The theoretical model of Beratan and Onuchic predicts a large attenuation of ET rates through hydrogen bonds; however, the effect of individual hydrogen bond on electron transfer reaction has not been systematically studied. The organic complexes in this study are a series of crown ether/ammonium salt, which incorporate a redox partner on each component of the complex. The dimethoxynaphthalene redox donor was attached to the crown ether and a series of ammonium salts was synthesized which bear substituted quinone and naphthoquinone acceptor. The complexes characterization and preliminary electron transfer rate measurement were completed with UV/Vis and steady-state emission spectroscopy.

Au cours de ma thèse, je me suis intéressée à l'interaction du complexe Nitrate Reductase A (NarGHI) avec les quinones et les lipides de la membrane chez E. coli. Nous avons identifié que les intermédiaires ménasmiquinones interagissent avec une liaison hydrogène avec l'histidine 66 du site Qd. Par ailleurs, nous avons mis en évidence par la fixation spécifique d'une molécule de cardiolipine est indispensable au fonctionnement du complexe NarGHI en permettant la fixation du quinol. Enfin, nous avons démontré l'existence d'une liaison fonctionnelle entre la voie de biosynthèse des hèmes et les complexes respiratoires via la protéine HemG, qui couple la réduction des quinones avec l'oxydation du protoporphyrinogène IX. Ces éléments prouvent qu'une voie catalytique peut contribuer à la synthèse ATP. L'ensemble de ces résultats indique une étroite interconnexion physique et fonctionnelle entre tous les éléments qui composent la membrane cytoplasmique d'E. coli / In this thesis, I study the interaction between the nitrate reductase A comlex (NarGHI) with the quinines and lipids of the E. coli cytoplasmic membrane. We demonstrate that His66 present at the Qd site is directly hydrogen bonded to both menasemiquinone and ubisemiquinone species. In addition, we show that functionning of the enzyme complex is controlled by cardiolipin binding in a specific cavity allowing quinol binding at the nearby QD site. Finally, we relealed that heme biosynthesis is a quinone-depended metabolic reaction during anaerobic growth of E. coli, in wich the HemG protein will direct electron transfer issued from oxidation of a heme biosynthetic intermediate towards quinone molecules via interaction between quinones, lipids and membrane- associated complexes that couple respiration and anabolic pathways to ATP generation in specialized domains of E. coli membrane

Une série de soixante deux molécules basées sur le motof 8-hydroxyquinoléine a été synthétisée pour évaluer les effets de changements structuraux sur l'activité antitumorale et comprendre les mécanismes d'action mises en jeu. L'étude a été réalisée sur un large panel de lignées cellulaires cancéreuses dont des gliomes, des carcinomes et des mélanomes. Des expériences in vivo impliquant des xénogreffes sur des souris transgéniques ont été réalisées pour confirmer les effets anticancéreux observés in vitro. De plus, une étude complète sur la cible biologique a été réalisée a été menée sur les récepteurs PPAR, la voie des caspases, l'activité ptotéosomique et l'assemblage des tubulines. Les analogues basés sur la 8-hydroxyquinoléine peuvent représenter une voie thérapeutique nouvelle et inédite dans le traitement anticancéreux avec des mécanismes d'action impliquant les thiols de certaines protéines / A series of sixty two molecules based on 8-hydroxyquinoline were synthesized to evaluate the effects of structural changes on antitumor activity and understand their mechanism of action. The studies were performed on a wide variety of cancer cell lines within glioma, carcinoma and melanoma models. In vivo experiments on mice brain wenagrafted by glioblastoma cells had been proceed to confirmate in vitro anti-cancer effects. Moreover a complete investigation about the biological target have been realised on PPAR receptors, caspase pathway, proteosomal activity and tubulin assembly. The described analogues could represent new promising anti-cancer candidates with specific action mechanisms, targeting accessible thiols from specific proteins and inducing potent anticancer effects.

Organic electrode materials are finding increasing use in energy storage devices due to their attractive properties that allow building of flexible and low weight devices in an environmentally friendlier manner than traditional alternatives. Among these organic electrode materials, conducting redox polymers (CRPs), consisting of conducing polymer (CP) with covalently attached redox active pendant groups (PG), have attracted our interests. This is due to the advantageous synergy between CP and PG, e.g. electronic conductivity, high stability and large charge storage capacity. In this thesis polypyrrole has been selected as CP and quinones as PGs. A series of quinone-pyrrole dyad polymers has been synthesized with a variety of quinone substituents, demonstrating the adjustability of quinone formal potentials by choice of substituents. Importantly, in this series we show that the CP-PG redox match, i.e. that the formal potential of the PG is within the conducting region of the CP, is a requirement for fast charge transfer from the electrode to the PGs. Moreover, a series of quinone-pyrrole dyad polymers with various linkers was synthesized, showing that the choice of linker has a pronounced impact on the interactions between the PG and CP. In addition, the temperature dependence of conductance during doping of the polymers reveals the charge transport mechanism. To summarize, the adjustability of the quinone formal potential as well as the fast charge transport in the bulk material ensures the applicability of the CRPs as electrode materials in organic batteries.

Dans le cadre de la recherche de nouvelles cibles pour le traitement du cancer, les phosphatases Cdc25 sont des candidats intéressants dont l'inhibition devrait permettre de ralentir la croissance tumorale et éventuellement d'améliorer les traitements actuellement en usage. Les objectifs de ce projet de thèse sont de concevoir et synthétiser de nouveaux composés capables d'inhiber les CDC25, et de déterminer l'efficacité des meilleurs composés dans les lignées cellulaires du cancer du sein. L'évaluation du potentiel inhibiteur des composés est réalisée in vitro par une méthode fluorimétrique très sensibilité (substrat 3-OMFP). Les effets des composés sont évalués dans les lignées cellulaires MCF-7 et MDA-MB-231 : La viabilité des cellules est évaluée par la méthode colorimétrique du MTT, la cytotoxicité est évaluée par coloration au bleu trypan et par observation microscopique avec le système de vidéomicroscopie Incucyte. La mort cellulaire est caractérisée par la détection de marqueurs apoptotiques (caspases) et de marqueurs des dommages de l'ADN (H.2AX Histone PARP) par western blot. L'analyses des mécanismes liés à la mort cellulaire sont explorées par cytométrie en flux via la détection d'espèces réactives de l'oxygène (ERO) avec les sondes H2DCFDA et Redox Sensor Red. L'inhibition de CDC25 dans les cellules est évaluée indirectement par détection des formes phosphorylées dse CDK en Western Blot. L'évaluation in vitro de 93 molécules synthétisées nous a permis d'identifier de nouveaux composés actifs. Ils appartiennent à diverses familles chimiques comprenant des stéroïdes, thiophènes, coumarines, imidazoles ainsi que des dérivés de quinone. Les dérivés coumariniques ont montré une intéressante inhibition de CDC25, non décrite jusqu'à présent. Une nouvelle structure coumarine-soufre-quinone, nommée SV37, a été conçue pour optimiser le potentiel d'inhibition. Ce composé présente un fort potentiel inhibiteur des CDC25 in vitro (CI50 < 5uM pour CDC25 A et C). L'effet de SV37 sur la croissance cellulaire a été évalué sur les lignées cellulaires MCF-7, MDA-MB-231, hTERT-HME1 et HepG2 sur lesquelles une inhibition de la croissance cellulaire est observée (CI50 de 9 à 18 µM). L'analyse de la viabilité des cellules traitées à la CI50 indique l'absence de mort cellulaire pour la lignée MCF7, tandis que pour la lignée MDA-MB-231 la diminution de la croissance cellulaire est liée à une augmentation de la mort cellulaire. Afin d'étudier les mécanismes liés à la mort cellulaire, nous nous sommes concentrés sur l'étude du modèle triple négatif MDA-MB- 231. Les modifications morphologiques de ces cellules sont caractérisées par l'apparition d'altérations cellulaires compatibles avec la mort cellulaire. Le clivage des caspase-3 et 7 a été observé dès 16h de traitement, ce qui suggère l'induction d'une mort apoptotique. Par ailleurs, des ERO ont été détectées 15 min après le début du traitement, cette émission d'ERO a pu être totalement bloquée par un prétraitement avec la N-acétylcystéine (NAC). La détection de marqueurs des dommages de l'ADN, entre 16 et 28 heures après début du traitement, corrobore l'activation des caspases et les observations réalisées en vidéo-microscopie. Après traitement à CI50, une accumulation des pCDK dans les cellules a été observée après 4 et 8 heures, suggérant une inhibition de l'activité CDC25. De plus, les cellules prétraitées avec la NAC n'ont montré aucune accumulation de pCDK après traitement par SV37. Ces résultats suggèrent un lien direct entre la production de ROS induit par le composé SV37 et l'inhibition des CDC25. Ce projet a permis de définir les coumarines en tant que nouvelle classe de composés inhibitrice des phosphatases CDC25. Ces travaux ont de plus permis l'identification d'un composé coumarine-soufre-quinone SV37 qui constitue une structure de base pour le développement d'inhibiteurs de plus en plus efficaces, ... / Within the context of research for new targets for cancer therapy, Cdc25 phosphatases are interesting candidates, the inhibition of which being able to slow down tumor growth and eventually improve the cancer treatments currently in use. The objectives of this PhD project are to design and synthesize new compounds able to inhibit CDC25 and to determine efficiency of identified compounds in breast cancer cell lines. In vitro evaluation of inhibitory potential of compound is realized through a high sensitivity fluorometric method (3-OMFP substrate). Cellular effects were evaluated in MCF-7 and MDA-MB-231 cell lines. Effects on cell viability are assessed through MTT assays, and cytotoxicity is evaluated through trypan blue assays and microscopic observations with Incucyte videomicroscopy system. Cell death was characterized by detection of apoptotic markers (caspases) and DNA damages markers (PARP Histone H.2AX) by Western Blotting. The analyses of mechanisms underlying cell death were explored through cytometric detection of reactive oxygen species (ROS) with H2DCFDA and Redox Sensor Red probes. Inhibition of CDC25 in cells was indirectly evaluated through detection of phosphorylated forms of CDK by Western Blotting. In vitro evaluation of 93 synthesized compounds allowed us to find new active compound in various chemical families including steroid, thiophene, coumarinic, imidazole and quinone derivatives. The coumarinic derivatives showed potent CDC25 inhibition. A new coumarin-sulfurquinone combined structure, named SV37, was designed to optimize efficiency of inhibition. In vitro tests on this compound, showed a strong CDC25 inhibitory potential (IC50 under 5µM for CDC25 A and C). Effect of SV37 on cell growth was evaluated on various cell lines (MCF-7, MDA-MB-231, hTERT-HME1 and HepG2). Results indicate inhibition of cell growth (IC50 values from 9 to 18 µM). Analysis of cell viability indicates no remarkable cell death in MCF7 at IC50 value whereas in MDA-MB-231 the cell growth decrease was characterized by an increase of cell death. For deeper investigations on the cell death and on the underlying mechanisms, we focused the study on the triple negative model MDA-MB-231. The morphological changes of MDA-MB-231 cells during the treatment were characterized by the appearance of cellular alterations compatible with a cellular demise and culminating with a disruption of cells after 20h. Caspase-3 and 7 cleavages were observed 16h after beginning of the treatment, suggesting an apoptotic cell death. A ROS induction was observed 15 min after the beginning of the treatment and was totally prevented by Nacetylcysteine (NAC) pretreatment. DNA damage markers were detected between 16 and 28 hours after beginning of treatment, a timing falling with caspase activation and with the appearance of cell demise observed by video microscopy. Accumulation of pCDK in cells was observed after 4 and 8 hr of treatment by SV37 at IC50 suggesting an inhibition of CDC25 activity, and cells pretreated with NAC showed no accumulation of pCDK after SV37 treatment. This strongly suggests a direct link between ROS generation by the compound SV37 and the accumulation of pCDK. This project increased knowledge on inhibitors of CDC25 phosphatases and allowed the identification of coumarine compound as new CDC25 inhibitors. This work will enable the development of ever more efficient inhibitors, leading to efficient inhibition of CDC25 and inhibition of tumor development

A thesis submitted in fulfilment of the requirements for the degree Magister Technologiae (Chemistry) in the Faculty of Applied Sciences, Department of Chemistry, Cape Peninsula University of Technology, 2008 / Green et al. attempted to synthesize linear naphthopyranquinones from a naphthyl dioxolane using a TiCl4 as a catalyst. They managed to synthesise an angular naphthopyran as well as a linear naphthopyran in low yield. They showed that reducing the steric strain at position 1 of the naphthyl dioxolane afforded a low percentage yield of the linear naphthopyran plus an angular one. This thesis describes the synthesis of linear naphthopyrans with an improved percentage yield using TiCl4 as a catalyst. This was achieved by placing a OMe group of less steric hinderance at position 1 and a Br atom at position 4 of a naphthyl dioxolane. The OMe group at position 1 was to allow isomerisation to occur at position 2, and the Br atom was to inhibit isomerisation at position 4, thereby inhibiting the formation of the angular naphthopyran.

Dihydronicotinamide riboside (NRH) quinone oxidoreductase 2 (NQO2) is involved in quinone metabolism reducing quinone to hydroquinone. Quinones are products of oestrogen metabolism and are responsible for the oestrogen-initiated breast carcinogenesis. It has been demonstrated that oestrogen quinones are endogenous biological substrates of NQO2 which acting as a detoxification enzyme catalyses the reduction of oestrogen quinones to hydroquinone. Hydroquinone can then be removed by conjugation to glutathione or glucuronic acid. In this study, the oestrogen dependent and oestrogen independent effects of NQO2 in a variety of networks implicated in breast tumorigenesis were investigated aiming to understand the potential role of NQO2 overexpression in mammary carcinomas. The use of NRH as a cofactor for NQO2 is being studied in parallel with the Î2-oestradiol and tamoxifen treatments. The MCF-7, T47D, MDA-MB-231 and MDA-MB-468 breast cancer cells were transfected with increasing amounts of NQO2 and its biological activity in regulating ERα transcriptional activity, reactive oxygen species (ROS) generation, cell cycle control, mitochondrial membrane potential and antioxidant activities including catalase activity, glutathione (GSH) levels and glutathione peroxidase (GPx) activity were studied. NQO2 overexpression in MDA-MB-231 and T47D cells reduced ROS generation. Increasing amounts of transfected NQO2 induced the ERα transcriptional activity in Î2-oestradiol treated MCF-7 and T47D cells and decreased cyclin D1 protein levels in these cells treated with Î2-oestradiol compared to untransfected cells. Reduction of catalase activity was detected in tamoxifen treated T47D cells overexpressing NQO2, an effect that was not evident in Î2-oestradiol treated cells, whereas NQO2 mediated reduction of GSH levels was detected in these cells treated with Î2-oestradiol but not with tamoxifen. Finally, NQO2 affected mitochondrial membrane depolarization in Î2-oestradiol treated MDA-MB-231 cells. Given the fact that NRH is not physiologically synthesized in humans, the results presented in this study are valuable from the fundamental science point of view indicating the existence of a potential link between NQO2 and estrogens affecting a number of biological pathways important for breast carcinogenesis and as such from the clinical angle it could be assumed that NQO2 effects could impact the design of personalised breast cancer treatment of oestrogen receptor positive and negative breast cancers.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Neste trabalho descreve-se a sÃntese, caracterizaÃÃo, reatividade e propriedades de novos complexos de rutÃnio com os ligantes o-fenilenodiamina, o-aminofenol, catecol, naftalenodiol, dopamina e adrenalina a partir do complexo precursor mer-[RuIIICl3(dppb)(H2O)]. Descreve-se tambÃm uma nova rota de desidrogenaÃÃo oxidativa do ligante o-fenilenodiamina a partir da interaÃÃo deste com o complexo mer-[RuIIICl3(dppb)(H2O)]. O complexo mer-[RuIIICl3(dppb)(H2O)] à extremamente versÃtil como precursor. Ao reagir com o ligante o-fenilenodiamina diretamente, forma uma mistura constituÃda por complexos que contÃm as formas oxidada (bqdi) e reduzida (opda) do ligante o-fenilÃnico, os complexos trans-[RuIICl2(dppb)(bqdi)] e trans-[RuIICl2(dppb)(opda)], que foi confirmada pela observaÃÃo de dois singletos em d 47 e d 26 no espectro de RMN 31P{1H}. Uma tentativa de atribuiÃÃo preliminar sugere que o ligante opda à oxidado a bqdi durante a reaÃÃo, conforme mecanismo proposto no presente trabalho. Entretanto, o produto obtido da reaÃÃo entre o ligante o-fenilenodiamina e o complexo mer-[RuIIICl3(dppb)H2O] por meio da lenta adiÃÃo do ligante apresentou apenas um sinal em d 26 no espectro de RMN 31P{1H}, indicando que o complexo trans- [RuIICl2(dppb)(bqdi)] à preferencialmente formado. Tal complexo foi caracterizado por anÃlise elementar, tÃcnicas espectroscÃpicas e eletroquÃmicas e sua estrutura determinada por difraÃÃo de raios X. Com o objetivo de reforÃar o mecanismo proposto, realizou-se a sÃntese entre o o ligante o-fenilenodiamina e o complexo [RuIICl2(dppb)(PPh3)]. Neste caso, o centro metÃlico de rutÃnio jà se encontra no estado reduzido e o metal nÃo promoverà nenhum tipo de mudanÃa no estado de oxidaÃÃo do ligante. Portanto, o produto obtido apresentou apenas um sinal em d 47 no espectro de RMN 31P{1H}, indicando a formaÃÃo do complexo trans-[RuIICl2(dppb)(opda)], caracterizado por microanÃlise, tÃcnicas espectroscÃpicas e eletroquÃmicas e cuja estrutura foi determinada por difraÃÃo de raios X. Os complexos isolados do tipo trans-[RuIICl2(dppb)(X)], onde X = quinona, dopamina e adrenalina e cis-[RuIICl2(dppb)(L)], onde L = o-aminofenol na forma quinonÃide e bqdi, foram caracterizados por espectroscopia eletrÃnica, vibracional e de ressonÃncia magnÃtica nuclear de fÃsforo, alÃm de tÃcnicas eletroquÃmicas, como voltametria cÃclica e de pulso diferencial. / This research work describes the synthesis, characterization, reactivity and properties of new complexes of ruthenium with the ligands o-phenylenediamine, oaminophenol, catechol, naphtalenediol, dopamine and adrenaline and the mer-[RuIIICl3(dppb)(H2O)] complex. Also, it describes a new metal-assisted oxidative dehydrogenation of the interaction o-phenylenediamine ligand and the mer- [RuIIICl3(dppb)(H2O)] complex. The mer-[RuIIICl3(dppb)(H2O)] complex has shown to be a versatile compound as starting material. The reaction of this compound with the o-phenylenediamine ligand produced a mixture of compounds with the bqdi and opda forms of the o-phenylene ligand, the trans-[RuIICl2(dppb)(bqdi)] and trans-[RuIICl2(dppb)(opda)] complexes, that it was confirmed for the observation of two singlet signals at d 47 and d 26 in the 31P{1H} NMR spectrum. One very first assignment suggests that the opda ligand is oxidized to bqdi form during the reaction, according to mechanism proposed in this work. However, the product of the reaction between the o-phenylenediamine ligand and the mer-[RuIIICl3(dppb)H2O] complex by the slow addition of the ligand showed only one signal at d 26 in the 31P{1H} NMR spectrum, indicating that the trans-[RuIICl2(dppb)(bqdi)] complex is preferentially produced. This complex was characterized by the elemental analysis, spectroscopic and electrochemical techniques and its structure has been determined by X-ray crystallography. Aiming to reinforce the proposed mechanism, we conducted the reaction of the o-phenylenediamine ligand with the [RuIICl2(dppb)(PPh3)] complex. Since the ruthenium metal center is already in the reduced state, it will not promote any redox change in the ligand. Thus, the complex produced showed only one signal at d 26 in the 31P{1H} NMR spectrum, indicating the formation of the trans-[RuIICl2(dppb)(opda)] complex that it was characterized by the elemental analysis, spectroscopic and electrochemical techniques and its structure has been determined by X-ray crystallography. The compounds isolated of type trans-[RuIICl2(dppb)(X)], X = quinone, dopamine and adrenaline and cis-[RuIICl2(dppb)(L)], L = o-aminophenol in the quinonoide form and bqdi, were characterized by the spectroscopic and electrochemical techniques.

Polychlorinated biphenyls (PCBs) are the persistent environmental pollutants with the continuous concerns over adverse human health effects. As semi-volatile compounds, PCBs were found in indoor and outdoor air. The observation of high levels of airborne PCBs in old school buildings raised the concerns of inhalation exposure and toxicity of PCBs. Lower chlorinated PCBs (LC-PCBs), major components of airborne PCBs, are subject to biotranformation. In vitro and in vivo studies revealed that reactive metabolites of LC-PCBs formed covalent adducts on DNA and proteins. The hypothesis of the project is that the reactive metabolites of LC-PCBs are able to form adducts on proteins or even protein crosslinks, and the formation of protein adducts and crosslinks causes the dysfunction of the target proteins. In addition, the objectives of the project are also to identify protein targets by PCB metabolites, which may be related to the mechanism of toxicity of LC-PCBs. The alkaline permethylation (AP) was established and optimized to identify and measure the protein adducts from LC-PCB metabolites. The AP method evidenced PCB metabolites formed protein adducts through the sulfhydryl groups and also one molecule of PCB quinoid metabolites was able to bind to more than one protein. Application of cytochrome c as the model protein revealed PCB quinoid metabolites also formed adducts on lysine and glutamic acid. The adduct formation and crosslinks caused the dysfunction of cytochrome c. In addition, the quinone protein adducts still kept the ability for redox reactions, which may lead to unexpected toxicity. The SILAC method was applied to identify the target proteins in the samples of in vitro proteome incubation. The instability of PCB quinone protein adducts was found by further reaction of quinone protein adducts. This may be the reason why cysteine-PCB quinone adducts were not frequently identified by proteomics method. The further understanding of protein adducts by reactive PCB metabolites helps to identify the target proteins, and ultimately reveal the role of protein adducts impacting on human health.

Multi-step photoinduced electron transfer takes place over a large distance in the photosynthetic reaction centres (PRCs). Electron donor in this life-spending event is the photo-excited 'special pair', a unit of two electronically coupled porphyrinoid chromophores. Bacteriopheophytin and two quinone molecules function as electron acceptors and contribute to the charge separation with almost unit quantum efficiency. The natural photosynthetic reaction centre is the most sophisticated molecular electronic device to date and interest is high in increasing our understanding of the basic quantum mechanical principles behind efficient electron transfer and ultimately copying Nature and construct similar efficient devices. Two main approaches towards a better understanding of the mechanisms involved have been taken. The more biological disciplines isolate, cultivate and alternate reaction centres whereas synthetic chemists prefer to construct well-defined models that mimic certain aspects of the reaction centres. Such a synthetic approach is described in the 'Synthesis of Advanced 'Special Pair' Models for the Photosynthetic Reaction Centre'. The aspect to be mimicked is the 'special pair'. One or two porphyrins in a well-defined spatial disposition (kinked or non-kinked in respect to each other) were to act as electron donor in rigid bichromophoric and trichromophoric systems. A tetracyanonaphthoquinodimethane (TCNQ) unit was employed as the electron acceptor in the series of dyads synthesised. The TCNQ acceptor was replaced by a naphthoquinone (NQ) primary acceptor covalently linked to a TCNQ secondary electron acceptor in the series of triads. Rigid norbornylogous bridges held the chromophores in place and Diels-Alder methodology as well as condensation reactions were applied to link donor, bridge and acceptor components. Despite larger interchromophoric separation than in the natural 'special pair', the two porphyrin chromophores of the series of 'special pair' dyads show some interaction and thereby prove the success of our approach towards 'special pair' mimics. Strong fluorescence quenching in the porphyrin-TCNQ dyads indicates the sought after electron transfer process. A number of synthetic problems experienced and overcome in the synthesis of the series of triads led to discovery of a one-step 'bis-ketonisation' from an olefin under Sharpless bis-hydroxylation conditions with N-methylmorpholine-N-oxide. High pressure was applied to circumvent a lack of reactivity in the condensation reaction used to attach the porphyrin moieties (one or two) to the donor backbone. For the linkage of donor, bridge and acceptor component, a procedure was developed and successfully applied to give the giant mono-porphyrin-NQ-TCNQ trichromophore. In a similar manner 'special pair' trichromophoric systems should be available as part of future work.