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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Ligands dérivés de saccharides et, ou supportés par un bras poly(éthylène) glycol : synthèse et applications en catalyse organométallique / Ligands derived from saccharides and, or supported on poly(ethylene) glycol arm : synthesis and applications in organometallic catalysis

Adidou, Ouissam 16 October 2009 (has links)
La synthèse de deux familles de ligands a été envisagée. La première famille de ligands concerne la préparation de nouveaux ligands dérivés de la D-glucosamine ou du D-glucose qui seront engagés dans la réaction de substitution allylique de type Tsuji-Trost en phase homogène. La deuxième famillede ligands concerne la préparation de ligand supportés par un bras poly(éthylène) glycol et dérivés dela D-glucosamine ou de la di-(2-pyridyl)méthylamine. Ces ligands hydrosolubles ont été engagés dans deux réactions pallado-catalysées en phase aqueuse à savoir la substitution allylique de type Tsuji-Trost et la réaction de couplage croisé de type Suzuki-Miyaura, respectivement. / Ligands derived from saccharides and, or supported on poly(ethylene) glycol arm: synthesis and applications in organometallic catalysis. The synthesis of two types of ligands has been investigated. The first family of ligands has been the preparation of new ligands derived from D-glucosamine or D-glucose, which have been tested in the allylic substitution of Tsuji-Trost in homogeneous phase. The second one has een the preparation of ligand supported on poly(ethylene) glycol arm and derived from D-glucosamine or di-(2- pyridyl)methylamine. These last hydrosoluble ligands have been tested in two Pd-catalyzed reactions in aqueous phase: the allylic substitution of Tsuji-Trost and the cross-coupling Suzuki-Miyaura reaction, respectively.
22

Composés radiopharmaceutiques marqués au fluor-18 utilisés en routine clinique: nouvelles méthodes de production et validation animale / Florine-18 labelled radiopharmaceuticals in clinical routine use: new methods of production and animal validation

Aerts, Joël 18 December 2008 (has links)
RESUME: Le travail de recherche rapporté dans cette thèse concerne lamélioration de traceurs marqués au fluor-18 utilisés en routine clinique : la 2-[18F]fluoro-L-tyrosine et le 2-désoxy-2-[18F]fluoro-D-glucose. Les résultats relatifs à lacide aminé, de valeur confirmative pour les connaissances publiées antérieurement dans la littérature, consistent en une validation chez le rat qui entérine le potentiel de ce traceur pour létude de la vitesse de synthèse des protéines cérébrales in vivo. Les perspectives futures pour ce traceur sont dès lors lextension de son utilité dans le domaine de loncologie et son utilisation pour létude de phénomènes physiologiques neurologiques. Durant ce travail, des techniques décrites dans la littérature, mais non pratiquées au CRC ont fait lobjet dune implémentation et sont maintenant accessibles (modèle du rat vigile, méthodes de synthèse de polymères à empreinte moléculaire). La partie principale du travail concerne la récupération du [18F]fluorure et son utilisation pour le marquage nucléophile sans étape dévaporation. La synthèse du 2-désoxy-2-[18F]fluoro-D-glucose a servi de réaction témoin pour tester lapplicabilité des méthodes développées dans ce cadre. Deux stratégies différentes, lune utilisant des supports ioniques et des solvants protiques, lautre utilisant des supports non ioniques et des solvants non protiques, ont permis datteindre les buts fixés avec des rendements dincorporation du [18F]fluorure de même ordre de grandeur que ceux obtenus en radiochimie usuelle du fluor-18. La méthode utilisant les supports non ioniques a par ailleurs démontré sa grande généralité vis-à-vis de précurseurs divers, aliphatiques et aromatiques, dans des conditions de marquage diverses, notamment à température modérée. Les perspectives de ces méthodes nouvelles pour la fabrication des traceurs TEP tirent parti de la possibilité de les implanter dans un automate miniaturisé (milli- ou micro-réacteur), à visée synthétique ou analytique. Lefficacité et la simplicité des méthodes de récupération sans évaporation mises au point dans ce travail les destinent à être utilisées aussi bien en développement des traceurs quen synthèse de routine. Elles sont applicables aussi bien à léchelle des automates courants quà celle des futures applications microfluidiques. Par ailleurs, nous sommes persuadés de lintérêt des polymères à empreinte moléculaire dans le créneau des méthodes analytiques. Egalement applicables à des systèmes miniaturisés, ils devraient aider à la réalisation danalyses automatisées des produits finis et à une libération accélérée. Le gain de temps et les moindres pertes de principe actif conduiront alors à une meilleure disponibilité des traceurs TEP et à leur participation accrue aux objectifs de la médecine personnalisée. Nous pensons dès lors avoir ouvert quelques pistes de recherche prometteuses pour la mise en application de ses nouvelles technologies au domaine de la tomographie à émission de positon. / SUMMARY: The results reported in this work concern the improvement of 18-fluorine labelled radiopharmaceuticals used in routine clinical applications: 2-[18F]fluoro-L-tyrosine and 2-deoxy-2-[18F]fluoro-D-glucose. The study of the metabolism of non carrier added 2-[18F]fluoro-L-tyrosine in rats confirms that this tracer is rapidly and extensively incorporated into cerebral proteins and is therefore well suited to the assessment of Protein Synthesis Rate (PSR) in vivo by PET. A correction for the appearance of metabolites is advised for quantitative interpretation of the data. An improvement in the radiosynthesis is necessary to make 2-[18F]fluoro-L-tyrosine widely available for its application in oncology and to envisage the extended use of this tracer for the study of the protein synthesis in other physiological or pathological processes. The second chapter deals with use of molecular imprints in the PET radiochemistry. The molecularly imprinted polymers were synthetized, characterized and tested for the production of specific PET tracers and the plasma analysis of the parent metabolites. The third part of the work consisted in a development of new methods for the [18F]fluoride recovery in order to permit the labelling of different precursors through nucleophilic substitution without the evaporation step classically performed in 18-fluorine radiochemistry. The synthesis of 2-deoxy-2-[18F]fluoro-D-glucose has been used as a tool for the evaluation of the developed methods. Two strategies were considered to concentrate and recover the [18F]fluoride. The first one used ionic solid supports and protic solvents. The second one relied on the use of non ionic solid supports and non protic solvents. Both strategies led us to reach [18F]fluoride incorporation yields as high as in classical radiosyntheses with evaporation. Ionic liquids and tertiary alcohols were also evaluated in order to improve the tolerance of the [18F]fluoride nucleophilic substitution to water. The molecularly imprinted polymers and the new methods for the recovery of [18F]fluoride will now be tested for the implementation of PET tracers radiosynthesis and quality control into microchip devices.
23

Stereospecific dehydroxyfluorination and the synthesis of trifluoro D-hexose sugar analogues

Bresciani, Stefano January 2011 (has links)
This thesis describes stereospecific fluorination reactions, and addresses the synthesis of fluorosugars. In Chapter 1, the influence of fluorine on the physical properties of organic molecules, as well as its stereoelectronic effects, are introduced. Furthermore, an overview of nucleophilic and electrophilic fluorination reactions is given. Chapter 2 describes the dehydroxyfluorination of allylic alcohol diastereoisomers 155a and 155b, which can proceed either by direct or allylic fluorination. The regio- and stereo- selectivities were also assessed. Chapter 3 outlines the synthesis of the novel trifluoro D-glucose analogue 193 and trifluoro D-altrose analogue 216. The transport of these hexose analogues across the red blood cell membranes was then explored, to investigate the influence of polarity versus hydrogen bonding ability in carbohydrate-protein interactions. Chapter 4 describes the development and optimisation of Bio’s methodology, to promote stereospecific dehydroxyfluorination of benzylic alcohols (R)-213 and (R)-227 by addition of TMS-amine additives 226 and 229. And finally Chapter 5 reports the experimental procedures as well as the characterisation and the crystallographic data of the molecules prepared in this thesis.
24

Nove izostere i bioizostere prirodnih stiril-laktona: dizajn, sinteza i antiproliferativna aktivnost / Novel isosteres and bioisosteres of natural styryl lactones: design,synthesis and antiproliferative activity

Francuz Jovana 14 April 2015 (has links)
<p>U&nbsp; radu&nbsp; su&nbsp; ostvarene&nbsp; vi&scaron;efazne&nbsp; sinteze&nbsp; većeg&nbsp; broja&nbsp; analoga&nbsp; prirodnih&nbsp; stiril-laktona&nbsp; (+)-goniofufurona&nbsp; i&nbsp; 7-epi-(+)-goniofufurona&nbsp; polazeći&nbsp; iz&nbsp; D-glukoze.<br />Ispitana&nbsp; je&nbsp; in&nbsp; vitro&nbsp; citotoksičnost&nbsp; sintetizovanih&nbsp; analoga&nbsp; prema&nbsp; devet<br />malignih&nbsp; i&nbsp; jednoj&nbsp; zdravoj&nbsp; ćelijskoj&nbsp; liniji.&nbsp; Uspostavljeni&nbsp; su&nbsp; korelacioni&nbsp; odnosi<br />izmedju&nbsp; strukture&nbsp; i&nbsp; antiproliferati vne&nbsp; aktivnosti&nbsp; sintetizovanih&nbsp; proizvoda, pored&nbsp; toga&nbsp; uradjeni&nbsp; su&nbsp; i&nbsp; dodatni&nbsp; biolo&scaron;ki&nbsp; testovi&nbsp; koji&nbsp; se&nbsp; odnose&nbsp; na dokazivanje&nbsp; mehanizma&nbsp; citotoksičnog&nbsp; dejstva&nbsp; pomenutih&nbsp; stiril-laktona&nbsp; i analoga.</p> / <p>Multistep&nbsp; synthesis&nbsp; of&nbsp;&nbsp; a&nbsp; number&nbsp; of&nbsp; natural&nbsp; styryl&nbsp; lactones&nbsp;goniofufurone&nbsp; and&nbsp; 7-epi-goniofufurone&nbsp; analogues&nbsp; was&nbsp; achieved&nbsp;starting&nbsp; f rom&nbsp; D-glucose.&nbsp; In&nbsp; vitro&nbsp; cytotoxicity&nbsp; of&nbsp; newly&nbsp; synthetized analogues&nbsp; against&nbsp; nine&nbsp; human&nbsp; tumour&nbsp; cell&nbsp; lines&nbsp; and&nbsp; against&nbsp; a single normal cell line was evaluated. Structure-activity relationships were&nbsp; established&nbsp; for&nbsp; both&nbsp; natural&nbsp; products&nbsp; and&nbsp; analogues.&nbsp; Some additional&nbsp; biological&nbsp; tests&nbsp; related&nbsp; to&nbsp; the&nbsp; cell mechanisms&nbsp; underlying the&nbsp; cytotoxicity&nbsp; of&nbsp;&nbsp; the&nbsp; mentioned&nbsp; styryl&nbsp; lactones&nbsp; and&nbsp; analogues, were also carried out.</p>
25

Prirodni stiril-laktoni, njihovi derivati i analozi kao potencijalni antitumorski agensi: Dizajn, sinteza i SAR ispitivanja / Natural styryl-lactones, their derivatives and analogues as potential antitumour agents: Design, synthesis and a SAR study

Kovačević Ivana 29 April 2015 (has links)
<p>U radu je ostvarena sinteza četiri prirodna proizvoda, goniobutenolida A i B,<br />krasalaktona D i 3-deoksi-kardiobutanolida i 32 derivata i analoga polazeći iz<br />D-glukoze. Sinteza prirodnog stiril-laktona, kardiobutanolida&nbsp; i njegova 4<br />derivata je izvedena polazeći iz&nbsp; D-ksiloze.&nbsp; Ispitan je uticaj sintetizovanih<br />jedinjenja&nbsp; na inhibiciju rasta 10 tumorskih i jedne zdrave ćelijske linije.<br />Uspostavljene su i&nbsp; korelacije izmedju strukture i antiproliferativne aktivnosti&nbsp;(SAR) i ispitan je mehanzam antitumorskog dejstva.</p> / <p>Synthesis of four natural products: goniobutenolide A and B,&nbsp;crassalactone D, 3-deoxy-cardiobutanolide and their 32 analogues&nbsp;and derivatives is accomplished starting from&nbsp; D-glucose. Synthesis of natural styryl lactone cardiobutanolide and its four derivatives is &nbsp;achieved&nbsp; starting&nbsp; from&nbsp; D-xylose.&nbsp; Synthesized natural lactones, their analogues and derivatives were evaluated for their antiproliferative activity against ten malignant cell lines&nbsp; as well as against a single normal cell line. Influence of functional groups on antitumour activity was established by correlating structures of synthesized compounds&nbsp; with&nbsp; their&nbsp; biological&nbsp; activity (SAR).&nbsp; Also, mechanism of antitumour action was investigated.</p>
26

Enantiodivergentna totalna sinteza odabranih stiril laktona i preliminarno ispitivanje njihove citotoksičnosti / Enantiodivergent total synthesis of selected styryl lactones and preliminary evaluation of their cytotoxicity

Benedeković Goran 11 October 2012 (has links)
<p>U radu je ostvarena enantiodivergentna totalna sinteza oba enantiomera goniofufurona, 7-epi-goniofufurona i krasalaktona C polazeći iz D-glukoze. Ključne faze u sintezi 7-epi-(+)-goniofufurona bile su stereoselektivna adicija fenilmagnezijum bromida na aldehidnu grupu pogodno za&scaron;tićene dialdoze, i stereospecifično formiranje furano-laktonskog prstena ciklokondenzacijom odabranog hemiacetalnog derivata sa Meldrum-ovom kiselinom. Sinteza (+)-goniofufurona i (+)-krasalaktona C zahtevala je inverziju konfiguracije na C-5<br />u zajedničkom intermedijeru, koja je efikasno ostvarena u uslovima Mitsunobu-ove reakcije, ili alternativno oksidacijom benzilne hidroksilne grupe u prohiralni keton, uz naknadnu stereoselektivnu redukcijom sa borohidridom. Sličan pristup je zatim primenjen za sintezu neprirodnih (&minus;)-enantiomera goniofufurona, 7-epi-goniofufurona i krasalaktona C, dva nova konformaciono ograničena analoga (+)- i (&minus;)-goniofufurona (oksetani 36 i ent-36), kao i odgovarajućih 7-deoksigenovanih derivata (31 i ent-31). Takodje je razvijena i prva totalna sinteza prirodnog (+)-krasalaktona B (3) i alternativna sinteza (+)-krasalaktona C (4) polazeći iz D-glukoze. Selektivni pristup molekulima 3, odnosno 4 omogućen je promenom uslova za TBDPS deprotekciju u finalnom intermedijeru 53. Osnovna karakteristika pomenutih pristupa je njihova generalnost i fleksibilnost. Na taj način je omogućena sinteza serije analoga i derivata (+)-goniofufurona, ili 7-epi-goniofufurona, uključujući i do sada nepoznate 7-epi-(+)-krasalaktone B (6) i C (7), 5,7-di-O-cinamoil derivate 8 i 9, 5,7-di-O-izopropilidenske derivate 5 i 10, kao i vi&scaron;e lipofilnih derivata (jedinjenja 26, 30, 33, 65, ent-30 i ent-33). Konačno, u drugom delu rada, ispitan je uticaj sintetizovanih stiril-laktona na rast odabranih tumorskih ćelijskih linija in vitro.</p> / <p> Enantiodivergent total syntheses of both (+)- and (&minus;)-enantiomers of goniofufurone, 7-epi-goniofufurone and crassalactone C have been accomplished starting from D-glucose. The key steps of the synthe-sis of 7-epi-(+)-goniofufurone were a stereo-selective addition of&nbsp;<br /> phenyl magnesium bromide to a protected dialdose, followed by a stereospecific furano-lactone ring formation by condensation of a partially protected lactole with Meldrum&rsquo;s acid. The synthesis of (+)-goniofufurone and (+)-crassalactone C required a configurational inversion at C-5 in the common intermediate that was efficiently achieved under the standard Mitsunobu conditions, or alternatively through a sequential oxidation of the benzylic hydroxyl group followed by a stereo-selective reduction with borohydride. A similar approach was applied to the synthesis of the unnatural enantiomers of goniofufurone, 7-epi-goniofufurone and crassalactone C, two novel, conformationally constrained analogues of both (+)- and (&minus;)-goniofufurone (oxetanes 34 and ent-34). as well as the corresponding 7-deoxygenated derivatives (31 and ent-31). We have also developed the first total synthesis of (+)-crassalactone B (2) and an alternative synthesis of (+)-crassalactone C (3) starting from D-glucose. Finally, the synthesized styryl-lactones were evaluated for their antiproliferative activity against a panel of human tumor cell lines.</p>
27

Multidisciplinary study of the role of calcium in plant in vitro embryogenesis

Calabuig Serna, Antonio 06 September 2023 (has links)
[ES] El calcio (Ca2+) es un catión esencial que juega un papel fundamental en todos los organismos vivos. Desde el punto de vista funcional, el Ca2+ actúa como un segundo mensajero que regula distintos procesos celulares. Trabajos anteriores indican que la señalización mediante Ca2+ podría estar implicada en las primeras etapas de la inducción de la embriogénesis in vitro de las plantas, pero el verdadero papel del Ca2+ en este proceso es aún desconocido. Por eso, el principal objetivo de la presente Tesis es el estudio del papel del Ca2+ en la embriogénesis in vitro mediante dos sistemas in vitro: la embriogénesis somática y la embriogénesis de microsporas. Para determinar la importancia de la homeostasis del Ca2+ en la inducción de la embriogénesis y las dinámicas de los niveles de Ca2+ durante la inducción y el establecimiento de embriones somáticos y derivados de microsporas, se utilizaron tratamientos químicos y se detectaron los niveles de Ca2+ mediante sondas fluorescentes y sensores cameleon codificados genéticamente, visualizados con microscopía fluorescente y confocal. Observamos que el aumento de Ca2+ es un marcador temprano en la inducción de la embriogénesis in vitro y que los niveles de Ca2+ durante la embriogénesis in vitro son dinámicos en todos los sistemas estudiados. Además, las oscilaciones en los niveles de Ca2+ podrían estar relacionadas con los procesos de diferenciación que ocurren en las células inducidas una vez une el Ca2+ a la calmodulina. Mostramos que un aumento de Ca2+ dentro de un rango definido de concentración tiene un efecto positivo, dependiendo del sistema, en la producción de embriones, siendo más sensibles aquellos sistemas basados en suspensiones de células aisladas que aquellos que usan tejidos como explantes. Finalmente, estudiamos el papel de la calosa durante la embriogénesis somática, observando que la inhibición de la deposición de calosa impide el desarrollo embrionario, lo que sugiere una relación entre la formación de una barrera de calosa y el establecimiento de la identidad embrionaria en las células somáticas. / [CAT] El calci (Ca2+) és un catió essencial que juga un paper fonamental en tots els organismes vius. Des del punt de vista funcional, el Ca2+ actua com a un segon missatger que regula diferents processos cel·lulars. Treballs anteriors indiquen que la senyalització mitjançant el Ca2+ podria estar implicada en les primeres etapes de la inducció de l'embriogènesi in vitro de les plantes, però el paper real del Ca2+ en aquest procés encara és desconegut. Per això, el principal objectiu de la present Tesi és l'estudi del paper del Ca2+ en l'embriogènesi in vitro mitjançant dos sistemes in vitro: l'embriogènesi somàtica i l'embriogènesi de micròspores. Per tal de determinar la importància de l'homeòstasi del Ca2+ en la inducció de l'embriogènesi i les dinàmiques dels nivells de Ca2+ durant la inducció i l'establiment d'embrions somàtics i derivats de micròspores, es van utilitzar tractaments químics i es van detectar els nivells de Ca2+ mitjançant sondes fluorescents i sensors de cameleon codificats genèticament, visualitzats amb microscòpia fluorescent i confocal. Vam observar que l'augment de Ca2+ és un marcador primerenc en la inducció de l'embriogènesi in vitro i que els nivells de Ca2+ durant l'embriogènesi in vitro són dinàmics en tots els sistemes estudiats. A més, les oscil·lacions en els nivells de Ca2+ podrien estar relacionades amb els processos de diferenciació que tenen lloc en les cèl·lules induïdes una vegada uneix el Ca2+ a la calmodulina. Vam mostrar que un augment de Ca2+ dins d'un rang definit de concentració té un efecte positiu, depenent del sistema, en la producció d'embrions, essent més sensibles aquells sistemes basats en suspensions de cèl·lules aïllades que aquells que usen teixits com a explants. Finalment, vam estudiar el paper de la cal·losa durant l'embriogènesi somàtica, i vam observar que la inhibició de la deposició de cal·losa impedeix el desenvolupament embrionari, la qual cosa suggereix una relació entre la formació d'una barrera de cal·losa i l'establiment de la identitat embrionària en les cèl·lules somàtiques. / [EN] Calcium (Ca2+) is an essential cation that plays fundamental roles in all living organisms. From a functional point of view, Ca2+ acts as a second messenger that regulates different cellular processes. Previous works point to the fact that Ca2+ signaling may be involved in the early stages of induction of in vitro plant embryogenesis, but the actual role of Ca2+ in this process remained unveiled. Thus, the main goal of the present Thesis is to study the role of Ca2+ in in vitro embryogenesis using two in vitro systems: somatic embryogenesis and microspore embryogenesis. Chemical treatments and detection of Ca2+ with fluorescent probes and genetically-encoded cameleon sensors imaged by fluorescence and confocal microscopy were performed to determine the importance of Ca2+ homeostasis for induction of embryogenesis and the dynamics of Ca2+ levels during the induction and establishment of somatic and microspore-derived embryos. We observed that Ca2+ increase is an early marker of induction of in vitro embryogenesis and Ca2+ levels during in vitro embryogenesis are dynamic in all the systems we studied. Moreover, Ca2+ oscillations might be related to the differentiation processes that take place in the induced cells upon binding to calmodulin. We showed that Ca2+ increase within a defined range has system-specific positive effects in embryo yield, being more sensitive those systems using isolated cell suspensions rather than those using tissues as explants. Finally, we studied the role of callose during somatic embryogenesis, and we observed that inhibiting callose deposition prevents embryo development, which suggests a relationship between the formation of a callose barrier and the establishment of embryo identity in somatic cells. / Calabuig Serna, A. (2023). Multidisciplinary study of the role of calcium in plant in vitro embryogenesis [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/196022

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