Dissertations / Theses: 'Flavonoli'

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McIntosh, Cecilia A. "Position-Specific Flavonoid Glucosyltransferases: Structure and Functional Analysis of Grapefruit Flavonol-Specific 3-O-GT." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/367.

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Owens, Daniel Kenneth. "Examination of 2-Oxoglutarate Dependant Dioxygenases Leading to the Production of Flavonols in Arabidopsis thaliana." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29144.

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The flavonols are a varied and abundant sub-class of flavonoids that are associated with a number of essential physiological functions in plants and pharmacological activities in animals. The 2-oxoglutarate-dependant dioxygenases(2-ODDs), flavonol synthase (FLS) and flavanone 3-hydroxylase (F3H), are essential for flavonol synthesis. The primary goal of this study has been to gain a deeper understanding of the biochemistry of these enzymes in Arabidopsis. To accomplish this goal, an activity assay employing recombinant protein expression and HPLC as a detection system was developed for F3H and adapted for use with FLS. The assay was employed to establish the biochemical parameters of F3H from Arabidopsis, and to further characterize the F3H mutant allele, tt6(87). Enzymatic activity was demonstrated for F3H enzymes from Ipomoea alba (moonflower), Ipomoea purpurea (common morning glory), Citrus sinensis (sweet orange), and Malus X domestica (newton apple), each of which had previously been identified solely based on sequence homology. Arabidopsis contains six genes with high similarity to FLS from other plant species; however, all other central flavonoid pathway enzymes in Arabidopsis are encoded by single genes. The hypothesis that differential expression of FLS isozymes with varying substrate specificities is responsible for observed tissue-specific differences in flavonol accumulation was tested. Sequence analysis revealed that AtFLS2, 4 and 6 contain premature stop codons that eliminate residues essential for enzyme activity. AtFLS1 was found to have a strong preference for dihydrokaempferol as a substrate. However, no enzyme activity was observed for AtFLS3 or AtFLS5 with a number of different substrates under a variety of reaction conditions. To identify structural elements that may contribute to the observed differences in biochemical activity, homology models for each of the isoforms were generated utilizing Arabidopsis anthocyanin synthase (ANS) as a template. A domain at the N-terminus of AtFLS1 that is missing in the other isozymes was insufficient to convey activity to an AtFLS1/5 chimera. These findings suggest a single catalytically-active form of FLS exists in Arabidopsis. The possibility that the apparently expressed but non-catalytic proteins, AtFLS2, 3, and 5, serve noncatalytic roles in flavonol production were explored by yeast 2-hybrid analysis.
Ph. D.

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Reinboth, Marianne. "Bioverfügbarkeit des Flavonols Quercetin beim Hund." Doctoral thesis, Universitätsbibliothek Leipzig, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-62483.

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6 Zusammenfassung Marianne Reinboth Bioverfügbarkeit des Flavonols Quercetin beim Hund Veterinär-Physiologisches Institut der Veterinärmedizinischen Fakultät der Universität Leipzig Eingereicht im Juni 2010 79 Seiten, 20 Abbildungen, 6 Tabellen, 211 Literaturangaben, 1 Anhang Schlüsselwörter: Quercetin, Bioverfügbarkeit, Hund, absolute Bioverfügbarkeit, Isoquercitrin, Rutin, Flavonole Für das pflanzliche Flavonol Quercetin werden vielfältige gesundheitsfördernde Wirkungen postuliert, so auch bei Hunden. Über die Bioverfügbarkeit des Flavonols bei dieser Spezies liegen bislang jedoch keinerlei Daten vor. Daher hatte diese Arbeit das Ziel, Bioverfügbarkeit und pharmakokinetische Parameter von Quercetin und wichtigen Quercetinglycosiden bei Hunden nach deren Verabreichung mit einer Testmahlzeit in einer praxisrelevanten Dosierung von 10 mg/kg Körpermasse zu untersuchen. Dazu erhielten 9 adulte Beagles beiderlei Geschlechts das zuckerfreie \"Aglycon\" Quercetin bzw. seine Glycoside Isoquercitrin (Quercetin-3-O-Glucosid) und Rutin (Quercetin-3-O-Glucorhamnosid) in jeweils äquimolarer Dosierung in einer Testmahlzeit verabreicht. Anschließend wurden Blutproben über einen Zeitraum von bis zu 72 Stunden entnommen und mittels HPLC die Konzentrations-Zeitverläufe der Metaboliten im Blutplasma, die Bioverfügbarkeit sowie weitere pharmakokinetische Parameter bestimmt. Weiterhin wurde die absolute Bioverfügbarkeit von Quercetin aus dem Vergleich einer oralen mit einer intravenösen Applikation bestimmt. Der weitaus größte Teil der Plasmametaboliten von Quercetin sowie seiner beiden Glycoside bestand aus glucuronidierten bzw. sulfatierten Quercetinkonjugaten. Nicht konjugiertes Quercetin-Aglycon kam nur in einem Anteil von etwa 20 % vor. Neben Quercetin machten seine Metaboliten Isorhamnetin und Kämpferol weniger als 10 % aller im Plasma zirkulierenden Flavonole aus. Die absolute Bioverfügbarkeit von Quercetin betrug nur etwa 4 %. Die relative Bioverfügbarkeit aus dem 3-O-Glucosid Isoquercitrin war mehr als doppelt so hoch wie aus dem Aglycon, die maximalen Plasmaspiegel lagen aber auch hier unter 1 µmol/l. Sowohl nach Aufnahme von Quercetin als auch nach Isoquercitrin kam es zu einer relativ schnellen Absorption aus dem Dünndarm mit einem ersten Plasmapeak ungefähr eine Stunde nach der Ingestion. Vier Stunden nach Aufnahme der beiden Flavonole trat ein zweiter Plasmapeak auf, der in der Regel höher als der erste ausfiel. Dies deutet auf einen enterohepatischen Kreislauf der über die Galle ausgeschiedenen Metaboliten hin. Nach Aufnahme von Rutin kam es zu einer verzögerten Absorption, da eine Deglycosylierung durch bakterielle Glycosidasen im Dickdarm Voraussetzung für die Absorption des Flavonols ist. Maximale Plasmakonzentrationen wurden im Mittel erst 11 Stunden nach Ingestion dieses Glycosids erreicht. Die maximalen Plasmakonzentra-tionen nach Rutin waren geringer als nach Quercetin oder Isoquercitrin, jedoch war die mittlere Verweildauer der Plasmametaboliten mit 18 Stunden auch wesentlich länger. Im Unterschied zu anderen Spezies war die relative Bioverfügbarkeit von Rutin gegenüber Quercetin nicht verringert. Obwohl Rutin eine relativ gute Quercetinquelle für Hunde zu sein scheint, muss bei der Einschätzung möglicher In-vivo-Wirkungen die relativ geringe Bioverfügbarkeit sowie die intensive Metabolisierung seines Aglycons Quercetin berücksichtigt werden
7 Summary Marianne Reinboth Bioavailability of the Flavonol Quercetin in Dogs Institute of Physiology of the Faculty of Veterinary Medicine, University of Leipzig Submitted in June 2010 79 pages, 20 figures, 6 tables, 211 references, 1 appendix Keywords: quercetin, bioavailability, dog, absolute bioavailability, isoquercitrin, rutin, flavonols The plant flavonol quercetin is supposed to exert multiple health-related effects in dogs. To date no information on its bioavailability in this particular species is avai-lable. This study intended to investigate bioavailability and pharmacokinetics of quercetin and certain quercetin glycosides in dogs after ingestion of a test meal sup-plemented with a quercetin dose equivalent to 10 mg/kg body weight. Nine adult beagle dogs of both sexes received the aglycon quercetin (sugarfree) or its glycosides isoquercitrin (quercetin-3-O-glucoside) and rutin (quercetin-3-O-glucorhamnoside) in equimolar amounts together with a test meal. Blood samples were taken over a period of up to 72 hours; bioavailability and pharmacokinetics were calculated from the HPLC-derived plasmaconcentration-time-curves. Absolute bioavailability was calculated by comparing an oral to an intravenous administration of quercetin. The majority of analysed plasma metabolites were glucuronidated and sulfated con-jugates of quercetin. Non-conjugated quercetin aglycon comprised only 20 %. Be-sides quercetin, its metabolites isorhamnetin and kaempferol made up less than 10 % of all circulating metabolites. The absolute bioavailability of quercetin was only 4 %. The relative bioavailability of quercetin from isoquercitrin was more than twice as high than from the aglycon, but even there maximal plasma concentrations were generally less than 1 μmol/l. Absorption from the small intestine was rather fast with a first plasma peak after 1 hour after ingestion of quercetin or isoquercitrin. A second, generally higher plasma peak occurred 4 hours after ingestion. This suggests an in-tensive enterohepatic recycling of biliary secreted metabolites. Absorption was significantly delayed after ingestion of rutin due to the necessity of bacterial deglycosilation in the large intestine. Plasma concentrations peaked only after 11 hours. Plasma concentrations after rutin were lower than after quercetin or isoquercitrin, but mean residence time of plasma metabolites was as long as 18 hours after rutin ingestion. Consequently, a once daily feeding of dogs with rutin might lead to relatively constant plasma metabolite concentrations. In contrast to other species, bioavailability from rutin was not smaller than that from quercetin. Although rutin seems to be a relative good quercetin source for dogs, estimations about potential in-vivo-effects of quercetin have to take into consideration its low bioavailabilty and intensive metabolism

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Costa, Patricia Miranda da. "Triterpenos, saponinas e flavono?des de L. arianeae (Chrysobalanaceae) e Eschweilera longipes (Lecythidaceae)." Universidade Federal Rural do Rio de Janeiro, 2003. https://tede.ufrrj.br/jspui/handle/jspui/1561.

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Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
Solvent partition and chromatographic fractionation of metanolic extract from the leaves and wood of L. arianeae lead to the isolation of triterpenes, one carboidrate, saponin and flavonoid. 3b,6b,19a -trihydroxiursa-12-en- 28-oic acid, 3b,6b,24-trihydroxiursa-12-en- 28-oic acid, 3,5,7-trihydroxi-4?-metoxi,6-flavone-( sulfonate), 3b-hydroxiolean-12-en-28- ?ico acid, 3b-O-b-D-galactopiranosyl-(6?-1 para hydroxi benzoil)-ursa-12-en-28-oic acid, 1-metyl glycopiranosyl and mixture of two flavonoids. The 3,5,7-trihydroxi-4?-metoxi,6- flavone-(sulfonate) and 3b-O-b-D-galactopiranosyl-(6?-1 para hydroxi benzoil)-ursa-12-en- 28-oic acid are being descricted for the first time in the literature. The IR, 1H NMR, 13C NMR and MS spectra analysis was used for structural determination.
O fracionamento dos extratos das folhas e madeira de L. arianeae atrav?s de processo de parti??o com solventes e t?cnicas cromatogr?ficas conduziu ao isolamento dos ?cidos 3b,6b, 19a -triidroxiursan-12-eno-28-?ico, 3b,6b,24,19a-tetraidroxiursan-12-eno-28-?ico, 3b-hidroxiolean-12-eno-28-?ico, da 3,5,7-triidroxi, 4?-metoxi, 6-sulfonato, flavona, da 3b- O-b-D-galactopiranosil-(6?-p-hidroxi-benzo?la)-ursan-12-eno-28-?ico, da 1-metil glicose, e da mistura de flavon?ides. As estruturas das subst?ncias foram deduzidas atrav?s da an?lise dos espectros de IV, RMN de 1H e 13C, incluindo experimentos 2D e espectro de massas das subst?ncias naturais e dos derivados. Este ? o primeiro registro destes constituintes no g?nero Licania. A flavona e saponina est?o sendo descritos pela primeira vez na literatura. As folhas e as cascas da esp?cie E. longipes foram submetidas a extra??o com solventes org?nicos e os extratos foram fracionados atrav?s de parti??o e t?cnicas cromatogr?ficas. As fra??es reunidas foram submetidas a t?cnicas cromatogr?ficas e cristaliza??o. Esses processamentos conduziram ao isolamento dos ?cidos 1a,2b,3a,19a -tetraidroxiursan-12- eno-28-?ico, da saponina 3b-O-b-D-glicopiranosil-sitosterol e dos triterpenos fridelinol e 3b,24-diidroxifridelano. As estruturas das subst?ncias foram deduzidas atrav?s das t?cnicas citadas acima. Este ? o primeiro registro desta saponina no g?nero Eschweilera. O triterpeno 3b,24-diidroxifridelano foi descrito pela primeira vez na literatura (COSTA, P.M. & Carvalho, M. G., Annais da Academia Brasileira de Ci?ncias, 2003).

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Jailani, Fadhilah. "Absorption and metabolism of flavonols." Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.634526.

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The consumption of flavonols, major sources of dietary flavonoids, have been linked to the reduction of risk factors for various chronic diseases. However, the bioavailability of flavonols would appear to be limited and not all compounds within the same subclass are absorbed with equal efficacy, thus compromising their nutritional relevance. The aim of this current study was to examine the absorption and metabolism of four major flavonols specifically quercetin, myricetin, kaempferol and galangin using both in vitro methods and healthy human volunteers to investigate how bioavailability was affected by the addition of other ingredients, specifically fat. Firstly, the enzymatic synthesis of flavonol metabolites was conducted using liver S9 homogenates, which demonstrated that all major flavonol aglycone generated several isomers of glucuronide or sulphate forms after the incubation period. The evidence for identification and characterisation of available authentic standards and synthesised flavonol metabolites using HPLC-DAD-MS-MS is presented. The success of this method was demonstrated through its application to assess the fate of flavonols in the cell culture transport experiments, which were examined using co-cultures of Caco-2 (enterocyte cell) and HT29-MTX (goblet cell) monolayers and the results partially substantiate that the absorption is most probably achieved by passive transport.

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De, Marchi Fabiola. "Studio dei metaboliti chimici dell'uva finalizzato a valutare le potenzialità enologiche, nutraceutiche ed industriali di alcune varietà di vite e nuovi approcci di metabolomica." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423516.

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Grape, wine and oenology by-products are rich in polyphenols and in particular flavonoids: flavonols, anthocyanins, flavanols and proanthocyanidins. Those molecules are plants secondary metabolites and may also contribute to the bitterness and astringency of grapes and wines. In recent years, epidemiological studies have revealed the great potential of polyphenols and flavonoids in human diet on protection against cancers, infections, their role in anti-aging and also against the development of several chronic diseases such as cardiovascular diseases (CVDs) or diabetes. Their role for human health is attributed mainly to their antioxidant, anti-inflammatory, antimicrobial activities. Therefore these bio-compounds could find promising applications in pharmaceutical, nutraceutical and food industries as active ingredients in supplements with antioxidant activity, value-added ingredients in fortified foods or as natural dyes and preservatives. The aim of this research is to investigate the contents of chemical metabolites in several unique Vitis vinifera varieties and hybrids, and to examine their potential for oenological, nutraceutical and industrial applications. Modern spectrophotometry, chromatography and mass spectrometry (MALDI/MS, LC/MS, GC/MS) analytical techniques were applied in order to achieve the aims of the research. Nine Vitis vinifera italian native grape varieties from Friuli Venezia Giulia and Veneto regions, were investigated for their enological potential, by studying the main classes of polyphenols and aroma compounds of grapes and their organoleptic wine characteristics. In addition 32 hybrid varieties (21 red, 11 white) that belong to the CRA-VIT Grapevine Germplasm Collection located in Conegliano (TV) were studied to evaluate their nutraceutical and industrial potential. The study of anthocyanins of red hybrids showed that some varieties (e.g. Seibel 8357) have rich content of pigments and are therefore attractive for the production of natural dyes that are used in the food and pharmaceutical industry. Moreover, some varieties (Bacò 1 and Seibel 10878) were also found interesting for their triglycerides content in grape seed oil with high linoleic acid content (up to 70%), which is essential fatty acid effective in reducing LDL cholesterol. The nutraceutical potential of hybrid varieties was investigated by studying grape seed proanthocyanidins. Oligomeric and polymeric proanthocyanidins with different degree of galloylation were determined in grape seed extracts suggesting potential application of the extracts as antioxidants in nutraceutical products and also as oenological tannins. Eventually, a new methodology was established for grape metabolome study based on High-Resolution Mass Spectrometry (HR-MS) analysis and the “suspect screening analysis” approach. This method was proved to be very effective due to the ability to identify hundreds of compounds in one single run and also individual classes of grape polyphenols
L’uva, il vino ed i sottoprodotti dell’industria enologica sono ricche fonti di polifenoli e flavonoidi, quali flavonoli, antociani, flavanoli e proantocianidine. Questi composti determinano le caratteristiche sensoriali delle uve e dei vini, come il colore, il sapore e l’astringenza. Numerosi studi epidemiologici hanno dimostrato che questi composti esercitano un’azione benefica sulla salute umana e proteggono dall’insorgere di patologie croniche e degenerative soprattutto a carico dell’apparato cardiovascolare, grazie alle loro proprietà antiossidanti, anticancro, antinfiammatorie ed antimicrobiche. Questi biocomponenti, una volta estratti dalle varie parti della pianta, possono trovare importanti applicazioni come principi attivi di supplementi farmaceutici con attività antiossidante, ingredienti a valore aggiunto in alimenti fortificati, coloranti e conservanti naturali per l’industria alimentare. Lo scopo della ricerca è quello di studiare, mediante le moderne tecniche analitiche di spettrofotometria, cromatografia e spettrometria di massa (MALDI/MS, LC/MS, GC/MS), i metaboliti nelle uve di alcune varietà di Vitis vinifera e di viti ibride ad oggi poco conosciute al fine di individuarne le potenzialità enologiche, nutraceutiche ed industriali. Sono state valutate le potenzialità enologiche di nove varietà di V. vinifera appartenenti a vitigni autoctoni del Friuli Venezia Giulia e del Veneto, attraverso lo studio delle principali classi di polifenoli e aromi delle uve e dei principali parametri chimici e profili organolettici dei vini. Inoltre, sono state studiate le uve di 32 varietà di viti ibride (21 rosse e 11 bianche) presenti nella collezione del Germoplasma viticolo del CRA-VIT al fine di valutarne le potenzialità per i loro impieghi industriali e nella nutraceutica. Lo studio degli antociani delle varietà ibride rosse ha evidenzato alcune varietà particolarmente ricche di pigmenti (es. il Seibel 8357) e quindi interessanti per la produzione di coloranti naturali che vengono impiegati in particolare nell’industria alimentare e farmaceutica. Lo studio dei trigliceridi dell’olio di vinaccioli delle uve ibride ha evidenziato che in generale queste varietà hanno un elevato contenuto di acido linoleico (superiore al 70%), un acido grasso essenziale avente la proprietà di diminuire i livelli di colesterolo LDL, ed alcune varietà particolarmente interessanti per la loro produttività (Bacò 1 e Seibel 10878). Le potenzialità nutraceutiche di queste varietà sono state investigate anche studiando le proantocianidine negli estratti di vinaccioli. Sono state determinate numerose proantocianidine oligomere e polimere aventi diversi gradi di galloilazione, utilizzabili, oltre che come preparati antiossidanti, anche come tannini enologici per la chiarifica di mosti e vini. Infine, è stato sviluppato un nuovo metodo per lo studio della metabolomica dell’uva mediante analisi di spettrometria di massa ad alta risoluzione (HR-MS) con un approccio di “suspect screening analysis”. Il metodo è risultato molto efficace, ed ha permesso l’identificazione di centinaia di metaboliti con una singola analisi, incluse diverse classi di polifenoli dell’uva

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Huber, Lisia Senger. "Flavinoides : identificação de fontes brasileiras e investigação dos fatores responsaveis pelas variações na composição." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256158.

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Orientador: Delia B. Rodriguez-Amaya
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Devido a crescente importância atribuída aos flavonóides nos últimos anos, decorrente de suas ações relacionadas à prevenção de doenças degenerativas, e aliada à carência de dados destes compostos em alimentos brasileiros, este estudo teve como objetivo determinar os teores de flavonóis e flavonas em alimentos consumidos no Brasil e avaliar alguns fatores que influenciam seus níveis nestes alimentos. Uma revisão bibliográfica é apresentada no Capítulo 1, na qual são descritos os principais efeitos benéficos à saúde, aspectos analíticos e fatores que influenciam os teores de flavonóides em alimentos. Estes compostos com ação benéfica à saúde, atuam como antioxidantes, inibidores da proliferação celular, antiestrogênicos e mediadores intracelulares, exercendo proteção principalmente contra câncer e doenças cardiovasculares. A determinação desses compostos normalmente é feita utilizando-se cromatografia líquida de alta eficiência com detector de arranjo de diodos. Os níveis de flavonóides em alimentos podem ser influenciados por vários fatores, como estação do ano, preparo e processamento de alimentos. O Capítulo 2 descreve o desenvolvimento e validação da metodologia analítica para determinação de flavonóis e flavonas em hortaliças. Utilizando-se Delineamento Composto Central Rotacional, obtiveram-se as melhores condições para extração e hidrólise dos flavonóides encontrados na natureza na forma glicosídica, a suas respectivas agliconas. Essas condições foram: 1,0M de HCl por 6 horas para espinafre e couve, 1,6M de HCl por 5 horas para rúcula, 1,2M de HCl por 2 horas para alface, 1,7M de HCl por 4,3 horas para salsa e 0,8M de HCl por 2,5 horas para cebola. As condições cromatográficas utilizadas foram coluna Nova-Pak C18 (4ìm, 3,9x150mm), e fase móvel constituída de metanol e água, acidificados com 0,3% de ácido fórmico, em gradiente linear. Utilizando a metodologia analítica validada no Capítulo 2, no Capítulo 3 foram identificados e quantificados os flavonóides de alface lisa (6,73-9,77'g/g de quercetina), alface crespa (7,18-30,8'g/g de quercetina), cebola branca (323-362'g/g de quercetina), cebola roxa (390-423'g/g de quercetina), couve (256-399'g/g de quercetina e 333-339'g/g de kaempferol), espinafre (52,8-62,3'g/g de quercetina e 145-170'g/g de kaempferol), rúcula (137-143'g/g de quercetina e 402-501'g/g de kaempferol) e salsa (1521-1636'g/g de apigenina). Também foi avaliado o efeito sazonal nos teores destes compostos, sendo que estes tenderam a ser maiores no verão que no inverno, embora as diferenças não tenham sido estatisticamente significativas. No Capítulo 4, foram determinados os teores de flavonóides em sucos prontos para o consumo, sucos concentrados e polpas de caju, acerola e pitanga, e em amostras de cebola e salsa desidratadas. Os resultados indicaram perdas de flavonóides durante o processamento destes alimentos. Os teores nas amostras processadas foram nitidamente menores aos obtidos previamente nas amostras in natura. Os derivados de frutas apresentaram teores decrescentes na seguinte ordem: polpas, suco concentrado, suco pronto para consumo. Os teores de quercetina nas amostras de cebola desidratada foram bastante variados, indicando diferenças de variedades utilizadas como matéria-prima ou nas condições de processamento empregadas. Os resultados sugerem que estudos de monitoramento das perdas de flavonóides, da matéria-prima ao produto final, são altamente requeridos. O comportamento de flavonóis em couve, espinafre e rúcula minimamente processados, estocados em atmosfera modificada, em diferentes temperaturas, na presença e ausência de luz, foi avaliado e discutido no Capítulo 5. A qualidade sensorial dessas amostras também foi avaliada, para verificar a vida-de-prateleira. No geral, a vida útil foi negativamente influenciada pelo aumento na temperatura de estocagem na presença de luz. Não ocorreram perdas pronunciadas nos teores destes compostos durante a estocagem das três folhas minimamente processadas, podendo inclusive aumentar em certos períodos do armazenamento
Abstract: Had the increasing importance attributed to the flavonóides in the last years, decurrent of its action related to the prevention of degenerative illnesses, and allied to the lack of data of these composites in Brazilian foods, this study it had as objective to determine texts of flavonóis and flavonas in foods consumed in Brazil and to evaluate some factors that influence its levels in these foods. A bibliographical revision is presented in Chapter 1, in which the main beneficial effect to the health, analytical aspects and factors are described that influence texts of flavonóides in foods. These composites with beneficial action to the health, act as antirust, inhibiting of the proliferation cellular, antiestrogênicos and mediating intracellular, exerting protection mainly against cardiovascular cancer and illnesses. The determination of these composites normally is made using liquid chromatography of high efficiency with detector of arrangement of diodes. The levels of flavonóides in foods can be influenced by some factors, as station of the year, preparation and processing of foods. Chapter 2 describes the development and validation of the analytical methodology for determination of flavonóis and flavonas in hortaliças. Using Rotational Central Composed Delineation, the best conditions for extration and hydrolysis of the flavonóides found in the nature in the glicosídica form, its respective agliconas had been gotten. These conditions had been: 1,0M of HCl for 6 hours for spinach and borecole, 1,6M of HCl for 5 hours for rúcula, 1,2M of HCl for 2 hours for lettuce, 1,7M of HCl for 4,3 hours for parsley and 0,8M of HCl for 2,5 hours for onion. The used chromatographic conditions had been column Nova-Pak C18 (4ìm, 3,9x150mm), and mobile phase consisting of methanol and water, acidified with 0,3% of acid fórmico, in linear gradient. Using the validated analytical methodology in Chapter 2, in Chapter 3 they had been identified and quantified the flavonóides of smooth lettuce (6,73-9,77'g/g of quercetina), lettuce crespa (7,18-30,8'g/g of quercetina), white onion (323-362'g/g of quercetina), purple onion (390-423'g/g of quercetina), borecole (256-399'g/g of quercetina and 333-339'g/g of kaempferol), spinach (52,8-62,3'g/g of quercetina and 145-170'g/g of kaempferol), rúcula (137-143'g/g of quercetina and 402-501'g/g of kaempferol) and parsley (1521-1636'g/g of apigenina). Also the sazonal effect in texts of these composites was evaluated, being that these had tended to be bigger in the summer that in the winter, the differences have even so not been estatisticamente significant. In Chapter 4, the texts of flavonóides in ready juices for the consumption, intent juices and cashew pulps, acerola and pitanga had been determined, and in samples of dehydrated onion and parsley. The results had indicated losses of flavonóides during the processing of these foods. The texts in the processed samples had been nitidamente lesser to gotten previously in the samples in natura. The derivatives of fruits had presented decreasing texts in the following order: pulps, concentrated juice, ready juice for consumption. The texts of quercetina in the samples of dehydrated onion sufficiently had been varied, indicating differences of used varieties as raw material or in the employed conditions of processing. The results suggest that studies of monitoramento of the losses of flavonóides, of the raw material to the end item, highly are required. The behavior of flavonóis in borecole, spinach and rúcula minimamente processings, storaged in modified atmosphere, in different temperatures, na.presença and absence of light, was evaluated and argued in Chapter 5. The sensorial quality of these samples also was evaluated, to verify the life-of-shelf. In the generality, the useful life negative was influenced by the increase in the temperature of stockage na.presença of light. Sharp losses in texts of these composites had not occurred during the stockage of three minimamente processed leves, also being able to increase in certain periods of the storage
Doutorado
Doutor em Ciência de Alimentos

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Bombonati, Aline Yashima. "Flavonois em frutas e hortaliças : efeito do co cozimento e microfiltração." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/322501.

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Orientador: Delia B. Rodriguez-Amaya
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Mestrado
Mestre em Ciência de Alimentos

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Eder, Christian. "Klonierung und Charakterisierung der Flavonoid 3'-Hydroxylase und der Flavonoid 3',5'-Hydroxylase." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963026275.

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Stewart, Amanda J. "Flavonoid occurrence, regulation in plant tissues and dietary contribution to health." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366202.

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Pap, N. (Nora). "Value-added processing of blackcurrants:use of membrane technologies for clarification and concentration of blackcurrant juice and extraction of anthocyanins from blackcurrant marc." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526220840.

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Abstract Blackcurrants (Ribes nigrum L.) are widely consumed due to their favourable taste and health-promoting effects. The berries and extracts from different parts of the plant show anticarcinogenic, antioxidative and anti-inflammatory properties, and are effective in reducing the risk of cardiovascular disease and in promoting brain health. These health-promoting benefits are due to high concentrations of valuable compounds such as anthocyanins and flavonols in blackcurrants. However, these compounds are sensitive to heat and processing and some are lost when the berries are processed into products such as jams, purees and juices. Industrial processing of juices is a multistep process that typically includes enzyme treatment, pressing, pasteurisation, clarification and usually also thermal concentration. Alternative minimal processing technologies are required to preserve the health-promoting compounds in products by avoiding the use of high temperatures and extensive clarification. Integrated membrane technology, i.e. combined ultrafiltration and reverse osmosis, was used in this thesis for the production of blackcurrant juice concentrate. Pre-treatment methods, such as enzymatic treatment, ultrafiltration, enzymatic treatment combined with ultrafiltration and centrifugation to increase the filtration efficiency in reverse osmosis were evaluated. Processing was modelled to define the resistances, using the resistance-in-series model. The preservation and concentration of anthocyanins and flavonols were analysed. The results indicated that the main resistance in the reverse osmosis process was polarisation resistance, while membrane resistance was lower and fouling resistance was one order of magnitude lower than the other resistances. The filtration efficiency results showed that the highest flux was achieved by ultrafiltered blackcurrant juice, but that the resulting juices were substantially lower in anthocyanins and flavonols, which were retained on the ultrafiltration membrane. Therefore, replacing ultrafiltration with centrifugation as the clarification method for juices is recommended. Value-added processing of blackcurrant was conceptualised by valorisation of the marc left in the berry pressing process for extraction of anthocyanin compounds. Conventional extraction was compared with microwave-assisted extraction (MAE), with the latter optimised using response surface methodology to achieve maximum efficiency in extracting anthocyanins. The optimum parameters found for MAE were: microwave power 700 W, extraction time 10 minutes, pH 2 adjusted with hydrochloric acid and a solid to solvent ratio of 0.05. Conventional extraction showed the best results when carried out at 80 °C for 300 minutes in aqueous solution with pH 2 adjusted by hydrochloric acid. Under these conditions, recovery of anthocyanins was still 10% lower than with MAE for only 10 minutes of extraction time
Tiivistelmä Mustaherukoita käytetään paljon niiden hyvän maun ja terveyttä edistävien vaikutusten ansiosta. Marjoilla ja marjakasvin eri osien uutteilla on osoitettu olevan antikarsinogeenisia, antioksidatiivisia ja tulehduksia estäviä ominaisuuksia ja ne ovat tehokkaita pienentämään sydän- ja verisuonisairauksia. Ne edistävät myös aivojen terveyttä. Marjojen arvokkailla yhdisteillä kuten antosyanideillä ja flavonoleilla on terveyttä edistäviä vaikutuksia. Mustaherukassa on runsaasti näitä yhdisteitä. Hillojen, soseiden ja mehujen prosessoinnissa menetetään näitä hyödyllisiä yhdisteistä, koska ne ovat herkkiä lämmölle ja prosessoinnin vaikutuksille. Mehujen prosessoinnissa käytetään entsyymikäsittelyjä, puristusta, pastörointia, selkeytystä ja usein myös lämpökonsentrointia. Tuotteiden terveyttä edistävien yhdisteiden säilyttämiseksi tarvitaan uudenlaisia hellävaraisia prosessointitekniikoita ilman korkeita lämpötiloja ja voimakasta selkeyttämistä. Tässä työssä tutkittiin yhdistettyjen kalvotekniikoiden kuten ultrasuodatuksen ja käänteisosmoosin käyttöä mustaherukkatiivistemehun prosessoinnissa. Esikäsittelymenetelmiä, mm. entsyymikäsittelyä, ultrasuodatusta, entsyymikäsittelyn ja ultrasuodatuksen yhdistelmää sekä sentrifugointia, arvioitiin käänteisosmoosin suodatustehokkuuden parantamisessa. Suodatusvastuksen määrittämiseksi prosessi mallinnettiin käyttäen sarja -vastus mallia. Antosyanidien ja flavonolien säilyminen ja konsentroituminen prosesseissa määritettiin. Tulokset osoittivat, että suurin vastus käänteisosmoosissa aiheutui polarisaatiovastuksesta, kun taas kalvon vastus oli pienempi. Mallinnus osoitti myös, että likaantumisen aiheuttama vastus oli yhtä magnitudia alhaisempi kuin muut vastukset. Suodatusteho osoitti, että suurin virtaus saavutettiin ultrasuodatetulla mustaherukkamehulla. Ultrasuodatetussa mehussa oli kuitenkin huomattavasti vähemmän antosyaniineja ja flavonoleja, mikä johtui näiden yhdisteiden tarttumisesta ultrasuodatuskalvoon. Näin ollen, tämän työn tulokset suosittelevat ultrasuodatuksen korvaamista sentrifugoinnilla mehun kirkastusprosessissa. Mustaherukkamehun tuotannossa muodostuu sivutuotteena ns. puristekakkua, joka sisältää runsaasti antosyaaneja. Työssä kehitettiin antosyaanien talteenottoa tästä sivutuotteesta vertaamalla tavanomaista uuttotekniikkaa mikroaaltoavusteiseen uuttoon. Prosessi optimoitiin vastepintamenetelmällä mahdollisimman suuren antosyaanien uuttotehokkuuden saavuttamiseksi. Optimaaliset parametrit saatiin mikroaaltoavusteisessa uutossa teholla 700 W, uuttoajalla 10 minuuttia, kiintoaines-liuotin -suhteella 0,05 pH-arvossa 2, mikä saavutettiin lisäämällä suolahappoa. Tavanomaisessa uutossa parhaat antosyaanisaannot saavutettiin suolahappo-vesiliuoksella pH-arvossa 2 uuttamalla 300 minuuttia lämpötilassa 80 °C. Antosyaanisaanto oli kuitenkin tavanomaisessa uutossa optimiolosuhteissa 10% pienempi kuin mikroaaltoavusteisessa uutossa 10 minuutin uuttoajalla

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Aziz, Azlina Abdul. "Investigations of the absorption and metabolism of antioxidant flavonols." Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392950.

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Pourcel, Lucille. "Identification du gène TT10 codant une laccase : caractérisation de sa fonction dans l'oxydation des flavonoïdes de la graine chez Arabidopsis thaliana." Paris 11, 2006. http://www.theses.fr/2006PA112282.

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Deux classes de flavonoïdes sont présents dans les graines d’Arabidopsis thaliana : les procyanidines (PAs) ou tannins condensés résultant de la condensation de sous-unités flavane-3-ols (épicatéchines) et les flavonols. Ces composés phénoliques jouent un rôle important dans la qualité des semences et en santé humaine, en particulier de par leurs propriétés antioxydantes et antimicrobiennes. Bien que les étapes de la biosynthèse des flavonoïdes soient bien caractérisées, les mécanismes de polymérisation, oxydation et compartimentation des PAs restent inconnues. Chez Arabidopsis, le brunissement des téguments de la graine résulte de l’oxydation des flavonoïdes au cours de la maturation. Ce brunissement est retardé chez le mutant tt10, par comparaison avec les graines de type sauvage. Des expériences réalisées in vivo ont montré que TT10 pouvait intervenir dans le brunissement des téguments en présence d’épicatéchine exogène. Les produits d’oxydation obtenus correspondent à des dimères jaunes appelés déhydrodiépicatéchine A, qui diffèrent des PAs par leur liaisons interflavaniques. Les graines tt10 accumulent également plus de monomères de quercétine-rhamnoside et moins de dimères de flavonols que celles du type sauvage. Le gène TT10 a été identifié par une approche gène-candidat. Il code une polyphénol oxydase de type laccase. TT10 est essentiellement exprimé dans les graines en développement. L’activité du promoteur, l’ARNm et la protéine sont détectés dans les téguments, où ils colocalisent avec les cellules accumulatrices de PAs et de flavonols. L’ensemble de ces résultats met en évidence une activité de la laccase TT10 dans l’oxydation des flavonoïdes. Des études ultérieures concernant la régulation spatio-temporelle de l’expression du gène, ainsi que la localisation subcellulaire de la protéine et son activité in vitro seront nécessaires pour comprendre les mécanismes d’interaction entre les flavonoïdes et TT10, ainsi que le rôle physiologique de l’enzyme dans la graine
The two major end-products of the flavonoid pathway present in Arabidopsis seeds are procyanidins (PAs; syn. Condensed tannins) and flavonols. These polyphenolic compounds have an important impact on agronomic and nutritional qualities of seeds. Whereas most biochemical steps of the flavonoid pathway are characterised, the mechanisms of PA polymerisation, oxidative browning and compartmentation remain to be elucidated. In Arabidopsis, seed coat browning is caused by the oxidation of PAs, which are polymers of flavan-3-ols subunits such as epicatechin. The tt10 mutant exhibits a delay in developmentally-determined browning of the seed coat. The tt10 seeds accumulate more soluble PAs than wild-type seeds. Moreover, in vivo studies using the mutant suggest that in seed-coat cells, TT10 is involved in browning activity in the presence of epicatechin, and that the major oxidation products are yellow dimers called dehydrodiepicatechin A. These products differ from PAs in the nature and position of their interflavan linkages. Flavonol composition was also affected in tt10 seeds, which exhibited a higher ratio of quercetin-rhamnoside monomers vs. Dimers, compared to the wild type. We identified the TT10 gene by a candidate-gene approach. TT10 encodes a protein with strong similarity to laccase-like polyphenol oxidases. We showed that TT10 is essentially expressed in developing seeds. TT10 promoter activity, mRNA and protein were detected in developing testa, where they co-localize with PAs and flavonols. Together, these data establish that the TT10 laccase-like protein is involved in flavonoid oxidation. Further investigations of the TT10 gene spatio-temporal regulation as well as protein subcellular localization and enzymatic activity will be necessary to understand how it interacts with the flavonoids substrates, and thus what is its physiological role in seeds

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Sanver, Didem. "Experimental modelling of flavonoid membrane interactions." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/17383/.

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Flavonoids, a class of polyphenols, are commonly found in fruits, vegetables, nuts, and grains. Increasing evidence from epidemiological and clinical studies show a relationship between high flavonoid consumption in diet and reduced risk of several chronic diseases. Several mechanisms, including specific binding of flavonoids to proteins, have been proposed for flavonoids to exert their biological activities. However, it has also been reported that nonspecific interactions of flavonoids with phospholipids can induce structural changes in the membrane’s features (e.g., thickness and fluctuations) and indirectly modulate membrane proteins, as well as influence their pharmacological potentials. This thesis investigates the interactions between flavonoids and model biomembranes through three distinctively different but complementary approaches, with a special emphasis on employing monolayer membrane model in proof of concept experiments using one lipid type; 1,2 dioleoyl-sn-glycero-3-phosphocholine (DOPC). Hence, a well characterised electrochemical sensor system; phospholipid monolayer coated mercury (Hg) film electrode was established by rapid cyclic voltammetry (RCV) to screen structure-dependent interactions of a variety of flavonoids. The data revealed that flavonoids adopting a planar configuration altered the membrane properties more significantly than nonplanar flavonoids. The extent of interactions can be ranked in the order of quercetin > kaempferol > naringenin > hesperetin > catechin for flavonoid aglycones and tiliroside > rutin > naringin for flavonoid glycosides. Quercetin, rutin, and tiliroside were selected for follow-up experiments with Langmuir monolayers, Brewster angle microscopy (BAM), and small-angle X-ray scattering (SAXS). Relaxation phenomena in DOPC monolayers and visualisation of the surface with BAM revealed a pronounced monolayer stabilisation effect with both quercetin and tiliroside, whereas rutin disrupted the monolayer structure rendering the surface entirely smooth. The following ranking of the interactions: quercetin>tiliroside>rutin, yielded comparable results to those obtained from the previous technique. SAXS showed a monotonous membrane thinning for all flavonoids studied associated with an increase in the mean fluctuations of the membrane. The extent of interactions was concentration and temperature dependent with an order of quercetin>tiliroside>rutin except for tiliroside where a high concentration of tiliroside (>2 mol%) revealed the most pronounced response. In addition to the novelty of employing phospholipid monolayers for the systematic characterisation of a variety of flavonoids, this is the first report investigating the effect of tiliroside with biomimetic membrane models. All the flavonoids studied are believed to be localised in the lipid/water interface region. Both this location and the membrane perturbations might have implications for the therapeutic features of flavonoids.

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Lemare, Rimlinger Nathalie. "Mise en évidence de synergies flavones-flavonols dans l'activité antivirale de la propolis." Rennes 1, 1995. http://www.theses.fr/1995REN1P022.

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Makris, Dimitrios. "Non-enzymic and enzymic degradation of flavonols in model systems." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246805.

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Barrington, Robert David. "The role of efflux transporters in the bioavailability of flavonols." Thesis, University of East Anglia, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445524.

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Anderson, Stacey N. "Carbon Monoxide on Demand: Light-Induced CO Release of Flavonols." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7388.

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Carbon monoxide (CO) is an extremely useful molecule with applications in industrial manufacturing, synthetic procedures as a C1 building block, and as a potential pharmaceutical to produce anti-inflammatory effects and vasodilation. However, the toxicity associated with CO has prevented its full utilization. In order to safely handle CO, compounds and molecules have been developed that act as storage materials for the gas. Ideal storage platforms only release CO upon stimulation via a trigger. Light activation is the most desirable trigger as it can be regulated in terms of the intensity and the wavelength of light used. The majority of light-induced CO-storage platforms that have been reported to date consist of metal carbonyl compounds where CO is bound directly to a metal center. However, disadvantages inherent to this motif, such as potential toxicity associated with the metal and lack of characterization of CO release remnant(s), has pushed the research community to search for alternative CO storage structures. The research presented in this dissertation outlines our approach toward the development of safe-to-handle, light-induced CO release platforms. We use a flavonol structure similar to those found in fruits and vegetables, such as quercetin, as a light-induced CO release unit. Through changes in the structure of the flavonol and its surrounding environment in chemical compounds, we have found ways to strategically control the light-induced CO release reactivity of the flavonol. Chemical compounds developed in this project are of interest for studying the effects of CO in biological systems and applications in synthetic processes.

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Alkhalidy, Hana Awwad. "Flavonol kaempferol in the regulation of glucose homeostasis in diabetes." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/82485.

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Diabetes mellitus is a major public health concern. Although the accessible novel drugs, techniques, and surgical intervention has improved the survival rate of individuals with diabetes, the prevalence of diabetes is still rising. Type 2 diabetes (T2D) is a result of chronic insulin resistance (IR) and loss of β-cell mass and function. Therefore, the search for naturally occurring, low-cost, and safe compounds that could enhance insulin sensitivity and protect functional β-cell mass can be an effective strategy to prevent this disease. Kaempferol, a flavonol present in various medicinal herbs and edible plants, has been shown to elicit various pharmacological activities in preclinical studies. However, studies investigating the effect of kaempferol on diabetes are limited. In this dissertation, I explored the anti-diabetic potential of dietary intake of kaempferol in diet-induced obese mice and insulin-deficient diabetic mice. First, kaempferol was supplemented in the diet to determine whether it can prevent IR and hyperglycemia in high fat (HF) diet-induced obese mice or STZ-induced obese diabetic mice. To evaluate its efficacy for treating diabetes, kaempferol was administrated once daily via oral gavage to diet-induced obese and insulin-resistant mice or lean STZ-induced diabetic mice. The results demonstrated that long-term oral administration of kaempferol prevents HFD-induced metabolic disorders in middle-aged obese mice. Oral administration of kaempferol improved glucose intolerance and insulin sensitivity, and this effect was associated with increased Glut4 and AMPKa expression in muscle and adipose tissues. Consistent with our findings from the in iii vitro study in C2C12 muscle cell line, these findings suggest that kaempferol may reduce IR at the molecular level by improving glucose metabolism in peripheral tissues. In the second study, dietary kaempferol supplementation prevented hyperglycemia and glucose intolerance by protecting β-cell against the induced damage in obese STZ-induced diabetic mice. In the third study, the administration of kaempferol by oral gavage significantly ameliorated hyperglycemia and glucose intolerance and reduced the incidence of diabetes from 100 % to 77.8% in lean STZinduced diabetic mice. This kaempferol effect was associated with reduced hepatic glucose production, the primary contributor to hyperglycemia, and increased glucose oxidation in the muscle of diabetic mice. Kaempferol treatment restored hexokinase activity in the liver and skeletal muscle and reduced pyruvate carboxylase (PC) activity and glycogenolysis in the liver. Unlike its effect on T2D mice, kaempferol effect in lean STZ-induced diabetic mice was not associated with changes in plasma insulin levels. In the last study, we found that administration of kaempferol by oral gavage significantly improved blood glucose control by suppressing hepatic glucose production and improving glucose intolerance in obese insulin-resistant mice. Similar to its effect in old obese mice, kaempferol enhanced whole-body insulin sensitivity. Kaempferol increased Akt and hexokinase activity and decreased PC activity in the liver. However, kaempferol did not exert any changes in glucose metabolism or insulin sensitivity when administered to healthy lean mice. Overall, findings from these studies provide new insight into the role of kaempferol in the regulation of glucose homeostasis and suggest that kaempferol may be a naturally occurring anti-diabetic compound by improving insulin sensitivity, improving glucose regulation and metabolism, and preserving functional β-cell mass.
Ph. D.

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Sayre, Casey L. "Contribution of selected flavonoid enantiomers implicated in chronic disease prevention to differential pharmacokinetic and pharmacodynamic behaviour." Canadian Society for Pharmaceutical Sciences, 2013. http://hdl.handle.net/1993/30075.

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Decreases in risk of chronic disease associated with diets high in fruits and vegetables have been observed. Difficulty in determining the active ingredients responsible for the beneficial effects of dietary plant intake comes in part from the lack of pre-clinical pharmaceutical characterization of compounds thought to play a role. Flavonoids are a class of low molecular weight secondary metabolites present in plants. Pinocembrin, pinostrobin, and liquiritigenin are three chiral flavonoid implicated in the chronic disease prevention seen in high plant diets. To further the pre-clinical development of novel compounds for the potential prevention of chronic disease, stereospecific analytical methods of detection and quantification were developed for pinocembrin, pinostrobin, and liquiritigenin in biological matrices. These methods were used to elucidate the enantiospecific pharmacokinetics of all three compounds in the rat. Additionally, pinocembrin, pinostrobin, and liquiritigenin enantiomers were quantified in multiple marketed natural health products and dietary supplements. Finally, the compounds were screened for activity in several in vitro pharmacodynamic assays with roles in chronic disease pathology to assess for potential stereopecific pharmacologic behaviour. The methods were successfully used to determine the stereospecific pharmacokinetics, pharmacodynamics, and content analysis of selected marketed products. Stereopecific differences were observed in several instances. Further stereospecific studies are needed, especially in the field of toxicokinetics.

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Cornish, Kelly Marie. "Dietary flavonoid quercetin in relation to cataract." Thesis, University of East Anglia, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247104.

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22

Day, Andrea Jill. "Uptake and metabolism of dietary flavonoid glycosides." Thesis, University of East Anglia, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327589.

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23

Caldwell, Stuart Thomas. "The synthesis of isotopically labelled flavonoid glucosides." Thesis, University of Glasgow, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250932.

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24

Dana, Christopher David. "Structural Characterization of the Flavonoid Enzyme Complex." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/28356.

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Flavonoid biosynthesis is an important secondary metabolic pathway in higher plants with a range of vital functions in plants and animals. This pathway has been developed as a model system for the study of multi-enzyme complexes. The goal of the work presented here was to structurally characterize a series of loss-of-function chalcone synthase (CHS) alleles and to define the molecular basis of the interaction between CHS and the second enzyme of flavonoid biosynthesis, chalcone isomerase (CHI). CHS proteins encoded by five previously characterized alleles were characterized by homology modeling in an effort to explain the alterations in function, stability, and dimerization exhibited by these variants. Four of the encoded proteins have a single amino acid substitution and the fifth is a truncated protein resulting from a frameshift. Models for each of these proteins were generated in silico and analyzed after molecular dynamics simulations. This analysis suggested reasons for changes in catalytic ability and stability for three of the five CHS variants. To characterize the molecular basis of the CHS-CHI interaction, a model was developed using X-ray crystallography, small-angle neutron scattering (SANS), in silico docking, molecular dynamics simulations, and yeast 2-hybrid analyses. These enzymes appear to be interacting in a manner that could facilitate the flow of intermediates from one active site to another. These experiments also identified a series of amino acids that appear to be involved in the interaction, which are currently undergoing alteration and analysis using a yeast 2-hybrid assay to verify the authenticity of the model. The data presented herein could be used in future engineering experiments to alter pathway flux to control the levels or types of flavonoid endproducts, resulting in more nutritious plants or flowers with novel pigments. These experiments advance the study of the structure of multi-enzyme complexes, an area that currently contains little information. As well, this is the first known use of SANS for the investigation of the architecture of metabolons. The techniques described herein could easily be applied to other systems in an effort to better understand the organization of multi-enzyme complexes and the implications of these assemblies on metabolic regulation.
Ph. D.

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Malbert, Yannick. "Flavonoid glucodiversification with engineered sucrose-active enzymes." Thesis, Toulouse, INSA, 2014. http://www.theses.fr/2014ISAT0038/document.

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Les flavonoïdes glycosylés sont des métabolites secondaires d’origine végétale, qui présentent de nombreuses propriétés physico-chimiques et biologiques intéressantes pour des applications industrielles. La glycosylation accroît généralement la solubilité de ces flavonoïdes mais leurs faibles niveaux de production dans les plantes limitent leur disponibilité. Ces travaux de thèse portent donc sur le développement de nouvelles voies de gluco-diversification des flavonoïdes naturels, en mettant à profit l’ingénierie des protéines. Deux transglucosylases recombinantes, structurellement et biochimiquement caractérisées, l'amylosaccharase de Neisseria polysaccharea et la glucane-saccharase de branchement α-(1→2), forme tronquée de la dextran-saccharase de L. Mesenteroides NRRL B-1299, ont été sélectionnées pour la biosynthèse de nouveaux flavonoïdes, possédant des motifs originaux d’α-glycosylation, et potentiellement une solubilité accrue dans l'eau. Dans un premier temps, une librairie de petite taille de mutants de l’amylosaccharase, ciblée sur le site de liaison à l’accepteur, à été criblée en présence de saccharose (donneur d’unité glycosyl) et de lutéoline comme accepteur. Une méthode de screening a donc été développée, et a permis d’isoler des mutants améliorés pour la synthèse de nouveaux glucosides de lutéoline, jusqu’à 17000 fois plus soluble dans l’eau que la lutéoline aglycon. Afin de glucosyler d’autres flavonoïdes, la glucane-saccharase de branchement α-(1→2), a été préférentiellement sélectionnée. Des plans expérimentaux alliés à une méthodologie en surface de réponse ont été réalisés pour optimiser la production de l’enzyme sous forme soluble et éviter la formation de corps d’inclusion. Cinq paramètres ont été ainsi analysés : le temps de culture, la température, et les concentrations en glycérol, lactose (inducteur) et glucose (répresseur). En appliquant les conditions optimales prédites, 5740 U.L-1 de culture d’enzyme soluble ont été produites en microplaques, alors qu’aucune activité n’était retrouvée dans la fraction soluble, lors de l’utilisation de la méthode de production précédemment utilisée. Finalement, Une approche de modélisation moléculaire, structurellement guidés par l’arrimage de flavonoïdes monoglucosylés dans le site actif de l’enzyme, a permis d’identifier des cibles de mutagenèse et de générer des libraries de quelques milliers de variants. Une méthode rapide de criblage sur milieu solide, basée sur la visualisation colorimétrique d’un changement de pH, a été mise au point. Les mutants encore actifs sur saccharose ont été sélectionnés puis analysés sur leur capacités à glucosyler la quercétine et la diosmétine. Une petite série de 23 mutants a ainsi été retenue comme plate-forme d’enzymes améliorées dédiées à la glucosylation de flavonoïdes et a été évalués pour la glycosylation de six flavonoïdes distincts. La promiscuité, remarquablement générée dans cette plateforme, à permis d’isoler quelques mutants beaucoup plus efficaces que l’enzyme sauvage, produisant des motifs de glucosylation différents et fournissant des informations intéressante pour le design et l’amélioration des outils enzymatiques de glucosylation des flavonoïdes
Flavonoid glycosides are natural plant secondary metabolites exhibiting many physicochemical and biological properties. Glycosylation usually improves flavonoid solubility but access to flavonoid glycosides is limited by their low production levels in plants. In this thesis work, the focus was placed on the development of new glucodiversification routes of natural flavonoids by taking advantage of protein engineering. Two biochemically and structurally characterized recombinant transglucosylases, the amylosucrase from Neisseria polysaccharea and the α-(1→2) branching sucrase, a truncated form of the dextransucrase from L. Mesenteroides NRRL B-1299, were selected to attempt glucosylation of different flavonoids, synthesize new α-glucoside derivatives with original patterns of glucosylation and hopefully improved their water-solubility. First, a small-size library of amylosucrase variants showing mutations in their acceptor binding site was screened in the presence of sucrose (glucosyl donor) and luteolin acceptor. A screening procedure was developed. It allowed isolating several mutants improved for luteolin glucosylation and synthesizing of novel luteolin glucosides, which exhibited up to a 17,000-fold increase of solubility in water. To attempt glucosylation of other types of flavonoids, the α-(1→2) branching sucrase, naturally designed for acceptor reaction, was preferred. Experimental design and Response Surface Methodology were first used to optimize the production of soluble enzyme and avoid inclusion body formation. Five parameters were included in the design: culture duration, temperature and concentrations of glycerol, lactose inducer and glucose repressor. Using the predicted optimal conditions, 5740 U. L-1of culture of soluble enzyme were obtained in microtiter plates, while no activity was obtained in the soluble fraction when using the previously reported method of production. A structurally-guided approach, based on flavonoids monoglucosides docking in the enzyme active site, was then applied to identify mutagenesis targets and generate libraries of several thousand variants. They were screened using a rapid pH-based screening assay, implemented for this purpose. This allowed sorting out mutants still active on sucrose that were subsequently assayed for both quercetin and diosmetin glucosylation. A small set of 23 variants, constituting a platform of enzymes improved for the glucosylation of these two flavonoids was retained and evaluated for the glucosylation of a six distinct flavonoids. Remarkably, the promiscuity generated in this platform allowed isolating several variants much more efficient than the wild-type enzyme. They produced different glucosylation patterns, and provided valuable information to further design and improve flavonoid glucosylation enzymatic tools

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26

Powell, Christopher. "The polyphenolic pigments of black tea." Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/843227/.

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The polyphenolic pigments of black tea include the theaflavins (TF), the flavonol glycosides (FG) and a group of uncharacterised brown pigments referred to as thearubigins (TR). The TR are shown to be a complex, heterogeneous group of compounds, the majority of which are unresolvable by reverse phase HPLC. Fractionation procedures have been modified, developed, combined and applied to black tea liquor, to improve the separation of black tea components and to allow fractions of less complexity be obtained. A degree of resolution has been achieved for TR fractions, unresolvable with reverse phase HPLC, using size exclusion HPLC. Calibration of the column suggested there may be little material above 2,000 daltons associated with the TR. Two heterogeneous TR fractions have been subjected to Porter's autoxidative assay for proanthocyanidins. The resulting solutions were analysed by reverse phase HPLC and shown to contain proanthocyanidins (9.4 and 16.1 %) and galloyl ester (7.1 and 7.4 %), some 73 and 84 % remains uncharacterised. A novel group of yellow pigments has been isolated for which the name theacitrins (TC) has been proposed. Data are presented that suggest the TC are possibly derived from the TF by oxidative opening of the dihydroxybenzene ring associated with the benztropolone structure. The contribution of the phenolic pigments to tea cream was investigated using reversed phase HPLC and found to be ? 86 % TR, 12 % TF and 2 % FG. Evidence is also presented for a synergistic interaction between TF and TR during cream formation. A method has been developed, using caffeine precipitation, for the isolation of TR material that is free from TF and FG Tea pigments have been stored in aqueous solutions to evaluate their potential for use as commercial colourants. The TF and TC were found to possess poor stability. The FG exhibited greater stability but possess low tinctoral power and poor water solubility. Many of the stability trials exhibited a darkening of colour associated with an increase in unresolvable TR material. Storage of an aqueous solution of a TF enriched fraction at 37 °C resulted in the production of unresolvable (TR-like) material. This material was found to possess molecular weights in excess of 2,000, indicating polymerisation. Evidence is presented to suggest the involvement of galloyl groups in the formation of non-hydrolysable bonds within this polymeric material.

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Khaja, Sara. "Site-Directed Mutagenesis in Citrus paradisi Flavonol-Specific 3-O-Glucosyltransferase." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etd/2453.

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Flavonoids are plant secondary metabolites that have significant biochemical and physiological roles. Biosynthesis of these compounds involves several modifications, most predominantly glucosylation, which is catalyzed by glucosyltransferases (GTs). A signature amino acid sequence, the PSPG box, is used to identify putative clones and has been shown to be involved in UDP-glucose binding. Site-directed mutagenesis is used to answer questions regarding the structure and function of this family of enzymes, particularly what allows some GTs to be more selective towards some substrates than others. The grapefruit (Citrus paradisi) flavonol-3-O-glucosyltransferase (CpF3GT) is specific for flavonol substrates and will not glucosylate anthocyanidins. Comparison of the CpF3GT sequence with that of Vitis vinifera GT, which glucosylates both flavonols and anthocyanidins, provided the basis for the amino acid substitution of proline 145, alanine 374, and alanine 375 in CpF3GT to threonine, aspartate, and glycine, respectively, to test the affect on GT’s affinity for flavonoid substrates.

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Esquer, Heredia Hector Jose. "Toxicity and Mitochondrial Delivery of Flavonol-Based Carbon Monoxide-Releasing Molecules." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6882.

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Despite the reputation of carbon monoxide (CO) as a silent killer, new evidence suggests that this gaseous molecule has anti-inflammatory, anti-cancer and vasoprotective properties. Unfortunately, little is known about the role of CO in the body. However, proteins present in mitochondria are believed to be important targets. We previously synthesized a class of novel and structurally modifiable flavonol-based CO-releasing molecules (CORMs). Flavonols are commonly found in fruits and vegetables. The base structure, Flav-1, is fluorescent, exhibits low toxicity, and releases CO after exposure to visible light. Previous reports indicate that addition of a triphenylphosphonium (TPP) tail allows chemical structures to enter mitochondria. We hypothesized that addition of a TPP tail of two or eight carbons in length to Flav-1 (Mito-Flav-C2 or -C8) would facilitate targeting of mitochondria, and thus, localized light-induced CO release. Toxicity of these TPP-tailed molecules was determined in human umbilical vein endothelial cells (HUVECs) and lung epithelial carcinoma cells (A549), using standard cell viability assays. Evaluation of toxicity using the MTT assay revealed lower toxicity of Flav-1 in HUVECs compared to A549 cells, but addition of the TPP tails increased toxicity in both cell lines. However, unlike the MTT assay, Flav-1 with and without tails had similar toxicity when measured in HUVECs by the lactate dehydrogenase assay. Photo-degradation experiments were performed by exposing cells until their light emission was undetectable by using lasers in the near-UV and within the visible light spectrum. Localization of the compounds was observed using a confocal microscope by co-staining with MitoTracker Red (MTR) and Hoechst to visualize the mitochondria and nucleus, respectively. Fluorescence microscopy images of cells treated with Mito-Flav-C2 or -C8 revealed an increase in uptake, compared to Flav-1, plus co-localization with MTR, which suggests mitochondrial localization. A549 cells exposed to laser light or a full spectrum of light lost all fluorescence of Mito-Flav-C2, which indicates CO release. This work highlights the successful synthesis of the first mitochondria targeting CORMs, and that CO release is achievable using different light sources. Moreover, these TPP-tailed CORMs will allow for controlled and localized release of CO to further study its physiological targets.

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Heigl, Dietmar. "Untersuchungen zur Stabilität von flavonoid- und gerbstoffhaltigen Drogen." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968310184.

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30

Fink, Brian N. Gammon Marilie D. "Flavonoid intake and breast cancer incidence and survival." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,1280.

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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2006.
Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Epidemiology, School of Public Health." Discipline: Epidemiology; Department/School: Public Health.

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Fourie, Petrus Michiel. "Neuroprotective effects of amantadine–flavonoid conjugates / Fourie P.M." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7339.

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Neurodegenerative disorders like Parkinson’s and Alzheimer’s disease affect millions of people around the world. Oxidative stress has been implicated in the pathogenesis of a number of neurodegenerative disorders, cancer and ischemia. The brain is particularly vulnerable to oxidative damage because of its high utilisation of oxygen, high levels of polyunsaturated fatty acids, relatively high levels of redox transition metal ions and low levels of antioxidants. Oxidative stress occurs due to an imbalance in the pro–oxidant and antioxidant levels. Reactive oxygen/nitrogen species (ROS/RNS) is a collective term used for free radicals and related molecules, promoting oxidative stress within cells and ultimately leading to neurodegeneration. Antioxidants counteract the excess in ROS/RNS, and is therefore of interest in the treatment and prevention of neurodegenerative disorders. Monoamine oxidases, especially monoamine oxidase B (MAO–B), also play an important role in neurodegenerative disorders. MAO–B is the main enzyme responsible for the oxidative deamination of dopamine in the substantia nigra of the brain. By inhibiting MAO–B, dopamine is increased in the brain providing symptomatic relief in Parkinson’s disease. The focus of the current study was to synthesise multifunctional compounds that could be used in the treatment and/or prevention of neurodegenerative diseases. In this study flavonoids were selected because of their wide spectrum of biological activities, including antioxidant activity and its monoamine oxidase inhibition. Flavones and chalcones are both classified under flavonoids and both structures were included. The amantadine moiety was included because of its known ability to inhibit calcium flux through the N–methyl–D–aspartate (NMDA) receptor channel. Six amantadine–flavonoid derivatives were synthesised using standard laboratory procedures and structures were determined with standard methods such as NMR, IR and mass spectrometry. The synthesised compounds were tested in a selection of biological assays, to establish the relative antioxidant properties and MAO inhibitory activity. The biological assays employed to test antioxidant properties were the thiobarbituric acid (TBA) and nitro–blue tetrazolium (NBT) assays. The TBA assay relies on the assessment of lipid peroxidation, induced via hydroxyl anions (OH), generating a pink colour with the complex formation between malondialdehyde (MDA) and TBA, which is measured spectrophotometrically at 532 nm. The principal of the NBT assay is the reduction of NBT to nitro–blue diformazan (NBD), producing a purple colour in the presence of superoxide anions (O2 –). The synthesised compounds were also evaluated for their MAO inhibitory activity toward recombinant human MAO–A and -B and inhibition values were expressed as IC50 values. The experimental data obtained in the NBT and TBA assay indicated a weak but a significant ability to scavenge O2 – and OH. In the NBT assay N–(adamantan–1–yl)–2–{3–hydroxy–4–[(2E)– 3–(3–methoxyphenyl)pro–2–enoyl]phenoxy}acetamide (6) had the best results with a 50.47 ± 1.31 uM/mg protein reduction in NBD formation, indicating that the hydroxyl group contributed to activity. The synthesised compounds were compared to the toxin (KCN) with a reduction in NDB formation of 69.88 ± 1.59 uM/mg protein. Results obtained from the TBA assay indicated that the flavone moiety had better OH scavenging ability than that of the chalcone moiety with N–(adamantan–1–yl)–2–[(5–hydroxy–4–oxo–2–phenyl–4H–chromen–7– yl)oxy]acetamide (3) showing the best activity at 0.967 ± 0.063 nmol MDA/mg tissue. The synthesised compounds were compared to the toxin (H2O2) 1.316 ± 0.028 nmol MDA/mg tissue. None of the test compounds could be compared to the results obtained with Trolox®. The IC50 values obtained for inhibition of recombinant human MAO indicated that the chalcone moiety (N–(adamantan–1–yl)–4–[(1E)–3–oxo–3–phenylpro–1–en–1–yl]benzamide (5)) showed the best inhibition of MAO–B with an IC50 of 0.717 ± 0.009 M and of MAO–A with an IC50 of 24.987 ± 5.988 M. It was further confirmed that N–(adamantan–1–yl)–4–[(1E)–3–oxo–3– phenylpro–1–en–1–yl]benzamide (5) binds reversible to MAO–B and that the mode of inhibition is competitive. Docking studies revealed that N–(adamantan–1–yl)–4–[(1E)–3–oxo–3–phenylpro– 1–en–1–yl]benzamide (5) traverses both cavities of MAO–B with the chalcone moiety orientated towards the FAD co–factor while the amantadine moiety protrudes into the entrance cavity.
Thesis (M.Sc. (Pharmaceutical Chemistry))--North-West University, Potchefstroom Campus, 2012.

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Burbulis, Ian E. "Macromolecular organization of flavonoid biosynthesis in Arabidopsis thaliana." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/26023.

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Living cells manufacture and degrade thousands of chemical compounds in vivo. To do this cells rely on the activities of thousands of different protein catalysts distributed in aqueous interior compartments. Over the past several decades studies have shown that the thermodynamic and kinetic properties of most proteins, including enzymes, are different in vivo as compared to in vitro. Based on in vitro studies metabolic pathways have traditionally been thought to consist of intermediates randomly diffusing between soluble enzymes and are still portrayed as such in many biochemistry textbooks. A large number of metabolic pathways however are now known to exist as enzyme complexes due to molecular crowding effects in vivo. These differences have contributed to the controversy that surrounds explanations of how metabolic pathways are spatially organized and regulated in the living cell. The organization of enzymes in vivo is now thought to play a significant role in normal cellular physiology but evidence of this role, beyond intermediate channeling, is lacking. The long term goal of this work is to develop an experimental model and test the validity of theories concerning the spatial arrangement of enzymes in regulating metabolic pathways. The studies described in this dissertation have been focused on understanding how living cells organize metabolic pathways. I have examined some of the theoretical aspects of enzyme-enzyme interactions by modeling the complex formed by mitochondrial malate dehydrogenase and citrate synthase. These studies show that MDH and CS may bind in a specific orientation that facilitates the direct transfer of oxaloacetate from MDH to CS through a molecular channel. During these studies it was determined that A. thaliana does not encode stilbene synthase (STS), which catalyzes the first step in a pathway that competes with flavonoid biosynthesis in other plant species. Moreover, it was shown that flavonols are not required for pollen viability in A. thaliana as they are in maize and petunia. I also describe a novel method to clone fragments of DNA without ligase using the polymerase chain reaction (PCR). To establish an experimental model I have used a variety of techniques to analyze interactions between enzymes in the well-characterized flavonoid biosynthetic pathway in Arabidopsis thaliana. Evidence is presented that indicates that the first four enzymes in this pathway form a complex. Collectively this work suggests that the structural organization of enzymes into complexes is an important aspect of cellular metabolism and might directly impact the relative levels of specific compounds that are synthesized in vivo.
Ph. D.

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Santos, Michael Carmelo Orda. "Immunomodulation of Flavonoid Biosynthesis in Transgenic Arabidopsis thaliana." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/27349.

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In an effort to test the feasibility of intracellular expression of enzyme-targeted antibodies to alter metabolism, recombinant antibody fragments in the single-chain format (scFv) were isolated from a phage display library using Arabidopsis chalcone isomerase (CHI) of the flavonoid biosynthetic pathway as the antigen. Each of the genes encoding the scFvâ s was cloned into a plant transformation vector, which was subsequently used to generate transgenic plants. One transgenic line with low expression of one of the scFvâ s appeared to have an altered flavonoid metabolism, as evidenced by a reduced capacity for anthocyanin accumulation and a reduction in flavonol glycosides in seedlings. Strong corroborating evidence that implicated the binding of scFv to CHI in the phenotypic alterations was obtained from protein mobility shift assays. Taken together, the results indicate that scFv-mediated metabolic alteration is possible in plants. Thus, we show that intracellular expression of scFvâ s can be exploited as an additional tool for metabolic engineering.
Ph. D.

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34

Liou, Geoffrey. "Enzyme structure, function, and evolution in flavonoid biosynthesis." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122067.

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This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biology, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
Plant specialized metabolism is a key evolutionary adaptation that has enabled plants to migrate from water onto land and subsequently spread throughout terrestrial environments. Flavonoids are one particularly important class of plant specialized metabolites, playing a wide variety of roles in plant physiology including UV protection, pigmentation, and defense against herbivores and pathogens. Flavonoid diversity has increased in conjunction with land plant evolution over the past 470 million years. This dissertation examines the structure, function, and evolution of enzymes in the flavonoid biosynthetic pathway. First, we structurally and biochemically characterized orthologs of chalcone synthase (CHS), the enzyme that catalyzes the first step of flavonoid biosynthesis, from diverse plant lineages. By doing so, we gained insight into the sequence changes that gave rise to increased reactivity of the catalytic cysteine residue in CHS orthologs in euphyllophytes compared to basal land plants. We then developed methods and transgenic plant lines to study the in vivo function of these CHS orthologs, as well as whether their functional differences play a role in redox-based regulation of flavonoid biosynthesis. Finally, we examined enzymes involved in the biosynthesis of galloylated catechins, a highly enriched class of flavonoids in tea that are thought to have health benefits in humans. These findings contribute to an understanding of the evolution of enzyme structure and function in flavonoid biosynthesis, and how it has facilitated the adaptation of plants to a wide variety of terrestrial habitats.
by Geoffrey Liou.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Biology

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Koupai-Abyazani, Mohammed R. "Analytical methods for the identification of biologically active flavonoids." Thesis, University of East Anglia, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280027.

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Sitthiphong, Piyawan. "Impact of flavonoid-rich and flavonoid-poor fruit and vegetables on biomarkers of cancer risk in a human randomized controlled trial." Thesis, University of Reading, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602467.

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Epidemiological studies have shown an association between fruit and vegetable (F&V) consumption and decreased risk of cancer at several sites. However, there are few human intervention studies that provide information about a causal link between F&V consumption and cancer risk and about the optimum amounts of F&V that need to be consumed and whether some types of F&V are more effective than others. This study aims to investigate the impact of increasing intake of flavonoid-rich and flavonoid-poor F&V in human subjects on three endpoints: lymphocyte DNA damage, inflammation markers and gene expression. Blood samples were collected from a randomised, controlled, parallel design study in 80 volunteers divided into three study groups. The participants in the two test groups: high flavonoid F&V (HF) and low flavonoid F&V (LF) were asked to increase F&V intake by 2, 4 and 6 portions/day for duration of 6 weeks each while subjects in the control group (CT) maintained their habitual diet. Increasing F&V intake by 4 and 6 portions/day reduced the endogenous oxidation of DNA bases in the LF group and increasing F&V intake at 6 portions/day enhanced the ability of lymphocytes to resist to exogenously induced ( by H,O,) DNA damage in both test groups. Increasing F&V consumption may reduce chronic inflammation as a consequence of a decrease in the expression of LFA-l in T lymphocytes by HF group at 4 or 6 portions of intake and an increase in the frequency of CCR-9+ on T cells at 6 portions/day when combining HF and LF data. Furthermore, increasing the intake of F&V of either high or low in flavonoids, modulated the expression of gene transcripts involved in cellular defence. In conclusion, increasing of F&V, either HF or LF, can improve cancer risk biomarkers when compared to CT group. However, flavonoid-rich F&V have no additional benefit compared to flavonoid-poor F&V. Moreover, most effects are found at additional amounts of F&V of 6 portions a day.

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Birchfield, Aaron, and Cecelia A. McIntosh. "Crystallization of a Flavonol-Specific 3-O-Glucosyltrasnferase found in Citrus paradisi." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/365.

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Citrus and other fruits produce secondary metabolites that are synthesized, regulated, and modified in part by a class of enzymes called glycosyltransferases. This class of enzymes is of substantial interest to this lab due to their unique structural and functional properties. Glycosides of flavonoids produced by glycosyltransferases have emerged in recent years as a critical part of plant metabolism, thus impacting every aspect of their growth, cultivation, production, and utilization. One such glycosyltransferase, found in Duncan Grapefruits (Citrus paradisi), was previously identified, recombinantly expressed, and shown through biochemical characterization to exclusively glycosylate the flavonol class of flavonoids. The structural basis that accounts for a glycosyltransferase's selectivity has been determined by protein crystallization in other labs, yet no structural basis currently exists for the specificity exhibited by this flavonol-specific glycosyltransferase. Currently, the WT enzyme and two mutants were expressed in E. coli, where they underwent site-directed mutagenesis to insert thrombin cleavage tags for removal of protein purification vectors, with the goal of transforming into yeast for adequate protein production. Subsequent purification and crystallization screens will allow for formation and acquisition of glycosyltransferase crystals, whose x-ray diffraction patterns will be decoded, thus revealing the enzyme's complete structure. We hypothesize that obtaining a crystal structure for this enzyme will illuminate the structural basis of its specificity. Additionally, we hypothesize that a thrombin- cleavage gene vector inserted for removal of purification tags will have no impact on enzyme activity or specificity.

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Devaiah, Shivakumar P., and Cecelia A. McIntosh. "Site-Directed Mutational Analysis of Flavonol 3-0-Glucosyltransferases from Citrus paradisi." Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/340.

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Glucosyltransferases (GTs) are the important group of enzymes which facilitates the incorporation of UDPactivated glucose to a corresponding acceptor molecule through glucosylation. Glucosylation is a common alteration reaction in plant metabolism and is regularly associated with the production of secondary metabolites. Glucosylation serves a number of roles within metabolism including: stabilizing structures, affecting solubility, transport, and regulating the bioavailability of the compounds for other metabolic processes. GTs involved in secondary metabolism share a conserved 44 amino acid residue motif (60–80% identity) known as the plant secondary product glucosyltransferase (PSPG) box, which has been demonstrated to include the UDP-sugar binding moiety. Among the secondary metabolites, flavonoid glycosides affect taste characteristics in citrus making the associated glucosyltransferases particularly interesting targets for biotechnology applications in these species. Custom design of enzymes requires understanding of structure/function of the protein. The present study focuses on creating mutant Flavonol- 3-O- Glucosyltransferases proteins using site-directed mutational analysis and testing the effect of each mutation on substrate specificity and kinetic properties of the enzyme.

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Ghidouche, Souhila. "Produits d’oxydation de flavonols et de flavanols par la laccase de Trametes versicolors." Rennes, Agrocampus Ouest, 2008. http://www.theses.fr/2008NSARB187.

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Les flavonols et les flavan-3ols représentent deux sous classes importantes tant pour les végétaux que pour les humains. Ces propriétés sont toutefois affectées par les phénomènes d’oxydation enzymatique. Les laccases constituent un des principaux groupes d’enzymes impliqués dans ces réactions. Peu d’études se sont intéressées aux mécanismes précis de ces oxydations ainsi qu’aux structures des produits obtenus. Le but de cette étude est de déterminer les structures des produits d'oxydation des flavonols et des flavan-3ols par la lacasse de Trametes versicolor et de comparer leurs mécanismes de formation. Après une première partie bibliographique qui montre clairement les fortes relations entre la structure et l’activité antioxydante des flanoïdes, nous exposons dans la deuxième partie les différents produits d’oxydation obtenus dans un premier temps avec la laccase d’Arabidopsis thaliana et avec la laccase de Trametes versicolor. L’étude de la structure des produits d’oxydation en fonction de la structure du substrat a permis de déterminer le mécanisme de ces réactions d’oxydation et de mettre en avant les spécificités de structure qui déterminent l’issue de la réaction
Flavonols and flavan-3-ols are two important sub-classes of flavonoïds, they are characterized by their biological properties which are important for both humans and plants. However, these properties are affected by the oxidation phenomenon. Laccases are among the enzymes involved in these enzymatic reactions. A few studies have been dedicated to the oxidation mechanisms and to the structures of the reaction products. The present study aims to identify and elucidate the structure of the oxidation products of flavanols and flavan-3-ols by the laccase of Trametes versicolor and compare their formation mechanisms. The first part is a review which clearly shows the strong structure-antioxidant activity relationship of flavonoïds. In the second part, we present the oxidation products generated by Arabidopsis thaliana laccase and Trametes versicolor laccase. The study of the structure of the oxidation products according to the substrate structure allowed the identification of the oxidation mechanisms. It also allowed to put forward that the structure specificities of the substrate affect the reaction’s outcome

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Behm, Norma. "Einfluss des Flavonols Quercetin auf ausgewählte Parameter des Energiestoffwechsels bei fettreich ernährten Ratten." Tönning Lübeck Marburg Der Andere Verl, 2009. http://d-nb.info/997031263/04.

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Jin, Xin. "Isoprenoid and flavonoid biosynthesis and regulation in higher plants." Doctoral thesis, Universitat de Lleida, 2019. http://hdl.handle.net/10803/667579.

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Aquesta tesi es centra principalment en l'anàlisi funcional i la caracterització dels gens que codifiquen per a alguns metabòlits secundaris i en l’estudi de la seva regulació en les plantes. Els objectius generals varen ser (a) entendre millor la regulació transcripcional del gen de la biosíntesi dels carotenoids, la β-carotè hidroxilasa 2 (BCH2) en el blat de moro i (b) l'anàlisi funcional de les dues isopentenil difosfat isomerasas (OsIPPI) d'arròs i determinar la seva localització subcel·lular. Simultàniament, es va estudiar com la llum afecta la via metabòlica i a la producció de pelargonidina en l'arròs; es van identificar també els gens essencials de la seva biosíntesi en Gentiana lutea L. var. aurantiaca. Les plantes de blat de moro i arròs es varen transformar amb els gens dels factors de transcripció ZmMYB i ZmPBF. Es va analitzar l’expressió gènica transitòria i es va realitzar transformació estable. Els resultats obtinguts indiquen que tant ZmPBF com ZmGAMYB poden transactivar l'expressió de ZmBCH2 a l’endosperm del blat de moro, i ZmPBF i ZmGAMYB transactiven independentment el promotor de ZmBCH2 en arròs. Els dos paràlegs de IPPI (OsIPPI1 i OsIPPI2) aïllats prèviament en arròs varen tenir un patró d'expressió diferent; l'ARNm de OsIPPI1 va ser més abundant que l'ARNm de OsIPPI2 en tots els teixits. Es va usar la microscòpia de fluorescència confocal i microscòpia inmunoelectrónica per determinar la localització de les dues proteïnes. Aquestes es localitzen en el reticle endoplasmàtic (RE), així com en els peroxisomes i les mitocòndries, mentre que només es va detectar OsIPPI2 en els plastidis. La detecció d'ambdues isoformes en el RE indica que DMAPP es pot sintetitzar de novo en aquest compartiment. Diferents tècniques com UPLC, GC-MS i qRT-PCR també es varen utilitzar per perfilar els metabòlits primaris i secundaris i l'expressió gènica relacionada en plàntules d'arròs des-etioladas. Els resultats varen revelar que el metabolisme primari i secundari i els gens corresponents estan regulats per la llum, especialment en la biosíntesi d'isoprenoides en fulles d'arròs. Onze derivats de pelargonidina es varen identificar en els pètals de G. lutea i es varen perfilar els gens de la seva via de biosíntesi, revelant que DFR, ANS i 3GT afecten principalment a l'acumulació dels glucòsids de pelargonidina. Tots aquests resultats suggereixen la idea que la biosíntesi dels carotenoids en plantes superiors és regulada a diferents nivells.
Esta tesis se centra principalmente en el análisis funcional y en la caracterización de los genes que codifican para algunos metabolitos secundarios y en el estudio de su regulación en las plantas. Los objetivos generales fueron (a) profundizar en el conocimiento de la regulación transcripcional del gen de la biosíntesis de los carotenoides, la β-caroteno hidroxilasa 2 (BCH2) en el maíz, y (b) analizar la función de las dos isopentenil difosfato isomerasas (OsIPPI) de arroz, determinando además su localización subcelular. Simultáneamente, se estudió cómo la luz afecta a la vía metabólica y a la producción de pelargonidina en el arroz; se identificaron también los genes esenciales de su biosíntesis en Gentiana lutea L. var. aurantiaca. Las plantas de maíz y arroz se transformaron con los genes de los factores de transcripción ZmMYB y ZmPBF. Se analizó la expresión génica transitoria y se realizó transformación estable. Los resultados obtenidos indicaron que tanto ZmPBF como ZmGAMYB pueden transactivar la expresión de ZmBCH2 en endospermo de maíz, y ZmPBF y ZmGAMYB transactivar independientemente el promotor de ZmBCH2 en arroz. Los dos parálogos de IPPI (OsIPPI1 y OsIPPI2) aislados previamente en arroz tuvieron un patrón de expresión diferente; el ARNm de OsIPPI1 fue más abundante que el ARNm de OsIPPI2 en todos los tejidos. Se usó la microscopía de fluorescencia confocal y microscopía inmunoelectrónica para determinar la localización de ambas proteínas. Estas se localizan en el retículo endoplásmico (RE), así como en los peroxisomas y las mitocondrias, mientras que solo se detectó OsIPPI2 en los plastidios. La detección de ambas isoformas en el RE indica que DMAPP se puede sintetizar de novo en este compartimiento. Diferentes técnicas como UPLC, GC-MS y qRT-PCR también se utilizaron para perfilar los metabolitos primarios y secundarios y la expresión génica en plántulas de arroz des-etioladas. Los resultados revelaron que los genes involucrados en la en el metabolismo primario y secundario están regulados por la luz, especialmente en la biosíntesis de isoprenoides en hojas de arroz. Once derivados de pelargonidina se identificaron en los pétalos de G. lutea y se perfilaron los genes de la vía de biosíntesis, revelando que DFR, ANS y 3GT afectan principalmente a la acumulación de los glucósidos de pelargonidina. Todos estos resultados contribuyen al conocimiento, a diferentes niveles, de la regulación de las rutas biosinteticas de los carotenoides en plantas superiores.
This thesis mainly focuses on functional analysis and characterization of a number of secondary metabolite biosynthetic genes and the regulation of the corresponding secondary metabolite biosynthetic pathway in plants. The overall aims were to elucidate the transcriptional regulation of β-carotene hydroxylase 2 gene (BCH2) in maize, the functional analysis of rice isopentenyl diphosphate isomerases (OsIPPI), and determine their subcellular localization. Simultaneously, the influence of light on the metabolic pathway in rice was studied and the pelargonidin quantification and essential pelargonidin biosynthesis genes in Gentiana lutea L. var. aurantiaca were identified. Maize and rice plants were transformed with transcription factor genes ZmMYB and ZmPBF, via transient gene expression and stable transformation respectively. The results indicated that both ZmPBF and ZmGAMYB can transactivate ZmBCH2 expression in maize endosperm and ZmPBF and ZmGAMYB independently transactivate the ZmBCH2 promoter in rice. The two IPPI paralogs (OsIPPI1 and OsIPPI2) isolated previously in rice had a different expression pattern; OsIPPI1 mRNA was more abundant than OsIPPI2 mRNA in all tissues. Confocal fluorescence microscopy and immuno-electron microscopy were used to determine the localization of both proteins. These localized to the endoplasmic reticulum (ER) as well as peroxisomes and mitochondria, whereas only OsIPPI2 was detected in plastids. The detection of both isoforms in the ER indicates that DMAPP can be synthesized de novo in this compartment. UPLC, GC-MS and qRT-PCR were used to profile the primary and secondary metabolites and gene expression in de-etioleted rice seedlings. The results revealed both primary and secondary metabolism and the corresponding genes are regulated by light, especially isoprenoids biosynthesis in rice leaves. Eleven pelargonidin derivatives were identified in the petals of G. lutea and the biosynthetic pathway genes were profiled, revealing DFR, ANS and 3GT mainly affect the accumulation of pelargonidin glucosides. Collectively my results provide novel insights of the regulation of carotenoid and flavonoid biosynthesis in higher plants at different levels.

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Jaakola, L. (Laura). "Flavonoid biosynthesis in bilberry (Vaccinium myrtillus L.)." Doctoral thesis, University of Oulu, 2003. http://urn.fi/urn:isbn:9514271599.

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Abstract Flavonoids are a class of secondary metabolites in plants that are involved in many important functions. Various flavonoid compounds have also been reported to be beneficial for human health. Bilberry (Vaccinium myrtillus L.) is the characteristic field layer species in boreal forests and the fruits of bilberry are rich in anthocyanin pigments, a subclass of flavonoids. In the present work, flavonoid biosynthesis was examined in different tissues of bilberry. The focus was on the developing fruits of wild type and natural color mutants of bilberry, and on effect of solar radiation on flavonoid biosynthesis in bilberry leaves. For the isolation of RNA for gene expression analysis, a method was optimized for different tissues of bilberry. The cDNA fragments of five genes from the flavonoid pathway, coding phenylalanine ammonia-lyase, chalcone synthase, flavanone 3-hydroxylase, dihydroflavanol 4-reductase and anthocyanidin synthase, were isolated from bilberry using polymerase chain reaction technique, sequenced, and labelled with dioxigenin-dUTP label. These homologous, bilberry-specific probes were used for determining the expression of the flavonoid pathway genes in bilberry fruits, flowers and leaves with a modified non-radioactive method developed in the course of the study. The anthocyanins, catechins, proanthocyanidins, flavonols and hydroxycinnamic acids in fruits, leaves and different fractions of bilberry were identified and quantified with high-performance liquid chromatography combined with a diode array detector and mass spectrometer. The results demonstrate a correlation between anthocyanin accumulation and expression of the flavonoid pathway genes during the ripening of berries. A correlation between flavonol and anthocyanin biosynthesis was detected in bilberry and also in previous literature collected from flavonol and anthocyanin analyses from other fruits. Accordingly, models for the connection between flavonol and anthocyanin synthesis in fruit species were suggested. Activation of the expression of flavonoid pathway genes and accumulation of flavonoids and hydroxycinnamic acids was detected in leaves growing under direct solar radiation, compared to the shadow leaves of the same plants. Based on the results, it is suggested that cyanidin of anthocyanins and flavonol quercetin play a predominant role in the defence against high solar radiation in Vaccinium leaves. The results give new information about the biosynthesis of flavonoids in bilberry at the gene level, in addition to the information of the composition and content of flavonoids during fruit development and in different parts of the bilberry plant. Also, new information was obtained of the roles of flavonoids in protecting plants from excess solar radiation.

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Wong, Chi Chun. "Metabolism and transport of flavonoid and hydroxycinnamic acid conjugates." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.545723.

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44

Schroeter, Hagen. "Oxidative stress and neuronal dysfunction : mechanisms of flavonoid protection." Thesis, King's College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396046.

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45

Pereira, Ana Bárbara Ferreira Neves Quatorze. "Flavonoid-cyclodextrin complexes and their incorporation in milk products." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15325.

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Mestrado em Bioquímica - Bioquímica Alimentar
The presented work describes the inclusion of the flavonoid quercetin into β and γ cyclodextrins and the subsequent incorporation of such complexes into a dairy product — fresh cheese. The characterization of the complexes was made using various techniques, and antioxidant assays were also performed to assess their antioxidant and anti-lipid peroxidation capacity in comparison to quercetin. The incorporation of the complexes in fresh cheese resulted in the modification of some of the characteristics of the food product, having these also presented promising antioxidant capacity.
O trabalho apresentado descreve a inclusão do flavonóide quercetina nas ciclodextrinas β e γ, com posterior incorporação dos complexos em laticínios, nomeadamente queijo fresco. A caracterização dos complexos de inclusão foi feita utilizando várias técnicas, tendo sido também realizados ensaios antioxidantes para avaliar a sua capacidade antioxidante e de anti-peroxidação lipídica, em comparação com a quercetina. A incorporação dos complexos no queijo fresco resultou na modificação de algumas características do produto alimentar, tendo estes complexos também apresentado uma promissora capacidade antioxidante.

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46

Watjen, W., A.-K. Suckow-Schnitker, R. Rohrig, A. Kulawik, Jonathan A. Addae-Kyereme, Colin W. Wright, and C. M. Passreiter. "Prenylated flavonoid derivatives from the bark of Erythrina addisoniae." American Chemical Society, 2008. http://hdl.handle.net/10454/4532.

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no
Two new prenylated flavanones, 2S-3¿-(2-hydroxy-3-methylbut-3-enyl)licoflavone-4¿-methyl ether (3) and 2S-3¿-(2- hydroxy-3-methylbut-3-enyl)abyssinone II (4), and four known flavanones (1, 2, 5, 6) were isolated from the stem bark of Erythrina addisoniae. The structures were elucidated on the basis of their spectroscopic and physicochemical data. None of the compounds showed antioxidative properties. 4¿-Methylabyssinone V (1) and abyssinoflavanone VII (6) showed moderate cytotoxic activity (IC50 ) 5 and 3.5 ¿mol/L, respectively), but apoptosis (caspase-3/7-activation, nuclear fragmentation) was selectively induced by abyssinoflavanone VII (6).

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47

King, Kathleen. "The Effect of R382W Mutation on Citrus paradisi Flavonol Specific 3-O-Glucosyltransferase." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/honors/355.

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Flavonoids are a class of plant metabolites with C6-C3-C6 structure responsible for many biological functions, including coloration and defense. Citrus paradisi, grapefruit, contains a wide variety of flavonoids which are grouped by the extent of modification, examples of which are flavonols, flavones, and flavanones. A major modification is the addition of glucose by glucosyltransferases (GTs) to stabilize the structure and provide ease of transport. Glucosyltransferases can be highly substrate and regiospecific. With Cp3OGT, glucose is added at the 3-hydroxy position. This 3GT only accepts flavonols as its substrate; however, a Vitis vinifera (grape) 3-GT can accept both flavonols and anthocyanidins. Homology modeling using the crystallized structure of the V. vinifera GT predicted sites of amino acids that could influence substrate binding. The 382 position was of particular interest with arginine in C. paradisi and tryptophan in V. vinifera. This research was designed to test the hypothesis that a R382W mutation would result in altered substrate specificity. Site-directed mutagenesis was performed to form the R382W mutant Cp3OGT and the gene was transformed into yeast for protein expression. Western blot determined the optimal protein induction period for the cells, after which the cells were broken to extract the recombinant mutant protein. Purification of the R382W 3GT allowed for enzyme analysis to be performed by measuring the incorporation of radioactive glucose into the reaction product. Docking analysis was performed using AutoDock software with both the wild type and R382W mutant protein with the substrates that showed interesting activity. The results of this study indicate that the point mutation of arginine to tryptophan at position 382 broadened substrate and regiospecificity to include flavanones.

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Carter, Lisa, Devaiah P. Shivakumar, and Cecelia A. McIntosh. "Mutagenesis of a Flavonol- 3-O-Glucosyltransferase and the Effect on Enzyme Function." Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/349.

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Flavonoids are an important group of secondary metabolites found in plants and have a wide variety of properties. Some play a role in fl ower pigmentation, while others have antimicrobial properties. Glucosylation is an important modifi cation of fl avonoids and is mediated by glucosyltransferases. In this process, the enzyme transfers glucose from UDP-glucose to a specifi c position on the fl avonoid. Previous study from the lab characterized a glucosyltransferase from C. paradisi that is fl avonol specifi c. In this study an attempt has been made to study the structure and function of this fl avonol specifi c glucosyltransferase using site directed mutagenesis. The glutamine residue at position 87 of the Cp-3-O-GT enzyme was changed to isoleucine, the analogous residue in the 3-O-glucosyltransferase of Clitoria ternatea. Similarly, the histidine at position 154 was changed to tyrosine. We hypothesize that these mutations will change substrate specifi city. The glutamate at position 88 was changed to an aspartic acid. We hypothesize that this will change the regiospecifi city of the enzyme, as aspartic acid is the analogous residue found in some 7-O-glucosyltransferases. Finally, we introduced a double mutation with glutamine 87 becoming isoleucine and glutamate 88 becoming aspartic acid, with the hypothesis that both regiospecifi city and substrate specifi city will be changed.

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Devaiah, Shivakumar P., and Cecelia A. McIntosh. "Substrate Specificity and Kinetic Properties of Flavonol-3-O-Glucosyltransferase From Citrus Paradisi." Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/342.

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Glucosyltransferases (GTs) are enzymes that expedite the incorporation of UDP-activated glucose to a corresponding acceptor molecule. This enzymatic reaction stabilizes structures and affects solubility, transport, and bioavailability of flavonoids for other metabolic processes. Flavonoid glycosides affect taste characteristics in citrus making the associated glucosyltransferases particularly interesting targets for biotechnology applications. Custom design of enzymes requires understanding of structure/function of the protein. The present study focuses on creating mutant flavonol-3-O-glucosyltransferase (F-3-O-GT) proteins using site directed mutagenesis and testing the effect of each mutation on substrate specificity, regiospecificity and kinetic properties of the enzyme. Mutations were selected on the basis of sequence similarity between grapefruit F-3- O-GT, an uncharacterized GT gene in blood orange (98%), and grape F3GT (82%). Grapefruit F-3-O-GT prefers flavonol as a substrate whereas the blood orange sequence is annotated to be a flavonoid 3GT and the grape GTs could glucosylate both flavonols and anthocyanidins. Mutants of F-3-O-GT were generated by substituting N242K, E296K and N242K+E296K and proteins were expressed in Pichia pastoris using the pPICZA vector. Analysis of these mF-3-O-GTs showed that all of them preferred flavonols over flavanone, flavone, isoflavones, or anthocyanidin substrates and showed decrease in enzyme activity of 16 to 51% relative to the wild type F-3- O-GT.

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50

King, Kathleen, Devaiah P. Shivakumar, and Cecelia A. McIntosh. "The Effect of R382W Mutation on C. paradisi Flavonol-Specific 3-O-Glucosyltransferase." Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/etsu-works/358.

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Flavonoids are a class of plant metabolites with C6-C3-C6 structure responsible for many biological functions, including coloration and defense. Citrus paradisi, grapefruit, contains a wide variety of flavonoids which are grouped by the extent of modification, examples of which are flavonols, flavones, and flavanones. A major modification is the addition of glucose by glucosyltransferases (GTs) to stabilize the structure and provide ease of transport. This process can be highly substrate and regiospecific. With Cp3OGT, glucose is added at the 3-hydroxy position. This 3GT only accepts flavonols as its substrate; however, a Vitis vinifera (grape) 3-GT can accept both flavonols and anthocyanidins. Homology modeling using the crystallized structure of the V. vinifera GT predicted sites of amino acids that could influence substrate binding site. The 382 position was of particular interest with arginine in C. paradisi and tryptophan in V. vinifera. This change is hypothesized to cause a shift in substrate specificity of the Cp3OGT to accept anthocyanidins as well as flavonols. Site-directed mutagenesis was performed to form the R382W mutant Cp3OGT and transformed into yeast for expression. Western blot determined the optimal protein induction period for the cells, after which the cells were broken to extract the recombinant mutant protein. Purification of the R382W 3GT allowed for enzyme analysis to be performed by measuring the incorporation of radioactive glucose into the reaction product. HPLC will be used to identify reaction products. An enzyme kinetics study will show the extent of any biochemical change in function as a result of this mutation; results will then be incorporated into a refined protein model.

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Dissertations / Theses on the topic 'Flavonoli'

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