The objective of this study is to evaluate pseudo-substrates of pantothenate kinase (PanK) for the therapeutic treatment of multidrug resistant bacterial infections of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Pantothenate (Pan) analogs, including N- pentylpantothenamide (N5-Pan) and N-heptylpantothenamide (N7-Pan), hamper bacterial growth by utilizing the PanK enzymes, which normally catalyze the rate determining step of the Coenzyme A biosynthetic pathway. Here we report the structures of SaPanK, Human PanK3 and EcPanK complexed with N7-Pan or N5-Pan, all of which have provided the opportunity to investigate the structural differences of bacterial and human Pan binding sites. The MTT assay showed these analogs to exhibit no apparent cytotoxicity against Human A549 lung adenocarcinoma cells, human HepG2 hepatoma cells and human umbilical vein endothelial cells (HUVEC). The presented structural differences have the potential for aiding the development of species-specific antimicrobial compounds with minimal effects on human cells.

Η Εκλυτική ορμόνη της Ωχρινοτρόπου Ορμόνης των θηλαστικών (GnRH-I ή GnRH) είναι ένα δεκαπεπτίδιο το οποίο εκκρίνεται από τον υποθάλαμο κατά ώσεις. Η GnRH είναι δυνατό να δρα σαν ρυθμιστής διαφόρων συστημάτων τα οποία, για τη λειτουργία τους, απαιτούν την έκκριση της LH και της FSH. Πράγματι, η GnRH και τα ανάλογα της χρησιμοποιούνται εκτεταμένα για τη θεραπεία ενός μεγάλου αριθμού ασθενειών οι οποίες σχετίζονται με τις φυλετικές ορμόνες. Η χρόνια χορήγηση αναλόγων της GnRH προκαλεί απευαισθητοποίηση των υποδοχέων το οποίο οδηγεί στην παύση της έκκρισης γοναδοτροπινών και κατά συνέπεια στην καταστολή της λειτουργίας των ωοθηκών και των όρχεων (chemical castration). Εκτός από την υπόφυση οι υποδοχείς της GnRH εκφράζονται σε αρκετούς φυσιολογικούς και διάφορους καρκινικούς ιστούς, συμπεριλαμβανομένων του μαστού, του ωοθηκών, του ενδομητρίου και του προστάτη. Ο ρόλος της GnRH και των υποδοχέων της σε αυτούς τους εξωϋποθαλαμικούς ιστούς δεν έχει ξεκάθαρος. Ωστόσο, έχει δειχθεί ότι σε διάφορα είδη καρκινικών κυττάρων συμπεριλαμβανομένων και των PC3 και LNCaP τα ανάλογα της GnRH αναστέλλουν τον πολλαπλασιασμό ή οδηγούν σε προγραμματισμένο κυτταρικό θάνατο (απόπτωση). Η lamprey Εκλυτική Ορμόνη της Ωχρινοτρόπου Ορμόνης (lGnRH-III) είναι η τρίτη μορφή της GnRH η οποία έχει απομονωθεί από τα ψάρια του είδους lamprey (το γένος Petromyzon marinus). Αυτό το δεκαπεπτίδιο το οποίο διαφέρει από τη GnRH των ανθρώπων (GnRH-I) στα αμινοξέα των θέσεων 5-8, διεγείρει την απελευθέρωση οιστραδιόλης και της προγεστερόνης στα ενήλικα θηλυκά lamprey αλλά έχει αμελητέα ενδοκρινή δράση στα συστήματα των θηλαστικών. Την τελευταία δεκαετία έχουν δημοσιευτεί στοιχεία τα οποία υποστηρίζουν την απευθείας αντικαρκινική δράση της lGnRH-III. Τα παραπάνω οδηγούν στο χαρακτηρισμό της lGnRH-III ως ένα εξαιρετικό μόριο-οδηγό για την ανάπτυξη αναλόγων της GnRH με αυξημένη και πιθανώς εκλεκτική αντικαρκινική δράση. Οι πιο πρόσφατες αναφορές για απευθείας δράση των αναλόγων της GnRH στην αναστολή του πολλαπλασιασμού καρκινικών κυττάρων τα οποία παράγουν τη φυσική ορμόνη και εκφράζουν τους υποδοχείς της εγκαινιάζουν ένα νέο πεδίο έρευνας και προσφέρουν νέα ώθηση στο σχεδιασμό και τη σύνθεση νέων αναλόγων της GnRH. Μελέτες οι οποίες διερευνούν τη σχέση δομής-δραστικότητας της GnRH-Ι και ιδιαιτέρως της lGnRH-III και των αναλόγων τους στο εξωϋποθαλαμικό σύστημα είναι περιορισμένες. Η ανάγκη διερεύνησης του πεδίου αυτού θεωρείται μείζονος σημασίας καθώς ο πληθυσμός των καρκινοπαθών αυξάνει συνεχώς και η πάθηση κατατάσσεται μεταξύ των σημαντικότερων πεδίων ερευνητικής μελέτης. Ανάλογα της GnRH χορηγούνται σε ασθενείς με ορμονοεξαρτώμενους όγκους με στόχο την αναστολή των γοναδοτροπινών και την παύση της έκκρισης των φυλετικών ορμονών. Η προσέγγιση του πεδίου με χρήση αναλόγων της GnRH με ενδεχόμενη κυτταροστατική δράση αποτελεί μια σύγχρονη και πολλά υποσχόμενη προοπτική. Από τη άλλη μεριά, ένα από τα μεγαλύτερα προβλήματα το οποίο εμφανίζεται στα φάρμακα πεπτιδικής φύσης είναι η γρήγορη και εκτεταμένη αποικοδόμηση τους από διάφορα ένζυμα. Προκειμένου να βελτιωθεί η βιοδιαθεσιμότητα των αναλόγων της GnRH έχουν χρησιμοποιηθεί διάφορες προσεγγίσεις. Η εισαγωγή N-μεθυλιωμένων-αμινοξέων περιορίζει διαμορφωτικά τον πεπτιδικό σκελετό και χρησιμοποιείται συχνά για την αύξηση της πρωτεολυτικής σταθερότητας των φαρμάκων πεπτιδικής φύσης. Μια πιο ολοκληρωμένη προσέγγιση είναι αυτή η οποία συνδυάζει την σταθερότητα έναντι της ενζυμικής αποικοδόμησης με τη διατήρηση της βιολογικής δράσης. Στόχος της ∆ιατριβής είναι η συμβολή στο πεδίο των σχέσεων δομής-δραστικότητας της GnRH μέσω του ορθολογικού σχεδιασμού, της ανάπτυξης και του ελέγχου νέων συνθετικών αναλόγων της. Συγκεκριμένα, συνθέσαμε δώδεκα νέα ανάλογα τα οποία περιλαμβάνουν διαμορφωτικά περιορισμένα αμινοξέα στις θέσεις 4 και 6 και μελετήσαμε τις δομικές αλλαγές οι οποίες προκύπτουν από τις αλλαγές αυτές με φασματοσκοπία NMR, τη σταθερότητα έναντι της ενζυμικής αποικοδόμησης από την α-χυμοθρυψίνη και τη σουμπτιλισίνη και την δράση τους επί του πολλαπλασιασμού των καρκινικών κυττάρων PC3 και LNCaP. Η NMeSer εισήχθη στη θέση 4 του μορίου αντικαθιστώντας τη Ser και η Gly6 αντικαταστάθηκε από διάφορα D- αμινοξέα (DLys, Nε- τροποποιημένη DLys, Glu, DGlu). Το Ν-τελικό γλυκιναμίδιο έχει επαλειφθεί και στη θέση του έχει γίνει εισαγωγή της αιθυλ-ομάδας (Fujino modification), όπως στο μόριο του Λεουπρολιδίου. Συνθέσαμε επίσης είκοσι δύο νέα ανάλογα της lGnRH-III με τροποποιήσεις σε διάφορες θέσεις του μορίου και μελετήσαμε τη δράση τους επί του πολλαπλασιασμού των PC3 και LNCaP κυττάρων. Η Asp6 της lGnRH-III αντικαταστάθηκε από Asn, Asn(OMe), Glu ή Gln, η Trp3,7 από DTrp ή L/D-Tic, το pGlu1 αντικαταστάθηκε από Glu ή Ac-Glu και η His5 με την Lys8 άλλαξαν μεταξύ τους θέσεις. Επιπλέον, συνθέσαμε και τέσσερα κυκλικά ανάλογα της lGnRH-III καθώς τα κυκλικά πεπτίδια συχνά χαρακτηρίζονται από μεγαλύτερη μεταβολική σταθερότητα και δραστικότητα σε σχέση με τα ευθύγραμμα. Τέλος, μελετήσαμε τη δομή της lGnRH-III με τη χρήση ΝΜR φασματοσκοπίας και τα χαρακτηριστικά της παρουσιάζονται σε σύγκριση με αυτά της GnRH-I. Για τη σύνθεση των αναλόγων της GnRH-I σαν στερεό υπόστρωμα χρησιμοποιήθηκε η [3-(αιθυλ-Ν-Fmoc-αμινομέθυλ)ινδολ-1- υλ] ακετυλ ΑΜ ρητίνη για την παραλαβή αμιδίων ενώ, για τη σύνθεση της GnRH-I, της lGnRH-III και των αναλόγων της lGnRH-III χρησιμοποιήθηκε η ρητίνη του Sieber χρησιμοποιώντας την Fmoc/tBu μεθοδολογία. Η ενζυμική σταθερότητα των αναλόγων της GnRH-I προσδιορίστηκε έπειτα από επώαση των πεπτιδίων με την α-Chymotrypsin και τη Subtilisin ενώ, η δράση έναντι του κυτταρικού πολλαπλασιασμού της GnRH-I, της lGnRH-III και των αναλόγων τους μελετήθηκε με ανθρώπινα καρκινικά κύτταρα προστάτη (PC3 και LNCaP). Το πρωτόκολλο σύνθεσης το οποίο ακολουθήθηκε οδήγησε στην παραλαβή πεπτιδίων σε μεγάλες αποδόσεις και υψηλή καθαρότητα. Η μελέτη της επίδρασης των νέων αναλόγων της GnRH στην αναστολή του πολλαπλασιασμού των καρκινικών κυττάρων του προστάτη εγκαινιάζει το πεδίο σε επίπεδο σχέσεων δομής-δραστικότητας και συνεισφέρει στην αδιάκοπη έρευνα των δομικών απαιτήσεων των αναλόγων της GnRH προσφέροντας νέες προοπτικές στον σχεδιασμό δραστικών αναλόγων της GnRH. Tέλος, προέκυψαν πεπτιδικά ανάλογα της ορμόνης τα οποία σε σχέση με το Λεουπρολίδιο, το οποίο αποτελεί δραστικό συστατικό φαρμάκων για την αντιμετώπιση των ανωτέρω ασθενειών και με τη lGnRH-III, εμφανίζονται στις βιολογικές δοκιμές στις οποίες εξετάστηκαν δραστικότερα και με αυξημένη πρωτεολυτική σταθερότητα και συνεπώς αποτελούν καλές, υποψήφιες για περαιτέρω βιολογική/κλινική μελέτη, ενώσεις. Σε επίπεδο σχέσεων δομής-δραστικότητας οι τελευταίες είναι δυνατόν να αποτελέσουν τη βάση για τον μελλοντικό σχεδιασμό νέων αναλόγων της GnRH με υψηλή δραστικότητα και ενδεχόμενη φαρμακευτική εφαρμογή. / Mammalian Gonadotropin-releasing hormone (GnRH-I or GnRH) is a neuroendocrine decapeptide secreted from the hypothalamus in a pulsatile manner. Due to its hypophysiotropic actions, GnRH may act as a modulator of the activity of diverse systems that require LH and FSH secretion for their function. Indeed, GnRH and its analogs are used extensively for the treatment of a wide range of hormone-dependent diseases, including steroid-dependent tumors. Chronic administration of GnRH analogs desensitizes GnRH pituitary receptors, results in arrest of gonadotropin secretion, and thereby suppresses ovarian and testicular function (chemical castration). In addition to its pituitary expression, the GnRHR is expressed in several normal tissues and in a number of malignant tumors, including cancers of the breast, ovary, endometrium and prostate. The specific function of GnRH and its receptor in these extrapituitary sites is not entirely clear. However, it was demonstrated that in many cancer cells including PC3 and LNCaP GnRH analogs inhibit cell proliferation or lead to a programmed cell death (apoptosis). Lamprey gonadotropin-releasing hormone III (lGnRH-III) is the third isoform of GnRH isolated from the sea lamprey (Petromyzon marinus). This decapeptide that differs in residues 5–8 from human GnRH (GnRH-I), stimulates the release of estradiol and progesterone in the adult female sea lamprey but has negligible endocrine activity in mammalian systems. In the last decade data concerning the superior direct antitumor activity of sea lamprey lGnRH-III have been published. These observations make lGnRH-III an excellent starting compound for the development for the development of constrained peptide analogs with increased and potentially selective anticancer activity. The direct antiproliferative effect of the GnRH analogs in many malignant tissues inaugurates the field and leads to the design of effective GnRH analogs with new perspectives. Information concerning the impact of systematic single amino acid modifications of GnRH-I and especially of lGnRH-III on malignant cells is still lacking. The structural investigation of this field seems to be a very important issue. On the other hand, one of the main problems of peptide drugs is their fast and extensive degradation by several peptidases. In order to improve the availability of GnRH analogs, various approaches have been adopted. Incorporation of N-methylated amino acids in peptides results in conformational constrained peptide backbones and is commonly used for increasing proteolytic stability of peptide drugs. In the latter approach, stability against proteolysis should be achieved along with preservation or enhancement of biological activity. The aim of this study was the contribution in the field of the structure-activity relationships based in the rational design, development (modern synthesis) and biological characterization of the new analogs of GnRH. Particularly, we synthesized twelve new GnRH-I analogs containing conformationally restricted amino acids in positions 4 and 6, and studied the structural changes imposed by these modifications through NMR spectroscopy, the stability against enzymatic degradation by α-chymotrypsin and subtilisin and their direct antiproliferative effect on prostate cancer cells PC3 and LNCaP. NMeSer was inserted in position 4 of the peptide sequence, replacing Ser4 and Gly6 was substituted by several D- amino acids (DLys, Nε- modified DLys, Glu, DGlu). The synthesized GnRH-I analogs lack the carboxy-terminal Gly10-amide of GnRH-I and an ethylamide residue has been added to Pro9 (Fujino modification), as in Leuprolide structure. We also synthesized twenty two lGnRH-III analogs with modifications in several positions of lGnRH-III and studied their effect on PC3 and LNCaP prostate cancer cell proliferation. Asp6 of lGnRH-III was substituted by Asn, Asn(OMe), Glu or Gln, Trp3,7 by DTrp or L/D-Tic, pGlu1 was replaced by Glu or Ac-Glu and His5 and Lys8 switched places. Cyclopeptides are of great importance both in pharmaceutical and chemical respect. These molecules often exhibit increased biological activity and selectivity. Furthermore, they are more stable in metabolism than the parent linear molecules. Taking into consideration of these potentials we synthesized four cyclic analogs of lGnRH-III as well. The new analogs of GnRH-I were assembled on a [3-((Ethyl-Fmoc-amino)- methyl)-1-indol-1-yl]-acetyl AM resin to provide the peptide amide while, GnRH-I, lGnRH-III and lGnRH-III analogs were assembled on a Sieber Amide resin using Fmoc/tBu methodology. The enzymatic stability of GnRH-I analogs were determined after incubation with α-Chymotrypsin and Subtilisin while the antiproliferative activity of GnRH-I, lGnRH-III and their analogs was performed with human prostate cancer cell lines (PC3 and LNCaP). Modern peptide synthesis afforded us peptides in high yields which could be easily purified. This study provides information which can be used in the design of new GnRH analogs with improved enzymatic stability and high antiproliferative activity on PC3 and LNCaP prostate cancer cell proliferation. This structure-activity relationship study of GnRH analogs contributes to the on-going research for more potent GnRH analogs with prolonged and selective activity.

Les maladies cardiovasculaires représentent la première cause de morbidité et mortalité dans le monde. L'athérosclérose, qui conduit à l'obstruction des artères, est à l'origine de 50% des décès dans les sociétés industrialisées. La rupture d'une plaque d'athérosclérose dite vulnérable entraîne de nombreuses complications qui, en fonction du territoire artériel considéré, vont de l'accident vasculaire cérébral à l'infarctus du myocarde. Pour pallier ce problème de santé publique majeur, l'enjeu clinique et en particulier diagnostic repose sur la prévention de ces complications cardiovasculaires dans une population à haut risque comme à l'île de la Réunion, qui se caractérise par une incidence élevée d'atteintes vasculaires et de mortalité associée. Or, il n'existe aucune technique d'imagerie permettant la détection précoce des plaques d'athérosclérose vulnérables. La médecine nucléaire possède une grande sensibilité et pourrait offrir des outils diagnostics performants permettant d'évaluer la formation de ces plaques. Parmi tous les biomarqueurs tissulaires et circulants produits lors de l'athérogenèse, nous avons choisi la Lp-PLA2 (phospholipase A2 associée aux lipoprotéines), enzyme associée aux processus inflammatoires (produite par les monocytes et macrophages) et transportée par les lipoprotéines, comme cible de l'athérosclérose en imagerie TEP (Tomographie par Émission de Positons). Nos travaux ont permis la synthèse puis le radiomarquage d'un puissant inhibiteur cette enzyme : le Darapladib, ainsi que d'analogues. Nous avons réussi à obtenir le 18F-Darapladib afin d'étudier son accumulation dans des modèles murin et ex vivo humain de plaques d’athérome. / Cardiovascular diseases are the leading cause of morbidity and mortality worldwide. Atherosclerosis, which leads to the obstruction of large arteries, represents 50% of deaths in industrialized societies. Rupture of a vulnerable atherosclerotic plaque can lead to several complications which, depending on the site, can cause stroke or myocardial infarction.To address this public health issue, there is a real need to develop new diagnostic tools to prevent these cardiovascular complications in a high risk population in Reunion island. However, no potent tool is available to doctors in order to predict the formation of vulnerable atherosclerotic plaques. Nuclear medicine with its high sensibility could offer new powerful diagnostic tools in order to assess vulnerable atheroma formation. Among all biomarkers available to the scientific community, we chose Lp-PLA2 (Lipoprotein-associated phospholipase A2) which is an enzyme associated to inflammatory processes (produced by monocytes and macrophages) as a target for PET (Positron Emission Tomography) imaging of atherosclerosis.Our work describes the radiolabelling of a potent inhibitor of this enzyme: Darapladib and associated analogs. We were able to perform its radiolabelling and to study its potential accumulation in atheroma murin models and in ex vivo human endarterectomy pieces.

La fumagilline est un antibiotique d’origine naturelle isolé du champignon Aspergillus Fumigatus en 1951. D’abord utilisée pour ses propriétés antiparasitaires, la fumagilline s’est révélée ensuite être un agent antiangiogénique puissant, qui se lie de façon covalente et irréversible par sa fonction époxyde spiro avec sa cible, l’enzyme MetAP-2. La forte toxicité de la fumagilline a incité les chercheurs à développer de nouveaux analogues, notamment réversibles sans fonction époxyde spiro, dans l’espoir d’atténuer la toxicité de la molécule. La première partie de notre travail a consisté à synthétiser des analogues réversibles de la fumagilline portant une fonction alcool tertiaire, site potentiel d’interaction faible avec l’enzyme.Ces analogues ont été obtenus de façon hautement diastéréosélective à partir de la 4-oxoisophoronecommerciale via un intermédiaire-clé de type aldéhydecyclohexanique.Le (+)-péloruside A, isolé en 2000 d’une éponge marine néo-zélandaise Mycale hentscheli, est un agent antimitotique puissant, d’activité comparable à celle du paclitaxel, utilisé en chimiothérapie anticancéreuse.L’investigation préclinique du péloruside A est actuellement ralentie à cause de la faible disponibilité de l’éponge et l’étude de la relation structure-activité est très limitée. Dans ce contexte, notre objectif a consisté à synthétiser des analogues simplifiés du péloruside A dans le but d’évaluer leur activité antiproliférative et leur incidence sur le cytosquelette. Notre stratégie très convergente a consisté à assembler 3 fragments de structure modulable en utilisant une nouvelle méthodologie de double aldolisation croisée sur l’α-triéthylsilyl diazoacétone. / Fumagillin is a natural antibiotic isolated from the fungusAspergillus Fumigatus in 1951. At first used for itsantiparasitic properties, fumagillin proved later to displaya potent antiangiogenic activity, by binding in a covalentand irreversible way to its biological target, the MetAP-2enzyme. The high toxicity of fumagillin led to the designof analogs, especially reversible analogs without thespiro epoxide function, in order to decrease the toxicityof the molecule. The first part of our work aimed atsynthesizing new reversible analogs of fumagillin,bearing a tertiary alcohol function, site of potential weakinteraction with the enzyme. These analogs wereobtained in a highly diastereoselective way from thecommercially available 4-oxoisophorone, via keyaldehydic cyclohexanic intermediates.(+)-Peloruside A, isolated in 2000 in New Zealand froma marine sponge Mycale hentscheli, is a potentantimitotic agent, displaying an activity similar topaclitaxel, currently used in anticancer chemotherapy.Preclinical investigation of peloruside A is currentlylimited by the low natural availability of the sponge andfew information is known about its structure-activityrelationship. In this context, our objective was tosynthesize new simplified analogs of peloruside A in aconvergent way, in order to assess their antiproliferativeactivity and their impact on the cytoskeleton. Our highlyconvergent strategy is based on the assembly of threefragments by a new methodology of double cross-aldoladdition on α-triethylsilyldiazoacetone.

abstract: The absorption spectra of metal-centered phthalocyanines (MPc's) have been investigated since the early 1960's. With improved experimental techniques to characterize this class of molecules the band assignments have advanced. The characterization remains difficult with historic disagreements. A new push for characterization came with a wave of interest in using these molecules for absorption/donor molecules in organic photovoltaics. The use of zinc phthalocyanine (ZnPc) became of particular interest, in addition to novel research being done for azaporphyrin analogs of ZnPc. A theoretical approach is taken to research the excited states of these molecules using time-dependent density functional theory (TDDFT). Most theoretical results for the first excited state in ZnPc are in only limited agreement with experiment (errors near 0.1 eV or higher). This research investigates ZnPc and 10 additional porphyrin analogs. Excited-state properties are predicted for 8 of these molecules using ab initio computational methods and symmetry breaking for accurate time- dependent self-consistent optimization. Franck-Condon analysis is used to predict the Q-band absorption spectra for all 8 of these molecules. This is the first time that Franck-Condon analysis has been reported in absolute units for any of these molecules. The first excited-state energy for ZnPc is found to be the closest to experiment thus far using a range-separated meta-GGA hybrid functional. The theoretical results are used to find a trend in the novel design of new porphyrin analog molecules. / Dissertation/Thesis / Doctoral Dissertation Materials Science and Engineering 2014

Diversas classes de compostos orgânicos de telúrio foram exploradas neste trabalho. Inicialmente foi estudada a transmetalação entre teluretos alílicos e dibutil cianocupratos de lítio de ordem superior, levando aos respectivos cianocupratos alílicos de lítio. Estes, por sua vez, foram acoplados com triflatos vinílicos, importantes intermediários sintéticos preparados previamente a partir de teluretos vinílicos, levando a sistemas altamente insaturados em ótimos rendimentos (Esquema 1). (Ver no arquivo em PDF) Em seguida, foi explorada a reatividade de teluretos aromáticos frente a reagentes organometálicos. Cianocupratos arílicos, gerados a partir da transmetalação entre teluretos aromáticos com cianocupratos de lítio de ordem superior, foram adicionados a cetonas α,β -insaturadas, levando aos produtos de adição 1,4 em bons rendimentos (Esquema 2). (Ver no arquivo em PDF) Teluretos vinílicos funcionalizados de configuração Z também foram alvo de estudo visando a formação de ligação carbono-carbono. Reações de substituição entre estes teluretos e cianocupratos de lítio de ordem inferior levaram a cetonas e ésteres α,β- insaturados com estereoquímica defInida em ótimos rendimentos (Esquema 3). (Ver no arquivo em PDF) De agosto/20OJ a março/2004, a aluna realizou um estágio sanduíche na University of California, Santa Barbara, sob a orientação do Prof. Bruce H. Lipshutz, onde realizou estudos sobre a ciclização de Bergman, visando a síntese do fragmentobiarílico A-B da vancornicina. Diversas condições para a ciclização foram estudadas com um composto modelo (Esquema 4) (Ver no arquivo em PDF) e parte da síntese total do fragmento da vancomlcma, onde a ciclização seria a etapa-chave, foi realizada com sucesso (Esquema 5). (Ver no arquivo em PDF) / Several classes of organotellurium compounds were explored in this work. First, transmetallation reaction between allylic tellurides and higher order dilithium dibutyl cyanocuprates was carried out, leading to the corresponding allylic cyanocuprates. Then these reagents performed cross-coupling reactions with vinylic triflates, important synthetic intermediates prepared previously from vinylic tellurides, affording highly unsaturated systems in high yields (Scheme 1). (See in file PDF) Next, the reactivity of aryl tellurides was explored with some organometallic reagents. Aryl cyanocuprates, generated by transmetallation reaction between aryl tellurides and higher order lithium cyanocuprates, were reacted with α,&$946;-unsaturated ketones, yielding 1,4-addition products (Scheme 2). (See in file PDF) Functionalized Z-vinylic tellurides were also investigated in reactions aiming carbon-carbon bond formation. Substitution reactions of these tellurides with lower order lithium cyanocuprates gave α,β-unsaturated ketones and esters with defined stereochemistry in good yields (Scheme 3). From Aug/03 to Mar/04, the student worked in the University of California, Santa Barbara, under the supervision of Prof. Bruce H. Lipshutz, where studies concerning the Bergman cyclization were performed, aiming the synthesis of the vancomycin A-B biaryl fragment. Several conditions for this cyclization were investigated using a model compound (Scheme 4) (See in file PDF) and part of the total synthesis of the vancomycin fragment, in which the Bergman cyclization would be the key-step, was accomplished (Scheme 5). (See in file PDF)

Le travail décrit dans cette thèse est basé sur la synthèse et l’étude de nanoparticules cœur-coquille capables de capter du césium radioactif. Ces travaux s’inscrivent dans l’amélioration d’un procédé de sorption du césium déjà existant et utilisant des monolithes de silice poreux fonctionnalisés avec des nanoparticules (NPs) d’Analogue du bleu de Prusse (ABP) ou plus précisément K2CuFe(CN)6 (CuABP). Les nanoparticules issues de cette famille sont très connues pour leur capacité de sorption et leur sélectivité vis-à-vis du césium. Ainsi afin d’éviter l’agrégation des NPs au sein du monolithe et d’augmenter les capacités de sorption, il a été décidé de synthétiser des nanoparticules cœur-coquille avec un cœur d’ABP protégé par une coquille de silice poreuse. La voie de synthèse choisie pour réaliser ce type de nanoparticules est celle qui utilise une microémulsion inverse afin de contrôler la forme et la taille des nanoparticules finales. Ce choix a permis de réaliser la synthèse in situ des NPs d’ABP avec une excellente stabilité des nanoparticules dans les gouttes d’eau dans certaines conditions opératoires. Les microémulsions ont été caractérisées grâce aux SAXS (Small Angle X-ray Scattering). Grâce à des modèles de simulation, des tailles de gouttes d’eau allant de 0.5 à 3 nm de rayon ont été déterminées selon la quantité d’eau introduite. Le paramètre w correspondant au rapport molaire entre l’eau et le tensioactif (w=[H2O]/[tensioactif]) es un bon moyen d’exprimer la quantité d’eau présente dans le système. La croissance de la coquille de silice est réalisée grâce au procédé sol-gel en milieu basique en présence de TEOS. La morphologie des nanoparticules cœur-coquille a ensuite été étudiée grâce à la microscopie électronique (HRTEM/STEM/HAADF) et l’analyse chimique et structurale a été réalisée grâce à la spectroscopie infrarouge (FTIR-ATR) et à la DRX. Ainsi, pour la première fois, des nanoparticules cœur-coquille telles que définies ici ont été synthétisées. Des tests de sorption du césium par ces nanoparticules cœur-coquille ont également été mis en œuvre avec des résultats encourageants (Qmax(NPs cœur-coquille)=125 mg/g). De plus ces nanoparticules ne sont pas seulement utiles pour la décontamination d’effluents aqueux, elles ouvrent aussi de nouvelles portes pour l’auto-irradiation et l’auto-confinement de radioéléments. / The research work described below is based on the synthesis and the study of core-shell nanoparticles able to entrap radioactive cesium. A sorption process of radionuclides on porous silica monoliths has already been described to capture radioactive cesium and to anchor it on a solid phase. Those materials were therefore functionalized with Prussian Blue Analogous (PBA) nanoparticles or more precisely K2CuFe(CN)6 (CuPBA) that are well known to be highly selective towards Cs. However, those materials did not allow optimal Cs sorption because of strong aggregation of PBA nanoparticles within the monoliths. Thereby, the solution developed is the use of core-shell nanoparticles in order to avoid the PBA aggregation. The core of these nanoparticles is made with PBA and protected by a porous silica shell.A reverse microemulsion is chosen as main synthetic route to synthesize and control the size and shape of these nanoparticles. That synthetic route allows in-situ synthesis of CuPBA nanoparticles in the microemulsion with an excellent stability of the particles in the water droplets. Microemulsions, characterized with SAXS, show droplets radius varying from 0.5 to 3 nm with regard to the water content defined by w parameter (w=[H2O]/[surfactant]). The growth of the silica shell is then achieved after the synthesis of CuPBA, using a classical basic conditions sol-gel process. The morphology of the core-shell nanoparticles is controlled with HRTEM/STEM-HAADF and the structural and chemical analysis are followed by XRD and FTIR-ATR. Finally, this study enables, for the first time, the synthesis of these core-shell nanoparticles. Then, recent sorption experiments highlighted that these core-shell nanoparticles can be used to entrap cesium with interesting capacity ((Qmax(core-shell NPs)=125 mg/g)). Moreover, these nanoparticles are useful for decontamination process and they open the way in the study of the self-irradiation and self-containment of radionuclides.

Este projeto tem como objetivo a derivatização de celulose sob condições homogêneas de reação, através de um método simples, reprodutível e eficiente nas três etapas do processo (ativação-dissoluçãoderivatização). O sistema de solvente DMAC/LiCI, utilizado na presente Dissertação, tem estado em crescente desenvolvimento nos últimos anos. Vários mecanismos têm sido propostos para uma dissolução rápida, com mínimo de formação de agregados e baixa degradação da cadeia de celulose. Foram utilizados nesse trabalho as celuloses Avicel PH 101 (DP = 150), eucalipto (DP = 685) e linter de algodão (DP= 850). Foi estudado o intumescimento (swelling) da celulose por uma série de solventes (próticos e apróticos) e misturas binárias, já que esta etapa é responsável pela degradação da estrutura fíbrilar por inchamento da fibra, e inserção de moléculas de solvente entre as cadeias, quebrando as ligações de H intermoleculares (etapa de ativação da celulose). O intumescimento determinado para solventes puros foi correlacionado com algumas propriedades dos solventes, incluindo seu volume molar, acidez, basicidade, polaridade/polarizabilidade e polaridade empírica, Vm, α; β; π*; e ET(30), respectivamente. Os resultados mostraram que: α ou β, Vm e π*; influenciam o intumescimento para os solventes próticos; Vm e π*; tem maior importância para os solventes apróticos; o DMSO é o solvente de maior poder de intumescimento. O último dado foi utilizado para modificar um método anteriormente desenvolvido, onde a celulose é dissolvida em LiCI/DMAC após uma etapa de ativação térmica, sob pressão reduzida. O método novo envolve pré-tratamento da celulose com DMSO, antes da sua dissolução no referido sistema de solvente. Este método, simples e eficaz, resultou em menor degradação da celulose, comprovada pela cor da solução (clara e límpida) e pela determinação do DP dos acetatos obtidos. Outro ponto positivo foi à dissolução do linter de algodão sem a necessidade de mercerização prévia. As relações Anidrido Acético/UAG na síntese de triacetatos de celulose foram 3, 3, 3,75 e 4,5 para as celulose Avicel PH 101, Eucalipto mercerizado, eucalipto e algodão respectivamente. O grau de acetilação foi determinado por RMN de 13C, indicando a seguinte ordem de reatividade: C6 > C2 > C3. / The objective of this work is the derivatization of cellulose, under homogeneous reaction conditions, bya simple, reproductive and efficient method, in the three steps of the process (activation-dissolution- derivatization). Previously, extensive work has been carried out on the solvent system studied in this work, DMAC/LiCl. Different mechanisms have been proposed to a fast dissolution with minimum aggregates formation and low degradation of cellulose chain. The following celluloses were used in this work: Avicel PH 101 (DP = 150), eucalyptus (DP = 685) and cotton linter (DP= 850). Cellulose swelling was studied in different solvents (protics and aprotics). This step is responsible for two phenomena: (i) fiber structure degradation through fiber swelling; and (ii) insertion of solvent molecules among the chains breaking intermolecular H-bonding (cellulose activation step). The determined swelling was correlated with some solvent properties as molar volume, acidity, basicidity, polarity/polarizability and empirical polarity, Vm, α; β; π*; and ET(30), respectively. The results showed that α or β, Vm and π* influence swelling in protic solvents; Vm and π* are important in aprotic solvents; and DMSO has the strongest swelling power. The last information was used to change a method developed before, where cellulose is dissolved in LiCI/DMAC after a thermal activation step under reduced pressure. The newmethod involves cellulose pre-treatment with DMSO, before the dissolution in the above-cited solvent system. This simple and efficient method resulted in smaller cellulose degradation verified by: (i) the color of the solution (clear and limpid) and (ii) the determination of PD of the obtained acetates. Another advantage of this method is the dissolution of cotton linter without previous mercerization. The relationship acetic anhydride/UAG found in the synthesis of cellulose triacetates were 3, 3, 3,75 e 4,5 for Avicel PH 101, mercerized eucalyptus, eucalyptus and cotton, respectively. Acetylation degree was determined by 13C NMR, the following reactivity order was observed C6 > C2 > C3.

O hormônio tireoideano (T3) desempenha papel importante no desenvolvimento, no crescimento e no metabolismo celular. Um dos seus principais efeitos é a ativação do metabolismo basal, contribuindo de forma importante com a regulação do peso corporal, enquanto diminui os níveis plasmáticos de triglicérides e colesterol. A ativação seletiva do receptor <font face=\"Symbol\">&#946 para o hormônio tireoideano (TR) por meio de agonistas seletivos reduziu níveis séricos de colesterol além de aumentar o metabolismo sem causar efeitos indesejáveis sobre o coração, osso ou músculo esquelético. Estes dados sugerem que estes agonistas poderiam ser úteis no tratamento das manifestações da síndrome metabólica tais como obesidade, hipercolesterolemia e resistência à insulina. Dessa forma, estudamos os efeitos da ativação do TR usando um agonista também da série GC, o GC-24, em ratos machos Wistar tratados com dieta rica em gordura e submetidos a injeções diárias de T3 correspondente a 10x a dose fisiológica (30g/g P.C./dia) ou GC-24 em dose equimolar (17g/g P.C./dia). Nosso estudo mostrou que o GC-24 preveniu algumas alterações metabólicas típicas da síndrome metabólica, tais como o aumento da massa gorda, intolerância à glicose e hipertrigliceridemia e corrigiu parcialmente outras como a hipercolesterolemia, o aumento do conteúdo de colesterol hepático e IL-6. Estes achados sugerem um papel importante do TR na mediação dos efeitos do T3 e devem ter repercussão importante na utilização potencial de agonistas seletivos ao TR<font face=\"Symbol\">&#946 como agentes hipocolesterolemiantes / Thyroid hormone (T3) plays an important role in the development, growth and cell metabolism. One of its main effects is to activate the basal metabolic rate significantly contributing to the regulation of body weight, while decreasing serum triglycerides and cholesterol levels. Thyroid hormone receptor selective activation through selective agonists reduced serum cholesterol levels besides increasing metabolic rate without causing undesirable side effects on the heart, bone or skeletal muscle. These data suggest that these agonists could be useful in the treatment of metabolic syndrome manifestations such as obesity, hypercholesterolemia and insulin resistance. Thus, we studied the effects of TR activation also using an agonist from the GC series, the GC-24 in male Wistar rats treated with high fat diet and submitted to daily T3 injections, corresponding to 10x physiological dose (30g/g B.W. /day) or equimolar doses of GC-24 (17g/g P.C. /day). Our study has shown that GC-24 prevented some of the metabolic abnormalities typical of metabolic syndrome such as increase in fat mass, glucose intolerance and hypertriglyceridemia and partially corrected other ones like hypercholesterolemia, the increase in hepatic cholesterol and IL-6 levels. These findings suggest that TR has an important role in the mediating of T3 effects and should have important repercussions in the potential use of selective agonists to TR as cholesterol lowering agents.

L'angiotensine II (Ang II) joue un rôle important dans la régulation du système cardiovasculaire par l’activation de plusieurs voies de signalisation. L’activation de ces voies passe par le récepteur de l'angiotensine II de type 1 (AT1R). Ce récepteur fait partie de la famille des récepteurs couplés aux protéines G (GPCRs). De plus, il est maintenant connu que certains ligands peuvent lier le récepteur et induire une conformation qui permet d'activer certaines voies de signalisation tout en n’étant pas favorable à l'activation d'autres voies. Il est alors question de sélectivité fonctionnelle, aussi appelée signalisation biaisée. Ainsi, avec cette approche, il est possible de cibler les voies qui produiront les effets thérapeutiques désirés sans toutefois activer les voies qui seraient responsables des effets indésirables. Nous avons émis l’hypothèse que de cycliser des ligands va restreindre les conformations possibles lors du couplage avec AT1R et induire un agonisme biaisé. Ainsi, des analogues cycliques de l’AngII substitués aux positions 3 et 5 par des cystéines et des homocystéines ont été synthétisés: [Sar1Hcy3,5]AngII, [Sar1Cys3Hcy5]AngII et [Sar1Cys3,5]AngII. D’abord, la capacité de ces analogues cycliques à activer la voie Gq a été évaluée par la mesure de la production des inositol phosphates. Puis, la capacité à activer les voies G12, le recrutement des β-arrestines (1 et 2) ainsi que l’activation de ERK1/2 a également été évaluée. Nos travaux ont montré que l’analogue cyclique [Sar1Hcy3,5]AngII a une puissance et une efficacité maximales sur toutes les voies testées à l'exception de la voie Gq. Des simulations de dynamique moléculaire ont été effectuées pour nous permettre de comprendre comment la conformation du ligand influence la structure d’AT1R et donc l’activation des différentes voies de signalisation. Les simulations en dynamique moléculaire ont montré que la barrière énergétique associée à l'insertion du résidu Phe8 de l’AngII dans le coeur hydrophobe d'AT1R est augmentée avec [Sar1Hcy3,5]AngII, pouvant expliquer que cet analogue active moins bien la voie Gq. D’autres analogues cyclisés aux positions 3 et 5 de l’AngII ont été synthétisés; [Sar1Hcy3Ile4Hcy5]AngII, [Sar1Hcy3,5Ile8]AngII et [Sar1Hcy3Cys5]AngII. Leur capacité à activer les voies Gq, ERK1/2 et le recrutement des β-arrestines (1 et 2) a été évaluée. L’analogue [Sar1Hcy3Cys5]AngII semblait bien activer la voie ERK1/2, mais pas les voies G12 et β-arrestines. Ces résultats suggèrent que le fait de contraindre les mouvements des déterminants moléculaires d’un ligand en introduisant des structures cycliques peut entraîner un biais dans la signalisation en stabilisant différentes structures du récepteur. / Abstract: Angiotensin II (Ang II) has an important role in the regulation of the cardiovascular system by its ability to activate several signaling pathways. The activation of these pathways occurs via the angiotensin II receptor type 1 (AT1R). This receptor belongs to the family of G protein-coupled receptors (GPCRs). Moreover, it is now known that certain ligands can bind to the receptor and induce a conformation that allow the activation of certain signaling pathways while not promoting the activation of other pathways. This concept is known as functional selectivity or biased signaling. With this approach, it is possible to target the signaling pathways that produce the desired therapeutic effects rather than activating the pathways responsible for adverse effects. We hypothesized that cyclizing ligands would restrict possible conformations when coupled with AT1R and induce biased agonism. Thus, cyclic AngII analogs substituted at positions 3 and 5 by cysteines and homocysteines were synthesized: [Sar1Hcy3,5]AngII, [Sar1Cys3Hcy5]AngII and [Sar1Cys3,5]AngII. First, the ability of these cyclic analogs to activate the Gq pathway was measured by the inositol phosphates production. Then, the G12 pathway activation, β-arrestin (1 and 2) recruitment and the ability of these analogs to activate the ERK1/2 pathway was evaluated. Our work has shown that [Sar1Hcy3,5]AngII has maximum potency and efficacy on all of the evaluated pathways, except for the Gq pathway. Molecular dynamic simulations were used to understand how a distinct ligand conformation influences the AT1R structure and the activation of signaling pathways. These studies have shown that the energy barrier associated with the insertion of the Phe8residue of AngII within the hydrophobic core of AT1R is increased with [Sar1Hcy3,5]AngII, possibly explaining why this analog is less potent in activating the Gq pathway. Other analogues cyclized at positions 3 and 5 of AngII were synthesized; [Sar1Hcy3Ile4Hcy5]AngII, [Sar1Hcy3,5Ile8]AngII and [Sar1Hcy3Cys5]AngII. Their ability to activate Gq, ERK1/2 and recruitment of β-arrestins (1 and 2) was evaluated. The analog [Sar1Hcy3Cys5]AngII appeared to activate the ERK1/2 pathway but not the G12 and β-arrestin pathways. These results suggest that constraining the movements of molecular determinants of a ligand by introducing cyclic structures can lead to a signaling bias by stabilizing different structures of the receptor.