Orientador: Flavia Maria Netto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-09T02:23:59Z (GMT). No. of bitstreams: 1 Tiengo_Andrea_M.pdf: 1037181 bytes, checksum: fa41390046e1fd743ebaf166db3e45ec (MD5) Previous issue date: 2007 / Resumo: O amaranto vem se destacando como uma excelente fonte alternativa ou complementar de proteínas alimentares devido à sua composição balanceada em aminoácidos essenciais. A cultura do amaranto (Amaranthus cruentus BR Alegria) vem sendo introduzida no Brasil por sua ótima qualidade nutricional, alto teor de proteínas e melhor valor biológico que a de cereais, e funcional, além de características agronômicas de adaptabilidade. Apesar de o amaranto ter sido bem caracterizado quimicamente e apresentar componentes relacionados a diferentes atividades bioquímicas com potencial fisiológico, pouco se conhece sobre seu potencial funcional. O presente trabalho teve como objetivo avaliar a atividade inibidora da enzima conversora da angiotensina (ECA) e a capacidade ligante de ácidos biliares (AB) da farinha desengordurada de amaranto e seus produtos. Farinha integral foi obtida pela moagem do grão de Amaranthus cruentus (variedade BR Alegria) e tratada com hexano para obtenção da farinha desengordura (FDA), utilizada para a produção do concentrado protéico de amaranto (CPA). Para obtenção de hidrolisados protéicos, CPA, sem e com tratamento térmico prévio (90°C/ 30 minutos), foi hidrolisado com a enzima Alcalase, até atingir 12% de grau de hidrólise (GH). As farinhas e seus produtos derivados foram caracterizados quanto à composição e perfis eletroforético e cromatográfico de suas proteínas. A digestão in vitro das proteínas também foi avaliada e o material digerido utilizado para avaliação da atividade inibidora da ECA. A farinha integral de amaranto e seus derivados apresentaram composição semelhante à encontrada na literatura. O tratamento térmico prévio do CPA não alterou o padrão de atividade das enzimas utilizadas, pois o perfil eletroforético e cromatográfico (fase reversa e exclusão molecular) mostraram-se semelhantes. Todos os hidrolisados protéicos e digeridos apresentaram capacidade de inibir a ECA in vitro. No entanto, os digeridos do CPA sem e com tratamento térmico prévio (DCPAst e DCPAtt respectivamente) apresentaram menor atividade inibidora da ECA (IC50 de 0,439 mg proteína/mL e 0,475 mg proteína/mL respectivamente) que os hidrolisados com Alcalase tanto antes (HPAst e HPAtt) como após a digestão in vitro (DHPAst e DHPAtt) que apresentaram IC50 0,118 a 0,176 mg de proteína/mL. Estes resultados sugerem que, in vivo, a ingestão da proteína de amaranto intacta pode apresentar menor atividade inibidora da ECA quando comparada à ingestão da proteína previamente hidrolisada com Alcalase. A digestão in vitro não alterou a atividade inibitória da ECA dos hidrolisados, sugerindo que os peptídeos inibidores da ECA liberados pela ação da Alcalase foram resistentes à hidrólise gastrintestinal. A capacidade ligante de ácidos biliares dos produtos de amaranto (FDA, CPA, HPAst e resíduo alcalino ¿ RA - obtido da extração do CPA) e da colestiramina (utilizada como controle positivo), foi diferente em função do ácido biliar estudado (ácidos cólico, taurocólico, glicocólico e deoxicólico). A colestiramina apresentou a maior atividade ligante para todos os AB testados, diferindo-se de todas as amostras (p<0,05). O RA, mais rico em fibras (8,6%), apresentou a menor atividade ligante para os AB testados, com exceção do ácido glicocólico, que os demais produtos. A FDA apresentou atividade ligante intermediária para todos os AB, porém semelhante à do CPA com o ácido deoxicólico e do HPAst com o ácido taurocólico, que apresentaram as maiores atividades. A FDA e CPA apresentaram capacidade ligante de ácidos biliares secundários tóxicos à mucosa intestinal. A partir dos resultados obtidos não foi possível afirmar se foram as proteínas, as fibras ou eventualmente outro componente não avaliado, o principal responsável por esta atividade. Com a comprovação das atividades inibidora da ECA e ligante de ácidos biliares in vitro, sugere-se a realização de estudos in vivo, sendo o experimento in vivo um método mais confiável para avaliar a atividade biológica das proteínas de amaranto e demais componentes / Abstract: Amaranth has been highlighted as an excellent alternative or complementary source of food protein due to its balanced amino acid composition. The culture of amaranth has been introduced into Brazil on account of its optimum nutritional (high protein content and better biological quality than that of cereal protein) and functional quality, apart from its agricultural characteristics and adaptability. Although amaranth has been well characterised chemically and present components related to different biochemical activities with physiological potential, little is known about its functional potential. The objective of the present work was to evaluate the inhibitory activity of the angiotensin converting enzyme (ACE) and the capacity to bind with the bile acids (BA) of defatted amaranth flour and its products. Whole flour was obtained by grinding the Amaranthus cruentus grain (BR Alegria variety), and treating with hexane to obtain the defatted flour (ADF), used to produce the amaranth protein concentrate (APC). To obtain the protein hydrolysates, APC, with and without prior heat treatment (90ºC/ 30 minutes), was hydrolysed using the enzyme Alcalase to a 12% degree of hydrolysis (DH). The flours and their derived products were characterised with respect to the electrophoretic and chromatographic compositions and profiles of their proteins. The in vitro digestibility of the proteins was also evaluated and the digested material used to determine the ACE inhibitory activity. The whole amaranth flour and its derivatives presented a composition similar to that found in the literature, and the prior heat treatment of the APC did not alter the activity pattern of the enzymes used, since the electrophoretic and chromatographic profiles (reverse phase and molecular exclusion) were shown to be similar. All the protein hydrolysates, before and after digestion, showed in vitro ACE inhibitory capacity. However, the digested APC, with or without prior heat treatment (DAPCnt and DAPCht, respectively) presented less ACE inhibitory activity (IC50 of 0,439 mg protein/mL and 0,475 mg protein/mL, respectively) than the Alcalase hydrolysates both before (APHnt and APHtt) and after in vitro digestion (DAPHnt and DAPHtt), which presented IC50 values of from 0,118 to 0,176 mg protein/mL. These results suggest that, in vivo, the ingestion of intact amaranth protein could present less ACE inhibitory activity than when ingesting protein previously hydrolysed with Alcalase. In vitro digestion did not change the ACE inhibitory activity of the hydrolysates, suggesting that the ACE inhibitory peptides liberated by the action of Alcalase were resistant to gastro-intestinal hydrolysis. The bile acid binding capacity of the amaranth products (ADF, APC, APHnt and the alkaline residue ¿ AR ¿ obtained from the extraction of APC) and of cholestyramine (used as the positive control), varied as a function of the bile acid studied (cholic, taurocholic, glycocholic and deoxycholic acids). The cholestyramine showed greater binding activity with all the BAs tested, differing from all the samples (p<0,05). The fibre-rich (8,6%) AR presented the least binding activity with all the BAs tested, as compared to the other products, with the exception of with glycocholic acid. The ADF presented intermediate binding activity with all the BAs, which was nevertheless similar to that of APC with glycocholic acid and of APHnt with taurocholic acid, which presented the highest activities. The ADF and APC presented binding capacity with the secondary bile acids toxic to the intestinal mucous membrane. From the results obtained, it was not possible to affirm if it was the proteins, fibres or even some other non-evaluated component, that was responsible for this activity. Having proven the ACE inhibitory and bile acid binding activities in vitro, it is important to also carry out in vivo studies, since the in vivo experiment is a more reliable method to evaluate the biological activity of the amaranth proteins and their other components / Mestrado / Nutrição Experimental e Aplicada à Tecnologia de Alimentos / Mestre em Alimentos e Nutrição

La cholestase est l'une des manifestations les plus courantes des lésions induitespar des médicaments. Dans 40% des cas elle n’est pas prévisible; une meilleure prédictibilité représente donc un défi majeur. Tout d'abord, nous avons démontré que les cellules hépatiques humaines HepaRG différenciées sont un modèle approprié pour étudier la cholestase induite par les médicaments en comparant la localisation et l’activité des transporteurs d'influx et d'efflux avec les hépatocytes humains primaires. Tous les transporteurs d'efflux et d’influx testés ont été correctement localisés au niveau des membranes canaliculaire (BSEP, MRP2, MDR1 et MDR3) et basolatéral (NTCP, MRP3) et sont fonctionnels. En outre, ces cellules expriment également les enzymes qui métabolisent les acides biliaires (ABs) et ont la capacité de les synthétiser et de les conjuguer avec la taurine, la glycine et le sulfate, à un taux similaire à celui des hépatocytes primaires. Des changements ont été observés sur la répartition des ABs totaux après traitements de cellules HepaRG par un médicament cholestatique, la cyclosporine A (CsA), de manière concentration- dépendante. L'inhibition de l'efflux et de l'influx de taurocholate a été observée après 15 min et 1 h respectivement. Ces premiers effets ont été associés à la dérégulation de la voie des cPKC et l'induction d’un stress du réticulum endoplasmique puis d’un stress oxydant. Nous avons également montré pour la première fois une accumulation intracellulaire d’ABs endogènes avec un médicament cholestatique in vitro. En outre, notre travail apporte des preuves que la motilité des canalicules biliaires (BC) est indispensable à la clairance des ABs. La voie ROCK et le complexe actomyosine sont fortement impliqués. Nous avons fourni la première démonstration que la voie ROCK et les dynamiques des BC sont des cibles majeures des composés cholestatiques. Nos données devraient contribuer à l'élaboration de méthodes de screening pour la prédiction précoce des effets secondaires induits par les médicaments cholestatiques. / Cholestasis is one of the most common manifestations of drug-induced liver injury (DILI). Since up to now it is unpredictable in 40% of all cases its accurate prediction represents a major challenge. First, we validated that differentiated HepaRG human liver cells are a suitable in vitro model to study drug-induced cholestasis, by comparing localization of influx and efflux transporters and their functional activity in these cells and primary human hepatocytes. All tested influx and efflux transporters were correctly localized to canalicular (BSEP, MRP2, MDR1, and MDR3) or basolateral (NTCP, MRP3) membrane domains and were functional. In addition, the HepaRG cell line also exhibits bile acids (BAs) metabolizing enzymes and has the capacity to synthesize BAs and to further amidate these BAs with taurine and glycine as well as sulfate, at a rate similar to that of primary hepatocytes. Concentration- dependent changes were observed in total BAs disposition after treatment of HepaRG cells by the cholestatic drug cyclosporine A (CsA). Inhibition of efflux and uptake of taurocholate was evidenced as early as 15 min and 1 h respectively. These early effects were associated with deregulation of cPKC pathway and induction of endoplasmic reticulum stress that preceded generation of oxidative stress. We also showed for the first time intracellular accumulation of endogenous BAs by a cholestatic drug in vitro. In addition, our work brings evidences that motility of bile canaliculi (BC) is essential for BAs clearance where ROCK pathway and actomyosin complex are highly implicated. We provided the first demonstration that ROCK pathway and BC dynamics are major targets of cholestatic compounds. Our data should help in the development of screening methods for early prediction of drug-induced cholestatic side effects.

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Chapter 1: Amphiphilic self-assembled systems as nanocarriers Nanocarriers are the nanometric size molecular assemblies that are used for the transport of small molecules into their non-solvating environments. These systems find major applications as drug delivery systems (DDS) in pharmacological research. These drug delivery systems improves solubility and stability of the drug molecules through encapsulation and also offer additional advantages like target specificity and stimuli responsive release of the drug molecules. Several types of DDS are reported in the literature, which can be prepared by a variety of processing techniques. Of these, molecular self- Chart 1: Developments in the design of amphiphilic nanocarriers assembly has attained considerable attention due to its greater tunability and control in the preparation of nanocarriers. In this chapter we discussed about the amphiphilic nanocarriers which are prepared through self-assembly of amphiphiles through hydrophobic interactions. Several developments in the area of amphiphilic nanocarriers such as di-block polymeric systems, dendritic systems and core-shell architectures are also mentioned. We also highlighted some recent developments in the design of amphiphilic nanocarriers through supramolecular interactions and advantages of such systems. Chapter 2: Bile acid derived dendrons and their application as nanocarriers Host-guest chemistry is well known for dendritic systems. To understand the influence of steric crowding, dendritic effect and importance of number of hydroxyl groups on the bile acid backbone in the host-guest chemistry of bile acid dendrons, we designed and synthesized a new series of C3 symmetric systems and studied the above-mentioned objectives through extraction of polar dyes into nonpolar media. Dye extraction experiments performed using trimeric molecules suggested that only the cholate derivatives (3 and 4) showed considerable extraction of the polar dyes into chloroform; deoxycholate derivatives did not show any extraction, thus emphasizing the importance of the number of hydroxyl groups for dye extraction in these molecular architectures. The effect of steric crowding at the core of these trimeric molecules was shown by efficient extraction of the dyes with the triethylbenzene core (4) compared to the benzene core (3). Greater influence of the aggregates in the case of triethylbenzene core on the extracted dye was also manifested in the Chart 2: Structures of the designed molecules 1-6 value of the induced circular dichroism signal. Surprisingly, a higher analogue in these molecular architectures showed lesser efficiency in dye extraction (on a per bile acid residue basis) compared to the trimers, suggesting a more compact structure for the higher analogue. This was supported by molecular modeling studies. Generality of these systems as nanocarriers for hydrophilic dyes was investigated by screening several other dyes and polar molecules, which are diverse in their structure and functionalities. All these experiments suggested a dependency of the extraction profile on the size of the dye molecule. This was also examined by dynamic light scattering studies, which showed larger size and wider distribution in the size of the aggregates in the case of larger dyes. We also demonstrated selective extraction of a single dye molecule from a blended food color (apple green) using one of the trimer (4) and demonstrated solvent dependent morphological changes in these compounds using electron microscopy. The self-assembly of these amphilic molecules at the air-water interface was studied through Langmuir monolayer studies. Chart 3: Structure of polar guest molecules (Cresol red (7). Erioglaucine (8), Eriochrome black T (9),) phenyl β-D-glucopyranoside (10) and Eosin B (11) Chapter 3: Design and synthesis of bile acid derived surfactants: Study of their aggregation and potential applications Bile acids are facially amphiphilic systems and their amphiphilicity can be improved by attaching polar groups on the bile acid back bone or by synthesizing oligomeric systems which show better self-assembly compared to their monomeric units. To study and improve the amphiphilicity of bile acids, we designed and synthesized a new tripodal surfactant system, with a phosphine oxide based central core to which the bile acids were attached through the C-3 position using click chemistry. Our molecular design also offers added advantage of studying the influence of the stereochemistry at the C-3 position on the aggregation of these molecular architectures. We synthesized trimeric systems with both cholic and deoxycholic acids attached to the central phosphine oxide core with α and β stereochemistry at the C-3 position. Aggregation of these molecules was studied by surface tension measurements, dye extraction studies and NMR. All these compounds showed aggregation at micromolar concentrations. NMR studies suggested changes in the structure of the aggregates at higher temperature and these changes were studied by DLS, which suggested thermodynamically stable monodispersed aggregates for cholic acid derivatives (13 and 15) at higher temperature. These aggregates are stable even after cooling to room temperature and with time. The aggregates of these derivatives were also characterized by atomic force microscopy. Gelation was observed in the case of α derivatives (12 and 13) in phosphate buffer (0.1 M) at pH 7.5 for both deoxy and cholic derivatives, which emphasized the influence of stereochemistry at C-3 position in these architectures. These gels were characterized by rheology experiments. Finally, the possible utility of these micellar systems as model systems to study photophysical processes was demonstrated through lanthanide sensitization experiments in these micellar solutions. Chart 4: Structure of the designed molecules Chapter 4: Synthesis of oligomeric bile acid-taurine conjugates: Study of their aggregation and efficiency in cholesterol solubilization Bile acids are bio-surfactants that are used for the emulsification of fats, vitamins etc. in our body. Bile salts also solubilize the excess cholesterol in our body through mixed micelle formation in the bile and when the bile gets saturated with cholesterol, it leads to cholesterol gallstone formation, which needs to be treated. Ursodeoxycholic acid (UDCA) is used as drug in some cases for the solubilization of (small) cholesterol gallstones, even though the efficiency to solubilize cholesterol is less for UDCA compared to the other bile acids (UDCA is less toxic than the others). So there is a need to develop new cholesterol solubilizing agents. Since oligomeric systems can aggregate better, we designed and synthesized two tetramer taurine conjugates, which differ in the spacer between the bile acid units. Since these conjugates are not soluble in water, their solubility and aggregation was studied in 10% MeOH/Water using pyrene fluorescence experiments. Aggregation studies suggested better aggregation for these molecules compared to their monomeric analogues. These aggregates were also characterized byDLS and electron microscopy. These systems were subsequently studied as nanocarriers for liphophilic dye molecules into aqueous media. Finally, the influence of oligomeric effect in cholesterol solubilization was investigated by cholesterol solubilization studied using these two tetramer taurine compounds and a control, sodium taurocholate. These studies suggested efficient solubilization of cholesterol by oligomers compared to monomeric analogues.(For structural formula pl see the abstract file)

In this doctoral thesis, a novel method for the determination of primary bile acids cholic acid and chenodeoxycholic acid is presented. Bile acids play various vital roles in the mammalian body. Moreover, their determination is extremely helpful in liver and biliary disease diagnosis and management. These saturated organic compounds lack strong chromophores and fluorophores in their structure, and thus are usually hard to detect in spectroscopy. For this reason, either instrumentally advanced but expensive methods, such as mass spectrometry, or less reliable enzymatic methods are commonly employed in bile acids quantitation. Hence, the demand for simple and reliable methods for their determination is strong. Bile acids are also known to be virtually inert for direct electrochemical oxidation. Herein, a simple method for their chemical activation for electrochemical oxidation on bare electrode materials was developed, optimized and applied to cholic acid and chenodeoxycholic acid determination. The activation is based on a dehydration reaction of a primary bile acid with 0.1 mol L-1 HClO4 in acetonitrile (water content 0.55%) that introduces double bond(s) into the originally fully saturated steroid core. This naturally increases the electron density in the structure, and thus allows electrochemical...

La cholestase intrahépatique de la grossesse (CIG) est la maladie du foie la plus répandue au cours de la grossesse. Elle est caractérisée par un prurit et est associée à une augmentation de la concentration des acides biliaires dans le sang, ce qui peut mener à un risque accru de conséquences périnatales indésirables, y compris un accouchement prématuré spontané et une augmentation des risques de mort de l’enfant à l’accouchement, entre autres. Le traitement médical de cette maladie repose actuellement sur l’acide ursodésoxycholique (UDCA) qui diminue le prurit et les anomalies biochimiques maternelles dans certains cas. Actuellement, le diagnostic de la CIG est posé suite à un test de quantification des acides biliaires sériques totaux par une méthode enzymatique. Nous émettons l'hypothèse que certains profils d’acides biliaires permettraient d’évaluer le risque de complications chez les femmes atteintes de CIG. En analysant les profilages, il pourrait être possible de déterminer la ou les espèces responsables de ces complications et ainsi déterminer des sous-groupes de patientes plus à risque de complications ou qui répondraient mieux au traitement. De plus, nous pensons que le traitement à l’UDCA, étant lui-même un acide biliaire, pourrait interférer lors de la quantification des acides biliaires totaux sériques, particulièrement dans les cas les plus problématiques de CIG où de fortes doses de ce composé sont administrées. Si c’était le cas, cela ferait en sorte que les valeurs de référence pourraient être modifiées en fonction du traitement administré. Le projet de recherche présenté vise au développement d’une méthode de quantification des acides biliaires sériques par la chromatographie liquide couplée à un spectromètre de masse en tandem (LC-MS/MS), qui permettrait un profilage des acides biliaires sériques chez les femmes enceintes atteintes de la CIG et qui permettrait également d’évaluer l’effet du traitement à l’UDCA sur ce profilage. Une méthode de quantification des acides biliaires par chromatographie liquide couplée à un spectromètre de masse en tandem a été développée et validée. Les surnageants obtenus par précipitation de protéines avec le méthanol ont été injectés sur le LC-MS/MS. La séparation est réalisée par chromatographie en phase inverse sur une colonne C18 de type interactions hydrophobes. Les transitions ioniques sur le spectromètre de masse ont été déterminées pour toutes les espèces d’acides biliaires au préalable et l’acide cholique deutéré, l’acide chénodésoxycholique deutéré ainsi que l’acide désoxycholique deutéré ont été utilisés comme standards internes. Quinze acides biliaires, y compris les acides biliaires conjugués et libres, ont été séparés et quantifiés par LC–MS/MS en utilisant l’ionisation par électro nébulisation (ESI) en mode ion négatif. La quantification a été réalisée en mode de surveillance de réactions multiples (MRM) avec des méthodes de courbes d'étalonnage externes. Les coefficients de corrélation des courbes standards pour tous les acides biliaires étaient supérieurs à 0,9966. La méthode développée a démontré une précision acceptable, avec une imprécision intra analyse inférieure à 3,2% pour toutes les espèces d’acide biliaire étudiées (pour des échantillons à 0,8 et 5 μg/mL) et une imprécision inter analyse inférieure à 15%. Une suppression d’ion moyenne de 8,2% a été observée, qui a été jugée acceptable. Une bonne corrélation a été obtenue entre la méthode LC-MS/MS et une méthode enzymatique (r=0,964). En conclusion, une méthode fonctionnelle, efficace et rapide a été développée pour quantifier les acides biliaires sériques individuels et différents profils d’acides biliaires représentant une large gamme de concentrations ont été comparés. La comparaison des profilages d’acides biliaires suggère que les acides biliaires principaux responsables de l’augmentation de la concentration des acides biliaires totaux dans le sang pour des échantillons à une concentration de plus de 10 μmol/L sont l’acide cholique glyco-conjugué (GCA), l’acide cholique tauro-conjugué (TCA) ainsi que l’acide ursodésoxycholique glyco- conjugué (GUDCA). Cette nouvelle méthode validée, et les données préliminaires sur les profils d’acides biliaires dans les échantillons cliniques, permettront de lancer des analyses cliniques prospectives pour évaluer l’effet du traitement par l’UDCA sur les concentrations totales d’acides biliaires sériques et sur les profils d’acides biliaires individuels chez les patientes atteintes de la CIG. / Intrahepatic cholestasis of pregnancy (ICP) is the most common liver disease during pregnancy. It is characterized by pruritus and is associated with an increased concentration of bile acids in blood, which may lead to an increased risk of perinatal consequences, including spontaneous preterm delivery and an increased risk of death at birth, among others. The medical treatment of this disease currently relies on ursodeoxycholic acid (UDCA) which reduces pruritus and maternal biochemical abnormalities in some cases. Currently, the diagnosis of ICP is made using an enzymatic assay to measure total serum bile acids. We hypothesize that profiling of the individual bile acids would make it possible to assess the risk of complications in women with ICP. By analyzing the bile acid profiles, it could be possible to determine which specie(s) is responsible for these complications and thus to distinguish subgroups of patients at higher risk of complications or who would respond better to treatment. In addition, we believe that UDCA treatment, being a bile acid itself, could interfere with the quantification of total serum bile acids, particularly in the most problematic cases of CIG where high doses of this compound are administered. If this was the case, it would mean that the reference values would need to be changed depending on the administered treatment. The research project aims to develop and validate a method for quantifying bile acids in serum by liquid chromatography coupled to a tandem mass spectrometer (LC-MS/MS), which would allow profiling of serum bile acids in affected women and which would also make it possible later to evaluate the effects of UDCA treatment on this profiling. A method for the quantification of bile acids by liquid chromatography coupled to tandem mass spectrometry has been developed and validated. The supernatants obtained by precipitation of proteins with methanol were injected onto the LC-MS/MS. The separation was carried out using reversed-phase chromatography on a C18 hydrophobic interactions type column. Ionic transitions on the mass spectrometer were determined for all bile acids species beforehand and deuterated cholic acid, deuterated chenodeoxycholic acid and deuterated deoxycholic acid were used as internal standards. Fifteen bile acids, including conjugated and free bile acids, were separated and quantified by LC–MS/MS using electrospray ionization (ESI) in negative ion mode. Quantification was performed in multiple reaction monitoring (MRM) mode with external calibration curve methods. Correlation coefficients for standard curves for all bile acids were greater than 0.9966. The method developed showed acceptable precision, with intra-assay imprecision of less than 3.2% for all the bile acid species studied (for samples at 0.8 and 5 μg/mL) and inter-assay imprecision under 15%. An average ion suppression of 8.2% was observed, which was judged acceptable. Finally, a good correlation was obtained between the LC-MS/MS method and an enzymatic method (r = 0.964). In conclusion, a functional, efficient and rapid method was developed to quantify the individual serum bile acids and different bile acids profiles representing a wide range of concentrations were compared. The comparison of the bile acid profiles suggests that the main bile acids responsible for the increase in total bile acids concentration in blood for samples at a concentration of more than 10 μmol/L are glycocholic acid (GCA), taurocholic acid (TCA), glycoursodeoxycholic acid (GUDCA). This new validated method, and the preliminary data on bile acid profiles in clinical samples, will allow us to initiate prospective clinical analyses to assess the effect of UDCA treatment on total bile acid concentrations and profiles in patients with intrahepatic cholestasis of pregnancy.

<p>Da bi se dobio sistem surfaktanata željenih osobina moguće je hemijski modifikovati već postojeće molekule povr&scaron;inski aktivnih supstanci, a druga mogućnost je konstrukcija binarnih sme&scaron;a surfaktanata. U farmaceutskoj i prehrambenoj industriji uveliko se primenjuju binarne sme&scaron;e povr&scaron;inski aktivnih molekula. Ukoliko je binarna me&scaron;ovita micela termodinamički stabilnija od hipotetičke idealne binarne me&scaron;ovite micele, onda je kritična micelarna koncentracija binarne sme&scaron;e surfaktanata niža čak i od hidrofobnije gradivne jedinice me&scaron;ovite micele, &scaron;to znači da je za isti efekat povr&scaron;inske aktivnosti potrebna manja količina binarne sme&scaron;e nego čistog surfaktanta. Različite gradivne jedinice binarne micele u micelarnoj pseudofazi mogu formirati specifične regije koje mogu vezivati lekove određenih strukturnih karakteristika. Pogodno je da jedna gradivna jedinica bude krute konformacije, npr. soli žučnih kiselina, dok je druga gradivna jedinica konformaciono pokretljiva (ugljovodonični nizovi iznad C10). Na taj način se povećava zapremina hidrofobne micelarne faze u odnosu na zapreminu hidrofobne micelarne faze monokomponentne micelle konformaciono krutog surfaktanta, &scaron;to povećava solubilizacioni kapacitet me&scaron;ovite micele u odnosu na monokomponentnu micelu krutog surfaktanta. Povećanjem dužine ugljovodoničnog niza konformaciono pokretnog surfaktanta povećava se stepen unutra&scaron;nje pokretljivosti u hidrofobnom domenu me&scaron;ovite micele, &scaron;to takođe povećava verovatnoću prihvatanja molekula gosta. Micelarni sistemi, kako monokomponentnih micela tako i binarnih me&scaron;ovitih micela dodatno se mogu termodinamički stabilizovati povećanjem jonske jačine rastvora. Za hidrataciju katjona tro&scaron;e se molekuli vode iz sistema, &scaron;to povećava efekat desolvatizacije hidrofobne povr&scaron;ine surfaktanata, pa se zbog toga pospe&scaron;uje samoasocijacija.</p> / <p>To obtain the surfactant system with the desired properties it is possible to chemically modify existing molecules of surface active agents. The other possibility is the construction of binary mixtures of surfactants. Binary mixtures of surface active molecules are widely used In the pharmaceutical and food industry. If the binary mixture micelle is more thermodynamically stable than the hypothetical ideal binary mixed micelle, then the critical micellar concentration (CMC) of the binary mixture of surfactants is even lower than the CMC of the more hydrophobic building block of the binary mixture. That means that for the same effect of surface activity less the amount of the binary mixture than the pure surfactants is required. The different building blocks of binary micelles in micelar pseudophase can form specific regions that can bind drugs of certain structural characteristics. It is suitable that one building block is of a rigid conformation, i.e. bile acid salts, while the second building block is of a flexible conformation (above C10 hydrocarbon arrays). In this way the volume of the hydrophobic micellar phase is increased in relation to the volume of the hydrophobic micellar phase of the monocomponent micelles of conformationally rigid surfactant, which increases the capacity of solubilisation of the mixed micelles, compared to the mono-component surfactant micelle of the rigid conformation. By increasing the length of the hydrocarbon array of the the conformational flexible surfactant, the degree of internal mobility in the hydrophobic domain of mixed micelles is also increased, which also increases the likelihood of acceptance of guest molecules. Micellar systems, of both monocomponent micelles and mixed micelles can be additionally thermodynamically stabilized by increasing the ionic strength of the solution. The hydration of cations uses the molecules of water from the system, which increases the effect of desolvatisation of the hydrophobic surface of the surfactants, and therefore promotes self-association.</p>

Es wurden 44 Hunde mit einem kongenitalen Portosystemischen Shunt präoperativ hinsichtlich ihrer Leberzellintegrität (ALT, AP, GLDH, GGT) und ihrer hepatischen Synthese- (Harnstoff, Cholesterin, Albumin) bzw. Metabolisierungsrate (Ammoniak) untersucht. Die hepatische Durchblutungs- und Resorptionsrate wurde anhand des Verlaufs der Serumgallensäuren im Gallensäuren-Stimulationstest mit Ceruletid (0,3µg/kg KM i.v.)vor und 30 min nach Stimulation (FSBA; PSBA) beurteilt. Eine Verlaufsuntersuchung erfolgte bei den Hunden, bei denen das Shuntgefäß in zwei Operationen verschlossen worden war. Die Untersuchungen wurden jeweils prae operationem, am zweiten, vierten und siebten Tag post operationem sowie abschließend mindestens 120 Tage nach vollständigem Verschluss des Shuntgefäßes durchgeführt. Es wurden die Ergebnisse der einzelnen Untersuchungstage untereinander mit Hilfe des gepaarten t-Tests sowie mit einer Kontrollgruppe (63 lebergesunde Hunde)unter Anwendung des unpaaren t-Tests verglichen. / The hepatic enzymes: alanine aminotransferase (ALT), alkaline phosphatase (AP), glutamat dehydrogenase (GLDH), gamma-glutamyl transferase (GGT); the hepatic synthetic (urea, cholesterol, albumin) and metabolic activity (ammonia) and the hepatic blood flow (serum bile acid stimulation test) were determined in 44 dogs with congeintal portosystemic shunt and in 63 healthy dogs. After determination of fasting serum bile acids (FSBA), the gallbladder contraction was induced by administration of 0,3µg/kg iv ceruletide (Takus). Blood samples of the poststimulatin serum bile acids (PSBA) were taken 30 minutes post administration. The portosystemic shunt was first attenuated (surgery 1) and 4 weeks later completely ligated (surgery 2). All dogs treated with this surgical procedure were examined with the described laboratory design before surgery, the second, the fourth, the seventh day after surgery and approxiamtely 120 days after complete ligation in a follow up study. To compare the developmentof the biochemical and hepatic alterations the paired and unpaired t-test were used.

Les acides biliaires sont cruciaux pour l’absorption intestinale des lipides et ils représentent une voie majeure d’élimination du cholestérol. À concentration élevée, ils sont cytotoxiques et potentiellement carcinogènes. Il est donc essentiel de maintenir des niveaux adéquats afin de préserver une homéostasie optimale. Le récepteur nucléaire FXR est grandement impliqué dans cette régulation, en étant activé par les acides biliaires qui agissent comme ligands et en régulant les gènes nécessaires à leur synthèse et leur métabolisme. FXR est aussi impliqué dans le métabolisme lipidique et glucidique, tout en ayant un rôle anti-inflammatoire et antiprolifératif. Les mécanismes régulant l’expression et l’activité transcriptionnelle de FXR sont toutefois peu connus. Leur caractérisation pourrait mener à l’identification de nouvelles cibles thérapeutiques pour les pathologies associées au syndrome métabolique. L’activation des récepteurs nucléaires peut se faire également de façon indépendante du ligand, soit via les modifications post-transcriptionnelles. Celles-ci permettent l’intégration d’une panoplie de signaux extracellulaires et l’adaptation de la réponse transcriptionnelle des récepteurs nucléaires aux variations de conditions cellulaires. La SUMOylation et l’ubiquitination sont deux modifications pouvant affecter la localisation cellulaire des récepteurs, leur interaction avec des partenaires protéiques, l’affinité de liaison au ligand, à l’ADN, leur dimérisation, la dégradation de leurs cibles et l’arrêt de la transcription. Étant donné le rôle important des modifications post-traductionnelles des récepteurs nucléaires en réponse aux divers signaux cellulaires, nous nous sommes intéressés particulièrement à leur impact sur la dégradation et l’activité transcriptionnelle de FXR. Nos études nous ont permis d’identifier et de caractériser un nouveau site de SUMOylation de FXR, impliqué dans la régulation du récepteur. Le résidu lysine responsable de conjuguer la protéine SUMO est localisé dans un motif non-consensus de SUMOylation, prénommé pSuM, qui est sous le contrôle de la phosphorylation d’un résidu serine régulé par la kinase CK2. Nous avons également déterminé que la modification de FXR par SUMO-2 permet le recrutement de l’ubiquitine E3-ligase SUMO-dépendante RNF4, qui induit l’ubiquitination et la dégradation de FXR. Cette cascade de signalisation est nécessaire pour l’activation transcriptionnelle de FXR et pour la régulation de l’expression des gènes cibles. Elle permet de contrôler ses niveaux protéiques de façon très dynamique et d’assurer ainsi une homéostasie optimale. Dans la deuxième étude, nous identifions un nouveau signal régulant l’activité transcriptionnelle de FXR. Les récepteurs tyrosine kinase de la famille EGFR/ErbB sont connus pour activer plusieurs voies de signalisation favorisant la croissance et la prolifération cellulaire. Cependant, leur expression et activité sont souvent altérées dans différents cancers, menant à une prolifération tumorale soutenue et dérégulée. Nous démontrons que l’activation des récepteurs de la famille EGFR/ErbB mène à la répression de l’activité transcriptionnelle de FXR en induisant la SUMOylation de FXR sur des résidus lysines situés dans des sites consensus de FXR. Étant donné le rôle antiprolifératif de FXR, l’impact répresseur des récepteurs ErbB sur l’activité de FXR pourrait contribuer à leur potentiel tumorigénique. Nos résultats approfondissent notre compréhension des mécanismes de régulation de l’expression et de l’activité de FXR. Étant donné son rôle important dans le métabolisme énergétique, la réponse transcriptionnelle de FXR doit être adaptée efficacement aux variations des conditions cellulaires dans un processus de régulation homéostatique. Les modifications post-traductionnelles assurent une régulation dynamique de l’activité de FXR et leur dérégulation pourrait être impliquée dans les pathologies associées au syndrome métabolique. / Bile acids are crucial for the absorption of intestinal lipids, and are directly involved in the efflux pathway to eliminate cholesterol. At high concentrations, bile acids are cytotoxic and potentially carcinogenic. It is therefore essential to maintain bile acids to adequate levels in order to preserve optimal homeostasis. Nuclear receptor FXR is directly involved in bile acid homeostasis by being activated by bile acids to regulate critical genes required for their synthesis and their metabolism. FXR is also involved in lipid and glucose metabolism, as well as having anti-inflammatory and anti-proliferative roles. However, the exact mechanisms regulating the degradation and activity of FXR are not well understood. Therefore, elucidation of FXR activity and response to cellular signals is essential to develop novel strategies and therapeutic targets for pathologies associated with the metabolic syndrome. Besides ligand activation, nuclear receptor can be regulated in a ligand-independent manner, mainly via post-translational modifications. Such modifications are important to allow homeostatic integration of diverse extracellular signals to ensure adaptation and transcriptional response of nuclear receptors. Among them, SUMOylation and ubiquitination are two modifications that modulate cellular localization of receptors, their interaction with protein partners, ligand binding and sensitivity, DNA affinity, receptor dimerisation, stability of their targets and transcriptional dynamics. Because of the important role of post-translational modifications in nuclear receptor function, we therefore study their specific impact in respect to FXR regulation and transcriptional competence. In this study, we have identified and characterized a new and non-consensus SUMOylation site involved in the regulation of FXR activity. This site, termed pSuM for phosphorylation-dependent SUMOylation motif, consists of a targeted lysine residue that conjugates SUMO proteins under the control of kinase CK2-mediated phosphorylation. We also determined that such modification of FXR with SUMO-2 induced the recruitment of SUMO-dependent E3 ligase RNF4, resulting in FXR ubiquitination and degradation. We demonstrate that this signaling cascade involving CK2 and RNF4 is required for FXR transcriptional activation and regulation of target gene expression. Our findings identify a cellular pathway that allows a dynamic control of FXR function to ensure efficient bile acid and energy metabolism in cells. In the second study, we identify a novel cellular signal that regulates FXR activity. Tyrosine kinase receptors of the EGFR/ErbB family are well known to participate in many signaling pathways, promoting cell growth and proliferation. Aberrant expression and activity of ErbB receptors are often associated to various cancers, leading to deregulated proliferation of tumors. Here, we show that ErbB activation leads to repression of FXR transcriptional activity by inducing FXR phosphorylation and specific SUMOylation at consensus sites. Because of the antiproliferative role of FXR, the negative impact of ErbB receptors on FXR transcriptional activity is thought to contribute to their tumorigenic potential. Altogether, our results expand our understanding of the mechanisms regulating FXR expression and activity. Because of its important role in lipid and energy metabolism, the transcriptional response of FXR needs to be efficiently adapted to variations of cellular conditions in order to achieve essential homeostatic control. As such, post-translational modifications ensure a dynamic regulation of FXR activity and their pathologic deregulation may be involved in diverse diseases associated with metabolic syndrome.

Les acides biliaires sont des composés naturels existants dans le corps humain. Leur biocompatibilité, leur caractère amphiphile et la rigidité de leur noyau stéroïdien, ainsi que l’excellent contrôle de leurs modifications chimiques, en font de remarquables candidats pour la préparation de matériaux biodégradables pour le relargage de médicaments et l'ingénierie tissulaire. Nous avons préparé une variété de polymères à base d’acides biliaires ayant de hautes masses molaires. Des monomères macrocycliques ont été synthétisés à partir de diènes composés de chaînes alkyles flexibles attachées à un noyau d'acide biliaire via des liens esters ou amides. Ces synthèses ont été réalisées par la fermeture de cycle par métathèse, utilisant le catalyseur de Grubbs de première génération. Les macrocycles obtenus ont ensuite été polymérisés par ouverture de cycle, entropiquement induite le catalyseur de Grubbs de seconde génération. Des copolymères ont également été préparés à partir de monolactones d'acide ricinoléique et de monomères cycliques de triester d’acide cholique via la même méthode. Les propriétés thermiques et mécaniques et la dégradabilité de ces polymères ont été étudiées. Elles peuvent être modulées en modifiant les différents groupes fonctionnels décorant l’acide biliaire et en ayant recours à la copolymérisation. La variation des caractéristiques physiques de ces polymères biocompatibles permet de moduler d’autres propriétés utiles, tel que l’effet de mémoire de forme qui est important pour des applications biomédicales. / Bile acids are natural compounds in the body. Their biocompatibility, facial amphiphilicity, rigidity of steroid nucleus, and ease of chemical modification make them excellent candidates as building blocks for making biodegradable materials used in drug delivery and tissue engineering applications. We have prepared main-chain bile acid-based polymers having high molecular weights. Macrocyclic monomers were synthesized from dienes, which consist of flexible alkyl chains attached to a bile acid core through either ester or amide linkages, via ring closing metathesis using first-generation Grubbs catalyst. They were polymerized using entropy-driven ring-opening metathesis polymerization using second-generation Grubbs catalyst. Copolymers were also prepared from monolactone of ricinoleic acid and cholic acid-based cyclic triester monomer via the same method. The thermal and mechanical properties and degradation behaviours of these polymers have been investigated. The properties can be tuned by varying the chemical linking with the bile acid moiety and by varying the chemical composition of the polymers such as copolymerization with ricinoleic acid lactones. The tunability of the physical properties of these biocompatible polymers gives access to a range of interesting attributes. For example, shape memory properties have been observed in some samples. This may prove useful in the design of materials for biomedical applications.