Dissertationen zum Thema „Lc-Ms/ms | 13c rmn“
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Gauthier, Lea. „Approche métabolomique pour la compréhension des mécanismes de résistance à Fusarium graminearum et accumulation de trichothécènes chez le maïs“. Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0235.
Der volle Inhalt der QuelleFusarium graminearum is the main causal agent of maize ear rot or Gibberella ear rot (GER), an important fungal disease affecting maize. GER leads to significant economic loss and serious health issues due to the ability of F. graminearum to produce mycotoxins such as type B trichothecenes. One promising approach to control Giberella Ear Rot and reduce mycotoxins contamination is to promote host-genetic resistance. Several Quantitative Trait Loci (QTLs) have been identified in maize. However molecular basis to resistance to Fusarium infection remains largely unknown and the success of selection for GER resistance is still challenging. Biochemical approaches can provide valuable insights in the mechanisms crops employ against F. graminearum and its production of mycotoxins. A biochemical profiling could actually be an efficient way to decipher plant-pathogen interactions and progress in screening resistant maize lines. This study aims to elucidate the metabolic profiling of F. graminearum resistance and toxin accumulation in kernels toward the combination of high resolution mass spectrometry and 1H NMR to identify a large set of metabolites, preformed, constitutive as well as inducible defense metabolites that could play a key role in GER resistance. This approach was applied to kernels harvested at two developmental stages. Twenty genotypes with contrasting levels of resistance were inoculated, or not, with a toxigenic Fusarium graminearum strain through the silk channel. The obtained data allowed highlighting a set of biochemical compounds linked to the resistance or susceptibility of maize genotypes
Bonneau, Natacha. „Acétogénines d’Annonaceae et parkinsonismes atypiques : de la biodisponibilité de l’annonacine à l’exposition alimentaire“. Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS271/document.
Der volle Inhalt der QuelleAbstract : A high proportion of atypical parkinsonisms was reported in French West Indies in 1999. Epidemiological studies pointed out an association with the consumption of fruits and medicinal herbs from Annonaceae of the Annona genera. Numerous Annonaceae members contain Annonaceous acetogenins (AAGs), which are highly cytotoxic molecules. They were found in the pulp fruit of Annona muricata. However, scarce only quantitative exist for this fruit and those of related species. Moreover, although annonacin, the major AAG of A. muricata proved neurotoxic in vivo, no quantitative data is available towards its distribution to the brain. We therefore developed a method for annonacin quantitation in Rat plasma and brain homogenate, in order to determine its bioavailability and the fraction reaching the brain, to understand why those highly cytotoxic molecules are not responsible for acute toxicity when fruits are ingested. We then developed a quantitation method for global estimation of AAGs in crude fruit extracts by 1H NMR, which we applied to the fruit pulp of A. muricata batches from diverse locations. An LC-MS/MS method was also developed for the qualitative study of AAGs. It was applied to different batches from A. squamosa fruits. The species A. reticulata and A. glabra were also examined. Those two approaches contributed in a better estimation of AAGs exposure by fruit consumption
Romminger, Stelamar. „Avaliação do potencial metabólico de linhagens de fungos isolados de uma espécie de alga marinha do gênero Sargassum“. Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-21082009-110418/.
Der volle Inhalt der QuelleFungi are widely disperse microorganisms, typically associated with plants, animals, soil and aquatic environments (fresh and sea water), participating in the elements cycling. Although many ecological roles have been described for terrestrial fungi, ecological studies of marine derived fungi are still scarce. Therefore, oceans, which represent approximately half of the global biodiversity, are a huge and virtually unexplored source of microorganisms producers of interesting metabolites. The aim of this study was to isolate fungal strains derived from a marine algae of the Sargassum genus, and the evaluation of their metabolical potential for the production of secondary metabolites. Overall, 58 strains were isolated, of which 52 were grown in liquid culture media and extracted with organic solvents, originating 99 crude extracts. These extracts were analyzed by bioassays, thin layer chromatography (TLC), nuclear magnetic resonance (NMR) and liquid chromatography coupled with a photo diode array, an evaporative light scattering, and a mass spectrometry detectors (LC - PDA - ELSD - MS). The evaluation with the antibiotic assay resulted in the largest number of active extracts (n = 13), followed by the enzymatic (n = 8), the cytotoxic (n = 3) and the antituberculosis (n = 1) assays. The crude extract AS Fub 39, which presented antibiotic activity, was selected for additional studies. This extract was purified by HPLC, and its major compound identified as the 8-methoxy-3,5-dimethylisocroman-6-ol. Later, the AS Fub 39 strain was taxonomically identified as Penicillium steckii.
Marchal, Axel. „Recherches sur les bases moléculaires de la saveur sucrée des vins secs : approches analytique et sensorielle“. Thesis, Bordeaux 2, 2010. http://www.theses.fr/2010BOR21779/document.
Der volle Inhalt der QuelleSweetness contributes to the balance in taste of dry wines. An increase in sweet taste isobservable during post-fermentation maceration and oak-barrel aging. We have revealed thatthese phenomena are respectively due to the release in wines of yeast peptides and nonvolatileoak wood compounds.The role of Hsp12 protein from S.cerevisae on the increase in sweetness is establishedwith both molecular biology and sensorial analysis techniques.The development of a method coupling centrifugal partition chromatography andgustatometry has enabled us to fractionate an oak-wood extract and to purify several sapidcompounds. Thanks to both the LC-FTMS and the NMR spectroscopy methods, we havehighlighted four new molecules, called quercotriterpenosides (QTT), out of which QTT Iand III are responsible for a sweet taste. The perception thresholds of QTT I and a bitterlignan, lyoniresinol, are respectively 590 μg/L and 1.52 mg/L.LC-FT/MS method has been used to develop a quantification method for these compoundsand we have demonstrated the organoleptic impact of lyoniresinol in wines.QTT I and III are likely to contribute, directly or indirectly, to the increase in sweetnessconsecutive to barrel aging in dry wines
Cardoso, Josiane de Oliveira. „Identificação estrutural de metabólitos provenientes do metabolismo in vitro de compostos bioativos e estudos de fenotipagem enzimática“. Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/7718.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
This work reports studies of in vitro metabolism involving the compound 3-(2-chloro-6-fluorobenzyl)- imidazolidine-2,4-dione (LPSF-PT-31), a new 2-adrenoceptor agonist and, studies of enzyme phenotyping of montelukast, a drug used for the treatment of asthma. The results of this study revealed that LPSF-PT-31 is metabolized via CYP P450s in rat and human liver microsomes, producing only one major hydroxy-metabolite. LPSFPT- 31 showed a higher rate of in vitro metabolism in rats, which suggests a greater exposure to the drug in humans. The structural identification of LPSF-PT-31 metabolite’s was achieved through LC-MSn and 1H-NMR analysis that provided data to conclude that the hydroxylation occurred in the 5th position of the imidazolidine ring yielding to the production of 3-(2-chloro-6-fluorobenzyl)-5-hydroxyimidazolidine-2,4- dione. Related to the studies of enzyme phenotyping of montelukast, it was observed that the glucuronidation is the main clearance pathway of montelukast accounting for ~85% of the total apparent in vitro Clint (CYPs +UGTs) and that the CYP-mediated oxidation accounts only for ~15% to the overall metabolism of the drug, being montelukast acyl-β-D-glucuronide and montelukast 1,2 diol the major metabolites formed via UGTs and CYPs, respectively. Kinetic studies, correlation analysis, inhibition studies and, experiments in expressed CYPs and UGTs revealed that the CYP2C9 and CYP2C8 are comparably involved in the formation of montelukast 1,2- diol. CYP3A4 was responsible for the formation of 21(R)-OH montelukast and 21(S)- OH montelukast, while multiple CYPs catalyzed the formation of 25-OH montelukast (CYP2C8>2C9>3A4>2C19). The direct glucuronidation of montelukast resulted in the formation of montelukast acyl-β-D-glucuronide and of a new metabolite (Mglucuronide) not reported previously and was exclusively catalyzed by isoform UGT1A3. In conclusion, the in vitro data suggest that the applicability of montelukast as a probe of CYP2C8 activity in vitro and in vivo may be severely compromised due to important role of UGT1A3 and involvement of multiple CYPs in its metabolism. In addition, considering the lack of selective markers for UGT1A3, montelukast may be used as a selective marker of the UGT1A3 in vitro and in vivo.
Este trabalho relata estudos de metabolismo in vitro envolvendo o composto 3-(2-cloro-6- fluorobenzil)-imidazolidina-2,4-diona (LPSF-PT-31), um novo agonista adrenérgico 2A, e estudos de fenotipagem enzimática do montelucaste, fármaco utilizado no tratamento da asma. Os resultados do presente estudo revelaram que LPSF-PT-31 é metabolizado via CYP P450s em microssomas de fígado de ratos e humanos, produzindo apenas um hidroxi-metabólito principal. LPSF-PT-31 apresentou uma maior taxa de metabolismo in vitro em ratos, o que sugere uma maior exposição ao fármaco em seres humanos. A identificação estrutural do metabólito do LPSF-PT-31 foi estabelecida através de análises por LC-MSn e 1H-RMN, o que indicou que a reação de hidroxilação ocorreu na posição 5 do anel da imidazolidina levando a produção do metabólito 3-(2-cloro-6-fluorobenzil)-5-hidroxi-imidazolidina-2,4-diona. Em relação aos estudos de fenotipagem enzimática do montelucaste foi observado que a glucuronidação é o principal mecanismo de eliminação deste fármaco, representando ~85% do Clint in vitro aparente total (CYPs +UGTs) e que a oxidação via CYPs representa somente ~15% do Clint in vitro, sendo os metabólitos majoritários formados via UGTs e CYPs o montelucaste acil-β-D-glucuronídeo e o montelucaste 1,2 diol, respectivamente. Estudos cinéticos, de correlação com a atividade enzimática, de inibição e empregando CYPs e UGTs expressas indicaram que as CYP2C9 e CYP2C8 estão comparavelmente envolvidas na formação do montelucaste 1,2 diol. A CYP3A4 foi responsável pela formação dos metabólitos 21(R)-OH montelucaste e 21(S)-OH montelucaste, enquanto múltiplas CYPs catalisam a formação do 25-OH montelucaste (CYP2C8>2C9>3A4>2C19). A glucuronidação direta do montelucaste resultou na formação do montelucaste acil-β- D-glucuronídeo e de um novo metabólito (M-glucuronídeo) não reportado previamente e foi catalisada exclusivamente pela isoforma UGT1A3. Deste modo, os dados in vitro sugerem que a aplicabilidade do montelucaste como marcador da CYP2C8 in vitro e in vivo pode ser severamente comprometida devido ao importante papel da UGT1A3 e o envolvimento de múltiplas CYPs no seu metabolismo. Ainda, considerando a falta de marcadores seletivos para a UGT1A3, montelucaste pode ser utilizado como um marcador seletivo da UGT1A3 in vivo e in vitro.
Nohra, Youssef A. „Résines végétales actuelles et fossiles : origine, caractérisation chimique et évolution“. Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S165.
Der volle Inhalt der QuelleThis work focuses on the chemical characterisation of amber from different outcrops from different localities, and varied ages. Some of these outcrops had never been studied. All the amber samples were analysed with the same analytical techniques. The combination of the data obtained from spectroscopic (IR and 13C NMR) and chromatographic (THM-GC-MS) analysis allows the identification of the botanical origin of the amber and provide some information, for the reconstruction of the palaeoenvironment. Biomarkers for the cheirolepidiaceous resins were proposed based on the chemical characterisation of different amber outcrops dating from the Upper Jurassic (Kimmeridgian) to the Upper Cretaceous (Santonian) from Lebanon, Jordan, Congo, Ecuador and France. The Cheirolepidiaceae familt was exclusively present in the Mesozoic era. Hence, the evolution of the botanical origins of the produced resins during the Mesozoic and Cenozoic eras was discussed. It seems that Araucariaceae and Cheirolepidiaceae were the dominant resin producing trees during the Upper Jurassic and the Lower Cretaceous. While, cupressaceous resiniferous plants were dominant during the Upper Cretaceous. Howerver, resins dating from the Cenozoic era, were produced by a wider variety of plants, as resiniferous families of Angiosperm intensively participated in the resin production, i.e. the Peruvian amber produced by Fabaceae. Conifer resins traces were also detected in the Tertiary, such as the amber from the Araucariaceae found in New Zealand. The obtained data allowed a re-evaluation of the classification of ambers by Py-GC-MS, leading to the discovery of a novel molecule. This molecule of an unknown structure brings a new discrimination factor between the classes Ib and Ic. Finally, the age / maturity relationship is showed to be dependent on the burial and the conservation conditions of the resins. A broad molecular database is established based a large group of amber outcrops from different ages, and having diverse botanical origins. This database could be used as a comparative platform for further work in the future
Prieri, Marion. „Reprogrammation de la bioactivation de prodrogues antituberculeuses : conception, synthèse et évaluation biologique de molécules bioactivables selon différents mécanismes oxydatifs et de composés potentialisant l’activité de nitro-imidazolés“. Thesis, Lille, 2018. http://www.theses.fr/2018LILUS056.
Der volle Inhalt der QuelleFor the last two decades, humanity has faced a dramatic increase in the number of resistant and multi-resistant bacteria, putting at risk the entire therapeutic arsenal. Tuberculosis is particularly affected by the spread of multi-resistant strains of antibiotics, very often forcing doctors to prolong patients care for several months and juggling with different antibiotics in the course of the treatment, which further delays recovery. In addition, if pan-resistant strains remain exceptional for the moment, they clearly illustrate the dangers of allowing an already worrying clinical situation to degenerate. It is therefore necessary today to develop innovative therapeutic approaches to fight more effectively against these phenomena of resistance. Unlike most conventional antibiotics, a large number of antituberculous drugs have the distinction of being prodrugs. They require bioactivation within the mycobacterium by the action of specific enzymes in order to be able to exercise their antibiotic effect. Over the last few years, research teams U1177 and U1019 have identified several families of compounds that potentiate or reprogram the bioactivation pathways of ethionamide. These compounds act via the inhibition of the transcriptional regulators of the bacterium involved in the bioactivation of ethionamide. These teams have shown that in addition to increasing the sensitivity of Mycobacterium tuberculosis to ethionamide, it is also possible to resensitize ethionamide-resistant clinical strains by stimulating cryptic bioactivation pathways of this antibiotic.The first objective of this thesis was to evaluate the substrate specificity of the three currently known pathways of ethionamide. This study was performed by producing ethionamide derivatives and studying their activation by alternately stimulating each of the three pathways using specific boosters. To do this, a new synthesis route of thioisonicotinamides has been developed in order to quickly obtain a large number of structural analogues of ethionamide. We were then able to explore the antimycobacterial activity of these analogues, alone or in combination with boosters which individually stimulate the three activation pathways. This study allowed us to highlight the specificities of each pathway. In parallel, a cyclic voltammetric study carried out on some of these compounds allowed us to correlate the oxidation potential of the analogues with their antimycobacterial activities.In a second axis, we tried to follow, by NMR and by LC-MS/MS, the bioactivation of ethionamide in a heterologous expression model of ethionamide bioactivation enzymes in E. coli.In a third part, we were interested in the identification and the characterization of new bioactivatable molecules by the different bioactivation pathways of ethionamide.Finally, phenotypic screening was performed on Mycobacterium tuberculosis to extend the concept of resistance reversal to other anti-tuberculosis pro-antibiotics. This approach has led to the identification of a molecule capable of reprogramming the bioactivation of nitroimidazoles of major clinical importance, such as pretomanid and delamanid. On this basis, we undertook a work of pharmacomodulation of this hit, which allowed us to determine the first structure-activity relationships in this chemical family
Traboulsi, Ali. „Radiolyse gamma et lixiviation post irradiation de résines échangeuses d'Ions“. Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4301/document.
Der volle Inhalt der QuelleThe knowledge of the behavior under irradiation and in presence of water of Ion Exchange Resins (IER) is very necessary to predict their impact on the environment during the storage phase and in a possible deep geological disposal. The IER studied are the MB400 mixed bed resin and its « pure » anionic and cationic components. The experimental strategy used in this work was based on the use of chemometric tools permitting to estimate the effect of the irradiation atmosphere, the dose rate, the absorbed dose and the leaching temperature. The gaseous and water-soluble radiolysis products were analyzed by gas Mass Spectrometry (MS) and Ion Chromatography (IC). The IER generated principally H2g, CO2g and amines for which quantities depended of the resin nature and the irradiation conditions. The analysis of solid irradiated resins was investigated by Fourier Transformed Infrared (FTIR) and Nuclear Magnetic Resonance (13C NMR) techniques. The last ones revealed structural modifications of the IER solid matrix in function of the experimental conditions. Their behavior in presence of water was studied during 143 days by characterization of the organic matter released after their post-irradiation leaching. The kinetics showed that all the water-soluble components were releasing at the first contact with water. The Total Organic Carbon (TOC) quantity released depends, according to the resin nature, either on the dose, either on the irradiation atmosphere. The dose rate has no effect on the degradation and the leaching of the MB400 resin, which behaved differently than its pure components
Cordonnier, Julien. „Toxoplasma gondii : identification par docking inverse sur des cibles moléculaires de composés actifs issus de ressources naturelles“. Electronic Thesis or Diss., Reims, 2024. http://www.theses.fr/2024REIMS001.
Der volle Inhalt der QuelleTree barks, by-product of forestry industry, constitute an abundant and sustainable source of natural compounds. Toxoplasma gondii is the parasite responsible for toxoplasmosis, posing a threat to fetuses, newborns, and immunocompromised individuals. The current therapeutics, limited and poorly tolerated, are now confronted to chemoresistant phenomena. This doctoral project aims to explore the chemical space associated with tree barks from the Champagne-Ardenne region, as relevant protein targets to fight T. gondii. An initial in silico evaluation using reverse docking (AMIDEv2.0) was carried out to identify biological target for triterpenes derived from betulone, isolated from the European alder, which had exhibited in vitro anti-toxoplasmosis activity. Among 87 proteins of T. gondii, CDPK3 was identified as the most probable target. Subsequently, a bank of 25 essential 3D protein structures for parasite survival, including 19 homology-modeled structures, was compiled. Thereafter, compounds from the Essential National Chemical Library were screened against this protein bank, using AMIDEv2.0. Two proteins were identified as potential targets; one of them was ATG3, a protein structure modeled from homologs with less than 50% identity. Subsequently, the barks of European Larch, whose n-heptane extract had shown significant activity (58% inhibition of parasitic growth at 100 µg/ml), were subjected to a chemical profiling. First, through a fractionation process using Centrifugal Partition Chromatography, and then a dereplication approach combining data from nuclear magnetic resonance and mass spectrometry. Tools like VersaDB and CATHEDRAL were developed to facilitate the creation of custom-databases and assess the confidence level of annotations. 52 molecules were annotated and associated with a confidence score. Simultaneously, in vitro tests demonstrated that 2 out of the 12 CPC fractions, primarily composed of terpenic derivatives, inhibited the parasite's survival by more than 40% at 25 µg/ml. Ultimately, the annotated compounds from L. decidua were subjected to AMIDEv2.0. The overlap between in vitro and in silico results highlighted 7-oxo-dehydroabietic acid and daniellic acid, strongly correlated with the in vitro inhibitory activity of the barks. CDPK1 and the SET-containing Protein are likely protein targets for these two ligands, thereby providing initial insights into their mechanism of action. These two hits are currently undergoing in vitro evaluation to verify the efficiency of developed approach during this doctoral project
Gabaston, Julien. „Stilbènes de la vigne et d’essences forestières (pin, épicéa) : Etude phytochimique et recherche d’activités anti-oomycète et insecticide“. Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0302/document.
Der volle Inhalt der QuelleNowadays, is a priority to turn towards a more eco- and consumer friendly agriculture resulting in the reduction of the chemical inputs. In a context of a sustainable development, the investigation of natural products to fight against diseases and pests raised a renewed interest. In this thesis, hydroalcoholic extracts derived from grapevine (cane, wood, root) and forest species (spruce bark, pine knot) by-products have demonstrated to be a great source of bioactive polyphenols, and particularly in complex stilbenes. Indeed, these extracts have proved to confer a broad spectrum of activities against different major plant diseases. In particular, an oomycide potential against downy mildew of the vine and an insecticidal capacity against Solanaceae pest were reported. Furthermore, the relevant use of “green chemistry” to extract stilbenes as an alternative method of organic solvents has been highlighted. The present findings strengthen an original line of research to advance in a more sustainable viticulture and agriculture, using less toxic and biodegradable biocontrol products, being this a possible and realistic solution to combat plant pathogens
Durand, Stéphanie. „Contribution à l'étude de la biodégradation et de la biodisponibilité dans les sols de la mésotrione et du glyphosate“. Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2007. http://tel.archives-ouvertes.fr/tel-00718186.
Der volle Inhalt der QuelleTraboulsi, Ali. „Radiolyse gamma et lixiviation post irradiation de résines échangeuses d'Ions“. Electronic Thesis or Diss., Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4301.
Der volle Inhalt der QuelleThe knowledge of the behavior under irradiation and in presence of water of Ion Exchange Resins (IER) is very necessary to predict their impact on the environment during the storage phase and in a possible deep geological disposal. The IER studied are the MB400 mixed bed resin and its « pure » anionic and cationic components. The experimental strategy used in this work was based on the use of chemometric tools permitting to estimate the effect of the irradiation atmosphere, the dose rate, the absorbed dose and the leaching temperature. The gaseous and water-soluble radiolysis products were analyzed by gas Mass Spectrometry (MS) and Ion Chromatography (IC). The IER generated principally H2g, CO2g and amines for which quantities depended of the resin nature and the irradiation conditions. The analysis of solid irradiated resins was investigated by Fourier Transformed Infrared (FTIR) and Nuclear Magnetic Resonance (13C NMR) techniques. The last ones revealed structural modifications of the IER solid matrix in function of the experimental conditions. Their behavior in presence of water was studied during 143 days by characterization of the organic matter released after their post-irradiation leaching. The kinetics showed that all the water-soluble components were releasing at the first contact with water. The Total Organic Carbon (TOC) quantity released depends, according to the resin nature, either on the dose, either on the irradiation atmosphere. The dose rate has no effect on the degradation and the leaching of the MB400 resin, which behaved differently than its pure components
Coelho, Maria Margarida Serra. „Quantification of glucose turnover and Cori cycling in ATGL-knockout mice by [U- 13C6]glucose infusion and LC-MS/MS analysis of glucose 13C-isotopomers“. Master's thesis, 2013. http://hdl.handle.net/10316/24622.
Der volle Inhalt der QuelleA patofisiologia de doenças metabólicas como a diabetes mellitus tipo II (T2DM) é caracterizada pela perda de sincronia entre a síntese e catabolismo de triacilgliceróis (TAG). A lipase adiposa de triacilglicerídeos (ATGL), uma enzima envolvida na hidrólise de TAGs, tem sido alvo de vários estudos de forma a compreender o seu papel na resistência à insulina. A razão para este aumento de interesse é o fato de os ATGL knock‐outs (ATGL‐/‐) terem demonstrado maior sensibilidade à insulina e tolerancia à glucose em comparação com ratinhos sem a delecção (WT). Apesar de eles não recorrerem a ácidos gordos armazenados como fonte de energia, estas características fazem dos ratinhos ATGL‐/‐ um modelo único para a melhor compreensão da relação entre o metabolismo de TAGs e a resistência à insulina. A taxa do turnover de glucose e reciclagem pelo ciclo de Cori é altamente suscetível tanto à sensibilidade a insulina como à disponibilidade de nutrientes. Sob condições normais de jejum, a maioria da glucose é reciclada pelo ciclo de Cori. No entanto, a maior dependência de glucose por parte dos ratinhos ATGL‐/‐, levou‐nos a colocar a hipótese de que estes ratinhos seriam mais dependentes da produção de glucose endógena (EGP) para fazer face a esta necessidade e que a glucose seria eliminada principalmente através da oxidação, resultando em menor reciclagem através do ciclo de Cori. Para estudar esta hipótese, os enriquecimentos de glucose de ratinhos ATGL‐/‐ e WT, infundidos com [U‐13C6]glucose, foram quantificados por análise de gotas de sangue (DBS) por cromatografia líquida acoplada à espectrometria de massa (LC‐MS/MS). Após o desenvolvimento e validação do método, a quantificação do enriquecimento da [U‐13C6]glucose precursora permitiu a determinação da taxa de EGP, enquanto a quantificação dos isotopómeros parcialmente marcados [1,2‐13C2]glucose e [1,2,3‐13C3]glucose, forneceram uma avaliação do ciclo de Cori. A análise da EGP e do metabolismo do ciclo de Cori entre ratinhos ATGL‐/‐ e wild‐type, revelou que as taxas de EGP eram tendencialmente mais baixas para ratinhos ATGL‐/‐, quando comparados com ratinhos wild‐type e que o ciclo de Cori contribuía quantitativamente para a EGP em ambos os grupos. Assim, estes dados não confirmam a hipótese de maior oxidação de glucose e ciclo de Cori reduzido em ratinhos ATGL‐/‐.
The pathophysiology of metabolic diseases such as type II diabetes mellitus (T2DM) is characterized by a loss of synchrony between triacylglycerols (TAG) synthesis and catabolism. The adipose triacylglyceride lipase (ATGL), an enzyme involved in TAGs hydrolysis, has been the target of several studies in order to understand its role in insulin resistance. The reason for this increasing interest is the fact that ATGL knock‐outs (ATGL‐/‐) have demonstrated to be more insulin sensitive and glucose tolerant in comparison to wild‐types. Even though they do not resort to stored fatty acids (FAs) as energy fuel, these characteristics make ATGL‐/‐ mice a unique model for the better understanding of the relationship between TAGs metabolism and insulin resistance. The rate of glucose turnover and recycling via the Cori cycle is highly susceptible to both insulin sensitivity and nutrient availability. Under normal fasting conditions, the majority of glucose is recycled via the Cori cycle. However, in the case of ATGL‐/‐ mice, since they are more dependent on glucose, it was hypothesized that these mice would be more dependent on endogenous glucose production (EGP) to meet this demand and that glucose would be disposed mainly through oxidation, resulting in less recycling via the Cori cycle. To study this hypothesis, glucose enrichments from ATGL‐/‐ mice and wild‐type mice, infused with [U‐13C6]glucose, were quantified by liquid chromatography coupled to tandem mass spectrometry (LC‐MS/MS) analysis of dried blood spots (DBS). After method development and validation, the quantification of the parent [U‐13C6]glucose enrichment allowed the determination of the rate of EGP, while the quantification of the partially labelled isotopomers [1,2‐13C2]glucose and [1,2,3‐13C3]glucose, provided a measure of the Cori cycle. Analysis of EGP and Cori cycle metabolism between ATGL‐/‐ and wild‐type mice revealed that EGP rates tended to be lower for ATGL‐/‐ mice compared to wild‐types and that the Cori cycle contributed quantitatively to EGP in both groups. Therefore, these data do not support the hypothesis of higher glucose oxidation and reduced Cori cycling in ATGL‐/‐ mice.
Duarte, Joana Filipa Lopes. „A reação de Buchwald-Hartwig no desenvolvimento de um novo método para a síntese de Minociclina“. Master's thesis, 2022. http://hdl.handle.net/10362/132232.
Der volle Inhalt der QuelleMinocycline is an active pharmaceutical ingredient (API) produced at Cipan, in the form of hydrochloride (M.HCl) – the process iniciates with the catalytic hydrogenation of DMCT.HCl (demethylchlortetracycline hydrochloride), requiring seven steps, including synthesis and purification, to obtain pure M.HCl. In order to reduce production time and the impurities formed, this project aims to develop and optimize a new minocycline synthesis process from DMCT.HCl or 7-iodosancycline.TFA (7-iodosancycline trifluoroacetate), based on literature procedures that use the Buchwald-Hartwig reaction. This reaction allows, by catalytic action of a palladium complex, the exchange of the halogen atom present in the raw materials by dimethylamine, obtaining minocycline in a more direct way. During the experimental part, several tests were performed, altering the combination of the factors necessary for the reaction: the catalyst, the ligand, the base, the solvent and the temperature, knowing that each one has an influence on the yield and formation of by-products. Despite several attempts, HPLC/LC-MS analyses did not detect formation of minocycline. The failure of its formation is thought to be due to a stereochemical impediment caused by the various substituent groups, characteristic of tetracyclines. Throughout the experiments with 7-iodosancycline.TFA, it was observed the formation of an unknown compound of mass 554 g/mol. Not being the product of any amination reaction, since it is formed without the presence of dimethylamine, its isolation by column chromatography was performed, for later characterization. Once dried by lyophilization, it was submitted to NMR analyses from which a possible molecular structure for the compound was proposed. It suggests the introduction of a carbonyl, possibly from
Carvalho, Maria João Menezes. „Caracterização e isolamento de compostos bioactivos do fungo Laurobasidium lauri (Madre de louro)“. Master's thesis, 2010. http://hdl.handle.net/10400.13/626.
Der volle Inhalt der QuelleUniversidade da Madeira