The use of vacuum coating is mostly limited to production of high fat containing extruded aqua and pet diets. The physical characteristics of extrudates are favourable for vacuum coating due to their high porosity and durability. However, with pelleted feed for broilers, there are potentially several opportunities, but there are also challenges; these are explored here. The opportunities identified were inclusion of high level of oils, protected delivery of feed additives (e.g., enzymes, probiotics, vaccines, etc.), improved and safe use of offensive feed additives and improvement of shelf-life of feed and additives. Challenges include the relatively high density of pellets (low porosity) which limits liquid infusion, increased processing cost and decreased feed throughput. However, feed ingredients selection and alternating processing variables (temperature, moisture, die specifications etc.) were deemed to overcome the challenges of low porosity. Three experiments were conducted to evaluate the use of vacuum coating in pelleted feed. In the first experiment, the effect of particle size on post-pellet oil absorption (OA), porosity, pellet durability index (PDI) and bulk density were investigated. The three particle sizes for three grains (wheat, barley and corn) were pelleted using a 4.7 mm die to get whole grain (WP), coarse (CP), and fine (FP) grind pellets. The pellets were coated with 15% canola oil without (VC-) and with (VC+; 0.3 bar) vacuum coating. The grain type was found to have a significant effect on the particle size when ground through either fine (3.2 mm) or coarse (6.4 mm) screen. With coarse grinding, the mean particle size was 1896, 1290 and 1057 µm, respectively for barley, wheat and corn; with fine grinding, the mean particle size was 1153, 767 and 732 µm, respectively. Porosity of CP from wheat and corn was significantly (P<0.01) higher than WP and FP. For barley, there was no difference in porosity of CP and FP but both were significantly higher than WP. For wheat, OA of CP was highest (P<0.01), but no significant difference was found between FP and WP. However, for barley, higher OA was found in FP followed by CP and WP. In corn, OA of CP was higher than for FP or WP. Vacuum coating (VC+) improved (P<0.01) OA of all pellets compared to VC-. Porosity was positively correlated with OA and negatively correlated to PDI and bulk density. Overall, the first experiment suggested that alteration of particle size and grain type could be the options for improving the oil absorption by vacuum coating. A second experiment was conducted to observe the effect of enzyme addition method (EAM; E-, without enzyme; PreE+, Pre-pellet addition of enzyme; PosE+, post-pellet addition of enzyme), conditioning temperature (CT; 65 or 95°C) and coating method (CM; VC- or VC+) on broiler performance when fed wheat-rye-based diets. Enzyme addition (pre or post-pellet addition in comparison to without enzyme) significantly improved (P<0.01) the body weight at 21 and 35d. Higher CT (95°C) improved feed conversion ratio (FCR) in both starter (P<0.01) and grow/finish phase (P=0.04) and PDI of both starter and grow/finish pellets (P<0.01) when compared to low CT (65°C). Vacuum coating did not have any effect on the diet extract viscosity, animal performance or digesta viscosity in either of the phases. However, with post-pellet vacuum coating, there was high retention of xylanase activity after processing. Vacuum coating significantly (P<0.05) reduced the relative length of small intestine of broilers at 21d but not at 35d. In the third experiment, broiler grow/finish diets were stored in an incubator (37°C) to see if vacuum coating can improve the shelf-life of feed. The results showed post-pellet vacuum-coated pellets retained higher enzyme activity after 15 days of storage. Although no effect of vacuum coating on animal performance was observed, vacuum coating was able to protect the enzyme during processing and storage. Further work needs to be done to translate these benefits to improve animal performance, which might be achieved using various vacuum coating and processing conditions, and bioactives.

Le bénéfice de l’encapsulation des molécules bioactives a séduit les industries agroalimentaires depuis plusieurs décennies. Plus récemment des études ont montré la capacité de protéines alimentaires de charge opposée à s’assembler en microsphères par coacervation complexe. La compréhension des forces gouvernant le processus de coacervation entre protéines et l’influence exercée par la présence de bioactifs demeurent des prérequis pour l’utilisation des coacervats complexes comme agent d’encapsulation. Dans ce contexte, l’objectif de mon projet de thèse a été de comprendre le mécanisme de coacervation complexe entre la ¿-lactoglobuline (¿-LG) chargée négativement, et la lactoferrine (LF) chargée positivement, en absence et en présence de petits ligands. La LF a présenté une coacervation préférentielle avec le variant A de la¿¿-LG qui se distingue du variant B par la substitution de 2 acides aminés. Au niveau moléculaire, deux sites de fixation de la ¿-LG sur la LF ont été identifiés.En outre, par la mesure d’une part des coefficients de diffusion rotationnel et d’autre part de la cinétique de diffusion des entités moléculaires constituant les coacervats, il est suggéré que ces derniers sont formés à partir de -LG libre¿¿de pentamère, LF(-LG2)2, ainsi que des entités plus larges, (LF-LG2)n. Afin d’évaluer l’effet de la présence de petits ligands sur la coacervation complexe entre la -LG et la LF, des ligands modèles (ANS et acide folique) ont été utilisés. Dans les conditions expérimentales testées ces deux ligands n’ont pas d’affinité pour la -LG, mais après interact / Encapsulation of bioactives has been used by the food industries for decades and represents a great potential for the development of innovative products. Given their versatile functional properties, milk proteins in particular from whey have been used for encapsulation purposes using several encapsulation techniques. In parallel, recent studies showed the ability of oppositely charged food proteins to co-assemble into microspheres through complex coacervation. Understanding the driving forces governing heteroprotein coacervation process and how it is affected by the presence of ligands (bioactives) is a prerequisite to use heteroprotein coacervates as encapsulation device. In this context, the objective of my thesis work was to understand the mechanism of complex coacervation between -lactoglobulin (-LG) and lactoferrin (LF) in the absence and presence of small ligands. The conditions of optimal ¿-LG - LF coacervation were found at pH range 5.4-6 with a molar excess of ¿-LG. RemarkabAt molecular level, the presence of two binding sites on LF for -LG was evidenced. Moreover, the heterocomplexes such as pentamers LF(-LG2)2 and quite large complexes (LF-LG2)n were identified as the constituent molecular species of the coacervate phase. To evaluate the -LG - LF complex coacervation in the presence of small ligands, models of hydrophobic (ANS) and hydrophilic molecules (folic acid) were used. Although under the experimental conditions tested the small ligands did not interact with -LG, both interacted with LF inducing its self-association into nanoparticles. High relati

El objetivo del presente trabajo ha sido la búsqueda de sustancias bioactivas en dos especies de la flora colombiana. Se pretendió aislar y caracterizar los metabolitos secundarios sintetizados por Phaedranassa dubia (Amaryllidaceae) y Garcinia madruno (Clusiaceae), además de estudiar la actividad antiprotozoaria in vitro y de evaluar la actividad antioxidante de los metabolitos aislados. El trabajo fitoquímico realizado con Phaedranassa dubia ha permitido el aislamiento de un nuevo alcaloide de tipo Amaryllidaceae, fedranamina, cuya estructura se ha establecido por análisis espectroscópicos (UV, EM, RMN y CD). Otros alcaloides identificados en esta especie han sido: pseudolicorina, sanguinina, galantamina, epinorgalantamina, hemantamina, ungeremina y zefbetaina. De otro lado, se ha reportado por primera vez el producto natural 7'-O-(6'-acetil)-glucósido de morelloflavona, al cual se ha dado el nombre trivial de madrunoudeasido, un nuevo biflavonoide aislado del extracto metanólico de las partes aéreas de Garcinia madruno (Clusiaceae). Es la primera vez que se reporta un biflavonoide acetil-glucósido, aislado del género Garcinia. Igualmente se reportan los biflavonoides amentoflavona, morelloflavona, volkensiflavona, fukugisido y spicatasido, a partir de la misma especie vegetal. La evaluación in vitro frente a cuatro diferentes parasitos antiprotozoarios se realizó utilizando los diferentes compuestos. Los alcaloides ungeremina, pseudolicorina y hemantamina presentaron buena actividad en el ensayo in vitro frente a Trypanosoma brucei rhodesiense, T. cruzi y Plasmodium falciparum con valores de IC50 menores de 1 µg/mL. Se ha estudiado, igualmente, la actividad antioxidante de los biflavonoides aislados de G. madruno, por medio de los métodos del 2,2'-difenil-1-picrilhidracil (DPPH·) y de la inhibición de la peroxidación de lipoproteínas de baja densidad (LDL). En general, los compuestos con enlace inter-flavonoide C3&#8594;C8' presentan una potente actividad captadora de radicales DPPH·. Los biflavonoides que presentan esta característica en combinación con una sustitución 3',4'-dihidroxi (catecol) en el anillo E, un doble enlace entre C-2' y C-3' y una función carbonilo en la posición C-4', son los captadores de radicales más activos. En relación a los inhibidores de la peroxidación de LDL, los mejores inhibidores son los compuestos con enlace inter-flavonoide C3&#8594;C8': morelloflavona y volkensiflavona. la fracción biflavonoide (FB) aislada de G. madruno, compuesta principalmente por morelloflavona, volkensiflavona y amentoflavona. Los datos sugieren que FB podría ser un excelente candidato para ser utilizado como antioxidante. Es probable que se produzcan procesos de sinergismo en la FB, toda vez que presenta una actividad captadora de radicales y una inhibición de la peroxidación de LDL superior, en algunos casos, a los compuestos más activos. / The bulbs of Phaedranassa dubia (Amaryllidaceae) were found to contain the novel compound phaedranamine, together with seven known alkaloids. The structure and stereochemistry of the alkaloids were determined by physical and spectroscopic methods. An in vitro screening against four different parasitic protozoa was carried out using the isolated compounds. The alkaloids ungeremine, pseudolycorine and haemanthamine showed good activity in in vitro assays against Trypanosoma brucei rhodesiense, T. cruzi and Plasmodium falciparum with IC50 values in the range of 1 µg/mL or lower. On the other hand, six biflavonoids were isolated from Garcinia madruno (Clusiaceae) and then 7"-O-(6""-acetyl)-glucoside of morelloflavone (5) has proven to be a new compound. The antioxidant activity of the biflavonoids against low-density lipoproteins peroxidation was studied by means of TBARS assay. The antioxidant potential of a biflavonoid fraction (BF) was also evaluated and correlated with its biflavonoid content. Lipid peroxidation was significantly reduced in the presence of the BF, morelloflavone being mainly responsible for this effect.

Probiotic bacteria are increasingly prevalent in food and nutritional products today. These remarkable microorganisms are capable of imparting exceptional health benefits on their host, including prevention of infection by pathogens and stimulation of immune system function. Their most common mode of delivery is through dairy products (e.g. yogurt), which are also one of their preferred habitats. The interactions between probiotic bacteria and dairy systems have been studied, but are still not well discerned. There is a need for better understanding of these associations, as well as those surrounding the mode of bacterial transfer from the food product to the human gastrointestinal tract. Discoveries into the optimal means of probiotic transport to the body may lead to great advancements in both the design of probiotic foods and their exploitation in the support of human health. Much of the previous research on probiotic bacteria has explored their possible means of adherence in the intestine, as well their strengths in the promotion of human health. Studies relating to their interaction with dairy products are lacking, however, thus this work aims to elucidate some of these aspects. The primary endeavor of this thesis was to develop a technique to quantify the binding affinity of probiotic lactic acid bacteria for milk phospholipids. An additional objective was to exploit these bacteria, as well as dairy ingredients rich in bioactive molecules, in the creation of a highly nutritious food product. In these experiments, a collection of methods were used in progression in order to arrive at a novel protocol to assess binding with excellent reproducibility and simplicity. These included various membrane blotting techniques, as well as thin-layer chromatography. Essentially, phospholipids from both animal-derived standards and milk extracts were applied to a surface (e.g. PVDF membrane), and bacteria were incubated with them to allow binding reactions. The lactic acid bacteria selected for the final assays consisted of four strains of Lactobacillus, including L. reuteri (SD2112 and T-1), L. acidophilus, and L. casei (LC-10). Their adhesion to phospholipids was detected by either colorimetric or fluorescent labeling systems. To illustrate this, the final method developed was a procedure in which bacteria fluorescently stained with acridine orange were allowed to bind to dots of PVDF membrane coated with phospholipids. The results of this study showed that lactic acid bacteria undeniably exhibit selective binding affinity for phospholipids as opposed to other lipids such as triglycerides. The bacteria demonstrated significantly greater binding for a phospholipid extract from milk as opposed to individual phospholipid standards from other sources (p<0.05). Nonetheless, adhesion to all phospholipids was substantially greater than that to triglycerides. These findings, as well as the development of this method, should prove valuable in future research regarding the associations of probiotics with dairy systems. An additional purpose of this thesis was to design a dairy-based food product containing ingredient sources rich in milk bioactives. A gel-type product was created using primarily colostrum, buttermilk powder, and whey protein isolate, as well as selected strains of Lactobacillus. With the inclusion of immunoglobulin-rich colostrum, the product was analyzed alongside fluid milk and colostrum in order to quantify and compare these bioactive molecules. An enzyme-linked immunosorbent assay (ELISA) was used to complete this, and the results revealed concentrations that would be expected by the literature. Specifically, immunoglobulin G (IgG) was quantified by interpolation from a bovine IgG standard regression curve. The results showed that the concentration of IgG in the gel was nearly twice that of colostrum, and almost eight-fold higher than that of milk. This indicates that use of bioactive-rich substances, such as colostrum, in a food product may serve as a means of delivering more concentrated doses of bioactives than their respective ingredients. The research completed in this thesis is significant in that it contributes a valuable method to the elucidation of bacterial binding interactions with milk components, and also demonstrates the successful application of dairy ingredients to an innovative food product high in beneficial compounds. The insight provided by these studies could encourage further work in improving the understanding of probiotic delivery and advancing the development of bioactive-rich food products.

Muitas drogas terapêuticas produzidas pela indústria farmacêutica são estruturas químicas isoladas de organismos encontrados na natureza ou moléculas baseadas nelas. Podem ser incluídas nesse grupo drogas isoladas de organismos marinhos, como corais, esponjas e algas marinhas, conhecidos como produtores de grandes quantidades de metabólitos secundários. Com base neste fato o presente estudo teve como objetivo realizar a prospecção de moléculas bioativas com propósito farmacológico, em extratos de algas marinhas vermelhas (Rhodophyta) e pardas (Heterokontophyta) coletadas no litoral brasileiro. A prospecção foi realizada por meio de avaliação de seus potenciais antioxidante, antibacteriano, antifúngico, anticancerígeno, e antiparasitário contra organismos causadores de leishmaniose e esquistossomose. Para as avaliações foram empregadas os extratos supercríticos de 5 espécies diferentes, sendo 2 pardas: Dictyota dichotoma e D. menstrualis e três vermelhas: Chondria littoralis, Spyridia hypnoides e Plocamium brasiliense. Os extratos foram avaliados quanto aos seus potenciais bioativos e os resultados mais promissores foram selecionados para as etapas seguintes do fracionamento. Em uma avaliação geral os extratos apresentaram bons resultados e representam uma potencial fonte de bioativos. Os extratos das espécies de D. dichotoma e D. menstrualis foram então submetidos a um procedimento de fracionamento bioguiado pela atividade esquistossomicida. Incorporou-se ainda um terceiro extrato de D. mertensii aos estudos e todas as etapas do fracionamento foram monitoradas por LC-MS. Comparando-se as massas detectadas em todas as frações que apresentaram atividade, para os 3 extratos, foi verificado que a substância de m/z 271,24 estava presente em todas elas, portanto os procedimentos de isolamento foram direcionados a esta molécula para a qual foi possível isolar 7 mg. Diferentemente do que era esperado a molécula quando avaliada isoladamente não apresentou atividade esquistossomicida, levando a hipótese de que a atividade seja decorrente de uma molécula diferente para cada espécie ou ainda que a mesma seja decorrente de uma interação com outras substâncias por um mecanismo de ação aditivo ou sinérgico. O trabalho avaliado de forma geral apresentou resultados promissores e representa um grande embasamento para servir como base para posteriores trabalho de fracionamento. / Several therapeutic drugs manufactured by the pharmaceutical industry are chemical structures isolated from organisms that are found in nature or molecules based on that. May be included at this group drugs isolated from marine organisms, like corals, sponges and seaweeds, known as great secondary metabolites producers. Based on this facts the objective of the present study is to perform a prospection study to achieve bioactive molecules with pharmaceutical purposes, on extracts made from red (Rhodophyta) and brown (Heterokontophyta) seaweed collected in the Brazilian shore. The prospection studies was performed by means of evaluation of the antioxidant, antibacterial, antifungal, anticancer and antiparasitic (against Leishmania and Schistosoma) potential. In the evaluation were tested the supercritical extracts of 5 different species, including 2 brown species: Dictyota dichotoma and D. menstrualis and 3 red species: Chondria littoralis, Spyridia hypnoides and Plocamium brasiliense. The extracts were evaluated by their potential bioactive compounds and the most promising results were selected for the following fractionation steps. Overall the extracts have shown good results and may be represent a potential source of bioactive molecules. The extracts of both D. dichotoma and D. menstrualis were submitted to a bioguided fractionation process by their antischistosomal activities. It was still included a third extract from D. mertensii to the studies and every step was monitored by LC-MS techniques. Comparing the detected mass for each active fraction, it was observed the presence of a substance with m/z 271,24 in all of the extracts, so the isolating procedures were directed to obtain that specific molecule, which was obtained in a biomass of 7 mg. Differently than expected the molecule when evaluated isolated do not show the antischistosomal activity, leading to the hypothesis that the activity was related to different molecules for each species or even the observed effect is resulted by an interaction mechanism with another substances by an additive or synergist mechanism. The overall evaluation of the whole work show some promising results and it represent a great support for future fractionation works.

L’agriculture moderne utilise depuis plus de cinquante ans de nombreux produits phytosanitaires de traitement dans le but d’assurer les meilleurs rendements et de limiter les pathogènes néfastes pour la santé humaine ou animale. Jusqu’à peu, la quantité de résidus phytosanitaires présents dans les denrées alimentaires (fruits, légumes, céréales, plantes fourragères, produits transformés…) était certes contrôlée mais en règle générale, ne soulevait que très peu d’interrogation en terme de conséquences à plus ou moins long terme. A l’heure actuelle, des exigences de plus en plus drastiques apparaissent et se généralisent. Les produits issus des industries agricole et agroalimentaire doivent répondre à des normes de plus en plus strictes en terme de résidus pour rester compétitives. En particulier, dans le cas des pommes, dont le nombre de traitements par saison est l’un des plus élevé en France, les exigences tendent vers le zéro résidu détectable. La stratégie de cette étude repose, dans un premier temps, sur la compréhension des phénomènes de transfert à la surface du fruit. Une caractérisation physico-chimique de l’épiderme de différentes variétés de pommes a conduit à l’identification des structures impliquées dans l’interaction molécule bioactivematrice biopolymérique. Le fludioxonil a été choisi comme molécule modèle en raison de sa fréquence d’utilisation comme fongicide de conservation et de sa composition atomique (présence de fluors). Les épidermes de pommes Fuji ont servi de matrice modèle. Dans un second temps, un procédé de traitement par voie chimique des pommes a été mis au point et développé pour extraire les résidus de 12 molécules de phytosanitaires parmi les plus couramment utilisées dans les vergers de pommiers du Midi-Pyrénées. Trois variétés de pommes populaires en France ont été sélectionnées pour leurs différentes périodes de récolte correspondant à des risques de contamination variables. Les résultats ont conduit à la proposition d’un schéma de désorption des molécules bioactives dans la matrice biopolymérique, basé sur les théories de la solubilité de Hildebrandt et de Hansen. En complément, le développement d’une méthode analytique de quantification par chromatographie en phase gazeuse couplée à la spectrométrie de masse trappe d’ions (GC/MS2) des molécules phytosanitaires dans la matrice épidermique des pommes a mis en évidence que : 1- l’augmentation de la concentration des analytes d’intérêt au-dessus des limites de détection de la technique analytique appliquée favorisait la quantification des très faibles traces, voire des ultratraces ; 2- les analytes d’intérêt subissaient en parallèle des effets matrice négatifs. Une forte interaction entre certains analytes de la matrice et les phytosanitaires a été démontrée et une méthode de purification basée sur un couplage chromatographie sur couche mince haute performance avec la GC/MS2 (CCMHP/GC/MS2) a été proposée afin de minimiser les effets matrice négatifs dans / For more than fifty years, the modern agriculture uses lots of products for crop protection in order to ensure optimum yields and to limit pathogens harmful for human or animal health. Until recently, the levels of pesticides in foodstuffs (fruits, vegetables, cereals, forage crops, processed food…) were controlled but usually not problematic regarding the effects over time. Nowadays, more and more drastic requirements are appearing and becoming widespread. The products from farming and food industries must satisfy stricter and stricter standards in terms of residues for maintaining competitiveness. Particularly, for apples, whose treatments per season are among the highest in France, requirements tend to the zero detectable residue. The strategy of this work deals with, on one hand, the understanding of the transfert stages involved at the outer surface of the fruit. A physicochemical characterizations of epiderms of different apples led to the identification of the structures involved in the relationship between bioactive molecule and biopolymeric matrix. Fludioxonil was chosen for modelization for its frequency of use and for its atomic composition (fluorine). The epiderms of Fuji apples were selected as the matrix-model. On the other hand, a chemically treatment process of apples was studied and developed to release the residues of 12 pesticides among the most currently used in apple orchards of Midi-Pyrenees. Three varieties of apples among the most popular in France were selected for their different periods of harvest corresponding to variable pests risks. The results led to a possible scheme of desorption of bioactive molecules in the biopolymeric matrix, based on the theory of solubility developed by Hildebrandt and Hansen. In addition, the development of an analytical mehtod of quantitation of pesticides in the epidermal matrix of apples by gas chromatography coupled with mass spectrometry ion trap (GC/MS2) highlighted that : 1- the increase of the concentrations of the analytes of interest over the limits of detection of the applied analytical method promoted the quantitation of very low traces, even ultratraces ; 2- the analytes of interest concurrently underwent negative matrix effects. A strong interaction between some matrix analytes with pesticides was demonstrated and a mehtod of cleanup based on the hyphenation of high performance thin layer chromatography with GC/MS2 (HPTLC/GC/MS2) was suggested to minimize the negative matrix effects in that kind of concentrated matrix extracts.

Muitas drogas terapêuticas produzidas pela indústria farmacêutica são estruturas químicas isoladas de organismos encontrados na natureza ou moléculas baseadas nelas. Podem ser incluídas nesse grupo drogas isoladas de organismos marinhos, como corais, esponjas e algas marinhas, conhecidos como produtores de grandes quantidades de metabólitos secundários. Com base neste fato o presente estudo teve como objetivo realizar a prospecção de moléculas bioativas com propósito farmacológico, em extratos de algas marinhas vermelhas (Rhodophyta) e pardas (Heterokontophyta) coletadas no litoral brasileiro. A prospecção foi realizada por meio de avaliação de seus potenciais antioxidante, antibacteriano, antifúngico, anticancerígeno, e antiparasitário contra organismos causadores de leishmaniose e esquistossomose. Para as avaliações foram empregadas os extratos supercríticos de 5 espécies diferentes, sendo 2 pardas: Dictyota dichotoma e D. menstrualis e três vermelhas: Chondria littoralis, Spyridia hypnoides e Plocamium brasiliense. Os extratos foram avaliados quanto aos seus potenciais bioativos e os resultados mais promissores foram selecionados para as etapas seguintes do fracionamento. Em uma avaliação geral os extratos apresentaram bons resultados e representam uma potencial fonte de bioativos. Os extratos das espécies de D. dichotoma e D. menstrualis foram então submetidos a um procedimento de fracionamento bioguiado pela atividade esquistossomicida. Incorporou-se ainda um terceiro extrato de D. mertensii aos estudos e todas as etapas do fracionamento foram monitoradas por LC-MS. Comparando-se as massas detectadas em todas as frações que apresentaram atividade, para os 3 extratos, foi verificado que a substância de m/z 271,24 estava presente em todas elas, portanto os procedimentos de isolamento foram direcionados a esta molécula para a qual foi possível isolar 7 mg. Diferentemente do que era esperado a molécula quando avaliada isoladamente não apresentou atividade esquistossomicida, levando a hipótese de que a atividade seja decorrente de uma molécula diferente para cada espécie ou ainda que a mesma seja decorrente de uma interação com outras substâncias por um mecanismo de ação aditivo ou sinérgico. O trabalho avaliado de forma geral apresentou resultados promissores e representa um grande embasamento para servir como base para posteriores trabalho de fracionamento. / Several therapeutic drugs manufactured by the pharmaceutical industry are chemical structures isolated from organisms that are found in nature or molecules based on that. May be included at this group drugs isolated from marine organisms, like corals, sponges and seaweeds, known as great secondary metabolites producers. Based on this facts the objective of the present study is to perform a prospection study to achieve bioactive molecules with pharmaceutical purposes, on extracts made from red (Rhodophyta) and brown (Heterokontophyta) seaweed collected in the Brazilian shore. The prospection studies was performed by means of evaluation of the antioxidant, antibacterial, antifungal, anticancer and antiparasitic (against Leishmania and Schistosoma) potential. In the evaluation were tested the supercritical extracts of 5 different species, including 2 brown species: Dictyota dichotoma and D. menstrualis and 3 red species: Chondria littoralis, Spyridia hypnoides and Plocamium brasiliense. The extracts were evaluated by their potential bioactive compounds and the most promising results were selected for the following fractionation steps. Overall the extracts have shown good results and may be represent a potential source of bioactive molecules. The extracts of both D. dichotoma and D. menstrualis were submitted to a bioguided fractionation process by their antischistosomal activities. It was still included a third extract from D. mertensii to the studies and every step was monitored by LC-MS techniques. Comparing the detected mass for each active fraction, it was observed the presence of a substance with m/z 271,24 in all of the extracts, so the isolating procedures were directed to obtain that specific molecule, which was obtained in a biomass of 7 mg. Differently than expected the molecule when evaluated isolated do not show the antischistosomal activity, leading to the hypothesis that the activity was related to different molecules for each species or even the observed effect is resulted by an interaction mechanism with another substances by an additive or synergist mechanism. The overall evaluation of the whole work show some promising results and it represent a great support for future fractionation works.

Dans le cadre de la recherche pharmaceutique, les propriétés relatives à l’Absorption, la Distribution, le Métabolisme, l’Elimination (ADME) et la Toxicité (Tox) sont cruciales pour le succès des phases cliniques lors de la conception de nouveaux médicaments. Durant ce processus, la chémoinformatique est régulièrement utilisée afin de prédire le profil ADME-Tox des molécules bioactives et d’améliorer leurs propriétés pharmacocinétiques. Ces modèles de prédiction, basés sur la quantification des relations structure-activité (QSAR), ne sont pas toujours efficaces à cause du faible nombre de données ADME-Tox disponibles et de leur hétérogénéité induite par des différences dans les protocoles expérimentaux, ou encore de certaines erreurs expérimentales. Au cours de cette thèse, nous avons d’abord constitué une base de données contenant 150 000 mesures pour une cinquantaine de propriétés ADME-Tox. Afin de valoriser l’ensemble de ces données, nous avons dans un deuxième temps proposé une plateforme automatique de création de modèles de prédiction QSAR. Cette plateforme, nommée MetaPredict, a été conçue afin d’optimiser chacune des étapes de création d’un modèle statistique, dans le but d’améliorer leur qualité et leur robustesse. Nous avons dans un troisième temps valorisé les modèles obtenus grâce à la plateforme MetaPredict en proposant une application en ligne. Cette application a été développée pour faciliter l’utilisation des modèles, apporter une interprétation simplifiée des résultats et moduler les observations obtenues en fonction des spécificités d’un projet de recherche. Finalement, MetaPredict permet de rendre les modèles ADME-Tox accessibles à l’ensemble des chercheurs. / Absorption, Distribution, Metabolism, Elimination (ADME) and Toxicity (Tox) properties are crucial for the success of clinical trials of a drug candidate. During this process, chemoinformatics is regularly used to predict the ADME-Tox profile of bioactive compounds and to improve their pharmacokinetic properties. In silico approaches have already been developed to improve poor pharmacokinetics and toxicity of lead compounds. These predictive models, based on the quantification of structure-activity relationships (QSAR), were not always efficient enough due to the low number of accessible biological data and their heterogeneity induced by the differences in experimental assays or the significant experimental error. In this thesis, we first built a database containing 150,000 data points for about 50 ADME-Tox properties. In order to valorize all this data, we then proposed an automatic platform for creating predictive models. This platform, called MetaPredict, has been designed to optimize each step of model development, in order to improve their quality and robustness. Third,, we promoted the statistical models using the online application of MetaPredict platform. This application has been developed to facilitate the use of newly built models, to provide a simplified interpretation of the results and to modulate the obtained observations according to the needs of the researchers. Finally, this platform provides an easy access to the ADME-Tox models for the scientific community.

Le but de cette étude est de mettre en oeuvre une nouvelle méthode de prétraitement de la biomasse afin d’isoler les métabolites secondaires qui peuvent inhiber la fermentation des glucides pour la production d’éthanol cellulosique. Avec la tendance grandissante vers la production de cultures énergétiques, potentiels intrants pour d’éventuelles bioraffineries, il importe de vérifier la composition et le potentiel des extractibles provenant de ces plantes. Les processus d’extraction actuels s’opèrent en discontinu, par alternance de grandes quantités de solvants organiques puis aqueux, et nécessitent des temps d’opération longs et beaucoup d’énergie. À cet effet, une nouvelle procédure d’extraction utilisant comme matières premières une culture végétale à croissance rapide appartenant à l’espèce Salix, a été mise en oeuvre. La technique choisie emploie un solvant sous forme d’émulsion composé d’eau et de carbonate de diméthyle avec des proportions volumiques (82,5 – 17,5%), diminuant ainsi la consommation de solvant et permettant de produire un procédé d’extraction en continu. Le mélange hétérogène, biomasse et émulsion, exposé aux ultrasons a permis la réduction du temps d’extraction mais aussi l’énergie consommée de 6 fois, tout en augmentant le rendement d’extraction de 25 % et en préservant les composés thermolabiles

Ce travail de thèse s’intéresse à la synthèse totale d'alcaloïdes de la famille des Lycorines, produits naturels isolés à partir de plantes des Amaryllidaceae qui possèdent de multiples activités biologiques. Leurs structures sont caractérisées par un squelette commun tétracyclique azoté : le galanthane. L’accès rapide au squelette galanthane a été développé via une étape clé de métathèse tandem cyclisante permettant d’obtenir deux cycles fonctionnalisés en une seule étape. La première partie de ce travail a conduit au développement d’une voie de synthèse asymétrique des (–)-α et (–)-β-lycoranes à partir d’un même intermédiaire, une sulfinylaldimine α-chirale, obtenue par réduction d’un N-sulfinylthioimidate α-chiral grâce à des conditions développées au laboratoire. La seconde partie de ce travail a porté sur la synthèse asymétrique de la (+)-kirkine, nécessitant une révision de la stratégie pour former le cycle B du squelette galanthane de manière précoce dans la synthèse. Nous avons réalisé la première synthèse totale asymétrique de la structure décrite de la (+)-kirkine. L’obtention des lycoranes et de la kirkine prouve la flexibilité ainsi que l'efficacité de la voie de synthèse, en particulier de l'étape clé de métathèse tandem et des N-sulfinylthioimidates comme intermédiaires clés. Cette voie est donc très prometteuse pour accéder à d'autres composés naturels de la famille des Lycorines. / This thesis work focuses on the total synthesis of alkaloids of the Lycorine family, natural products isolated from the plants of Amaryllidaceae, owning many biological properties such as anticancer, antiviral, antimicrobial or anti-inflammatory. Their structure is characterized by a nitrogen-containing tetracyclic galanthan skeleton. A fast access to the galanthan skeleton was developed by a key tandem ring closing metathesis step to obtain two cycles in a single step. The first part of this work concerns the development of an asymmetric synthetic pathway to obtain the (–)-α and (–)-β-lycoranes from a common central intermediate, an α-chiral sulfinylaldimine, obtained by reduction of the corresponding α-chiral sulfinylthioimidate. The second part of this work focuses on the asymmetric synthesis of (+)-kirkine, which required a strategy revision for the formation of the B cycle of the galanthan skeleton earlier in the synthesis. We have succeeded in realising the first asymmetric total synthesis of the described structure for (+)-kirkine. The asymmetric synthesis of lycoranes and kirkine proves the flexibility and efficiency of the synthetic route, in particular of the tandem metathesis step and the N-sulfinylthioimidates as key intermediates. This synthetic pathway is therefore very promising to obtain other natural products of the Lycorine family.