analyses carried out by LC-MS, indicate that the production of powders under laboratory scale is generalizable to industrial scale. In addition, for the first time, the application of the CDS process under laboratory scale for four fruits: cherry (Prunus avium L.), peach (Prunus persica L.), damson (Prunus domestica subsp. Insititia L.) and mirabelle (Prunus domestica. subsp. Syriaca) from Lorraine Region shows that CDS is a new dry extraction method to enhance bioactive compound concentrations in particular granulometric classes
Pierre, Camille. "Elaboration, caractérisation et étude des propriétés de revêtements bioactifs à la surface d'implants dentaires." Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0084/document.
Numerous surface treatments have been developed in order to improve osseointegration of dentalimplants (sandblasting, acid etching…). Moreover, various strategies involving calcium phosphate coatings have emerged for the same target for a few decades. The main purpose of this work is todevelop a low temperature process allowing the deposition of a thin calcium phosphate layer at the titanium implant surface. The composition and structure of this calcium phosphate coating have to be close to the bone mineral to enable osseointegration improvement. Moreover, thecoating should have antibacterial properties in order to prevent post-operative infections. A surfacetreatment protocol composed of sandblasting and acid etching was firstly developed creating anaverage roughness of 1.4 – 1.8 µm with micropits and improved wettability. Secondly, two processes were studied to produce the calcium phosphate coating: the alternate soaking processand the electrodeposition. It was demonstrated that the centrifugation step implemented in thealternate soaking process is crucial and a coating of about 2 µm thick composed of biomimeticapatite was obtained. Among all the operating parameters of the electrodeposition process, time ofelectrodeposition has the major impact on the composition and the thickness of the coating. An electrodeposition of 1 mn at -1.6 V/SCE leads to a 1.5 µm thick coating composed of a layer ofoctacalcium phosphate and dicalcium phosphate dihydrate crystals. A screw/unscrew test demonstrated the mechanical stability of the coatings obtained by both processes. Finally,antibacterial ions such as silver, copper and zinc were incorporated in the coatings. Highincorporation rate up to 40 mol.% compared to calcium were determined for copper and zinc.Biological tests were conducted to qualify the effect of these coatings on the biological activity ofhuman mesenchymal cells and on the formation of a biofilm (peri-implantitis model) to preventpost-operative infections. They led to promising results for the development of such bioactivecoatings. This work is part of the BIOACTISURF project, supported by the Midi-Pyrénées Region,and carried out in collaboration with the Laboratory of Chemical Engineering (LGC) and an industrial partner
Ho, Cuong. "Études des anti-oxydants-antimicrobiens provenant de fruits et légumes." Doctoral thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27670.
Cette étude suggère également que l'activité anti-oxydante d'une substance, déterminée par un ou plusieurs essais, ne donne pas une image complète de son efficacité contre les diverses espèces de radicaux oxygénés; et elle montre que la détermination du spectre de l'activité anti-radicalaire serait nécessaire. L'activité antimicrobienne des extraits de plantes sélectionnés a été évaluée en détail par turbidimétrie en milieu liquide et par diffusion en milieu solide (gel). L'activité antimicrobienne a été exprimée dans la première méthode par l'inhibition de la croissance (GI), par la concentration minimale inhibitrice (MIC) et par une nouvelle expression, dénommée index antimicrobien (AMI). Dans la seconde méthode, l'activité a été exprimée en zone d'inhibition. L'AMI prend en compte les trois phases de croissance des bactéries. Bien que les méthodes turbidimétriques soient fiables dans l'évaluation de l'activité antimicrobienne des substances, la nouvelle expression (AMI) semble être plus significative car, elle comprend l'information sur l'interaction entre la substance et le micro-organisme et sa vitesse de croissance en présence de cette substance. De plus, l'AMI démarque l'activité des échantillons, même ceux qui sont très actifs. Le spectre d'activité antimicrobienne des extraits de plantes sélectionnés a été également étudié. Seulement quelques extraits ont montré un spectre d'activité antimicrobienne assez large. En effet, seul l'extrait de feuille de bétel a un large spectre d'activité contre les bactéries, les levures et les champignons, suivis des extraits de grenade et de fruits d'argousier qui semblent être efficaces contre les bactéries et les levures. L'extrait de cassis est effectivement une substance antibactérienne. Finalement, différentes stratégies pour améliorer l'activité antimicrobienne d'extraits anti-oxydants-antimicrobiens sélectionnés ont été explorées. Trois approches, incluant l'extraction par solvants sélectifs, le mélange binaire des extraits et l'addition de composés végétaux, ont été étudiées. L'activité anti-oxydante-antimicrobienne et le profil phytochimique ont été analysés. Le résultat montre que l'eau chaude peut être utilisée comme solvant pour l'extraction d'agents anti-oxydants-antimicrobiens d'origine végétale, bien qu'un solvant polaire extrait en préférence les substances phénoliques et modestement les substances non polaires comme les terpénoïdes. Toutefois, compte tenu du rendement et de l'activité des extraits, l'eau semble être appropriée, et elle peut être considérée comme un solvant efficace pour les fruits qui sont riches en substances phénoliques. Néanmoins, d'autres solvants sélectifs doivent être considérés pour l'extraction des substances actives non-polaires issues de matière première végétale comme les feuilles. Certaines augmentations de l'activité antimicrobienne sont possibles par le mélange de deux extraits de plantes ou par l'addition de composés végétaux. On a aussi observé que la composition des mélanges peut être importante, car les interactions synergiques ou antagonistes se retrouvent dans certaines proportions. Le mélange des extraits de grenade et cassis d'une part et le mélange des extraits de thé vert et pomme de cajou d'autre part ont montré une amélioration d'activité. L'ajout de glyoxal de méthyle et mono-caprine a également produit une augmentation de l'activité des extraits de plantes. L'addition de glyoxal de méthyle à 25 % (p/p) a amélioré l'activité des extraits de grenade et de cassis. Dans l'ensemble, ce travail a exploré le potentiel des extraits des sous-produits de fruits et de légumes comme agent anti-oxydant-antimicrobien. Les extraits de plantes montrant des potentiels anti-oxydants et antimicrobiens regroupent: olive, canneberge, noni, feuille de bétel, cassis, grenade, citronnelle, épinard, raisin vert (vin), cassis (résidu), aubergine, ramboutan, prune indienne, feuille de canneberge, feuille de romarin, feuille de vigne (sauvage), thé vert, mangoustan et feuille de framboise. Cependant, de cette liste, seuls quelques extraits (feuille de bétel, grenade, résidus de cassis) présentent un large spectre d'activité anti-oxydante et antimicrobienne. En outre, cette étude a introduit de nouvelles expressions pour l'activité anti-oxydante (ARP) et antimicrobienne (AMI) des mélanges complexes tels que les extraits de plantes. Ces expressions peuvent être utiles pour le criblage de matériels d'origine végétale dans la recherche de ces activités. Un autre enseignement de cette étude est que l'amélioration de l'activité antimicrobienne des extraits de plantes ne peut pas être possible simplement par le mélange d'extraits, en raison des interactions potentielles entre les composants des extraits. La connaissance de la composition phytochimique est essentielle pour comprendre de telles interactions, dans la sélection des mélanges et pour déterminer les approches possibles pour améliorer l'activité antimicrobienne.
Les sous-produits de végétaux peuvent être une source potentielle d'antioxydant-antimicrobiens pour une application dans la conservation des aliments, comme alternative aux agents synthétiques, mais beaucoup de travaux sont encore nécessaires pour atteindre ce but, ce qui nécessiterait une approche systémique.
There is a growing interest in the development of strategies to use agricultural and industrial residues as a source of high value-added, including bioactive products. The residues of fruits and vegetables may be a potential source of bioactive compounds. The major objective of this work is to conduct studies to pave the way for the development of antioxidant-antimicrobials from plant by-products for use in food preservation, as alternative to synthetic chemicals. The starting point was the identification of extracts of fruit and vegetable extracts exhibiting high antimicrobial and antioxidant properties. The selected extracts were then characterized for their spectrum of antioxidant and antimicrobial activities. Finally, simple ways of enhancing the antimicrobial activity of the selected extracts were examined. Aqueous extracts of about 160 fruit and vegetable by-products were evaluated for their potential as antimicrobial and antioxidant agents. The growth inhibiting activity of all the 160 extracts were tested against Escherichia coli, and Bacillus Subtilis; and the antioxidant activity was determined by DPPH radical scavenging assay. The pH of the extract, type of tissue (fruit, leaf and root) and physiological type of fruits (climacteric) had impact on the bioactive properties. There was some relationship between antioxidant and antimicrobial properties of the plant extracts. The proposed antioxidant-antimicrobial index may be useful in the selection of plant sources of bio-actives. Consideration of rate of radical quenching (time factor) to define actual efficacy (capacity) of antioxidant system was found to be a better and reliable way of expressing the real antioxidant power. The new expression, antiradical power - ARP, generated from DPPH assay may be more useful in identifying the antioxidant activity of biological samples. Some samples exhibited high ARP value such as rambutan, cranberry leaf, blueberry leaf, grape leaf (wild), raspberry leaf, betel leaf, avocado, pomegranate and custard apple. Leaf extracts possess, in general, higher ARP than fruits, and root extracts possess low ARP. In addition, this study also suggests that average carbon oxidation number of complex mixtures such as plant extracts may portend their antioxidant power, in spite of the disparity between leaf and fruit materials. In chapter 4, plant extracts selected from the original 160 were investigated for their spectrum of anti-radical activity. The antioxidant activity was evaluated by Trolox equivalent antioxidant capacity (TEAC), DPPH free radical assay (DPPH), ferric reducing power assay (FRAP), redox potential measurement, hydrogen peroxide, hydroxyl radical, superoxide anion, nitric oxide and iron chelating activities. Their total phenolic content (TPC) and total flavonoid content (TFC) were also determined. Betel leaf, blueberry fruit and black currant and cranberry leaf showed high radical scavenging activity (TEAC assay); apple, sorrel, red grape and dandelion root were effective against SOA; cranberry leaf, blueberry leaf, black currant and Rosemary against hydroxyl radical; rainbow chard, parsnip, broccoli and orange against H2O2; and potato, banana, sorrel, sea buckthorn leaf against nitric oxide. Blueberry leaf and fruit, pomegranate, black currant and betel leaf showed high ferric ion reducing power. The extracts showing high iron binding capacity were: sea buckthorn leaf, radish, parsnip, betel leaf and mangosteen. Betel leaf extract exhibited high activities, including iron binding and scavenging of various radicals except nitric oxide, where the activity was moderate. TEAC, DPPH and FRAP assays provide essentially the same response with respect to the antioxidant activity of plant extracts, suggesting that any one of them would be adequate to evaluate their anti-radical capacity. This study also suggests that antioxidant activity of a substance, determined by one or more related assays, does not give the complete picture of its effectiveness against various species of oxygen radicals; and emphasizes that determination of the spectrum of the anti-radical activity would be necessary. In chapter 5, the antimicrobial activity of selected plant extracts was evaluated in detail by turbidimetric methods in liquid medium, and by well-diffusion method in gel medium. The antimicrobial activity was expressed in the former by growth inhibition, minimum inhibitory concentration - MIC and by a new expression, the antimicrobial index – AMI; and in the latter, expressed by zone of inhibition. AMI takes into account all the three growth phases of the bacteria. Although the turbidimetric methods were in good agreement in the assessment of the activity of the substances, the new expression, AMI, appears to be more meaningful since it carries the information regarding interaction between the substance and the microorganism and the growth rate in the presence of that substance. In addition, AMI demarcates the activity of samples, even those found to be highly active. Furthermore, the spectrum of antimicrobial activity of selected plant extracts was also examined. Only a few extracts showed some broad spectrum in their activities. In effect, only betel leaf extract showed a broad spectrum of antimicrobial activity against bacteria, yeasts and fungi; whereas pomegranate and sea buckthorn fruit extracts appear to be effective against both bacteria and yeasts. Black currant extract is effectively an antibacterial substance. In chapter 6, various ways of enhancing the antimicrobial activity of selected antioxidant-antimicrobial extracts were explored. Three approaches, including selective solvent extraction, binary blending of extracts and addition of plant compounds were investigated. Antioxidant, antimicrobial activity and the profile of phytochemical classes were analyzed. The results showed that hot water could be used for solvent extraction of antioxidant-antimicrobials from plant materials, albeit a polar solvent that extracts phenolic substances preferably and only modestly non-polar substances such as terpenoids. However, considering the yield of the extracts and the activity, water appeared to be an effective solvent solvent for fruit sources that are rich in phenolic substances. Other selective solvents must be considered for extraction of active non-polar substances for plant sources such as leaves. Some enhancement in antimicrobial activity was possible by either mixing plant extracts or by the addition of plant compounds. It was also observed that the composition of blends or mixtures might be important, since synergistic or antagonistic interactions occurred at certain proportions. Pomegranate and black currant extract blends and green tea and cashew apple extract blends showed enhancement in activity. The addition of methyl glyoxal and mono-caprin also showed enhancement in the activity of plant extracts. Methyl glyoxal at 25 % (w/w) addition improved the activity of pomegranate and black currant extracts. Overall, this work explored the potential of extracts of fruit and vegetable by-products as anti-oxidant-antimicrobials. Some plant extracts having potential as antioxidant-antimicrobial agents. They include: olive, cranberry, noni, betel leaf, black currant, pomegranate, lemon grass, spinach, green grape (wine), black currant (residue), egg plant, rambutan, Indian plum, cranberry leaf, rosemary leaf, grape leaf (wild), green tea, mangosteen and raspberry leaf. However, the list is reduced to a few (betel leaf, pomegranate, black currant residue), should broad antioxidant and antimicrobial activities are taken into account. In addition, this study introduces new expressions for antioxidant (ARP) and antimicrobial (AMI) activities of complex mixtures such as plant extracts, and they can be useful in the screening of plant materials for these activities. The knowledge of the phytochemical composition is essential to understand such interactions, in the selection of mixtures and to determine possible approaches to enhance the antimicrobial activity. Plant by-product can be a potential source of antioxidant-antimicrobial for use in food preservation, as alternative to synthetic agents, but much work is needed to realize this goal, and that would require a systemic approach.
Bradette, Hébert Marie-Eve. "Étude du potentiel biopharmaceutique du Solidago canadensis Linné /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2008. http://theses.uqac.ca.
La p. de t. porte en outre: Mémoire présenté à l'Université du Québec à Chicoutimi comme exigence partielle de la maîtrise en ressources renouvelables. CaQQUQ Comprend des réf. bibliogr. (f. [59]-64). Publié aussi en version électronique. CaQQUQ
Fadlallah, Hicham. "Influence de revêtements bioactifs sur les cellules endothéliales : vers des prothèse vasculaires non thrombotiques." Mémoire, École de technologie supérieure, 2013. http://espace.etsmtl.ca/1231/1/FADLALLAH_Hicham.pdf.
Roufik, Samira. "Étude des interactions ß-Lactoglobuline bovine: peptides bioactifs et digestibilité in vitro des complexes." Thesis, Université Laval, 2005. http://www.theses.ulaval.ca/2005/22998/22998.pdf.
Bovine β-lactoglobulin (β-Lg) contains numerous peptide sequences with biological activities, which have a high potential as nutraceutical ingredients. However, studies have demonstrated that some of these peptides, which are active during in vitro tests, loose their activity in animal models following oral ingestion, suggesting their enzymatic degradation during gastrointestinal transit. The aim of this work was to study β-Lg:bioactive peptide interactions and to investigate the in vitro digestibility of the resulting complexes. Firstly, it was shown that pepsic and chymotryptic digestions of some bioactive peptides varied according to the peptide chain length, the nature of the peptide and the presence of other peptides in the reaction medium. Using an ultrafiltration method, it was demonstrated that peptides β-Lg f102-105, f142-148 and f69-83 bind to β-Lg A in significant amounts corresponding to 1.5, 1.1 and 0.7 moles of peptides per mole of protein respectively. These results were validated by front-face fluorescence spectroscopy, which also provided evidences that the binding of the three peptides to β-Lg A modified the polarity of tryptophan environment in the protein structure. In addition, binding isotherms obtained by isothermal titration calorimetry showed that the binding of the antihypertensive peptide β-Lg f142-148 to β-Lg A followed a sequential three-site binding model with constants of associations of 2 X 103, 1 X 103 and 0.4 X 103 M-1 for the 1st, 2nd, and 3rd binding sites respectively. The enthalpy of binding was exothermic for the 1st and 2nd binding sites and endothermic for the 3rd binding site. Lastly, the in vitro digestibility of the protein and the complexes with pepsin, trypsin, chymotrypsin, and pancreatin showed that the complexes were hydrolyzed more slowly than the native protein by chymotrypsin or pepsin/chymotrypsin. The overall results support the hypothesis that the binding of bioactive peptides to β-Lg A could improve their resistance to proteolysis, and thus could contribute to maintain their structural integrity and bioactivity during gastrointestinal transit.
Le, Goff Géraldine. "Métabolites secondaires microbiens bioactifs : cas particulier des géralcines issues de Streptomyces sp. LMA-545." Paris, Muséum national d'histoire naturelle, 2012. http://www.theses.fr/2012MNHN0028.
Meda, Naamwin-So-Bâwfu Romaric. "Potentiel de valorisation d'extraits bioactifs issus de bourgeons d'érable à sucre et d'érable rouge." Doctoral thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/34941.
Les résidus provenant de l’activité de l’industrie forestière canadienne sont estimés chaque année à plus de 20 millions de tonnes de matière sèche. Des extraits réalisés à partir des écorces de troncs retrouvés dans ces résidus et présentant d’intéressantes propriétés biologiques ont été présentés comme une opportunité de valorisation des produits forestiers vers des domaines de plus fortes valeurs ajoutées. Pourtant, les branches des arbres éliminées durant des éclaircies de peuplements forestiers ou pendant les campagnes d’élagage portent également d’autres tissus végétaux dont la composition chimique et les propriétés biologiques peuvent s’avérer distinctes de celles des écorces. Notre hypothèse de recherche est que les érables, espèces d’importance économique majeure et très répandues des forêts canadiennes, dont les bourgeons se retrouvent dans les résidus forestiers, peuvent également servir à la production d’ingrédients actifs pour les secteurs de l’agroalimentaire, des produits cosmétiques et même de la santé (médicaments, phyto-médicaments, nutraceutiques). En effet, du fait de leur caractère indifférencié, ces bourgeons pourraient contenir des métabolites différents de ceux des autres tissus. Notre projet de recherche a donc eu pour principal objectif, l’exploration des domaines potentiels de valorisation de produits naturels issus de bourgeons de l’érable à sucre et de l’érable rouge. Du fait de la quasi inexistence de données dans la littérature, notre étude a consisté essentiellement à acquérir des connaissances sur la composition chimique de cette matière végétale et à évaluer les effets biologiques in vitro d’extraits et / ou de molécules issues de bourgeons d’érable. Pour cela, différentes méthodes d’extractions et différents solvants peu toxiques et respectueux de l’environnement ont été envisagés. Des explorations chimiques par Chromatographie sur Couche Mince (CCM), des dosages colorimétriques et des déterminations d’activité antioxydante ont ensuite été utilisés pour caractériser et évaluer l’extrait le plus prometteur. La détermination de la nature chimique des constituants majeurs de ce dernier ainsi que des essais biologiques ont été conduits afin de mesurer son potentiel de valorisation dans divers domaines. Les rendements en extraits secs, la nature et quantité en certains types de composés ainsi que les résultats de tests chimiques d’activité antioxydante ont montré que l’extrait à l’eau chaude de bourgeons d’érable rouge présentait un réel potentiel de valorisation comme antioxydant naturel. L’identification des composés phénoliques contenus dans cet extrait et leur quantification ont permis de révéler une forte présence de gallo-tannins, mais également d’hétérosides de quercétine et de cyanidine qui ont été décrits pour la première fois dans cette espèce. L’exploration des effets de cet extrait sur les neutrophiles humains comme première approche n’a indiqué aucune toxicité ni modification significative de leur viabilité jusqu'à 100 μg/mL. Cependant pour des plus fortes concentrations, l’extrait a montré une capacité à accélérer la mort programmée de ces cellules majeures de l’inflammation et cette activité serait due à certains gallotanins. Cette propriété biologique mis en évidence pour la première fois ouvre le champ à de nombreuses voies de valorisation notamment dans la résolution du processus inflammatoire où la survie des neutrophiles est incontestablement liée au développement de pathologies chroniques
The residues from the activities of Canadian forest industry are estimated to be more than 20 million tons of dry matter per year. The extractives of trunk barks from these residues have been studied as a way to valorize these non- wood forest products in areas with higher added values based on their interesting biological properties for human health. However, branches of the trees removed during thinning or pruning also carry other plant tissues with chemical composition and biological properties distinct from barks. Our research hypothesis was that maples, the widespread trees with major economic value from Canadian forests, represent a source of important quantities of forest residues containing buds which could be used to produce active ingredients for food industry and healthcare (drugs, phytomedications, and nutraceuticals). Indeed, buds contain important amount of meristems, undifferentiated embryonic tissues that may be rich in some bioactive compounds that are often found only in small quantities in other plant parts. Thus, the main objective of our research project was to explore the potential areas of valorization of natural products derived from sugar and red maple buds No data dealing with the chemical composition of this plant material nor biological effects of extracts and / or molecules derived from maple buds were found in scientific literature. The extracts of maple buds (therefore obtained with not toxic and environment- respectful solvents), were analysed by qualitative approach by Thin Layer Chromatography (TLC) assays for screening of phytochemicals. The quantitative assays and antioxidant activity assessment were used to characterize and evaluate the best promising extract. The major phytochemicals of the latter were identified, along with the biological tests undertaken in order to measure its potential of valorization in several fields The yields of dry matter, the nature and quantity of some potential bioactive compounds and the results on antioxidant activities evaluation showed that the hot water extract of red maple buds has a real potential for development as natural antioxidant. The identification of the major phenolic compounds contained in this extract and their quantification revealed an important concentration of gallo-tannins, along with quercetin and cyanidin glycosides, determined in this study for the first time in this species. Exploration of the effects of water extract from red maple buds on human neutrophils as a first approach indicated no toxicity nor significant modification of their viability up to 100 μg / mL. However, for higher concentrations, the extract showed an ability to accelerate the programmed death of these major cells of inflammation. Further studies revealed that this activity was due to particular gallotannins. This biological property highlighted for the first time opens the field to several ways of valorization especially for the resolution of inflammatory processes in which neutrophil survival is undoubtedly linked to the development of chronic pathologies.
Roufik, Samira. "Étude des interactions β-Lactoglobuline bovine : peptides bioactifs et digestibilité in vitro des complexes". Doctoral thesis, Université Laval, 2005. http://hdl.handle.net/20.500.11794/18110.
Bovine β-lactoglobulin (β-Lg) contains numerous peptide sequences with biological activities, which have a high potential as nutraceutical ingredients. However, studies have demonstrated that some of these peptides, which are active during in vitro tests, loose their activity in animal models following oral ingestion, suggesting their enzymatic degradation during gastrointestinal transit. The aim of this work was to study β-Lg:bioactive peptide interactions and to investigate the in vitro digestibility of the resulting complexes. Firstly, it was shown that pepsic and chymotryptic digestions of some bioactive peptides varied according to the peptide chain length, the nature of the peptide and the presence of other peptides in the reaction medium. Using an ultrafiltration method, it was demonstrated that peptides β-Lg f102-105, f142-148 and f69-83 bind to β-Lg A in significant amounts corresponding to 1.5, 1.1 and 0.7 moles of peptides per mole of protein respectively. These results were validated by front-face fluorescence spectroscopy, which also provided evidences that the binding of the three peptides to β-Lg A modified the polarity of tryptophan environment in the protein structure. In addition, binding isotherms obtained by isothermal titration calorimetry showed that the binding of the antihypertensive peptide β-Lg f142-148 to β-Lg A followed a sequential three-site binding model with constants of associations of 2 X 103, 1 X 103 and 0.4 X 103 M-1 for the 1st, 2nd, and 3rd binding sites respectively. The enthalpy of binding was exothermic for the 1st and 2nd binding sites and endothermic for the 3rd binding site. Lastly, the in vitro digestibility of the protein and the complexes with pepsin, trypsin, chymotrypsin, and pancreatin showed that the complexes were hydrolyzed more slowly than the native protein by chymotrypsin or pepsin/chymotrypsin. The overall results support the hypothesis that the binding of bioactive peptides to β-Lg A could improve their resistance to proteolysis, and thus could contribute to maintain their structural integrity and bioactivity during gastrointestinal transit.
Hamadouche, Moussa. "Amélioration de l'ancrage osseux de l'alumine : revêtement par verres bioactifs conventionnels et sol-gel." Paris 7, 2001. http://www.theses.fr/2001PA077202.
Liszewska, Ewa. "Médiateurs lipidiques bioactifs au cours du développement et de l'implantation de l'embryon de brebis." Versailles-St Quentin en Yvelines, 2008. http://www.theses.fr/2008VERS0040.
Chez les mammifères, des interactions réciproques entre le blastocyste prêt à s’implanter et l’utérus en état de le recevoir est nécessaire pour permettre la réussite de l’implantation et l’établissement de la gestation. Bien que de nombreuses voies métaboliques soient connues pour participer à ces échanges, une compréhension intégrée du processus de l’implantation fait encore défaut. Les études d’expression de gènes et l’élaboration de modèles génétiques chez la souris ont apportées des preuves que les lipides bioactifs ou médiateurs lipidiques, sont d’importantes molécules de signalisation et qui coordonnent des séries d’événements au début de la gestation dont la formation et le développement de l’embryon pré-implantatoire, l’implantation et la croissance post-implantatoire. Dans ces travaux nous avons tenté de comprendre le rôle des médiateurs lipidiques tel l’acide lysophosphatidique (LPA) et les prostaglandines (PGs) au début du développement de l’embryon et au cours de l’implantation chez le mouton