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1
Oosthuizen, Francois Jacobus. "Syntheses of the enantiopure quinones A and A' and their C-1 epimers". Thesis, Oosthuizen, Francois Jacobus (2002) Syntheses of the enantiopure quinones A and A' and their C-1 epimers. PhD thesis, Murdoch University, 2002. https://researchrepository.murdoch.edu.au/id/eprint/234/.
Testo completoAbstract (sommario):
The 3,4-dihydro-1H-naphtho[2,3-c]pyran ring system is found in many natural products as the 5,10- or 6,9-quinones. These compounds have been synthesized by various research groups as a result of their wide range of biological activities. This thesis describes several investigations directed towards syntheses of compounds in this general area. Quinone A (16) and quinone A'(17), derived from the naturally occurring aphid insect pigments protoaphin-fb and protoaphin-sl respectively, were of particular interest.
The first chapter describes the previous syntheses of some naphtho[c]pyrans including those relating to the aphid pigment derivatives, followed by the isolation and identification of the aphid pigments. Also described was the ability of these naphthopyranquinones to act as potential bioreductive alkylating or dealkylating agents. The latter part of the chapter deals with the syntheses of the racemates of the aphid pigment derivatives quinones A and A' and deoxyquinone as well as model studies toward the non-quinonoid cleavage product, glucoside B. The chapter concludes with the progress made towards the first asymmetric synthesis of these compounds.
Chapter 2 reports the establishment of conditions which led to ortho or para regioselectivity in the intramolecular cyclisation of tethered lactaldehydes to form benzo[c]pyrans. This regioselectivity depended on whether either benzyl or tbutyldimethylsilyl was used as protecting group. This chapter also described a model for the control of stereochemistry leading to quinone A'.
Chapter 3 describes the syntheses of naphthalenes as potential precursors to the naphthopyranquinones derived from the aphid insect pigments. This followed after problems were encountered in previous work with inappropriate protection in the oxidation of halogenated benzopyrans.
Chapter 4 develops the first successful syntheses of enantiopure quinone A and quinine A' with the correct absolute stereochemistry. This involved the regioselective addition of 1,3-bis(trimethylsilyloxy)-1-methoxybuta-1,3-diene toselectively halogenated benzopyranquinones. The latter were obtained through complementary series of highly diastereoselective transformations based on 2,5- dihydroxyacetophenone as starting material and (R)-lactate from the chiral pool as the source of asymmetry.
2
Oosthuizen, Francois Jacobus. "Syntheses of the Enantiopure Quinones A and A' and Their C-1 Epimers". Murdoch University, 2002. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040820.123649.
Testo completoAbstract (sommario):
The 3,4-dihydro-1H-naphtho[2,3-c]pyran ring system is found in many natural products as the 5,10- or 6,9-quinones. These compounds have been synthesized by various research groups as a result of their wide range of biological activities. This thesis describes several investigations directed towards syntheses of compounds in this general area. Quinone A (16) and quinone A(17), derived from the naturally occurring aphid insect pigments protoaphin-fb and protoaphin-sl respectively, were of particular interest.
The first chapter describes the previous syntheses of some naphtho[c]pyrans including those relating to the aphid pigment derivatives, followed by the isolation and identification of the aphid pigments. Also described was the ability of these naphthopyranquinones to act as potential bioreductive alkylating or dealkylating agents. The latter part of the chapter deals with the syntheses of the racemates of the aphid pigment derivatives quinones A and A and deoxyquinone as well as model studies toward the non-quinonoid cleavage product, glucoside B. The chapter concludes with the progress made towards the first asymmetric synthesis of these compounds.
Chapter 2 reports the establishment of conditions which led to ortho or para regioselectivity in the intramolecular cyclisation of tethered lactaldehydes to form benzo[c]pyrans. This regioselectivity depended on whether either benzyl or tbutyldimethylsilyl was used as protecting group. This chapter also described a model for the control of stereochemistry leading to quinone A.
Chapter 3 describes the syntheses of naphthalenes as potential precursors to the naphthopyranquinones derived from the aphid insect pigments. This followed after problems were encountered in previous work with inappropriate protection in the oxidation of halogenated benzopyrans.
Chapter 4 develops the first successful syntheses of enantiopure quinone A and quinine A with the correct absolute stereochemistry. This involved the regioselective addition of 1,3-bis(trimethylsilyloxy)-1-methoxybuta-1,3-diene toselectively halogenated benzopyranquinones. The latter were obtained through complementary series of highly diastereoselective transformations based on 2,5- dihydroxyacetophenone as starting material and (R)-lactate from the chiral pool as the source of asymmetry.
3
Cassagnes, Laure-Estelle. "Cycle redox quinone-quinone réductase 2 et conséquences sur la production d'espèces oxygénées réactives dans le contexte cellulaire". Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30148/document.
Testo completoAbstract (sommario):
La quinone réductase 2 ou QR2 est une enzyme qui, comme son homologue QR1, joue un rôle de détoxification des quinones, molécules fortement réactives, en les réduisant en hydroquinones. Cependant, il a été observé au niveau cellulaire et tissulaire que l'activité de cette flavoprotéine pouvait avoir des effets délétères en déclenchant une surproduction d'espèces réactives de l'oxygène (ROS). D'autre part, on observe une surexpression ou une sous expression de QR2 dans certaines maladies neurodégénératives comme la maladie de Parkinson et la maladie d'Alzheimer. Dans ce contexte, ce travail a porté sur l'étude des espèces oxygénées réactives produites lors du cycle redox quinone / QR2 et leurs variations en fonction de la nature de la quinone, sur protéine purifiée et sur modèles cellulaires comparativement à QR1. Les propriétés d'oxydo-réduction des substrats, co-substrats et inhibiteurs de QR2 étudiées par électrochimie ont permis de les classer en fonction de leur capacité à être réduits. L'activité enzymatique de la protéine, qu'elle soit purifiée ou intracellulaire, a été suivie par différentes méthodologies (résonance paramagnétique électronique, spectroscopie UV-visible et de fluorescence, U(H)PLC-MS, microscopie confocale de fluorescence). La production du radical superoxyde est observée en présence de lignées cellulaires surexprimant ou non QR1 et QR2. Les quinones sont réduites enzymatiquement pour donner des hydroquinones via l'activité des quinones réductases (QR1 et QR2) et des semiquinones via l'activité de réductases à un électron (CytP540 réductase par exemple). La réoxydation de ces produits est responsable d'une production plus ou moins forte de radicaux superoxydes selon la structure initiale de la quinone et l'affinité pour les différentes réductases. La ménadione provoque une production cellulaire de superoxyde plus importante en l'absence de QR1 et QR2. Ces analyses ont également démontré que, comme son homologue QR1, QR2 est capable de réduire les ortho-quinones dont certaines catécholquinones (aminochrome, dopachrome, adrénochrome) reconnues pour leur toxicité neuronaleQuinone reductase 2 or QR2 is an enzyme that, like its counterpart QR1, plays a role in detoxification of the highly reactives quinones by reducing them into hydroquinones. On one hand, it has been observed at the cellular and tissue level that the activity of this flavoprotein could have deleterious effects by triggering an overproduction of reactive oxygen species (ROS). On the other hand, overexpression or under expression of QR2 has been observed in some neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease. In this context, this work focused on the study of reactive oxygen species produced during the quinone / QR2 redox cycle and their variations depending on the nature of the quinone, on both purified protein and cell models, in comparison to QR1. The redox properties of the substrates, co-substrates and inhibitors ok QR2 studied by electrochemistry allowed to classify them according to their capacity to be reduced. The enzymatic activity of the protein, either purified or intracellular, was followed by various methodologies (electron paramagnetic resonance, UV-visible and fluorescence spectroscopy, U(H)PLC-MS, confocal fluorescence microscopy). Production of superoxide radical is observed in the presence of cell lines overexpressing or not QR1 and QR2. Quinones are reduced enzymatically to form hydroquinones via the activity of quinone reductase (QR1 and QR2) and semiquinone via the activity of one electron reductases (e.g. CytP540 reductase). Reoxidation of these products is responsible for a greater or lesser production of the superoxide radical, according to the initial structure of the quinone and the affinity for different reductases. Menadione causes a higher production of cellular superoxide in the absence of QR1 and QR2. These analyzes have also shown that, like its counterpart QR1, QR2 is capable of reducing ortho-quinones including catecholquinones (aminochrome, dopachrome, adrenochrome) known for their neuronal toxicity
4
Minhas, Gurdeep Singh. "Interaction of quinone and quinone-like inhibitors with Thermus thermophilus complex I". Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707994.
Testo completo
5
Chauncey, Marek Anthony. "Reactions heterocyclic quinone methides". Thesis, University of Ulster, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328193.
Testo completo
6
Chhour, Monivan. "Etude de la métabolisation intracellulaire de quinones, du stress oxydant généré et des processus de détoxification associés". Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30004.
Testo completoAbstract (sommario):
Les quinones sont des composés ubiquitaires naturels indispensables aux organismes vivants. Cependant leur métabolisation est considérée comme toxique en raison de leur réactivité élevée. Les quinones sont en effet facilement réductibles à un ou deux électrons. La métabolisation intracellulaire de ces quinones par des réductases à un électron telles que le cytochrome P450 réductase ou d'autres flavoprotéines génèrent des semiquinones instables à l'origine de la production de radicaux libres conduisant à un stress oxydant. Les quinones-réductases 1 et 2 (QR1 et QR2) catalysent leur réduction à deux électrons pour former des hydroquinones chimiquement plus stables. Cette propriété est à l'origine du caractère détoxifiant généralement associé aux quinone-réductases. Cependant des analyses antérieures ont montré que ce caractère détoxifiant était remis en cause pour certains types de quinones et dépendait, notamment, du type de cellules. Ainsi afin de mieux comprendre les mécanismes conduisant à la génération d'espèces réactives et compte tenu du lien évoqué dans la littérature entre QR2 et neurodégénérescence, des études ont été menées sur des neurones primaires et des neuroblastomes génétiquement modifiés pour surexprimer QR2. Ces études ont mis en évidence, par diverses techniques analytiques telles que la résonance paramagnétique électronique ou la LC-MS, une augmentation de la toxicité de la ménadione mais également de l'adrénochrome en présence de la quinone-réductase 2. Afin d'expliquer les caractères contradictoires de QR2 d'une cellule à l'autre nous avons proposé l'hypothèse qu'une coopération avec une enzyme de conjugaison pouvant réagir avec la forme réduite instable et empêcher sa réoxydation soit nécessaire pour effectivement détoxifier les quinones. Des analyses complémentaires (RPE, LCMS, fluorescence) menées sur des neuroblastomes surexprimant à la fois QR2 et une enzyme de conjugaison spécifique des para-hydroquinone (UGT) ont en effet mis en évidence une diminution du stress oxydant lorsque les deux enzymes sont co-expriméesQuinones are ubiquitous compounds in nature. They are also one of the essential elements in living organisms. However, their metabolisms are considered as toxic because there are highly reactive. Their structure is easily reduced by one or two electrons. The intracellular metabolism of these quinones via one-electron reduction such as cytochrome P450 reductase or others flavoproteins generates an unstable semiquinones which leads to a burst of free radical production that results in oxidative stress. On the other hand, quinone-reductases 1 and 2 (QR1 and QR2) catalyze quinone reduction via two electrons to form hydroquinones that chemically more stable. This property is well-known as the detoxifying character of quinone-reductase enzymes. However, previous analyses have shown that this detoxifying effect was appeared only for certain types of quinones and depended, in particular, on the type of cells. Thus, in order to better understand the mechanisms leading to the generation of reactive species and in consideration to those links that were mentioned in the literature between QR2 and neurodegeneration, studies were conducted on primary neurons and neuroblastoma cells genetically modified to overexpress in QR2. These studies have shown, by various analytical techniques such as electron paramagnetic resonance or LC-MS, an increase in the toxicity of menadione but also of adrenochrome in the presence of quinone- reductase 2. In order to explain the contradictory characteristics of QR2 from one cell to another, we proposed a hypothesis that a cooperation with another conjugating enzyme, which could react with the unstable reduced form that prevent its reoxidation, is needed to effectively detoxify quinones. Additional analyses (RPE, LCMS, fluorescence) conducted on neuroblastoma cells overexpressing both QR2 and a para-hydroquinone specific conjugation enzyme (UGT) have shown a decrease in oxidative stress when both enzymes are co-expressed
7
Colucci, Marie A. "Quinone based inhibitors of NQ01". Thesis, University of Nottingham, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.478964.
Testo completo
8
Sunassee, Suthananda Naidu. "Studies in marine quinone chemistry". Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1005020.
Testo completoAbstract (sommario):
This thesis is divided into two parts and the rationale of the research conducted is based on the cytotoxicity of the prenylated quinones 1.24-1.29, isolated from the South African nudibranch Leminda millecra, against oesophageal cancer cells. The first part (Chapters 2 and 3) of the thesis initially documents the distribution of cytotoxic and antioxidant prenylated quinones and hydroquinones in the marine environment. We have been able to show, for the first time, that these compounds can be divided into eight structural classes closely related to their phyletic distribution. Secondly, we attempted to synthesize the two marine natural products 1.24 and 1.26 in an effort to contribute to an ongoing collaborative search with the Division of Medical Biochemistry at the University of Cape Town for new compounds with anti-oesophageal cancer activity. Accordingly, we followed the published synthetic procedure for 1.26 and, although we were unable to reproduce the reported results, we have generated five new prenylated quinone analogues 3.53-3.55, 3.63 and 3.71, which are a potentially viable addition to our ongoing structure-activity relationship (SAR) studies. Moreover, we embarked on a 7Li NMR mechanistic study for the synthesis of 3.2 from 3.1 which rewarded us with an improved and reproducible methodology for this crucial reaction that is detailed in Chapter 3. The second part of this thesis (Chapters 4 and 5) is concerned with a synthetic, structural, electrochemical and biological exploration of the 1,4-naphthoquinone nucleus as a primary pharmacophore in our search for new chemical entities which can induce apoptosis in oesophageal cancer cells, thus contributing to our overall ongoing SAR study in this class of compounds. Seven new naphthoquinone derivatves (4.19, 4.30, 4.31, 4.33 and 4.46-4.48) of the natural products 2-deoxylapachol (2.44), lapachol (4.1) and β-lapachone (5.2) were synthesized and 2-(1`-hydroxy-`-phenylmethyl)-1,4-naphthoquinone (4.29) was found to be the most cytotoxic (IC50 1.5 μM) against the oesophageal cancer cell line WHCO1, while 5.2, which is currently in phase II clinical trials as an anticancer drug, was found to be similarly active (IC50 1.6 μM). Electrochemical investigations of the redox properties of the benzylic alcohol derivatives 4.29-4.31 indicated a higher reduction potential compared to their oxidized counterparts 4.45-4.48, and this finding has been correlated to the increased activity of 4.29-4.31 against the WHCO1 cell line. Additionally, 4.29 is synthetically more accessible than either 1.26 or 5.2 and potentially a lead compound in our search for new and more effective chemotherapeutic agents against oesophageal cancer
9
Ferreira, Janaina Gomes. "Estudo de compostos quinônicos com potencial atividade contra a doença de Chagas". Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-23062008-163355/.
Testo completoAbstract (sommario):
Este trabalho apresenta as estruturas determinadas por difração de raio X de dois compostos naftoquinônicos, 3,4-diidro-[2,2-dimetil]-2H-nafto[1,2-b]pirano-5,6-diona (β-lapachona) e dimetil-1,4-naftoquinona. A estrutura cristalina destes compostos mostrou que estes são estabilizados por ligações de hidrogênio do tipo C-H...O, formando estruturas supramoleculares. Dos compostos derivados da β-lapachona, os naftoimidazóis têm-se mostrado muito ativos contra o T. cruzi, agente causador da doença de Chagas. Partindo das estruturas modeladas de 29 compostos naftoimidazólicos, propriedades eletrônicas, geométricas e topológicas foram calculadas para análise estatística por mínimos quadrados parciais (PLS). Após a análise e redução das variáveis foram selecionados os descritores Morp17p, X4a, piPC09, RDF065v, BELp6, RDF060p, R4u, RDF035m e RCI que foram utilizados para a construção um modelo de regressão com o método de PLS. Para o modelo, o menor erro de validação foi obtido com 3 fatores e os coeficientes de correlação R= 0,71 e Q= 0,82. O estudo de docking de alguns compostos naftoquinônicos e naftoimidazólicos mostrou que, do ponto de vista energético e de complementaridade química, estes compostos possuem pouca probabilidade de se ligarem no sítio ativo da tripanotiona redutase (TR), uma enzima essencial para o metabolismo do T. cruzi, bem como no sítio ativo da enzima humana glutationa redutase (GR), homóloga a TR. Há, no entanto, uma tendência geral destes compostos se ligarem no sítio da interface, sobretudo, de se ligarem neste sítio da enzima humana.This work presents the structure determined by X-ray analyses for two naphthoquinone compounds 3,4-dihydro-2,2-dimethyl-2H-naphtho[1,2-b]pyran-5,6- dione and dimethyl-1,4-naphthoquinone. The crystal packing of these compounds showed the existence of intermolecular hydrogen bonds of the type CH...0. These intermolecular forces are responsible for the self-assembly in three-dimensional supramolecular structure. A set of 29 naphthoimidazoles, derived from β-lapachone, that has shown activity against T. cruzi, the agent of Chagas disease, were modeled. From these structures electronic, geometric, topological, etc, properties were calculated to be used in the investigation by statistic analysis, using the partial least squares method (PLS). After reduction of the number of variables, the best PLS model found was the one obtained with the following variables: Morp17p, X4a, piPC09, RDF065v, BELp6, RDF060p, R4u, RDF035m and RCI. For the PLS model, the lower error of validation was obtained using 3 factors with the coefficients R=0.71 and Q=0.82. Two sets of compounds, naphtoquinones and naphthoimidazoles, were studied by docking method. The results showed that, for both, naphtoquinones and naphthoimidazoles and both trypanothione and glutathione reductase, the compounds have low probability to bind in the active site, and are more likely to bind in the interface site, especially in the interface site of the human protein.
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Cardoso, Mariana Filomena do Carmo. "Síntese de derivados 5-amino-1H-pirazólicos da nor-β-lapachona com potencial perfil anticancerígeno". Niterói, 2017. https://app.uff.br/riuff/handle/1/3283.
Testo completoAbstract (sommario):
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Esse trabalho descreve uma nova metodologia sintética de novos derivados pirazólicos análogos a 2,2-dimetil-2,3-di-hidronafto[1,2-b]furan-4,5-diona (nor-β-lapachona), através da inserção do núcleo pirazólico a posição C-3 da nor-β-lapachona. Nesta dissertação foram sintetizados 16 (dezesseis) substâncias inéditas, sendo oito da família 3-pirazolil-2,2-dimetil-2,3-di-hidronafto[1,2-b]furan-4,5-diona contendo o núcleo pirazólico acoplado à naftoquinona os quais foram submetidos a testes biológicos para avaliação de suas atividades citotóxicas in vitro contra quatro linhagens de células tumorais humanas e uma linhagem de células normais humanas. Todas as amostras mostraram-se ativas para as linhagens tumorais e não apresentaram hemólise. A metodologia clássica para a substituição nucleofílica no carbono 3 da nor-β-lapachona desenvolvida pelo nosso grupo de pesquisa mostrou-se pouco eficaz, levando a baixos rendimentos com formação de vários produtos colaterais. Desta forma, realizou-se um estudo metodológico a fim de se viabilizar a síntese de uma família de 3-pirazolil-nor-β-lapachonas com rendimentos satisfatórios. Assim, após várias modificações nos parâmetros reacionais, observou-se que o melhor intermediário sintético era o 3-hidroxi-2,2-dimetil-2,3-di-hidronafto[1,2-b]furan-4,5-diona
This paper describes a new synthetic methodology to new pyrazole derivatives analogous to the 2,2-dimethyl-2,3-dihidronaphtho-[1,2-b]-furan-4 ,5-dione (nor-β-lapachone) by inserting the core pyrazolic on the C-3 position of the nor-β-lapachone. In this essay were synthesized 16 (sixteen) new compounds, being eight 3-pyrazolyl-2,2-dimethyl-2,3-dihidronaphtho [1,2-b]-furan-4 ,5-dione family containing core pyrazolic naphthoquinone attached to which were submitted to biological tests to evaluate their in vitro cytotoxic activities against four human tumor cell lines and normal human cell line. All samples were active for tumor cell lines and showed no hemolysis. The classical methodology for the nucleophilic substitution at carbon 3 of the nor-β-lapachone developed by our research group proved to be ineffective, leading to low yields with the formation of various side products. Thus, there was a methodological study in order to facilitate the synthesis of a family of 3-pyrazolyl-nor-β-lapachones with satisfactory yields. Then, after the various modifications on the reaction parameters, it was found that the better synthetic intermediate was the 3-hydroxy-2,2-dimethyl-2,3-dihidronaphtho-[1,2-b]-furan-4 ,5-dione
11
Urdang, Zachary D. "Towards Quinone Methids Releasing Disassembling Dendrimers". Thesis, The University of Arizona, 2010. http://hdl.handle.net/10150/146912.
Testo completo
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Cossette, Michael Vernie. "The Synthesis of Quinone-Capped Cyclodextrins". W&M ScholarWorks, 1988. https://scholarworks.wm.edu/etd/1539625451.
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Greenaway, Kevin. "Development of methodologies for the organocatalytic addition of pro-nucleophiles to o-quinones and o-quinone methides". Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525288.
Testo completo
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Chen, Chung-pin. "Part I: Steric and inductive effects on the hydrolysis of quinone bisketals ; Part II: A convenient route to ortho-alkylated phenols and quinone monoketals. Part III: A general approach to quinone ketals. Part IV: Preparation and chemistry of quinone... /". The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487268021749158.
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Giraud, Luc. "Synthèses d'agents alkylants bioréductibles en série 1,4-benzoquinonique : étude de leur réactivité dans des réactions de transfert monoélectronique". Aix-Marseille 3, 1992. http://www.theses.fr/1992AIX30033.
Testo completoAbstract (sommario):
Ce travail est consacre a la synthese de derives quinoniques substitues par un groupement nucleofuge en position benzylique et a l'etude de leur reactivite dans des reactions de transfert monoelectronique. L'etude mecanistique de la reaction de ces agents alkylants bioreductibles avec le sel de lithium du 2-nitropropane et l'etude de ces composes par les techniques electrochimiques et de rpe ont permis pour cette reaction de satisfaire les principaux criteres de la mise en evidence d'un mecanisme de substitution radicalaire-nucleophile unimoleculaire (s#r#n#1). L'extension de cette reaction a divers anions nitronate, aliphatiques et heterocycliques puis a des anions ambidents derives de l'hydroxycoumarine et de l'acide ascorbique et enfin a des anions centres sur le soufre, l'azote, l'oxygene et l'hydrogene donne a cette reaction un caractere generale. Enfin, l'etude de composes encombres steriquement au niveau de l'atome de carbone portant le groupement liberable a permis de mettre en evidence l'influence determinante de la structure de ces molecules sur le deroulement de la reaction de c-alkylation
16
Fernando, J. Roshan C. "Theoretical studies on quinone reactivity a thesis presented to the faculty of the Graduate School, Tennessee Technological University /". Click to access online, 2009. http://proquest.umi.com/pqdweb?index=50&did=1908035911&SrchMode=1&sid=1&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1265041952&clientId=28564.
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Leach, Graeme Richard. "Regulation of respiratory activity in plant mitochondria : interplay between the quinone-reducing and quinol-oxidising pathways". Thesis, University of Sussex, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320417.
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Humphries, Matthew Philip. "NAD(P)H Quinone Oxidoreductase 1 (NQO1) and NRH Quinone Oxidoreductase 2 (NQO2) : their inhibition by triazoloacridinones and imidazoacridinones". Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/nadph-quinone-oxidoreductase-1-nqo1-and-nrh-quinone-oxidoreductase-2-nqo2-their-inhibition-by-triazoloacridinones-and-imidazoacridinones(f5753d13-fffb-4ca6-9e99-bd475f6eb498).html.
Testo completoAbstract (sommario):
The human enzymes NQO1 and NQO2 are cytosoloic flavoproteins that catalyze the two electron reduction of a broad range of quinone substrates. NQO1 and 2 are over-expressed in several types of tumours, consequently making them attractive targets for drug development. Inhibition of NQO1 and NQO2 has been shown to reduce the development of some cancers. However current agents demonstrate off target effects and therefore more pharmacologically applicable compounds are needed. Initially a computational screen of the NCI database identified NSC 645827, a triazoleacridin-6-one (TA) with an IC50 of 0.7 µM. From this, a range of TAs were synthesised and evaluated for their ability to inhibit NQO1 and NQO2. From these data we identified several TAs which were the most potent inhibitors of NQO2 reported. The most potent compound being 10a (98 ± 10 nM), an N-oxide with low cellular toxicity and no DNA interaction. Taking the main pharmocaphore of the TA, a substructure search of the NCI database identified the imidazoacridin-6-one (IA) C1311, a known DNA binding agent and inhibitor of FLT3 kinase. Quantities of several IAs were obtained from the NCI and were investigated as potential NQO1 and NQO2 inhibitors. NSC 660841 was identified as the most potent inhibitor of NQO2 yet reported (6 ± 3 nM). Compounds were further investigated for potential off target effects.Representative compounds from both series were evaluated for their ability to modulate the cytotoxic effect of doxorubicin (DOX). There was no obvious relationship between the compound structures and the toxicity of DOX. Although no clear relationship could be determined between the compounds, a novel association between DOX, NQO1 and NQO2 was established. Compound A6B1 demonstrated the ability to increase the toxicity of DOX. It is hypothesised that a combination treatment of NQO2 inhibitors and DOX could lead to a greater therapeutic response as apposed to DOX alone. In summary, the results identify TAs and IAs to have the ability to inhibit both NQO1 and NQO2. The low cellular toxicity and high inhibitor potency of the N-oxide compounds makes them a suitable tool to study the enzymes without off target effects. Also these data provide a direction for future compound synthesis
19
Mbiya, Wilbes. "Substituent Effects on Reactivity and Allergenicity of Benzoquinone". PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1406.
Testo completoAbstract (sommario):
Benzoquinone (BQ) is an extremely potent electrophilic contact allergen that haptenates endogenous proteins through Michael addition (MA). It is also hypothesized that BQ may haptenate proteins via free radical formation. The objective of this study was to assess the inductive effects (activating and deactivating) of substituents on BQ reactivity and the mechanistic pathway of covalent binding to nucleophilic thiols. The BQ binding by Cys34 on human serum albumin was studied, and for reactivity studies, nitrobenzenethiol (NBT) was used as a surrogate for protein binding of the BQ and benzoquinone derivatives (BQD). Stopped flow techniques were used to determine pseudo-first order rate constants (k) of methyl-, t-butyl-, and chlorine-substituted BQD reactions with NBT, whereas electron pair resonance (EPR) studies were performed to investigate the possible free radical mediated binding mechanism of BQD. Characterization of adducts was performed using mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR). The rate constant values demonstrated the chlorine substituted (activated) BQD to be more reactive toward NBT, than the methyl and t-butyl-substituted (deactivated) BQD, and this correlated with the respective EPR intensities. The EPR signal, however, was quenched in the presence of NBT suggesting MA as the dominant reaction pathway. MS and NMR results confirmed adduct formation to be a result of MA of NBT onto the BQ ring with vinylic substitution also occurring for chlorine-substituted derivatives. The binding positions on BQ and NBT/BQD stoichiometric ratios were affected by whether the inductive effects of the substituents on the ring were positive or negative. The reactivity of BQ and BQD is discussed in terms of the potential relationship to allergenic potency. Hammett and Taft (HT) constants were then used to estimate the influence of these substituents on chemical reactivity. HT values demonstrated chlorine substituted BQD to be more reactive than methyl substituted BQD. BQ and BQD dermal allergenicity, as evaluated in the murine local lymph node assay, (LLNA) was consistent with that predicted by reactivity and HT parameters. These results demonstrate the effect of substituents on BQ reactivity and dermal allergic sensitization, and suggest the potential utility of chemical reactivity data and HT values for electrophilic allergen identification and potency ranking.
20
Taljaard, Jana Heloïse. "Synthesis, properties and reactions of Novel Quinone Methides". Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/616.
Testo completoAbstract (sommario):
Novel p-quinone methides have been synthesized by the dealkylation of 5-(p-alkyloxyaryl)- 10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ols and related compounds. Aspects of the dealkylation reaction were investigated using computational methods in order to identify possible intermediates and postulate reasons for the observed reactivity patterns. This included studying the effect of varying the size of the central B-ring, changing the alkyloxy group, and altering the substitution pattern on the parent alcohols. We have assessed the relative energies of reaction intermediates and have also evaluated the influence of factors such as charge delocalisation, LUMO properties of the carbocations and thermodynamic factors on the dealkylation reaction. The use of different dealkylating reagents was also briefly investigated. Demethylation of 1,3- dimethyl-11-(4-methoxyphenyl)-6,11-dihydrodibenzo[b,e]oxepin-11-ol with pyridine hydrochloride led to acid-catalyzed ring-contraction of the parent alcohol to form a novel substituted anthraquinone, 9-(4-hydroxyphenyl)-1,3-dimethyl-anthracen-10-(9H)-one, in good yield. The general reactivity of the p-quinone methides of interest to us was explored by subjecting these compounds to reaction with a range of nucleophiles (bases, Grignard reagents and alcohols). A range of aryl Grignard reagents were reacted with the p-quinone methides, with the main product isolated in almost all cases being the aryl-coupled 1,2-addition product. The nucleophilic addition reactions of alcohols were supported by a computational study and a probable reaction mechanism has been postulated. A base-catalyzed rearrangement is proposed to account for the formation of products in which dehydrogenation of the ethane bridge was observed. These studies showed that in these p-quinone methides, chemical reactivity is strongly influenced by steric crowding, resulting in reversal of the normal 1,2- vs. 1,6- selectivities expected for nucleophilic addition. The ketalization process was explored further using diols and thiols. Products analogous to those obtained with the monohydric alcohols resulted from the diols, along with a series of novel bis-ethers. A range of miscellaneous reactions of 4-(dibenzo[a,d]cycloheptan-5-ylidene)cyclohexa-2,5,- dienone and related systems were investigated. Functionalization by epoxidation, dichlorocarbenation and Diels-Alder reactions, photochemical and [2+2] cycloaddition were attempted and reduction and oxidation reactions were also explored. Photochemical demethylation of an ortho-methoxyl substituent on the p-quinone methide system was observed to occur in good yield. The p-quinone methides underwent reductive coupling in the presence of Zn/AlCl3. The electronic spectra of highly conjugated carbocations were obtained and their potential as novel dyes evaluated. A low-temperature Grignard exchange reaction followed by spontaneous cyclization upon workup, was successful in synthesizing the lactone, spiro[10,11- dihydro-5H-dibenzo[a,d]cyclohepten-(3’,4’H)-phenyl-5,2’(5’H)-furan-5’-one], in one step from the starting ketone. A novel seven-membered Malachite Green dye analogue, 11-(4- dimethylamino-phenyl)-3-morpholin-4-yl-6,11-dihydro-dibenzo[b,e]oxepin-11-ol, was also synthesized and its electronic spectra compared to that of the unannulated Malachite Green dye series. All novel compounds synthesized were characterized using NMR, IR and HRMS-analysis.
21
McCracken, Paul G. "The biological chemistry of quinone methides and benzisoxazoles". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq22479.pdf.
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22
Loughran, Michael Gerard. "Quinoprotein dehydrogenase and pyrroloquinoline quinone modified enzyme electrodes". Thesis, Cranfield University, 1995. http://dspace.lib.cranfield.ac.uk/handle/1826/6457.
Testo completoAbstract (sommario):
This thesis concerns the use of the coenzyme PQQ and quinoprotein dehydrogenase enzymes for the development of enzyme electrodes. A general introduction to the area which describes the properties of quinoprotein dehydrogenases is given. The reactivity and redox properties of the quinone cofactor, PQQ, are also outlined.
23
Parry, Joel D. "Transcriptomic assessment of quinone mediated hepatic oxidative stress". Thesis, University of Leicester, 2007. http://hdl.handle.net/2381/30781.
Testo completoAbstract (sommario):
Quinone based drugs are complex structures with multiple chemical properties. Therefore in this work to further understand quinone toxicity in drugs simpler structures with defined chemistry were used as tools. To discern mechanistic insight transcriptomic investigations were undertaken in rat hepatocytes and in vivo mouse liver exposed to a range of prototypical quinines. Genes important in response to quinone exposure were identified and analysed using several bioinformatic tools. Transcriptomics in hepatocytes could not differentiate quinone redox effects from other interactions, although 22 'quinone signature genes' indicated a coordinated response to redox stress. A central role for mitochondria as targets of quinone interaction was confirmed, the transcriptomic profile indicating optimisation of energy metabolism and suppression of intrinsic apoptosis. Pim1 and Pim3 kinases were central to this response, confirmed in follow up experiments. Pharmacokinetics from mice treated in vivo with 25mg/kg DMNQ or menadione interperitoneally indicated DMNQ to be more widely distributed and better suited as an in vivo redox model compound than menadione. However, in vivo redox challenge from DMNQ in the liver was transient and insufficient to cause oxidative damage. The findings indicate that DMNQ has utility for studying redox stress in vivo, although a repeat dosing approach is required in future. The findings add to the knowledge-base of quinone toxicity. Particularly the increased responsiveness and sensitivity of hepatocytes in vitro compared to in vivo which may lead to an erroneous perception of toxicity if in vitro systems are studied alone.
24
Zhu, Tianxia. "Detection of Thiols by o-Quinone Electrocatalytic Sensors". University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1340981269.
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25
Boone, Harold Wesley 1969. "Polyaromatic quinone diimines: A novel family of polymers". Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290592.
Testo completoAbstract (sommario):
Polyaniline has attracted much interest due to its unusual physical properties. A polycondensation route to polyanilines is a desirable alternative to the currently used non-discriminating oxidative polymerization. The oxidative synthesis does not allow structural diversity in the monomer and the polymer's structure is not well defined. A synthetic route to polyanthraquinone diimines was recently developed in this laboratory. These pernigraniline analogs are similar in structure to the fully oxidized polyaniline and may display electrical conductivity and optoelectronic properties. The aim of the current study was to investigate the incorporation of solubilizing substituents into the polyquinone diimine backbone, determine the molecular dynamics and microstructure of the polyquinone diimine through the use of model compounds, and reduce the polyquinone diimines to the emeraldine oxidation level. This dissertation accomplished the condensation polymerization of 1,5-di(oligo-(ethyleneoxy)) anthraquinones (EOn n = 1-3) and 1,4-, 1,5-, and 2,6-dioctyloxy-anthraquinones with both phenylenediamine and 4,4'-thiodianiline. Higher molecular weights were accomplished due to increased solubility. The polymers' microstructure and molecular dynamics were determined by X-ray crystallographic structure analysis and through NMR studies of model compounds. Model compounds and polymers were reduced by a hydrazine reduction method. Stereoregular polymers with molecular weights Mw, of 30,000 were obtained with 4,4'-thiodianiline and polymers having Mw 10,000-20,000 were obtained with phenylene-diamine. Model compounds were synthesized from aniline and the corresponding anthraquinone to provide structural characterization for the polymers. The model compounds revealed that an anti configuration is obtained with 1,5-disubstituted anthraquinones, while a syn configuration is obtained with 1,4-disubstituted anthraquinones. X-Ray crystal structure determinations were essential in determining the conformations of the model compounds. Variable temperature NMR studies gave detailed information about the molecular dynamics of the polymer chains for all polyquinone diimines. A syn/anti-isomerization was identified for unhindered anthraquinone diimines and a unique butterfly inversion was discovered for all anthraquinone diimines. A reduction method using hydrazine and palladium was applied to the reduction of quinone diimines to produce the corresponding diamines. Polymer studies indicate no generation of an emeraldine analog upon reduction. 2,6- and 2,5-Dimethyl and 2,3,5,6-tetramethyl benzoquinones were investigated as alternative quinones for obtaining emeraldine analogs.
26
Sabuco, Jean-François. "Recherches sur la réactivité chimique et les activités biologiques potentielles liées aux réactions de transfert monoélectronique d'azoles quinoniques". Aix-Marseille 3, 1991. http://www.theses.fr/1991AIX30067.
Testo completoAbstract (sommario):
Dans ce memoire est decrit la preparation de derives azoliques substitues par un groupement quinonique et un nucleofuge en position benzylique. Les syntheses mises au point sont selectives et les differents composes imidazoliques, oxazoliques et thiazoliques sont obtenus sous forme d'un seul isomere au niveau de l'heterocycle. Ces substrats ont une structure d'agent alkylant bioreductible et leur reactivite vis a vis du sel de lithium du 2-nitropropane a ete etudiee dans des reactions de substitution par transfert d'electron. La structure des molecules a une influence determinante sur le deroulement de cette reaction et seuls les substrats qui presentent un bon recouvrement entre l'heterocycle et la quinone ainsi qu'un positionnement adequat ds substituants conduisent a la formation du produit de c-alkylation du nitronate. La sensibilite de cette reaction aux inhibiteurs des reactions de substitution par transfert monoelectronique est caracteristique d'un mecanisme radicalaire en chaine (s#r#nl). Les etudes de ces composes par les techniques electrochimiques et de rpe ainsi que l'utilisation de la modelisation moleculaire confirment l'importance des facteurs structuraux pour l'obtention de derives susceptibles d'etre alkyles suivant ce mecanisme
27
Andersen, Svend Olav, Martin G. Perter e Peter Roepstorff. "Cuticle-catalyzed coupling between N-acetylhistidine and N-acetyldopamine". Universität Potsdam, 1992. http://opus.kobv.de/ubp/volltexte/2008/1676/.
Testo completoAbstract (sommario):
Several types of insect cuticle contain enzymes catalyzing the formation ofof adducts between N-acetyldopamine (NADA) and N-acetylhistidine (NAH). Two such adducts, NAH-NADA-I and NAH NADA-II, have been isolated and their structures determined.
In one of the adducts the link connecting the two residues occurs between the I-position (ß-position) in the NADA side chain and the 1-N atom (τ-N) in the imidazole ring of histidine. Diphenoloxidase activity alone is not sufficient for formation of this adduct, whereas extracts containing both diphenoloxidase and o-quinone-p-quinone methide isomerase activities catalyze the coupling reaction. The adduct consists of a mixture of two diastereomers and they are presumably formed by spontaneous reaction between enzymatically produced NADA-p-quinone methide and N-acetylhistidine.
The other adduct has been identified as a ring addition product of N-acetylhistidine and NADA. In contrast to the former adduct it can be formed by incubation of the two substrates with mushroom tyrosinase alone.
An adduct between N-acetylhistidine and the benzodioxan-type NADA-dimer is produced in vitro, when the N-acetylhistidine-NADA adduct is incubated with NADA and locust cuticle containing a 1,2-dehydro-NADA generating enzyme system.
Trimeric NADA-polymerization products of the substituted benzodioxan-type have been obtained from in vivo sclerotized locust cuticle, confirming the ability of cuticle to produce NADA-oligomers.
The results indicate that some insect cuticles contain enzymes promoting linkage of oxidized NADA to histidine residues. It is suggested that histidine residues in the cuticular proteins can serve as acceptors for oxidized NADA and that further addition of NADA-residues to the phenolic groups of bound NADA can occur, resulting in formation of protein-linked NADA-oligomers. The coupling reactions identified may be an important step in natural cuticular sclerotization.
28
Franjesevic, Andrew Joseph. "Design, Synthesis, and Evaluation of Therapeutics for the Treatment of Organophosphorus Poisoning by Nerve Agents and Pesticides". The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563349257142378.
Testo completo
29
Diao, Li. "Photogeneration and chemistry of quinone methides from hydroxybenzyl alcohols". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ37339.pdf.
Testo completo
30
Refaey, Rana Hosny. "Structural and mechanistic studies of quinone oxidoreductase II (NQO2)". Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/13566/.
Testo completoAbstract (sommario):
Flavoenzymes are a widely diverse group of enzymes that are able to catalyze a variety of different chemical reactions. A growing interest in flavoenzymes capable of reducing aromatic nitro groups may be attributed to their ability to reduce anticancer prodrugs such as CB 1954. Similarly, quinine oxidoreductases are able to activate anticancer prodrugs such as mitomycin derivatives by reducing the quinone derivative to the hydroxyl derivative. Some oxidoreductases are able to reduce nitro aromatic compounds. These enzymes may be either mammalian such as NQO1 and NQO2 which are over expressed in certain cancerous cells or bacterial which can be introduced into the cancerous growth. The bacterial nitroreductases have been previously well characterized and were found to share several similarities. On the other hand, other nitro reducing enzymes have not been investigated to determine the presence of any shared similarities. Another aim of this thesis is to identify the differences between the structure of the oxidized and reduced forms of NQO2. The similarities shared between the flavoenzymes which are known to reduce nitroaromatic compounds to their hydroxylamine or amine derivative were investigated in this thesis. Both the sequences and 3D structures of the selected proteins were compared and investigated using a variety of bioinformatics tools such as sequence and structure alignment, in addition to homology modelling. It was discovered that there are several aromatic residues conserved in different positions, relative to the flavin cofactor, in the catalytic sites of the proteins. The 3D structure of the reduced NQO2 was determined using X-ray crystallography. The oxidized and reduced protein structures were compared to determine the structural differences. The expression, purification and crystallization of the NQO2 protein, as well as the reduction of the protein crystals are described in this work. The determination of the structure of the reduced protein provided new insights into the mechanism of electron transport to and from the flavin cofactor. Moreover, kinetics studies were undertaken on the purified NQO2 protein using fluorescence spectroscopy. These resulted in the identification of several new substrates for NQO2.
31
Soper, R. J. "The synthesis and biological activities of natural quinone metabolites". Thesis, University of Essex, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402818.
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32
McGaw, Oliver. "Studies towards the novel synthesis of benzoisochromane quinone polyketides". Thesis, University of East Anglia, 2014. https://ueaeprints.uea.ac.uk/58538/.
Testo completoAbstract (sommario):
Granaticin is a structurally unique member of the benzoisochromane quinone (BIQ) family of antibiotics. The molecule and its derivative exhibit a sugar moiety fusted to the naphthazarin core, only exhibited by one other natural compound, by a C-C glycosidic bond and an aldol like bond. The mechanism of enzymatic attachment of this substituent is currently unknown. This project aimed to devise a novel and elegant synthesis towards the granaticin aglycone and other benzoisochromane quinone natural compounds with the long term aim of discerning the mechanism of glycosylation. This thesis shows a novel route for the synthesis of highly substituted isochromane and isochromane quinone compounds towards the eventual synthesis of the desired natural molecules.
33
Thomas, Terrance Augustine. "Studies of 1,2-quinone monooximes and their metal complexes". Thesis, London Metropolitan University, 1993. http://repository.londonmet.ac.uk/3299/.
Testo completoAbstract (sommario):
The chemistry of 1,2-quinone monooximes hi« been reviewed. The synthesis of 5-amlno, 5-alkylamino and 5-acylamino substituted 1,2-benzoquinone monooximes was systematically studied. Thus, It has been found that 5-amino-1,2-benzoquinone-2-oxime (5-AqoH), 5-ethylamino-4-methyl 1-1,2- benzoquinone-2-ox I me (5-Et-4-MeqoH), 5-hexylamino-1,2-benzoquinone-2-oxime (5-HxqoH) and 5-heptylamino-1,2-benzoquinone-2-oxime (5-HptqoH) were best prepared by the reaction of the corresponding phenol with sodium nitrite In the presence of concentrated hydrochloric acid. Under these conditions, N-nitrosation was inhibited and the 1,2-benzoquinone- 2-oxlme hydrochlorides were formed. The 5-acylaminc1,2-benzoqulnone-2- oximes, 5-propionylamino-1,2-benzoquinone-2-oxime (5-PrqoH), 5-butyrylamino-l,2-benzoquinone-2-oxime (5-BuqoH), 5-pentanoylamino-1,2-benzoquinone-2-oxime (5-PeqoH), and 5—heptanoylamino-1,2-benzoquinone-2-oxime (5-HpqoH) were obtained from their metal complexes, since the direct reaction of the phenol with sodium nitrite failed to give the compounds giving the corresponding l,4-benzoquinone-4-oximes,3- proplonylamino-1,4-benzoquinone-4-oxime (3-PrqoH), 3-butyrylamino-1,4- benzoquinone-4-oxlme (3-BuqoH), 3-pentanoylamino-1,4-benzoquinone-4- oxime (3-PeqoH) and 3-heptanoylamino-1,4-benzoquinone-4-oxime (3-HpqoH) instead. Spectroscopic analysis has shown the compounds to exist in the quinone oximic rather than In the nitrosophenollc form. X-ray crystallographic studies of 5-HxqoH, 5-Et-4-MeqoH and 5- Et-4-MeqoH.HCI have shown ail three compounds to have some 1,4-oxime- imino character. The synthesis of nlckel(ll), copper(ll), palladium(ll) and platinum(ll) complexes of the acylamino and alkylamino substituted 1.2- benzoqulnone-2- oximes both by the direct and nitrosation methods was examined. The nitrosation method gave rise to complexes NI(qo)2.nH20, Cu(qo)2.nH20 and Pd(qo)2 but failed to give the corresponding platinum complexes. The latter were only obtained by the direct method. The nickel(ll) and oopper(ll) complexes reacted with pyridine and 2,2-dlpyrldyl to give adducts of the type NI(qo)2(py)2 Cu(qo) (py) and M(qo) (dipy) respectively. The palladium and platinum complexes however failed to react with either of the Lewis bases. Magnetic moment studies showed the hydrated complexes and Lewis base adducts to be magnetically dilute and thus monomeric. Such studies, as well as IR and LSIMS mass spectral analysis of the anhydrous complexes Ni(qo) and Cu(qo) , showed them to be associated both in the solid State and in solution. The reaction of selected 1,2-quinone monooximes (qoH) and metal 1.2- quinone monooximates (M(qo)2; qoH = 1,2-nap ht hoqu I none-1-oxime (1-nqoH), 1,2-naphthoquinone-2-oxime (2-nqoH), 3-butyrylamino-1,2-benzo-quinone-2-oxime, 4-chlora-1,2-benzoquinone-2-oxlme (4-ClqoH), 4-bromo-1,2-benzoquinone-2-oxime (4-BrqoH), 5-acetylamino-1,2-benzoquinone-2-oxime (5-AcqoH), 5-hydroxy-1,2-benzoquinone-2-oxlme (5-HqoH); M = Nl and Cu) with dimethyl acetylenedicarboxylate (DMAD) was systematically examined. The reaction of 1-nqoH and 5-HqoH gave rise to nucleophile addition products cis- and trans-(0-1,2-dicarbomethoxyethenyl)-1,2-naphthoquinone-1 -oxime, trans-(0-dicarbomethoxyethenyI)-5-hydroxy-1,2-benzoquinone-2-oxime. The yields were enhanced by the presence of small amounts of alkali and alkaline earth metal chlorides. With M(1-nqo)2 and M(Buqo)2 (M = Ni, Cu) 1,4-oxazines were the only products formed. However, M(4-Clqo)2 and M(4-Brqo)2 1,4-benzoxazinones and 1,4-benzoxazines were isolated. The reaction of the structurally related 1,2-dloxlmes emd metal 1,2-dioxlmates M(dmgH)2 and M(dagH)2» (dmgH2 = dimethylglyoxime; dagH_ = 1,2-dlaminoethanedlone dIoxIme; M = NI, Cu) with DMAD was also examined. The dimethylglyoxime and its metal complexes failed to afford any adducts while the 1,2-diaminoethanedione dioxIme and its metal complexes gave nucleophilic addition products cis- and trans-bls(0-1,2-dicarboxyethenyl)-1,2-diaminoethanedione dioxime. Mechanisms for the reaction of DMAD with both the quinone monooximes and the 1,2-dioximes have been proposed.
34
Kosgei, Cosmas Kipyego. "Investigation of the effect of basicity and Concentration ofproton accepting bases on the potential of Quinones for highpotential quinone based cathode materials". Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-288369.
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35
Ramdohr, Jurgen Ernst. "Synthesis of naphtho{2,3-c}pyrans including the aphin-derived quinone A'". Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/15896.
Testo completoAbstract (sommario):
Bibliography: pages 76-78.Chapter One describes the synthesis of a trifluoroethylnaphtho-1, 4-quinone via a regiospecific trifluoroacetylation of an appropriately substituted naphthalene. Chapter Two describes the synthesis of the methyl ethers of the naturally occurring quinones A and deoxyquinone A for evaluation of their "anti-cancer" activity by the National Institutes of Health. In Chapter Three the final few steps of the synthesis of the aphid-derived quinone A' are described. This was made possible by the development of an efficient route for the conversion of a precursor to quinone A' via the corresponding chloro-derivative.
36
Longatte, Guillaume. "Dérivation des électrons photosynthétiques par des médiateurs de type quinone". Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066322/document.
Testo completoAbstract (sommario):
La photosynthèse consiste en la conversion photo-induite du dioxyde de carbone et de l'eau en matière organique et en dioxygène. Utilisée par les algues, les plantes ou certaines bactéries, la photosynthèse est pourtant intrinsèquement bridée puisque seulement 4 % de l'énergie lumineuse sont convertis en énergie chimique. Sous forte irradiation, ceci peut engendrer une dénaturation de l'appareil photosynthétique. Par ailleurs, dans le contexte environnemental actuel, cette limitation représente également une opportunité d'utiliser l'énergie non convertie sous forme d'énergie électrique. Le travail présenté dans ce manuscrit a donc pour but de créer une voie secondaire d'écoulement des électrons photosynthétiques excédentaires afin de réduire l'endommagement du système sous forte irradiation et de les transcrire sous la forme d'un photo-courant. C'est pourquoi un système impliquant une électrode collectrice de carbone et des médiateurs redox de type quinone a été envisagé. La capacité acceptrice de certaines quinones, connues pour être de bons accepteurs du Photosystème II, a été évaluée au moyen d'études de fluorescence. La facilité de restitution des électrons dérivés par les quinones réduites a été quant à elle étudiée par électrochimie. Au bilan, les meilleures quinones (DCBQ, PPBQ) permettent d'obtenir des photo-courants de l'ordre de quelques µA.cm-2. La corrélation entre données expérimentales et théorie a également permis de mieux cerner le mécanisme de dérivation des électrons photosynthétiques par les quinones exogènes mais aussi de mettre en évidence des effets d'empoisonnement et/ou de perte d'accepteur dans les membranesPhotosynthesis can be views as the conversion of carbon dioxide and water into organic matter and dioxygen. Used by algae, plants or some bacteria, photosynthesis efficiency is limited because only 4% of light energy is converted into chemical energy. Under high light conditions, this can induce serious damages of the photosynthetic machinery. Besides, if considering the current environmental context, this limitation is an opportunity to use the part of not converted energy to generate some useable electricity. The aim of the work developed in this manuscript is thus to create an additional pathway for derivating the photosynthetic electrons flow. In this way, the system damages are expected to be reduced under hight light conditions as well as some photocurrent to be generated. This is why an experimental set-up involving carbon working electrode and some quinone type redox mediators has been developed. The quinone ability to accept some electrons from Photosystem II has been studied by the mean of fluorescence techniques. Their ability to be re-oxidised at the carbon electrode surface has been investigated by cyclic voltametry. As a conclusion, the best quinones (selected after the fluorescence investigations) are DCBQ and PPBQ and correspond to photocurrent values about several µA.cm-2. A correlation between experimental data and theoretical predictions helped us to best understand the photosynthetic electrons derivation pathway and to evidence concomitant phenomenon like poisoning and quinone partition effects
37
Martin, Claire Marie. "Synthesis and bioactivation of redox-activated quinone prodrugs of guanidine". Thesis, Bangor University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.568210.
Testo completoAbstract (sommario):
This thesis describes the preparation of several novel guanidine derivatives (where X= tetrarnethyl, dipiperidine and dimorpholine); three containing a previously described trimethyl-substituted quinone I and three analogous guanidines containing the novel phenyl-substituted quinone H. These conformationally locked derivatives were tested as substrates in a benzoquinone-based drug delivery system which is activated by the enzyme human quinone-oxidoreductase I (hNQOI). Molecular modelling studies were initially performed and demonstrated that all six derivatives were viable substrates of the enzyme hNQOI, as determined by the drug/hNQOI i~teractions. Following their successful preparation, these derivatives were subsequently analysed by high performance liquid chromatography (HPLC). Preliminary findings confirmed their ability to act as substrates for the enzyme hNQOI and showed they followed the intended mechanistic pathway for this drug delivery system. These results also indicated that the rate of reaction with hNQOI was faster for quinone I versus H and the reaction of H did not proceed to completion.
38
Cadd, Duncan Howard. "Some potential precursor routes to aromatic polyesters via quinone methides". Thesis, Durham University, 1992. http://etheses.dur.ac.uk/6032/.
Testo completoAbstract (sommario):
Poly(para-hydroxybenzoic acid) [pHBA] was discovered in the late 1950s and found to have chemical and mechanical properties which make it attractive for use as a high-performance polymer, potentially in engineering applications. However, the same properties make it difficult to fabricate into films or fibres. This thesis examines the philosophy of the precursor approach to intractable polymers as applied to the synthesis of aromatic polyesters generally and to pHBA specifically, by means of a review on the production of benzene derivatives by ring synthesis, and the polymerisation of 1,4-benzoquinone methides. Work undertaken includes the synthesis and characterisation of a precursor to 7,7-dichloro-1,4-benzoquinone methide, endo-cis-6-dichloromethylenetricyclo[6.2.1.0(^2,7)]undeca-4,9-dien-3-one, and the assignments of the (^1)H and (^13)C NMR spectra of endo-cis-6,6-dimethoxytricyclo- [6.2.1.0(^2,7)]undeca-4,9-dien-3-one (a correction to the published assignment) and its intramolecular 2+2 photocycloaddition product, 8,8-dimethoxypentacyclo- [8.1.0(^1,5).0(^2,9).0(^4,7).0(^6,10)]undecan-3-one.
39
Moya, Eduardo. "Ortho-quinone methides from the pyrolysis of substituted benzyltriphenylphosphonium compounds". Thesis, University of Kent, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235694.
Testo completo
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Raghvani, Dinesh V. "Studies of 1,2-quinone monooximes and their use in synthesis". Thesis, London Metropolitan University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300685.
Testo completo
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Marini, Stefano. "Studies on a monoclonal antibody against the coenzyme pyrrolequinoline quinone". Thesis, Cranfield University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359521.
Testo completo
42
Simpson, Grant J. "Quinone derivatives as novel single-molecule components for nano-electronics". Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/6309.
Testo completoAbstract (sommario):
In this thesis, quinone derivative molecules supported on a Cu(110) surface are studied using scanning tunnelling microscopy (STM). The experimentally investigated system is based on the bistable nature of these compounds, and so the work is introduced in the wider context of molecular electronics (Chapter 1). The theory and experimental techniques are also described (Chapters 2 and 3). In Chapter 4 the switching behaviour of azophenine (AP) and azotolyline (AT) is characterised using STM imaging and spectroscopy, and is demonstrated to be based on a hydrogen tautomerisation reaction. The activation energy for switching is quantified by measurement of the rate of switching as a function of varying bias voltage, and the process is determined to be stimulated by inelastic electron tunnelling. The reaction pathway is also revealed using theoretical modelling. Chapter 5 focusses on the condensed phase of AP on the Cu(110) surface. The switching behaviour is found to be largely quenched in the self- assembled phase, so statistical analyses of the AP-AP and AP-Cu interactions are conducted in order to try to explain this. Chapter 6 returns to the study of isolated AP molecules and investigates the spatial dependence of the switch with respect to the location of electronic excitation. It is shown that the final state of the molecule can be accurately selected by exciting specific functional groups within the molecule. This control originates from the non- degenerate reaction pathways for the sequential transfer of the two tautomeric protons. The work is then discussed in terms of future outlook and potential applications for bistable molecules.
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Dollberg, Christopher L. "Zinc and ruthenium quinone diimine complexes: synthesis and photophysical properties". The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1071171484.
Testo completo
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Dollberg, Christopher Lawrence. "Zinc and ruthenium quinone diimine complexes synthesis and photophysical properties /". Columbus, Ohio Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1071171484.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Ohio State University, 2003.Title from first page of PDF file. Document formatted into pages; contains xvii, 171 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Claudia Turro, Dept.of Chemistry. Includes bibliographical references (p. 168-171).
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Labenski, Matthew Thomas. "Identification and Characterization of Quinone-Thioether Protein Adducts In Vivo". Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/193748.
Testo completoAbstract (sommario):
Quinones represent an important class of endogenous compounds such as neurotransmitters and coenzyme Q10, electrophilic xenobiotics and environmental toxicants that have known reactivity based on their ability to redox cycle and generate oxidative stress, as well as to alkylate target proteins. 1,4-Benzoquinone (BQ) is a reactive quinone that we have used to help predict target residue covalent binding by such compounds. Hydroquinone glutathione conjugates (HQ-GSH) cause renal cell necrosis by producing reactive oxygen species (ROS) and by adducting proteins preferentially localized in the S3 segment of the renal proximal tubules. In vitro experimentation using model peptides and proteins have identified cysteine, lysine, arginine, and glutamic acid as amino acids targeted for quinone-thioether adduction. By mimicking a standard protein digestion protocol (100 mM ammonium bicarbonate pH 7.5, or 50 mM Tris-HCl pH 7.5), we demonstrated that cysteine-BQ adducts are unstable. Taken together, these results indicate that BQ-adduct formation on cysteine residues may be a transient interaction, where physiological conditions may play a role in adduct stability. In vivo experimentation following administration of 2-(glutathion-S-yl)HQ (MGHQ, 400 μmol/kg, iv, 2 hr) to Long Evans rats identified the specific site of quinone-thioether protein adduction on a number of proteins. Urinary proteins were isolated, and either trypsin digested en masse and analyzed by multi-dimensional protein identification technology (MuDPIT) or, following SDS-PAGE, single immunopositive bands were excised, trypsin digested and analysed by LC-MSMS. Following site-specific identification of adducts, 3-dimensional protein modeling of adducts on the protein was performed as a way to reveal the potential structural consequence of the modification on 3D structure. The outer stripe of the outer medulla (OSOM) is the target site of protein adduction caused by quinone-thioethers. Using a 2DGE-Western blot approach, in combination with an extensive knowledge of quinol-thioether chemistry, LC-MSMS, and the latest MSMS analysis software, we identified the specific amino acid site of adduction on 17 unique peptides from 34 target proteins within the OSOM. Of the 22 bands analyzed, adducted peptides were identified in 11 of them. Many of the target proteins identified have previously been identified as a target of other electrophiles, producing additional evidence that such protein adduction is selective rather than random. The site-specific identification of covalently adducted proteins is a prerequisite for understanding the biological significance of chemical-induced PTMs and the subsequent toxicological response.
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Westerlund, Kristina. "Exploring amino-acid radicals and quinone redox chemistry in model proteins". Doctoral thesis, Stockholm University, Department of Biochemistry and Biophysics, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8170.
Testo completoAbstract (sommario):
Amino-acid radical enzymes have been studied extensively for 30 years but the experimental barriers to determine the thermodynamic properties of their key radical cofactors are so challenging that only a handful of reports exist in the literature. This is a major drawback when trying to understand the long-range radical transfer and/or catalytic mechanisms of this important family of enzymes. Here this issue is addressed by developing a library of well-structured model proteins specifically designed to study tyrosine and tryptophan radicals. The library is based on a 67-residue three-helix bundle (α3W) and a 117-residue four-helix bundle (α4W). α3W and α4W are single-chain and uniquely structured proteins. They are redox inert except for a single radical site (position 32 in α3W and 106 in α4W). Papers I and II describe the design process and the protein characteristics of α4W as well as a voltammetry study of its unique tryptophan. Paper III and V describe two projects based on α3C, which is a Trp-32 to Cys-32 variant of α3W. In Paper III we use α3C to investigate what effect the degree of solvent exposure of the phenolic OH group has on the redox characteristics of tyrosine analogs. We show that the potential of the PhO•/PhOH redox pair is dominated by interactions with the OH group and that the environment around the hydrophobic part of the phenol has no significant impact. In addition, we observe that interactions between the phenolic OH group and the protein matrix can raise the phenol potential by 0.11-0.12 V relative to solution values. The α3C system is extended in Paper V to study quinone redox chemistry. Papers III and V contain protocols to generate the cofactor-containing α3C systems and descriptions of their protein properties. Paper IV describes efforts to redesign α3Y (a Trp-32 to Tyr-32 variant of α3W) to contain an interacting Tyr-32/histidine pair. The aim is to engineer and study the effects of a redox-induced proton acceptor in the Tyr-32 site.
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Pokharel, Uttam Raj. "ORGANOMETALLIC HETEROCYCLES AND ACENE-QUINONE COMPLEXES OF RUTHENIUM, IRON AND MANGANESE". UKnowledge, 2012. http://uknowledge.uky.edu/chemistry_etds/6.
Testo completoAbstract (sommario):
A variety of organometallic-fused heterocycles and acene quinones were prepared and characterized. This work was divided into three parts: first, the synthesis of 5,5-fused heterocyclic complexes of tricarbonylmanganese and (1’,2’,3’,4’,5’-pentamethylcyclopentadienyl)ruthenium; second, the synthesis of 1,2-diacylcyclopentadienyl p-cymene complexes of ruthenium(II); and third, synthesis of cyclopentadienyl-fused polyacenequinone complexes of ruthenium, iron and manganese.
The first examples of the convenient, versatile and symmetric cyclopentadienyl-fused heterocycle complexes of (1’,2’,3’,4’,5’-pentamethylcyclopentadienyl)ruthenium(II) and tricarbonylmanganese(I) were synthesized starting from (1,2-dicarbophenoxycyclopentadienyl)sodium. The sodium salt was transmetalated using [MnBr(CO)5] and 1/4 [Ru(μ3-Cl)(Cp*)]4 to give [Mn(CO)3{η5-C5H3(CO2Ph)2-1,2}] and [Ru{η5-C5H3(CO2Ph)2-1,2}(Cp*)]. The diester complexes were saponified under basic conditions to obtain the corresponding dicarboxylic acids. The dicarboxylic acids were used to synthesize unique cyclopentadienylmetal complexes including diacyl chlorides, anhydrides, thioanhydrides and p-tolyl imides of ruthenium and manganese.
Similarly, a series of 1,2-diacylcyclopentadienyl-p-cymene cationic complexes of ruthenium were synthesized using thallium salt of 2-acyl-6-hydroxyfulvene and [Ru(η6-p-cymene)(μ-Cl)Cl]2 in a 2:1 ratio with an intension of converting them into heterocycle-fused cationic sandwich complexes. However, our attempts of ring closing on 1,4-diketons with sulfur or selenium were unsuccessful. A methodology involving the synthesis of metallocene-fused quinone complexes was employed starting from pentamethylruthenocene-1,2-dicarboxylic acids. The diacyl chloride was prepared in situ from the dicarboxylic acids and used for Friedel-Crafts acylation. We observed single-step room-temperature diacylation of aromatics, including benzene, o-xylene, toluene, 1,4-dimethoxybenzene and ferrocene with pentamethylruthenocene-1,2-diacyl chloride to obtain the corresponding quinone complexes. Similarly, we synthesized mononuclear and binuclear γ-quinones by aldol condensation of 1,2-diformylcyclopentadienylmetal complexes with cyclohexane-1,4-dione or 1,4-dihydroxyarenes.
The third methodology involves the Friedel-Crafts acylation of ferrocene with 2-carbomethoxyaroyl chlorides followed by saponification, carbonyl reduction, and ring closing by second Friedel-Crafts acylation to give Ferrocene-capped anthrone-like tricyclic and tetracyclic ketones. The oxidation of the ketones gave [3,4-c]-fused α-quinone complexes of iron. The oxidative and reductive coupling, enolization and C-alkylation of the anthrone complex were studied. Solvolysis of α-carbinol gave α-ferrocenylcarbenium salt, which underwent dimerization on treatment with non-nucleophilic base. We were successful to trap the in situ generated trimethylsilylenol ether of ferrocene-anthrone using dienophiles like N-phenylmaleimide or dimethylacetylenedicarboxylate under Diels-Alder conditions.
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Caraher, Mary Clare. "Biological analysis of NRH quinone oxidoreductase 2 (NQO2) using novel inhibitors". Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/biological-analysis-of-nrh-quinone-oxidoreductase-2-nqo2-using-novel-inhibitors(bca95b5b-b9d3-4e68-aeb6-d666b7df80e3).html.
Testo completoAbstract (sommario):
NQO2 is a member of the oxidoreductase family. It is a cytosolic, flavin-dependent, ubiquitous protein that is expressed in many human tumours. Liao and Williams-Ashman discovered the enzyme 51 years ago, however its cellular role has yet to be fully characterised. Intracellular NQO2 activity has been associated with various diseases; cancer, malaria and neurodegenerative disorders including schizophrenia, Alzheimer’s disease and Parkinson’s disease. Some of these associations have been related to the stability and activity of redox-sensitive factor NFκB, as well as tumour suppressor p53. Hence, suggesting NQO2 could be an important therapeutic target. However, the full extent of NQO2’s role in mediating these diseases has not been elucidated. In order to gain more insight into the cellular function of NQO2, a series of potent novel NQO2 inhibitors were identified from the NCI database. These compounds were assessed for their inhibition of NQO2 activity in cell-free systems as well as in cellular environments. Their inhibition potency of intracellular NQO2 was determined utilising NQO2’s ability to activate prodrug CB1954. These novel inhibitors were then used as a tool to evaluate NQO2’s role in the NFκB pathway; measuring TNFα-induced NFκB luciferase activity, using western blotting to assess NQO2’s impact on IκB-α and IKKβ protein stability, and the griess assay to analyse downstream product iNOS. In addition, regulation of redox status by NQO2 was determined using flow cytometry analysis. To help understand the underlying physical processes involved in binding interactions with chaperone proteins such as p53, NQO1 and NQO2 enzyme kinetics were studied and analysed using the Hill Equation as an indicator of cooperativity. Amongst the most potent inhibitors of intracellular NQO2 activity were NCI compounds NSC71795, NSC164016 and NSC305836 with IC50 values of 54nM, 2.3μM and 18μM compared to resveratrol, the ‘classic’ NQO2 inhibitor, with an IC50 value of 150μM. Each of these inhibitors attenuated TNFα-induced NFκB activity, as well as reduced intracellular iNOS concentration, and they partially protected IκB-α from proteasome degradation. NQO2’s involvement in some of these observations was confirmed through siRNA experiments. However, there was no clear modulation of IKKβ protein expression by NQO2. Inhibition experiments also identified NQO2 can alter the cellular redox. Additional findings include, NRH appears to modulate NFκB activity in an NQO2-dependent fashion, and the observed NQO2 regulation of NFκB activity and redox status appears to be more prevalent in tumour cells as opposed to normal cells. Kinetic analysis of NQO1 and NQO2 activity suggests the active sites in both enzymes are non-equivalent. The calculated Hill coefficients indicate the inhibitors induce negative cooperativity within the enzymes, which is altered in the additional presence of electron donor. Western blot analyses demonstrate inhibitor-induced destabilisation of p53 can be protected by electron donor. Thus, potential changes to the enzyme’s structure as a result of cooperativity could influence binding and stability of p53.In summary, the identified novel NQO2 inhibitors have helped to evaluate NQO2’s role in the NFκB pathway, and strengthen the theory this is achieved through alteration of cellular redox. Also, this study has re-opened the discussion that the active sites of NQO1, and NQO2, are non-equivalent as originally suggested by Ernster and colleagues.
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Liu, Yang. "Selective delivery of a quinone methide precursor by peptide nucleic acids". College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/7809.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Chemistry and Biochemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Bayer, Uwe [Verfasser]. "Cerium Complexes for para-Quinone and Carbon Dioxide Activation / Uwe Bayer". Tübingen : Universitätsbibliothek Tübingen, 2021. http://d-nb.info/1225740207/34.
Testo completo