Dissertations / Theses on the topic 'Xanthophylls'
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Davies, Bethan Wyn. "Xanthophylls as metabolic precursors." Thesis, Aberystwyth University, 1986. http://hdl.handle.net/2160/92d4cd09-9ea7-4e80-9af4-a3aecccd778b.
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Etienne-Leveille, Valerie. "Three studies of natural xanthophylls." FIU Digital Commons, 2003. http://digitalcommons.fiu.edu/etd/3282.
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The purpose of this work was to isolate and study the oxidation of a carotenoid known as lactucaxanthin; to determine the dose vs. serum response of human subjects in a supplementation study of lutein, zeaxanthin, and meso-zeaxanthin; and to initiate an investigation of lutein in larval monarch butterflies.
Our interest in lactucaxanthin arises because of its close structural homology to a keto carotenoid in human blood. The isolation of lactucaxanthin from Romaine Lettuce was accomplished by use of the reversed-phase HPLC. Preliminary results from the oxidation of lactucaxanthin using MnO2 show that two products are formed.
Human subjects participated in supplementation studies of lutein and mesozeaxanthin. The effects of three daily dosages (5 mg, 10 mg, and 20 mg) of lutein on serum lutein concentrations were investigated to determine the magnitude of the serum response
The concentration of lutein in larval monarch butterflies was investigated. These caterpillars have stripes of three distinct colors: black, white, and yellow. The striped sections of the skin were separated by color, extracted and analyzed using reversed-phase HPLC. The concentration of lutein was highest in the yellow stripes.
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Phillip, Denise Mary. "Xanthophylls in light-harvesting complexes of higher plants." Thesis, Liverpool John Moores University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242313.
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史賢明 and Xianming Shi. "High yield production of lutein by Chlorella protothecoides under heterotrophic conditions of growth." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31237666.
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Shi, Xianming. "High yield production of lutein by Chlorella protothecoides under heterotrophic conditions of growth /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19859880.
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Li, Tao. "Characterization of lutein biosynthesis in green alga chlorella pyrenoidosa under heterotrophic condition." HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1399.
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Kim, Joonyul. "Functional and evolutionary characterization of Arabidopsis carotenoid hydroxylases." Diss., Connect to online resource - MSU authorized users, 2008.
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Thesis (Ph.D.)--Michigan State University. Dept. of Biochemistry and Molecular Biology, 2008.Title from PDF t.p. (viewed on Mar. 30, 2009) Includes bibliographical references (p. 127-139). Also issued in print.
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Schlatterer, Jörg [Verfasser]. "Analysis of Xanthophylls in Food and their Behaviour during Human Digestion / Jörg Schlatterer." Aachen : Shaker, 2007. http://d-nb.info/1163609641/34.
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Derenick, Rhianna A. "The role of lutein and zeaxanthin in protecting the retina from light damage /." Connect to this title online, 2007. http://hdl.handle.net/1957/3823.
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Terry, Christian James. "Gene expression and ABA biosynthesis in water stressed plants." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308310.
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Chitchumroonchokchai, Chureeporn. "Lutein and zeaxanthin use of in vitro models to examine digestive stability, absorption, and photoprotective activity in human lens epithelial cells /." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1095778573.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xiii, 179 p.; also includes graphics (some col.). Includes bibliographical references (p. 147-179).
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Griffith, Gary P., and n/a. "The photoprotective xanthophyll cycle in Southern Ocean phytoplankton and Antarctic sea-ice algae." University of Otago. Department of Marine Science, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080704.111758.
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When light intensities become supersaturating for photosynthesis, phytoplankton must be able to protect the photosynthetic machinery from potential damage by excess energy absorption. One of the most important photoprotective mechanisms involves the nonradiative dissipation of excess light energy by the interconversion of the carotenoid pigments of the so-called xanthophyll cycle. Very little is known about how the xanthophyll cycle of natural communities of phytoplankton responds to high light conditions and the relationship of this photoprotective mechanism to the surrounding physical environment. The purpose of this thesis was to examine the functioning, activation and relationship to the physical environment of the xanthophyll cycle in phytoplankton from the Antarctic ecosystem and the Southern Ocean. Experiments in Antarctica were conducted in austral spring under various natural and artificial light regimes including the use of a newly developed light mixing simulator (LMS). Photoprotective carotenoid pigment concentrations were determined using a carotenoid specific protocol for High Performance Liquid Chromatography (HPLC). The photoprotective xanthophyll cycle was not active in Antarctic sea ice algae under the low light conditions under the annual sea ice. When sea ice algae are exposed to high irradiance, there was an initial rapid deepoxidation of the xanthophyll pigment diadinoxanthin (DD) to diatoxanthin (DT). With on-going irradiance exposure, slower deepoxidation of DD continued. The recovery of DD in the dark or under low light was found to be significantly faster than in temperate algal communities, and is likely a particular adaptation to the unique light environment in Antarctica. The temporal accumulation of pigments of the violaxanthin (VX) xanthophyll cycle was observed for the first time in a natural phytoplankton population. It is hypothesized that the VX cycle may function as a pathway to maintain the pool of DD cycle pigments rather than as a separate photoprotective pathway as observed in higher plants. The high irradiances of ultraviolet - B (290 - 320 nm) radiation (UVB) as a result of stratospheric ozone depletion over Antarctica in spring was found to significantly impact on the DD cycle. Exposure to high levels of both ultraviolet-A (320- 400 nm) radiation (UVA) and UVB reduced the photoprotective xanthophyll pigment pool with the greatest reduction occurring after exposure to high levels of UVB. The reduction in the amount of cellular DD after exposure to high levels of UVB was greater than can be explained by deepoxidation activity, which implies that high UVB exposure can lead to a loss of DD from the community. The first-order kinetic rates of the DD cycle were found to be similar to other studies and did not vary with light intensity. Simulations under natural light using the LMS demonstrated that the response of the DD cycle to static in situ incubations and when subject to vertical mixing was not similar, and that static incubations overestimate DD-cycle activity Over the long term, algae in a simulated vertically mixed environment were able to increase the pool of xanthophyll pigments compared to static conditions where the pool remained the same or decreased. Oceanographic observations from the subantarctic waters south-east of New Zealand in austral autumn provided the physical background for new insights into the xanthophyll cycle of Southern Ocean phytoplankton. The circulation flow and water masses between the Bounty Plateau and Bollons Seamount was resolved and shown to differ from numerical models. Relatively little of the warm and salty Subantarctic Mode Water (SAMW) from the Tasman Sea is carried in the flow of the Subantarctic Front (SAF). The spatial distribution of photoprotective xanthophyll pigments showed higher than expected concentrations in the surface mixed layer of the region. The high concentration of photoprotective pigments is considered to be a consequence of the low iron concentrations in southern waters and the highly variable light and vertical mixing environment. The high cellular concentrations of photoprotective pigments constrains photosynthetic activity implying that the photoprotective pigments may play a more significant role in controlling phytoplankton production in the Southern Ocean than previously thought. Analysis of the xanthophyll pigments and physical oceanography with a Self-Organising map (SOM) Artificial Neural Network (ANN) showed that the photophysiological index DT/ (DD+DT) can be used to resolve a change in water type properties. A simple numerical model was developed which can be used to provide a quantitative index of the relative magnitudes of vertical mixing and phytoplankton photoprotection in the water column. This approach may be useful to identify the effects of physical changes in the surface mixed layer of the Southern Ocean as predicted by climate change modelling.
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Woo, Tak-yunn Tiffany, and 胡德欣. "Neuroprotective strategies in a rat model of retinal detachment." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48334911.
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Retinal detachment (RD) is a leading cause of blindness and although final surgical reattachment rate has greatly improved, visual outcome in many macula-off detachments is disappointing, mainly because of photoreceptor cell death. We previously showed that both lutein and Lycium barbarum polysaccharides (LBP) are neuroprotective in a rodent model of ischemia/reperfusion injury. The objective of this study is to investigate lutein and LBP as possible pharmacological adjuncts to surgery.
Lutein:
Subretinal injections of 1.4% sodium hyaluronate were used to induce RD in Sprague-Dawley rats until their retinae were approximately 70% detached. Daily injections of corn oil (control group) or 0.5mg/kg lutein in corn oil (treatment group) were given intraperitoneally starting 4 hours after RD induction. Animals were euthanized 3 days and 30 days after RD and their retinae were analyzed for photoreceptor apoptosis and cell survival at the outer nuclear layer (ONL) using TUNEL staining and cell counting on retinal sections. Glial fibrillary acidic protein (GFAP) and rhodopsin (RHO) expression were evaluated with immunohistochemistry. Western blotting was done with antibodies against cleaved caspase-3, cleaved caspase-8 and cleaved caspase-9 to delineate lutein’s mechanism of action in the apoptotic cascade. To seek a possible therapeutic time window, the same set of experiment was repeated with treatment commencing 36 hours after RD.
When lutein was given 4 hours after RD, there was significantly fewer TUNELpositive cells in ONL 3 days after RD when compared with the vehicle group. Cell counting showed that there were significantly more nuclei in ONL in lutein-treated retinae by day 30. Treatment groups also showed significantly reduced GFAP immunoreactivity and preserved RHO expression. At day 3 after RD, Western blotting showed reduced expression of cleaved caspase-3 and cleaved caspase-8 in the treatment group. No difference was found for cleaved caspase-9. When lutein was given 36 hours after RD similar results were observed.
Our results suggest that lutein is a potent neuroprotective agent that can salvage photoreceptors in rats with RD, with a therapeutic window of at least 36 hours. The use of lutein in patients with RD may serve as an adjunct to surgery to improve visual outcomes.
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The same RD model was used for the LBP experiment. Phosphate buffered solution (PBS) or LBP in PBS was given orally through a gavage at 1mg/kg and 10mg/kg concentrations. For this experiment, animals were sacrificed 7 days after RD, and only cell counting of the ONL and TUNEL staining were performed. Both sets of results did not produce statistically significant changes with the use of LBP. Our preliminary data for the effect of LBP on retinal detachment shows no significant beneficial effect.published_or_final_version
Medicine
Master
Master of Research in Medicine
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Sandeski, Lígia Mara [UNESP]. "Otimização da pigmentação da gema do ovo: Lígia Mara Sandeski. -." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/94680.
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The color of the egg yolk depends on the absorption and the deposition of carotenoids present in the hens´ diets and represents a sensory characteristic of great impact on the product acceptance. Corn is commonly used as energy value ingredient for hens´ diets formulations. Moreover, due to its additional pigmentation properties, it might be used to color egg yolk. The purpose of this research was to optimize the proportions between yellow and red pigments in hens´ corn based rations to provide color maximization for yolks. Sixty Dekalbe laying hens were separately distributed in cages inside a rearing barn to receive the experimental diets for 21 days at a daily feeding of 110 g and water ad libitum. Fifteen treatments were defined by means of a central composite rotatable design in which the variables were the yellow pigments from the diets (corn + gluten meal), the yellow supplementary pigments (lutein + zeaxanthin) and the red supplementary pigments (cantaxanthin), each of them at three different concentrations. Hens´ weights were recorded at the beginning and at the end of the experiment and the eggs weights were recorded daily. Yolks colors were determined by means of objective (L, a, b) and subjective (color fan) measurements. Global acceptance of yolks color was investigated with a five points hedonic scale. The results were analyzed by ANOVA, means comparison tests (t test and Dunn test) and regression analysis by Response Surface Methodology, at 5% significance level. Hens` final weights and eggs weights were not influenced by the treatments. Seven distinct colors for yolks were identified with the color fan. The most preferred yolks scored 9 and derived from the treatment which provided the highest yellow pigments concentrations (2.0 mg/hen/day) and no red pigments while the most rejected yolks scored 14 and derived from treatments which provided the highest concentration of red pigment (0.7 mg/hen/day), besides the yellow...
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Sandeski, Lígia Mara. "Otimização da pigmentação da gema do ovo / Lígia Mara Sandeski. -." Araçatuba, 2013. http://hdl.handle.net/11449/94680.
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Orientador: Elisa Helena Giglio PonsanoBanca: Cecilio Viega Soares Filho
Banca: Otto Mack Junqueira
Resumo: A coloração da gema é dependente da absorção e da deposição dos carotenoides presentes na dieta da ave e representa uma característica sensorial de grande influência sobre a aceitabilidade do produto. O milho, ingrediente energético bastante utilizado na composição de ração de galinhas poedeiras, também apresenta potencial pigmentante, que deve ser explorado quando o objetivo é fornecer pigmentação à gema. Este trabalho teve como objetivo determinar as proporções entre pigmentos amarelos e vermelhos em rações contendo milho como principal fator energético para galinhas poedeiras visando promover a maximização da coloração de gema. Sessenta galinhas poedeiras da linhagem Dekalbe em fase de postura foram alocadas individualmente em gaiolas em galpão apropriado, onde receberam as rações experimentais durante 21 dias, com arraçoamento diário de 110 g e água à vontade. Foram aplicados 15 tratamentos, definidos por um delineamento composto central rotacional em que as variáveis estudadas foram os pigmentos amarelos provenientes dos ingredientes da ração (milho + farelo de gluten de milho), os pigmentos amarelos suplementares (luteína + zeaxantina) e os pigmentos vermelhos suplementares (cantaxantina), cada uma com três concentrações distintas. As aves foram pesadas no início e ao final do experimento e o peso dos ovos foi registrado diariamente. A cor das gemas foi determinada pelos métodos objetivo (L, a, b) e subjetivo (leque colorimétrico). A aceitação global das gemas foi determinada por meio de escala hedônica de cinco pontos. Os resultados obtidos foram submetidos a análises de variâncias, testes de comparação de médias (teste t e teste de Dunn) e à análise de regressão pela metodologia de superfície de resposta, adotando-se o nível de significância de 5%. O peso final das aves e o peso dos ovos não foram influenciados pelos diferentes... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The color of the egg yolk depends on the absorption and the deposition of carotenoids present in the hens' diets and represents a sensory characteristic of great impact on the product acceptance. Corn is commonly used as energy value ingredient for hens' diets formulations. Moreover, due to its additional pigmentation properties, it might be used to color egg yolk. The purpose of this research was to optimize the proportions between yellow and red pigments in hens' corn based rations to provide color maximization for yolks. Sixty Dekalbe laying hens were separately distributed in cages inside a rearing barn to receive the experimental diets for 21 days at a daily feeding of 110 g and water ad libitum. Fifteen treatments were defined by means of a central composite rotatable design in which the variables were the yellow pigments from the diets (corn + gluten meal), the yellow supplementary pigments (lutein + zeaxanthin) and the red supplementary pigments (cantaxanthin), each of them at three different concentrations. Hens' weights were recorded at the beginning and at the end of the experiment and the eggs weights were recorded daily. Yolks colors were determined by means of objective (L, a, b) and subjective (color fan) measurements. Global acceptance of yolks color was investigated with a five points hedonic scale. The results were analyzed by ANOVA, means comparison tests (t test and Dunn test) and regression analysis by Response Surface Methodology, at 5% significance level. Hens' final weights and eggs weights were not influenced by the treatments. Seven distinct colors for yolks were identified with the color fan. The most preferred yolks scored 9 and derived from the treatment which provided the highest yellow pigments concentrations (2.0 mg/hen/day) and no red pigments while the most rejected yolks scored 14 and derived from treatments which provided the highest concentration of red pigment (0.7 mg/hen/day), besides the yellow...
Mestre
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Brackenridge, Anika Elma. "Over-expression and analysis of two Vitis vinifera carotenoid biosynthetic genes in transgenic Arabidopsis." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019/508.
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Babino, Darwin O. "High-performance liquid chromatography measurement of carotenoids in human serum, etoposide in pig cerebrospinal fluid and measurement of the aggregation of xanthophylls in aqueous solutions." FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/1360.
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The present study measured a chemotherapy drug, etoposide, in pig cerebrospinal fluid after intraventricular administrations were made directly into the fourth ventricle of the brain; cytotoxic concentrations for a twenty-four hour period after infusions. The analytical method developed validates the potential treatment of malignant brain tumors. The increase in serum carotenoid concentration in 30 healthy individuals was measured after supplementation with lutein. HPLC analysis of serum levels of carotenoids showed an increase in the concentration of lutein and a constant concentration of other major serum carotenoids. An initial attempt to measure the enthalpy of aggregation of xanthophylls was conducted by using ultraviolet-visible spectroscopy. The enthalpy of lutein aggregation and AH range of zeaxanthin disordering of aggregation are reported. Monomethyl ether of lutein did not aggregate in any of the aqueous solutions.
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Mubaiwa, Byron Tawanda. "The quantification of fucoxanthin from selected South African marine brown algae (Phaeophyta) using HPLC-UV/Vis." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1017879.
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Marine brown algae (seaweeds) are a rich source of fucoxanthin, a xanthophyll carotenoid that is naturally, an accessory pigment in the process of photosynthesis of sea vegetation such as Sargassum incisifolium. Fucoxanthin has been exploited by nutraceutical companies for its anti-obesity effects that has resulted in an increase of seaweed slimming preparations such as FucoThin™. The field is getting widespread consumer attention as interest in fucoxanthin has also transcended to its widespread biological potential which include cytotoxicity, anti-diabetic, anti-oxidant, anti-inflammatory and anti-plasmodium effects. We therefore wanted to identify a reliable source(s) of fucoxanthin from diverse samples of South African marine brown algae in order to explore our medicinal chemistry interests around the cytotoxicity and anti-malarial potential of fucoxanthin. A known source, Sargassum incisifolium, was used to isolate (maceration in CH₂Cl₂/MeOH at 35 °C followed by a hexane/EtOAc step gradient silica column of the crude extract and reversed phase semi-prep HPLC) and characterize (1D and 2D NMR) fucoxanthin (reference standard) in order to develop an analytical method for its determination in selected diverse brown algae commonly found in South Africa. The HPLC [Column: Phenomenex® Synergi™ (250 x 3.0 mm i.d); Mobile phase: ACN/H2O (95:5)] method developed for this analysis was validated according the guidelines set by the International Conference on Harmonization (ICH). Fifteen species were then assessed for fucoxanthin content (μg/g of dried weight) using the developed method. Stability studies on fucoxanthin were also carried out to assess photo- and pH degradation of fucoxanthin. Zonaria subarticulata (KOS130226-18) from Kenton-On-Sea beach and Sargassum incisifolium (PA130427-1) from Port Alfred beach were found to be the highest producers of fucoxanthin with 0.50 mg/g and 0.45 mg/g dried weight respectively. Fucoxanthin was found to be both photo-labile and sensitive to both acidic and basic pH environments. However, the pigment was more photostable in pure as opposed to extract form and also showed to be more stable at pH 10.0. Our findings show that Z. subarticulata and S. incisifolium could be reliable sources of fucoxanthin and can be considered as the algae to use in optimized extraction procedures in further studies. Also, when working with fucoxanthin, it is important to protect it from light. Any consideration of taking fucoxanthin preparation orally (as a nutraceutical) should consider protecting the active from the harsh conditions of the gastrointestinal tract. Any upscale production of fucoxanthin from seaweed should consider variations such as geographical, seasonal, lifecycle stage, etc. of identified algae as these may be important factors in obtaining effective concentrations of fucoxanthin.
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Giossi, Chiara. "Photoacclimation and photoprotection strategies in siphonous green algae of the order Bryopsidales (Codium tomentosum and Bryopsis plumosa)." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/19835/.
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Several species of Bryopsidales (Chlorophyta) are known for displaying functional absence of the xanthophyll cycle, a common photoprotection mechanism responsible for qE component of NPQ. To cope with the extreme variability of their natural environment, these algae must be able to avoid photodamage. Previous works reported significant accumulation of all-trans-neoxanthin and violaxanthin under high light acclimation in different Bryopsidales, and speculated that these xanthophylls might control the amount of energy that reaches the photosystems, causing photoprotection. In this work, we investigated photoacclimation and photoprotection strategies in two species of Bryopsidales (Codium tomentosum and Bryopsis plumosa). We first characterised the acclimation state of algae exposed for 7 days to low light or high light (respectively 20 and 1000 μmol photons m2 s−1) in terms of pigment content (HPLC) and chlorophyll a variable fluorescence (PAM). We confirmed that high light triggers significant alteration of pigment content with accumulation of trans-Neoxanthin and Violaxanthin, and for the first time we characterised thoroughly how the pigment pool is altered during acclimation. We also confirmed that no evidence of any xanthophyll cycle is present in high light acclimated cultures. On a second note we tried to answer another major question: are trans-neoxanthin and violaxanthin photoprotective? Using a novel chlorophyll a variable fluorescence approach (pNPQ assessment) and performing quantification of PSII repair capacity (via lincomycin treatment) we were not able to give a clear answer to this question. Nonetheless, we concluded that despite trans-Neoxanthin and Violaxanthin might contribute to photoprotection, this process in Bryopsidales algae is likely given by the coordination between different mechanisms that deserve to be further investigated, including chloroplast movement, PSII repair/modulation, state transitions, and PSI cyclic electron transport.
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Garcia, Mendoza Ernesto. "Photoadaptation in microalgae: xanthophyll cycle and state transitions strategies." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/56679.
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Thomas, Sara E. "Mechanisms of Xanthophyll Uptake in Retinal Pigment Epithelial Cells." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1478183410555123.
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Johnson, Matthew Paul. "Role of the xanthophyll cycle in photoprotection in Arabidopsis thaliana." Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485881.
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The xanthophyll cycle has a major role in protecting plants from photo-oxidative stress, although the mechanism of its action is unclear. Here, Arabidopsis plants overexpressing a gene encoding {3-carotene hydroxylase, containing nearly three-times the amount of xanthophyll cycle carotenoids present in the wild-type have been investigated. Although the capacity of non-photochemical quenching is not significantly different in transformed plants compared to wild-type, altered kinetics were observed. In transformed plants the kinetics of non-photochemical quenching were found to be less responsive to changes in light environment. The kinetics were found to correlate with de-epoxidation state of the xanthophyll cycle pool rather than absolute zeaxanthin concentration. This result strongly suggests zeaxanthin and violaxanthin act as allosteric regulators of non-photochemi~al quenching. In high light at low temperature wild-type plants exhibited symptoms of severe oxidative stress - lipid peroxidation, chlorophyll bleaching and photoinhibition. In transformed plants, which accumulate over twice as much zeaxanthin as the wild-type, these symptoms were significantly ameliorated. As no enhancement in nonphotochemical quenching was detected an enhancement of this mechanism cannot be the cause of the stress tolerant phenotype. Rather, It is concluded that it results from the antioxidant effect of zeaxanthin. 80-90% of violaxanthin and zeaxanthin in wild-type and transformed plants was localized to an oligomeric fraction of the light harvesting complex of photosystem II (LHCII) prepared from thylakoid membranes. The binding of these pigments in intact membranes was confirmed by resonance Raman spectroscopy. Based on the structural model of LHCII, it is suggested that the protein/lipid interface is the active site for the anti-oxidant activity of zeaxanthin, which mediates stress tolerance by the protection of bound lipids. Therefore both roles of the xanthophyll cycle in photoprotection involve the same conserved binding sites in the thylakoid membrane.
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Weller, Philipp [Verfasser]. "Xanthophyll Esters: Occurrence and Comparative Studies on their Bioavailability / Philipp Weller." Aachen : Shaker, 2005. http://d-nb.info/1181616166/34.
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Savill, Julia. "Carotenoid biosynthesis in higher plants." Thesis, Liverpool John Moores University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313103.
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Savy, Stephanie. "Biosynthèse de caroténoïdes aromatiques hydroxyléspar des bactéries non photosynthétiques :Des carotènes aux xanthophylles." Phd thesis, Université de Bretagne occidentale - Brest, 2005. http://tel.archives-ouvertes.fr/tel-00193188.
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Ces travaux portent sur la production de caroténoïdes aromatiques par des bactéries non photosynthétiques. Les trois bactéries retenues pour cette étude sont Brevibacterium linens, Streptomyces mediolani et Mycobacterium aurum. Ces bactéries sont connues pour produire les mêmes caroténoïdes aromatiques à savoir l'isoréniératène et ses dérivés hydroxylés. La voie de biosynthèse de ces pigments est décrite jusqu'au stade isoréniératène, l'étape ultérieure permettant la formation de caroténoïdes hydroxylés constitue le sujet de cette étude.Dans un premier temps, les pigments produits par ces bactéries sont étudiés par HPLC et LCMS. Ces études ont montré que B. linens et S. mediolani synthétisent majoritairement du 3,3'-di-hydroxy-isoréniératène. Elles ont également révélé l'absence de ce composé chez M. aurum. Contrairement à ce qui est décrit dans la littérature cette bactérie accumule un caroténoïde de masse moléculaire supérieure à celle du di-hydroxy-isoréniératène. Une purification a été entreprise pour une analyse en RMN mais les faibles quantités obtenues n'ont pas permis la détermination de la structure.
Dans un second temps, la réaction d'hydroxylation, dernière étape dans la biosynthèse de ces caroténoïdes a été étudiée. On cherche à identifier le type d'enzyme et le substrat de cette étape. L'utilisation d'inhibiteurs spécifiques de cytochrome P450 dans les cultures bactériennes se traduit par l'accumulation d'isoréniératène et la disparition des formes hydroxylées chez B. linens et S. mediolani. Ces résultats montrent l'implication d'un cytochrome P450 dans l'hydroxylation de l'isoréniératène pour ces bactéries.
Le cluster de la caroténogénèse a été récemment séquencé et identifié chez les trois bactéries étudiées. Seul le cluster de B. linens comporte un gène (orf 10) pouvant coder une hydroxylase qui présente un motif caractéristique d'un cytochrome P450, cependant son implication dans l'hydroxylation des caroténoïdes aromatiques n'est pas précisée.
Une série de mutagénèse aléatoire par rayonnement U.V. a été entreprise sur B. linens. Elle a permis d'obtenir un mutant noté BLMJ. Les analyses HPLC et LCMS des pigments produits par BLMJ montrent qu'il accumule très majoritairement de l'isoréniératène. Le système responsable de l'hydroxylation de l'isoréniératène de BLMJ apparaît défectueux. L'analyse de la séquence de l'ORF 10 de BLMJ révèle la présence d'une mutation au niveau de l'acide aminé 84 où la phénylalanine est remplacée par une sérine. Après comparaison avec des structures 3D de P450 connus il semblerait que cet acide aminé soit important dans la stabilisation du groupement prosthétique de l'enzyme. Sa mutation entraînerait donc une perte d'activité de l'enzyme.
Pour s'assurer de l'implication de l'ORF 10 dans l'hydroxylation de l'isoréniératène chez B. linens, nous avons électroporé B. linens avec l'orf 10 muté de BLMJ. Un mutant (noté BLE7J) accumulant majoritairement de l'isoréniératène a pu être isolé. L'analyse de la séquence de l'ORF 10 de BLE7J révèle la présence d'une mutation au niveau de l'acide aminé 267 où l'acide glutamique est remplacé par une glutamine. Après comparaison de séquences, il apparaît que cet acide aminé appartient à un motif conservé dans les séquences de P450 car impliqué dans la stabilisation du groupement prosthétique de l'enzyme. Sa mutation entraînerait donc une perte d'activité de l'enzyme.
Les mutants BLMJ et BLE7J montrent que le P450 responsable de l'hydroxylation de l'isoréniératène en 3,3'-di-hydoxy-isoréniératène est codé par l'orf 10 du cluster crt de B. linens.
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Tardy, Florence. "Localisation et fonctions du cycle des xanthophylles dans les chloroplastes des plantes supérieures." Lyon 1, 1997. http://www.theses.fr/1997LYO10281.
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Le cycle des xanthophylles, i. E. La deepoxydation enzymatique de la violaxanthine (vio) en antheraxanthine et zeaxanthine (zea) mise en place sous forte lumiere et reversible a l'obscurite, constitue un systeme photoprotecteur dont le mode d'action est controverse. Nous proposons que l'interconversion vio->zea participe a la photoprotection non seulement au niveau des photosystemes mais egalement au niveau de la matrice lipidique des membranes thylacoidiennes. Des lhc du photosysteme ii (lhcii) purifies a partir de plantes soumises a un bref stress luminieux contiennent une quantite de zea inferieure a la fraction de vio effectivement deepoxydee. De plus, la conversion vio->zea s'accompagne d'une modification transitoire des proprietes physiques des membranes thylacoidiennes (fluidite et permeabilite ionique). Ces resultats suggerent que, suite a la deepoxydation de la vio, une part importante de la zea est liberee dans la phase lipidique des membranes photosynthetiques ou elle exerce un role photoprotecteur (limitation des peroxydations lipidiques) et stabilisateur (thermoresistance accrue des membranes). L'importance de ce mecanisme pour la fonctionnalite des membranes photosynthetiques et leur adaptation aux fortes lumieres et aux temperatures elevees est discutee. Par ailleurs, sous forte lumiere, un decouplage energetique carotenoides/chlorophylles independant de la conversion vio->zea se met en place au niveau des photosystemes. Il pourrait refleter des modifications de conformation des lhc de l'etat collecteur d'energie a l'etat de dissipation d'energie. Dans ce contexte, nous avons montre que le cycle des xanthophylles ne participe que tres indirectement (comme catalyseur cinetique) a la dissipation thermique de l'exces d'energie et que l'accumulation constitutive de zeaxanthine dans les lhcii chez le mutant aba-l d'arabidopsis thaliana n'assure pas a elle seule une meilleure photoprotection des photosystemes. La conversion dynamique vio->zea possede donc un double role de consolidation des structures membranaires et de modification de la reponse des antennes chlorophylliennes a la lumiere suite a un changement de leur composition en xanthophylles. La compatibilite eventuelle de notre modele avec d'autres hypotheses proposees dans la litterature est examinee.
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Wentworth, Mark. "Quenching of chlorophyll fluorescence in plant light-harvesting complexes." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340168.
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Morin-Savy, Stéphanie. "Biosynthèse de caroténoi͏̈des aromatiques hydroxylés par des bactéries non photosynthétiques : Des carotènes aux xanthophylles." Brest, 2005. http://www.theses.fr/2005BRES2002.
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Ces travaux portent sur l'étape d' hydroxylation dans la biosynthèse de caroténoi͏̈des aromatiques chez des bactéries non photosynthétiques : Brevibacterium linens, Streptomyces mediolani et Mycobacterium aurum. Les analyses HPLC et LCMS des pigments produits montrent que seules B. Linens et S. Mediolani synthétisent majoritairement du di-hydroxy-isoréniératène. L'utilisation d'inhibiteur enzymatique spécifique a montré l'implication d'un cytochrome P450 dans l'hydroxylation de l'isoréniératène chez B. Linens et S. Mediolani. Des expériences de mutagénèse aléatoire puis dirigée ont permis d'obtenir deux mutants de B. Linens : BLMJ et BLE7J. Chez ces mutants le système responsable de l'hydroxylation de l'isoréniératène est défectueux. De plus l'orf 10 du cluster crt codant un P450 est muté dans les deux cas. Après analyse des séquences des protéines mutantes il semble que l'orf 10 code le P450 responsable de l'hydroxylation de l'isoréniératène en di-hydoxy-isoréniératène chez B. LinensThis research work aims at studying the hydroxylation step interfering in the biosynthesis of aromatic carotenoids in some non-photosynthetic bacteria: Brevibacterium linens, Streptomyces mediolani and Mycobacterium aurum. HPLC and LCMS analyses of the pigments produced show that only B. Linens and S. Mediolani synthetize di-hydroxy-isorenieratene. With the use of specific enzymatic inhibitors, we have come to the conclusion that for B. Linens as well as for S. Mediolani, the isorenieratene seems to be hydroxylated by a P450 cytochrome. Two mutants in hydroxylation step were obtained after random then supervised mutagenesis experiments on B. Linens. Mutants have a mutation on the orf 10 in crt cluster. After sequence analysis of mutants proteins, it seems orf 10 in crt cluster of B. Linens encodes the cytochrome P450 involved in hydroxylation of isorenieratene into di-hydroxy-isorenieratene
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Scherrers, Roger. "Carotinoide und Sauerstoff antioxidative Eigenschaften von aromatischen und nicht aromatischen Xanthophyllen /." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=982670982.
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Pieters, Alejandro J. "Photosynthetic carbon and energy balance in tobacco : relation to phosphoribulokinase and phosphate." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312233.
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Zamboni, Alessandro <1978>. "Role of xanthophyll and water-water cycles in the protection of photosynthetic apparatus in Arbutus unedo and Arabidopsis thaliana." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/518/.
Full textAbstract:
Photosynthetic organisms have sought out the delicate balance between
efficient light harvesting under limited irradiance and regulated energy
dissipation under excess irradiance. One of the protective mechanisms is the
thermal energy dissipation through the xanthophyll cycle that may
transform harmlessly the excitation energy into heat and thereby prevent the
formation of damaging active oxygen species (AOS). Violaxanthin deepoxidase
(VDE) converts violaxanthin (V) to antheraxanthin (A) and
zeaxanthin (Z) defending the photosynthetic apparatus from excess of light.
Another important biological pathway is the chloroplast water-water cycle,
which is referred to the electrons from water generated in PSII reducing
atmospheric O2 to water in PSI. This mechanism is active in the scavenging
of AOS, when electron transport is slowed down by the over-reduction of
NADPH pool.
The control of the VDE gene and the variations of a set of physiological
parameters, such as chlorophyll florescence and AOS content, have been
investigated in response to excess of light and drought condition using
Arabidopsis thaliana and Arbutus unedo.. Pigment analysis showed an
unambiguous relationship between xanthophyll de-epoxidation state
((A+Z)/(V+A+Z)) and VDE mRNA amount in not-irrigated plants.
Unexpectedly, gene expression is higher during the night when
xanthophylls are mostly epoxidated and VDE activity is supposed to be
very low than during the day.
The importance of the water-water cycle in protecting the chloroplasts from
light stress has been examined through Arabidopsis plant with a suppressed
expression of the key enzyme of the cycle: the thylakoid-attached
copper/zinc superoxide dismutase. The analysis revealed changes in
transcript expression during leaf development consistent with a signalling
role of AOS in plant defence responses but no difference was found any in photosynthesis efficiency or in AOS concentration after short-term
exposure to excess of light.
Environmental stresses such as drought may render previously optimal light
levels excessive. In these circumstances the intrinsic regulations of
photosynthetic electron transport like xanthophyll and water-water cycles
might modify metabolism and gene expression in order to deal with
increasing AOS.
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Alvarez-Calderon, Francesca. "Calculations on the end-group conformational barrier in carotenoids and a study of the bioavailability of xanthophyll esters in humans." FIU Digital Commons, 2007. http://digitalcommons.fiu.edu/etd/1272.
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The present study measures the increase in serum carotenoid concentration in 30 healthy individuals after supplementation with a low dose xanthophyll ester (3 and 6 mg of lutein equivalent/per day) when compared to a placebo. Serum levels of carotenoids were measured using HPLC and showed an increase in the concentration of lutein, zeaxanthin and four lutein metabolites proportional to dose.
In order to further assess the importance of the end-group structure in carotenoids we have investigated the influence of the end-group type and functionality on the conformational energy barrier. We used the density functional method implemented on GAUSSIAN 98 to calculate the conformational energy curves for rotation of the P-ring or the E-ring relative to short polyene chains around the C6-C7 single bond. A large barrier is observed for the interconversion of conformers in the E-rings (8 kcal/mol) when compared to beta rings (2.3-3 kcal/mol).
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Zhao, Liang. "Effects of altered levels of expression of β-carotene hydroxylase on xanthophyll cycle pool size and stress tolerance of rice (Oryza sativa L.)." Thesis, University of Nottingham, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.718983.
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Plants have varied biochemical and physiological responses to excessive light to optimise photosynthesis and to protect their photosynthetic apparatus against photooxidative stress. An important mechanism which protects plant photosystems from light-dependent damage by harmless thermal dissipation of the excitation energy is defined as non-photochemical quenching (NPQ). Extensive studies have shown that the formation and relaxation of qE, the major component of NPQ, are regulated by the xanthophyll cycle (XC, the reversible inter-conversion between the carotenoids violaxanthin and zeaxanthin) as well as pH gradient across thylakoid membrane (ApH) and PsbS protein. Studies using Arabidopsis overexpressing gene (chyB) encoding (3- carotene hydroxylase have shown possibilities to manipulate the kinetics of NPQ and therefore photoprotection by altering the XC pool size. We characterised the changes of xanthophyll cycle pool size, carotenoids composition and NPQ induction in ChyB overexpressing (OE) transformants of rice and compared with ChyB defective (RNAi) and the wild type plants. The XC pool size had nearly twofold increase in the overexpressing plants without affecting the functioning XC, compared to greatly reduced size of XC pool in the ChyB RNAi plants. Accordingly, ChyB OE plants had enhanced capacity of maximal qE and faster formation of qE in comparison with the wild type, while ChyB RNAi plants present retarded qE formation and inferior qE capacity. However, ChyB OE plants showed slow formation of DES (de-epoxidation state of the XC pool) associated with the enlarged XC pool size. Under high light and high temperature conditions, ChyB OE also showed improved resistance to photooxidative stress while ChyB RNAi showed increased sensitivity to photooxidative stress. To investigate the effects of altered XC pool size on modulating NPQ. two types of environment were imposed where light was fluctuating: firstly in a glasshouse (natural rapidly fluctuating light environment) where complete rice canopies were formed. Second in a CE growth chamber experiments where LED lights imposed an artificial growth condition where light continually fluctuated between limitation and saturation. In both environments ChyB RNAi plants also showed inferior growth and biomass production and we conclude that the formation of xanthophyll-dependent NPQ is vital for optimal growth in a variable light environment.
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Dujardyn, Marie-Christine. "Régulation de la photosynthèse de l'orge sous fort éclairement : photoinhibition et reprise." Paris 11, 1989. http://www.theses.fr/1989PA112264.
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Des plantes d’orge cultivées sous un faible éclairement présentent, lorsqu’elles sont exposées à un fort éclairement, une photo inhibition de la photosynthèse. Celle-ci se caractérise par une diminution de l’assimilation du co2 associée à une baisse du rendement quantique et de la fluorescence variable à 690 nm. Elle traduit une perte partielle et réversible de l’efficacité et des capacités photosynthétiques ; Le principal facteur responsable du ralentissement du fonctionnement du cycle de Calvin-Benson serait la limitation de production du pouvoir réducteur. Il interviendrait en diminuant la réduction du PGA et, en conséquence, la régénération du RuBP et en abaissant les activités de certaines enzymes photo réguléesExposure of low-light-grown barley plants to high irradiance resulted in the loss of photosynthetic capacity called photo inhibition. This was characterized by a decrease in the quantum yield for CO assimilation and the loss of variable fluorescence at 690 nm. Photinhibition resulted in a partial (but reversable) decline in photosynthetic efficiency and capacity. The principal factor responsible for the inhibition of Benson-Calvin cycle activity was the resultant deficit in provision of reducing power. This is evidenced by the failure to maintain PGA reduction (and as a consequence RuBP regeneration) and also by the decrease in the activities of redox-modulated enzymes
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Lavaud, Johann. "Stratégies d'adaptation des diatomées phytoplanctoniques aux variations de l'intensité lumineuse rencontrées dans leur environnement naturel." Paris 6, 2002. http://www.theses.fr/2002PA066212.
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Damaraju, Sridevi. "Analysis of proteins involved in chlorophyll catabolism." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://dx.doi.org/10.18452/16322.
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Der Abbau des Chlorophyll (Chl) ist ein Prozess, der typischerweise während der Blattseneszenz und der Reifung von Früchten und Samen stattfindet. Eine Störung dieses koordinierten Prozesses unter Frostbedingungen verzögert den Chl-Abbau und ist ein grosses Hindernis bei der Herstellung von hochwertigem Rapsöl. Der Abbau von Chl zu farblosen Kataboliten erfolgt in einer Serie von enzymatischen Schritten und wird durch die Chlorophyllase begonnen (Chlase). Es wurde vorgeschlagen, dass ein wasserlösliches Chl Protein (WSCP) den Transport des Chl von der Thylakoidmembran zum Wirkort der Chlase übernimmt. Weiterhin wurde angenommen, dass die Steigerungen der Genexpressionen dieser frühen Schritte den Prozess des Chl-Abbaus beschleunigen. In der vorliegenden Arbeit werden die Auswirkungen der Überexpression der Chlase aus Citrus clementii (CcCHLASE) und von WSCP aus Blumenkohl (Cau-WSCP) in transgenen Tabakpflanzen analysiert. Dazu wurde die cDNA Sequenz der CcCHLASE in E. coli exprimiert und mittels in vitro Experimenten die Hydrolysierung von Chl durch die Chlase bestätigt. Anschließend wurden CcCHLASE exprimierende Tabakmutanten generiert und drei T1-Linien wurden unter verschiedenen Stress- und Seneszenzbedingungen untersucht. Die Chlase überexprimierenden Linien zeigten unter allen getesteten Bedingungen einen im Vergleich zum Wildtyp erhöhten Chlide a Gehalt. Trotzdem unterschied sich die Menge an Endkataboliten in diesen Mutanten nicht vom Wildtyp. Andererseits zeigten WSCP überexprimierende Linien zwar keine erhöhten Chlide a Gehalte jedoch erhöhte Protochlorophyllid-(Pchlide)-Level. Das deutet auf eine Rolle des WSCP als Speichermolekül für Chlorophyllvorstufen hin. Die photoprotektive Funktion des WSCP wurde zusätzlich in WSCP überexprimierenden Linien bestätigt. Diese zeigen im Vergleich zu Wildtyp-Tabakpflanzen auch bei hohen Lichtintensitäten von 700 – 900 µmol Photonen m-2 s-1 verringerte Gehalte an Zeaxanthin und reduzierte Peroxidaseaktivitäten.Chlorophyll (Chl) catabolism is characteristically seen during leaf senescence, fruit ripening and seed maturation. Disruption of this coordinated process under frost conditions delays Chl breakdown and is a great concern in rapeseed oil production. The present work addresses this problem by studying the effect of enhanced Chl catabolism in genetically modified tobacco plants. Chl is catabolised to colourless catabolites through a series of enzymatic reactions initiated by Chlorophyllase (Chlase). A water soluble chlorophyll protein (WSCP) has been proposed to transport Chl from thylakoid membranes to the site of action of Chlase. It was assumed that enhancing the gene expression of these early events in Chl catabolism would increase the Chl breakdown process. The present work analysed the overexpression of Chlase from Citrus clementii (CcCHLASE) and WSCP gene from cauliflower (Cau-WSCP) in modified tobacco plants. Initially, the cDNA sequence of CcCHLASE was expressed in E. coli and in vitro tests confirmed the hydrolytic activity of Chlase on Chl. Subsequently, tobacco plants overexpressing CcCHLASE were generated and three T1 lines were analysed at various stress and senescence conditions. The in vivo production of Chlorophyllide (Chlide) indicated the extent of increased Chl breakdown. The Chlase overexpressor lines showed higher Chlide a steady state levels under all tested conditions in comparison to the WT tobacco plants. However, the end catabolites did not show much difference from WT plants. On the other hand, WSCP overexpressor lines did not show any increase in Chlide a levels, but demonstrated an increased protochlorophyllide (Pchlide) levels. This suggested the role of WSCP as a storage molecule of Chl precursors. Additionally, photoprotective function of WSCP was confirmed in WSCP overexpressors, by lower zeaxanthin levels and peroxidase activity even at high light intensities of 700 – 900 µmol photons m-2 s-1 in comparison to the WT tobacco plants.
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Stella, Giulio Rocco. "Light stress and photoprotection in green algae, mosses and diatoms." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066430/document.
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Les bases moléculaires des réponses aux excès de lumière chez les organismes photosynthétiques appartenant à des lignées évolutives distinctes ne sont toujours pas complètement caractérisées. Par conséquent, j'ai caractérisé des antennes photoprotectrices dans les algues vertes, les mousses et les diatomées et j'ai exploré la fonction de deux cycles de xanthophylles chez les diatomées.J'ai étudié les protéines Light Harvesting Complex Stress-Related (LHCSR) dans tous ces organismes. Chez l'algue verte Chlamydomonas reinhardtii, j’ai identifié par mutagénèse dirigée, complémentation fonctionnelle et par une approche biochimique les acides aminés responsables de l'activation de LHCSR3, une protéine importante pour le NPQ.Dans le modèle de mousse Physcomitrella patens, j'ai etudié in vitro les caractéristiques spectroscopique ainsi que le quenching de différents mutants de liaison de pigment sur la protéine LHCSR1.Les protéines LHCSR dans les diatomées sont nommées LHCXs, et dans Phaeodactylum tricornutum j'ai montré que l'expansion de la famille des gènes LHCX reflète une diversification fonctionnelle de ces protéines permettant de répondre à des environnements marins très variables.L'autre acteur principal de la photoprotection dans les diatomées est le cycle des xanthophylles. J’ai trouvé que l'accumulation d'une grande quantité de viola- et zéaxanthin a un effet négatif sur le NPQ montrant que la zéaxanthin ne participe pas au NPQ chez diatomées.Grâce à ces études effectuées, nous avons acquis une connaissance plus approfondie sur les caractéristiques communes et les spécificités de la photoprotection.chez différents organismesThe molecular bases of responses to light excess in photosynthetic organisms having different evolutionary histories and belonging to different lineages are still not completely characterized. Therefore I explored the functions of photoprotective antennae in green algae, mosses and diatoms, together with the role of the two xanthophyll cycles present in diatoms.I studied the Light Harvesting Complex Stress-Related (LHCSR) proteins in different organisms. In the green alga Chlamydomonas reinhardtii, LHCSR3 is a protein important for photoprotection. I used site-specific mutagenesis in vivo and in vitro and identified three residues of LHCSR3 that are responsible for its activation.With the moss Physcomitrella patens I studied the in vitro spectroscopic and quenching characteristics of different pigment-binding mutants of the protein LHCSR1, focusing in particular on chlorophylls A2 and A5.LHCSRs in diatoms are named LHCXs, and in Phaeodactylum tricornutum I found that multiple abiotic stress signals converge to regulate the LHCX content of cells, providing a way to fine-tune light harvesting and photoprotection.The other main driver of photoprotection in diatoms is the xanthophyll cycle. Here I found that the accumulation of viola- and zeaxanthin in P. tricornutum have a negative effect in the development of NPQ, showing that zeaxanthin does not participate in the enhancing of NPQ in diatoms.Thanks to these studies done on different organisms, we gained a deeper knowledge on the shared characteristics and on the peculiar features about photoprotection in green algae, mosses and diatoms
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LINS, NETO João da Rocha. "Potencial antioxidante de plantas da flora pernambucana." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/16900.
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CAPEs
O Brasil é considerado o país com a maior biodiversidade do mundo, nele as formações vegetais do Bioma Caatinga e Mata Atlântica representam fontes potenciais para a prospecção de biomoléculas de interesse científico. Entre essas biomoléculas encontram-se aquelas com atividade antioxidante, substâncias que são capazes de neutralizar ou reparar a ação dos radicais livres e dessa forma combatendo o estresse oxidativo. Vários antioxidantes sintéticos estão presentes no mercado, porém estudos vêm demonstrando a possibilidade de efeitos tóxicos desses produtos sintéticos, fato que gerou estímulo para a busca de antioxidantes naturais. O presente trabalho visou investigar a atividade antioxidante de extratos de folhas de 5 espécies vegetais encontradas no Bioma Caatinga e Mata Atlântica, a saber: Abarema cochliacarpos (AC), Croton nummularius (CN), Myroxylon Peruiferum (MP), Stryphnodendron pulcherrimum (SP) e Tanaecium xanthophyllum (TX) por 3 metodologias in vitru: ensaio do DPPH, ABTS e fosfomolibdênio (capacidade antioxidante total - CAT). Adicionalmente foi realizada uma investigação fitoquímica dos extratos por cromatografia em camada delgada (CCD) bem como dosagem do teor de fenóis e flavonoides totais com o intuito de apontar os possíveis compostos ativos responsáveis por tal atividade. A análise do perfil fitoquímico evidenciou a presença de saponinas, fenilpropanoides e flavonoides em todas os extratos, enquanto que terpenoides e proantocianidinas foram encontrados em AC, alcaloides em CN, cumarinas em MP, proantocianidinas e mono-sesquiterpenoides em SP. As dosagens de fenóis e flavonóides totais dos extratos variaram de 28,84 a 120,39 (mg EAG. g-1 extrato) e 3,84 a 10,52 (mg EQ. g-1 extrato), respectivamente. Os valores de CI50 da atividade sequestradora de radicais DPPH variaram de 31,62 a 87,84 μg/mL. A porcentagem de sequestro de radicais ABTS variou de 20,92 a 75,69 % e a porcentagem da capacidade antioxidante total (%CAT) de 15,13 a 43,71 %. Foi evidenciado também uma correlação positiva entre o conteúdo de fenóis totais e atividade antioxidante pelos ensaios do radical ABTS (ρ = 0,926; R2 = 0,858) e CAT (ρ = 0,933; R2 = 0,872), o que indica o papel chave dos compostos fenólicos na atividade antioxidante dos extratos estudados. Mais estudos são requeridos no sentido de se isolar esses compostos para melhor caracterizá-los, assim como a realização de testes de atividade antioxidante in vivo.
Brazil is considered the most biodiverse country in the world. Its vegetation areas from the Caatinga and Atlantic forest biomes represent potential sources for scanning biomolecules of scientific interest. Among these biomolecules are those endowed with antioxidant activity, substances capable to neutralize or repair the action of free radicals and thus fighting against oxidative stress. Several synthetic antioxidants are out there in the market, but studies have shown the possible toxic effects of these synthetic products, which became a stimulus for the search of natural antioxidants. This study aims to investigate the antioxidant activity of leaf extracts from 5 plant species found in the Caatinga and Atlantic forest biomes, namely: Abarema cochliacarpos (AC), Croton nummularius (CN), Myroxylon Peruiferum (MP), Stryphnodendron pulcherrimum (SP) e Tanaecium xanthophyllum (TX) by 3 in vitru methodologies: DPPH, ABTS radical scavenging activities and phosphomolybdenum method (total antioxidant capacity – TAC). Additionally a phytochemical screening of the extracts by thin layer chromatography (TLC) was conducted as well as measurement of total phenolic and flavonoid content in order to point out the possible active compounds responsible for such activity. The phytochemical screening analysis revealed the presence of saponins, flavonoids and phenylpropanoids in all plant extracts. However, terpenoids and proanthocyanidins were found in CA, alkaloids in CN, coumarins in MP, proanthocyanidins and mono-sesquiterpenoids in SP. Total phenolic and flavonoid content of the extracts ranged from 28.84 to 120.39 (mg GAE. g-1 extract) and 3.84 to 10.52 (QE mg. g-1 extract), respectively. The IC50 values of DPPH radical scavenging activity ranged from 31.62 to 87.84 μg/mL. The percentage ABTS radical scavenging activity ranged from 20.92 to 75.69 % and the percentage total antioxidant capacity (%TAC) ranged from 15.13 to 43.71 %. It was also demonstrated a positive correlation between total phenolic content and ABTS radical scavenging activity (ρ = 0.926, R2 = 0.858) and TAC (ρ = 0.933, R2 = 0.872), which denotes the key role of phenolic compounds in the antioxidant activity of the extracts studied. Further studies are required in order to isolate these compounds to characterize them better as well as assessment of their antioxidant activity in vivo.
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Damerval, Marc. "Identification et rôle physiologique des inclusions contenues dans le système nerveux central de la moule Mytilus edulis et de la crépidule Crepidula fornicata." Caen, 1985. http://www.theses.fr/1985CAEN2004.
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Les inclusions des cellules gliales et des neurones des ganglions cérébroïdes de crépidule et cérépleuraux de la moule ont été examinés. Une première approche a permis de distinguer les granules de neurosécretion de type neuroendocrine des inclusions pigmentées. L'ultrastructure de ces inclusions permet de les caracteriser avec précision. L'étude biochimique révèle la présence de carotènes et de différentes xanthophylles. On précise enfin le rôle de ces inclusions dans des conditions d'hypoxie et d'anoxie du milieu
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Dagenais, Guillaume. "Effet des pigments xanthophylles jaunes du gluten de maïs et utilisation de différents niveaux de lysine dans la moulée d'élevage; impacts sur les performances et la coloration de la truite arc-en-ciel (Onchorynchus mykiss)." Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25766/25766.pdf.
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Andersson, Jenny. "Dissecting the photosystem II light-harvesting antenna." Doctoral thesis, Umeå University, Plant Physiology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-25.
Full textAbstract:
In photosynthesis, sunlight is converted into chemical energy that is stored mainly as carbohydrates and supplies basically all life on Earth with energy.
In order to efficiently absorb the light energy, plants have developed the outer light harvesting antenna, which is composed of ten different protein subunits (LHC) that bind chlorophyll a and b as well as different carotenoids. In addition to the light harvesting function, the antenna has the capacity to dissipate excess energy as heat (feedback de-excitation or qE), which is crucial to avoid oxidative damage under conditions of high excitation pressure. Another regulatory function in the antenna is the state transitions in which the distribution of the trimeric LHC II between photosystem I (PS I) and II is controlled. The same ten antenna proteins are conserved in all higher plants and based on evolutionary arguments this has led to the suggestion that each protein has a specific function.
I have investigated the functions of individual antenna proteins of PS II (Lhcb proteins) by antisense inhibition in the model plant Arabidopsis thaliana. Four antisense lines were obtained, in which the target proteins were reduced, in some cases beyond detection level, in other cases small amounts remained.
The results show that CP29 has a unique function as organising the antenna. CP26 can form trimers that substitute for Lhcb1 and Lhcb2 in the antenna structure, but the trimers that accumulate as a response to the lack of Lhcb1 and Lhcb2 cannot take over the LHC II function in state transitions. It has been argued that LHC II is essential for grana stacking, but antisense plants without Lhcb1 and Lhcb2 do form grana. Furthermore, LHC II is necessary to maintain growth rates in very low light.
Numerous biochemical evidences have suggested that CP29 and/or CP26 were crucial for feedback de-excitation. Analysis of two antisense lines each lacking one of these proteins clearly shows that there is no direct involvement of either CP29 or CP26 in this process. Investigation of the other antisense lines shows that no Lhcb protein is indispensable for qE. A model for feedback de-excitation is presented in which PsbS plays a major role.
The positions of the minor antenna proteins in the PS II supercomplex were established by comparisons of transmission electron micrographs of supercomplexes from the wild type and antisense plants.
A fitness experiment was conducted where the antisense plants were grown in the field and seed production was used to estimate the fitness of the different genotypes. Based on the results from this experiment it is concluded that each Lhcb protein is important, because all antisense lines show reduced fitness in the field.
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Fondom, Nicolas Yebit. "PHYSIOLOGICAL AND BIOCHEMICAL ADAPTATIONS IN SOME CAM SPECIES UNDER NATURAL CONDITIONS: THE IMPORTANCE OF LEAF ANATOMY." Oxford, Ohio : Miami University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1260552594.
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Rockholm, David C. "Purification and characterization of violaxanthin de-epoxidase, an enzyme of the xanthophyll cycle." Thesis, 1995. http://hdl.handle.net/10125/9479.
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Kale, Aniket. "Purification of zein and xanthophylls from corn by process chromatography /." 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3242886.
Full textAbstract:
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006.Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6128. Adviser: Munir Cheryan. Includes bibliographical references (leaves 128-137) Available on microfilm from Pro Quest Information and Learning.
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Yen, Wen Jye, and 晏文潔. "Isolation of Xanthophylls from Orange Peels and Their Effects on the Oxidation Stability of Vegetable Oil." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/11258131833693462738.
Full textAbstract:
碩士輔仁大學
食品營養學系
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Carotenoids are important biological compounds, and some of them have been found effective against oxidation and skin cancer. Xanthophylls are important in the pigmentation of foods. However, the antioxidant action of xanthophylls remains unknow. The objective of this study is (1) to pre- pare xanthophylls by open column chromatography and compare the separation efficiency of xanthophylls with various ad- sorbents; (2) to identify xanthophylls by HPLC and spectrum analysis; (3) to investigate the antioxidant action of each xanthophyll when adding to vegetable oil. Results implied that the best separation efficiency of xanthophylls was achieved with cellulose as adsorbent, followed by magnesium oxide and calcium hydroxide. Purity of each xanthophyll was in the same order. Six bands of beta- cryptoxanthin, lutein 5,6-epoxide, violeoxanthin, 13-cis-vio- laxanthin, violaxanthin and sinesiaxanthin were resolved for cellulose, and four bands of beta-cryptoxanthin, violeoxan- thin, 13-cis-violaxanthin and violaxanthin were resolved for magnesium oxide. As for calcium hydroxide, only three bands were resolved, which included violeoxanthin, violaxanthin and sinesiaxanthin. A new reversed-phase HPLC solvent system of acetonitrile /methanol/ethyl acetate (80:10:10, v/v/v ) was developed to separate xanthophylls in orange peels. The flow rate was set at 0.7ml/min in the first 20 min and increased to 2.0 ml/min thereafter, and detection was set at 450nm and sensitivity at 0.2 AUFS. Ten pigments, sinesiaxanthin, neoxanthin, cis-neo- xanthin, violaxanthin, 13-cis- violaxanthin, violeoxanthin, lutein 5,6-epoxide, lutein, lutein 5,8-epoxide and beta-cry- ptoxanthin were found in Valencia orange peels, while seven pigments, sinesiaxanthin, neoxanthin, violaxanthin, 13-cis- violaxanthin, violeoxanthin, lutein and beta-cryptoxanthin were found in Taiwan orange peels.
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Liu, Cheng-Ju, and 劉千如. "A study on Pigment and Xanthophylls Content in the Difference Degree of Chlorophyll b-Deficient Mutants of Rice (Oryza sativa)." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/80049356964348329175.
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Gilmore, Adam Matthew. "Biochemistry of xanthophyll-dependent non-photochemical fluorescence quenching in isolated chloroplasts." Thesis, 1992. http://hdl.handle.net/10125/9472.
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Leandro, Filipa Ferreira. "Effects of thermal stress on the photoinactivation and repair of photosystem II in a xanthophyll cycledeficient green alga." Master's thesis, 2021. http://hdl.handle.net/10773/33639.
Full textAbstract:
Photosynthesis and primary productivity are very temperature-dependent.
Extremely high or low temperatures affect the enzymatic mechanisms of
photoprotection (xanthophyll cycle) and exacerbate the photo-imaging effects
of high light on photosystem II (PSII). A recently proposed hypothesis states
that abiotic stress, including mild cold and heat, enhances photoinhibition of
photosynthesis not by directly damaging the PSII, but by inhibiting repair
mechanisms. This work intends to test this hypothesis in an as yet unexplored
group of green algae (Bryopsidales) without a xanthophyll functional cycle.
In order to test this hypothesis, we used the measurement of chlorophyll
fluorescence, under light and thermal stress, and subsequent quantification of
D1 protein, using the Western blot technique. Our findings showed that for this
group of algae, the aforementioned hypothesis is not applicable, as the abiotic
stresses affected not only repair mechanisms but also exacerbated
photoinhibition. Consequently, the group of green algae (Bryopsidales)
showed great potential for future studies in the scope of the investigation
regarding repair mechanisms of photosystem II.A fotossíntese e a produtividade primária dependem profundamente da temperatura. Temperaturas extremamente altas ou baixas afetam os mecanismos enzimáticos de fotoproteção (ciclo das xantofilas) e exacerbam os danos provocados pela irradiação elevada no fotossistema II (PSII). Uma hipótese recentemente proposta afirma que o stress abiótico, incluindo frio e calor moderado, aumenta a fotoinibição da fotossíntese não por efeitos diretos no PSII, mas sim pela inibição dos mecanismos de reparação. Este trabalho pretende testar essa hipótese num grupo ainda inexplorado de algas verdes (Bryopsidales) que não possuem um ciclo das xantofilas funcional. Para testar esta hipótese, recorremos a medições da fluorescência da clorofila a, sob stress luminoso e térmico, e posterior quantificação da proteína D1, através da técnica do Western blot. Os nossos resultados mostraram que, para este grupo de algas, a hipótese acima mencionada, não é aplicável, pois os stresses abióticos afetaram não apenas os mecanismos de reparo, mas também exacerbaram a fotoinibição. Consequentemente, o grupo de algas verdes (Bryopsidales) apresentou um grande potencial para futuros estudos no âmbito da investigação dos mecanismos de reparação do fotossistema II.
Mestrado em Biologia Aplicada
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Scherrers, Roger [Verfasser]. "Carotinoide und Sauerstoff : antioxidative Eigenschaften von aromatischen und nicht aromatischen Xanthophyllen / vorgelegt von Roger Scherrers." 2006. http://d-nb.info/982670982/34.
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Poon, Wing Yee Louisa. "Comparative carotenoid and xanthophyll identification, accumulation, and retention as affected by the rp and RP genes in different colored carrots (Daucus carota)." 1997. http://catalog.hathitrust.org/api/volumes/oclc/39099946.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1997.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 98-102).