Würzburg, University, Diss., 2002.

Würzburg, Univ., Diss., 2003. / Erscheinungsjahr an der Haupttitelstelle: 2002. Computerdatei im Fernzugriff.

Würzburg, Univ., Diss., 2003. / Erscheinungsjahr an der Haupttitelstelle: 2002. Computerdatei im Fernzugriff.

In the experiments presented in this work, third-order, time-resolved spectroscopy was applied to the disentanglement of nuclear and electronic degrees of freedom in polyatomic molecules. The motivation for approaching this problem was given by the decisive role that the coupling of nuclear and electronic dynamics plays in the mechanism of photochemical reactions and photobiological processes. In order to approach this complex problem, different strategies within the framework of time-resolved, four-wave mixing spectroscopy were developed that allowed for the dynamic as well as the energetic aspects of vibronic coupling in non-radiative transitions of polyatomic molecules to be addressed. This was achieved by utilizing the influence of optical as well as Raman resonances on four-wave mixing processes. These resonance effects on third-order, optical processes allow for a high selectivity to be attained with respect to the interrogation of specific aspects of molecular dynamics. The development of different strategies within the framework of time-resolved, four-wave mixing spectroscopy for addressing the problem of vibronic coupling began with the experiments on gaseous iodine. This simple, well investigated molecular system was chosen in order to unambiguously characterize the effect of Raman resonances on four-wave mixing processes. A time-resolved degenerative four-wave mixing (DFWM) experiment was carried out on gaseous iodine that allowed for the dynamics of coherent Stokes Raman scattering (CSRS) as well as a coherent anti-Stokes Raman scattering (CARS) to be observed parallel to the dynamics of a DFWM process at different spectral positions of the FWM signal. Here, the state-selectivity of these different FWM processes manifests itself in the vibrational wave packet dynamics on different electronic potentials of iodine. It could be shown that Raman resonances determine the selectivity with which these FWM processes prepare and interrogate nuclear dynamics in different electronic states. With the insight gained into the relevance of Raman resonant processes in FWM spectroscopy, an experimental scheme was devised that utilizes this effect to selectively interrogate the dynamics of a specific vibrational mode within a polyatomic molecule during a radiationless electronic transition. Here, a CARS process was employed to selectively probe specific vibrational modes of a molecular system by variably tuning the energy difference between the lasers involved in the CARS process to be in Raman resonance with the vibrational energy spacing of a particular vibrational mode. Using this aspect of a tunable resonance enhancement within a CARS scheme, this optical process was incorporated in a time-resolved pump-probe experiment as a mode-selective probe mechanism. This type of experimental configuration, that employs four pulsed laser fields, was classified as a pump-CARS scheme. Here, a laser pulse independent of the CARS process initiates the molecular dynamics that are interrogated selectively with respect to the vibrational mode of the system through the simultaneous interaction of the three pulsed fields involved in the CARS process. Time-resolution on a femtosecond timescale is achieved by introducing a time delay between the independent pump laser and the laser pulses of the CARS process. The experimental configuration of a pump-CARS scheme was applied to the study of the nuclear dynamics involved in the radiationless electronic transition between the first excited singlet state (S1) and the electronic ground state (S0) of all-trans-b-carotene. The mode-selective CARS probe allowed for the characteristic timescale with which specific vibrational modes are repopulated in the S0 state to be determined. From the varying repopulation times of specific vibrational modes, a mechanism with which the full set of vibrational states of the S0 potential are repopulated subsequent to the internal conversion process could be postulated. Most importantly, the form of nuclear motion that primarily funnels the population between the two electronic states could be identified as the C=C symmetric symmetric stretch mode in the polyene backbone of b-carotene. With this, the reaction coordinate of this radiationless electronic transition could be identified. The experiment shows, that the CARS probe is capable of determining the nuclear motion coupled to a radiationless electronic transition in complex polyatomic systems. The S1/S0 internal conversion process in b-carotene was further investigated with time-resolved transient gratings. Here, the energetic aspects of a non-adiabatic transition was addressed by determining the influence of the vibrational energy on the rate of this internal conversion. In order to compare the rate of internal conversion taking place out of vibrational ground state modes versus this transition initiating out of vibrationally hot modes, the strategy of shifting the probe mechanism in the transient grating scheme to spectral positions within and out of the red flank of the S1 absorption profile was pursued. The interrogation of different vibrational states was verified by determining the degree of vibrational cooling, taking place parallel to the internal conversion process. With this strategy, it could be shown that vibrationally hot states contribute to the internal conversion with a higher rate than vibrational ground state modes. In summary, different third-order, optical processes in the framework of time-resolved FWM were applied to the study of non-adiabatic dynamics in polyatomic molecules. By utilizing the effect of optical as well as Raman resonances on different FWM processes, it could be shown that third-order, time-resolved spectroscopy is a powerful tool for gaining insight into complex molecular dynamics such as vibronic coupling. The experiments presented in this work showed that the CARS process, as a mode-selective probe in time-resolved experiments, is capable of disentangling nuclear and electronic dynamics. / In der vorliegenden Arbeit wurden verschiedene zeitaufgelöste, optische Prozesse dritter Ordnung zur Untersuchung nicht-adiabatischer Dynamiken in polyatomaren Molekülen vorgestellt. Derartige Dynamiken haben ihre Ursache in Kopplungen zwischen der Kern- und Elektronenbewegung im jeweiligen molekularen System und spielen eine entscheidende Rolle in vielen photochemischen und photobiologischen Prozessen. Es wurden unterschiedliche Strategien im Rahmen der zeitaufgelösten Vierwellenmisch-Spektroskopie entwickelt, die die Untersuchung sowohl dynamischer als auch energetischer Aspekte der vibronischen Kopplung bei strahlungslosen elektronischen Übergängen in polyatomaren Systemen ermöglichen. Dabei wurden sowohl elektronische als auch Raman-Resonanzen ausgenutzt, um eine hohe Selektivität in der Abfrage der molekularen Dynamik zu erzielen. Um den Einfluss von Raman-Resonanzen auf Vierwellenmisch-Prozesse (FWM = four-wave mixing) eindeutig zu bestimmen, wurde zuerst das einfache und gut charakterisierte molekulare System Jod untersucht. Femtosekunden-zeitaufgelöste entartete Vierwellenmischung (DFWM = degenerate four-wave mixing) an gasförmigem Jod ermöglichte eine simultane Beobachtung der Dynamik kohärenter Stokesscher Raman-Streuung (CSRS = coherent Stokes Raman scattering) und kohärenter anti-Stokesscher Raman-Streuung (CARS = coherent anti-Stokes Raman scattering) zusammen mit der Dynamik des eigentlichen DFWM-Prozesses durch Detektion an unterschiedlichen spektralen Positionen des FWM-Signals. Die Zustandsselektivität dieser drei FWM-Prozesse, die sich in der Generierung und Abfrage von Schwingungswellenpaketen auf verschiedenen elektronischen Potentialen von Jod manifestiert, konnte innerhalb eines einzigen Messvorgangs charakterisiert werden. Es zeigte sich, dass die Selektivität der unterschiedlichen FWM-Prozesse maßgeblich durch den Einfluss von Raman-Resonanzen bestimmt wird. Basierend auf den so gewonnenen Erkenntnissen über den Einfluss von Raman-Resonanzen bei FWM-Prozessen, wurde ein experimentelles Schema entwickelt, das es ermöglicht, selektiv bestimmte Schwingungsmoden eines polyatomaren Moleküls während eines strahlungslosen elektronischen Übergangs abzufragen. Hierzu wurde ein CARS-Prozess, der auf eine Raman-Resonanz in einem molekularen System abgestimmt wurde, als Abfrageschritt in einem pump-probe-Schema eingesetzt. Dieses experimentelle Schema, bei dem vier gepulste Laser zum Einsatz kommen, wird in Analogie zu einem herkömmlichen pump-probe-Experiment als pump-CARS-Messung bezeichnet. Hierbei regt ein vom CARS-Prozess unabhängiger pump-Laser einen elektronischen Zustand an, dessen Besetzung durch die simultane Wechselwirkung mit den drei Laserpulsen des CARS-Prozesses modenselektiv abgefragt wird. Durch Einführung einer variablen Verzögerungszeit zwischen dem initiierenden pump-Laser und dem CARS-Prozess lässt sich die Relaxationsdynamik auf einer Femtosekunden-Zeitskala auflösen. Diese experimentelle Konfiguration wurde zur Untersuchung der Kerndynamik des strahlungslosen elektronischen Übergangs zwischen dem ersten elektronisch angeregten Zustand (S1) und dem elektronischen Grundzustand (S0) des b-Carotin eingesetzt. Die zustandsselektive Beobachtung der internen Konversion liefert die Zeitkonstanten, mit denen ausgewählte Schwingungsmoden im S0-Zustand von b-Carotin wiederbevölkert werden. Aufgrund der Tatsache, dass unterschiedlichen Moden unterschiedliche Zeitkonstanten zugeordnet werden konnten, wurde ein Modell aufgestellt, welches die Konversion in den elektronischen Grundzustand in Abhängigkeit von den Schwingungszuständen beschreibt. So konnte festgestellt werden, dass der Populationstransfer beim strahlungslosen Übergang von der S1- auf die S0-Potentialfläche vornehmlich über die symmetrische C=C-Streckschwingung verläuft.Mit diesem Experiment konnte gezeigt werden, dass ein CARS-Prozess als Abfrageschritt in einem zeitaufgelösten pump-probe Experiment, in der Lage ist, die Kerndynamik zu bestimmen, die mit einem strahlungslosen elektronischen Übergang in einem komplexen polyatomaren Molekül verbunden ist. Der energetische Aspekt des nicht-adiabatischen Übergangs zwischen dem S1- und S0-Zustand in b-Carotin wurde mittels zeitaufgelöster transienter Gitter untersucht (TG = transient grating). Hierbei wurde der Einfluss der Schwingungsenergie auf die Geschwindigkeit der internen Konversion bestimmt. Um die Reaktionsgeschwindigkeit der internen Konversion aus schwingungsangeregten Zuständen und Moden im Schwingungsgrundzustand des S1-Potentials zu vergleichen, wurde das Signal spektral aufgelöst detektiert. Hierbei beinhaltete die rote Flanke des Absorptionsprofils des S1-Zustandes die Dynamik der angeregten Schwingungsmoden. Die Abfrage der Dynamik an einer spektralen Position, die sich im Zentrum des Absorptionsprofils befindet, ermöglichte hingegen die Beobachtung der internen Konversion aus dem Grundzustand der Schwingungszustände. Mit der gewählten experimentellen Methode konnte gezeigt werden, dass schwingungsangeregte Zustände mit einer höheren Reaktionsgeschwindigkeit an der internen Konversion teilnehmen als Moden im Schwingungsgrundzustand. Zusammenfassend wurden in dieser Arbeit unterschiedliche optische Prozesse dritter Ordnung zur Untersuchung nicht-adiabatischer Dynamiken in polyatomaren Molekülen angewandt. Durch Ausnutzung von sowohl elektronischen als auch Raman-Resonanzen auf unterschiedliche FWM-Prozesse konnte gezeigt werden, dass optische Prozesse dritter Ordnung ein geeignetes Werkzeug zur Untersuchung komplexer Moleküldynamiken darstellen. Die Experimente in dieser Arbeit verdeutlichten, dass der CARS-Prozess als modenselektiver Abfrageschritt die spezifische Beobachtung von Kerndynamik während eines elektronischen Übergangs erlaubt.

Universiẗat, Diss., 2003--Hamburg.

No description available.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / As algas marinhas sÃo fontes de uma grande variedade de compostos benÃficos para o homem, dentre os quais se destacam os minerais, as fibras dietÃrias e as vitaminas (A, B, C e E). O objetivo deste trabalho foi verificar a existÃncia de variaÃÃo sazonal nos teores de α- e β-caroteno (carotenÃides provitamina A) e de α-tocoferol (vitamina E), em cinco espÃcies de macroalgas marinhas pertencentes ao gÃnero Caulerpa (FamÃlia Caulerpaceae, DivisÃo Chlorophyta), âin naturaâ e desidratada. Os conteÃdos desses nutrientes nas algas desidratadas foram comparados com aqueles nas algas âin naturaâ, com o objetivo de verificar se houve alteraÃÃo pelo processo de desidrataÃÃo. As espÃcies de macroalgas marinhas foram coletadas mensalmente, de janeiro a dezembro de 2006, durante as marÃs baixas na Praia do Pacheco, Caucaia- CE. As anÃlises de α- e β-caroteno e α-tocoferol foram realizadas a partir da extraÃÃo da alga em metanol-Ãgua (90:10) nas proporÃÃes 1:10 (p/v), nas amostras âin naturaâ, e 1:20 (p/v), nas desidratadas, saponificaÃÃo com hidrÃxido de potÃssio 5% por 30 min a 70ÂC e partiÃÃo em n-hexano que foi evaporado sob corrente de ar. O resÃduo foi suspenso em 1 mL de metanol no momento da anÃlise cromatogrÃfica e 100 μL foram injetados manualmente. O sistema cromatogrÃfico consistiu em uma coluna Waters Spherisorb-Hichrom S5ODS-2 (4,6 x 250 mm) e uma fase mÃvel constituÃda de metanol:tetrahidrofurano (90:10, v/v), com fluxo de 1,5 mL min-1. O detector foi ajustado em 450 nm e 292 nm e os cromatogramas registrados atravÃs do sistema UnicornTM versÃo 5.0. Todas as espÃcies de Caulerpa âin naturaâ e desidratadas analisadas no presente trabalho apresentaram tanto α-caroteno quanto β-caroteno e as suas distribuiÃÃes mostraram diferenÃas ao longo dos doze meses de coleta. De um modo geral, os teores de α-caroteno foram superiores aos de β-caroteno. As perdas nos conteÃdos de carotenÃides provitamina oscilaram entre 10% e 94%. Para que as algas analisadas neste trabalho fossem consideradas fontes excelentes de vitamina A seria necessÃrio que as porÃÃes consumidas diariamente variassem de 52 g a 689 g, quando consumidas âin naturaâ ou de 42 g a 469 g, quando desidratadas. As cinco espÃcies analisadas neste trabalho apresentaram α-tocoferol, tanto nas amostras âin naturaâ quanto nas desidratadas, com exceÃÃo de C. racemosa coletada em marÃo que apÃs ser submetida a secagem nÃo foi detectado α- tocoferol, e sua distribuiÃÃo foi variÃvel ao longo do ano. Nos teores de α- tocoferol foi observado perdas que variaram de 22 a 91%. As porÃÃes que deveriam ser consumidas diariamente para que as espÃcies de Caulerpa estudadas fossem capazes de fornecer 1/2 da IDR sÃo relativamente pequenas, devendo oscilar entre 11 g e 168 g, quando âin naturaâ, ou entre 13 g e 70 g, quando desidratadas. As quantidades de retinol equivalente e α-tocoferol equivalente nas algas analisadas no presente trabalho nÃo diferiram muito daquelas encontradas nos vegetais normalmente consumidos / Marine macroalgae are sources of a great variety of beneficial compounds such as minerals, dietary fibers and vitamins. The aim of this work was to verify seasonal variation upon both provitamin A carotenoids (α- and β-carotene) and vitamin E (α-tocopherol) contents in five species of the marine green macroalga Caulerpa both fresh and oven-dried at 40ÂC for 15 h. The contents in dried algae were compared to those in fresh algae to evaluate the losses after drying. Algal material was collected monthly from January to December 2006, in Pacheco Beach, Caucaia, CearÃ. Analyses of α- and β-carotene and α-tocopherol were carried out in extracts 1:10 (p/v) for fresh alga and 1:20 (p/v) for dried alga using aqueous methanol (90:10, v/v). They were saponified with 5% KOH and partitioned into n-hexane, which was then evaporated. The residues were suspended in 1 mL methanol prior to HPLC analyses. Aliquots of 100 μL were injected in a HPLC system consisting of a Waters Spherisorb-Hichrom S5 ODS-2 column (4.6 x 250 mm) and a mobile phase of methanol:tetrahydrofurane (90:10, v/v), delivered at 1.5 mL min-1. The detector was set at 450 nm for α- and β-carotene and 290 nm for α-tocopherol. Chromatograms were registered at UnicornTM version 5.0. All samples showed α- and β-carotene and α-tocopherol, but their distribution along the year was variable. In general, the contents of α-carotene were greater than those of β-carotene. The losses of α- and β-carotene varied between 10% and 94%. In order to be considered an excellent source of vitamin A, the daily consumption would be 52 g to 689 g of fresh alga or 42 g to 469 g of dried alga. α-Tocopherol was detected in all samples except in dried C. racemosa collected in March. Similar to the distribution of α- and β-carotene along the year, α-tocopherol contents varied too. Losses varied from 22% to 91%. Daily portions to supply 50% of the Recommended Daily Allowance (RDA) would be 11 g to 168 g of fresh alga or 13 g to 70 g of dried alga. Amounts of vitamin A (retinol equivalents) and vitamin E (tocopherol equivalents) in all algae analyzed were not very different from most vegetables normally consumed

<p></p><p></p><p><br></p><p></p><p>Vitamin A deficiency is the leading cause of childhood blindness affecting over 190 million preschool children around the world where the highest rates are found in Sub-Saharan Africa (1). The coexistence of this deficiency with shortfalls in iron and zinc has resulted in a shift in intervention strategies from single targeted approach to broader diet diversification. As a result, food-based strategies leveraging local nutrient-dense plants as natural fortificants have gained significant interest for their potential to simultaneously address multiple micronutrient, and in some instances macronutrient, deficiencies. However, the efficacy of such approach depends upon several factors including knowledge on the nutritional composition of native plant materials as well as strategies for their incorporation into staple consumer products. Additionally, there is lack of information on impact of concurrent introduction of mineral and provitamin A rich plants on the stability and bioavailability of each individual nutrients including changes in these factors over extended periods of exposure. This is a key point considering that many of these materials are reported to have potential inhibitors of carotenoid absorption (minerals, fiber and phenolics).</p><p></p><p>To address these research gaps, this dissertation focuses on three areas including 1) micronutrient, phytochemical and polysaccharide characterization of three commercially available native micronutrient dense African plant materials [Adansonia digitata (baobab), Moringa Oleifera (moringa) and Hibiscus Sabdariffa (hibiscus)] that have been targeted for use as natural iron fortificants; 2) determination of the impact of these materials on the bioaccessibility and intestinal uptake of provitamin A carotenoids from model composite cereal products and 3) assess the effect of longer term exposure to baobab and moringa on provitamin A carotenoid absorption and cellular differentiation biomarkers of human intestinal Caco-2 cells to better understand the potential impacts of extended exposure periods on long term micronutrient uptake. </p><p><br></p><p>Characterization of the plant fortificants focused on understanding both nutritive components and potential limiters of carotenoid bioavailability. Baobab, moringa and hibiscus all were found to contain key phytochemical and polysaccharide components that could be leveraged as nutritional and function ingredients. The relatively higher levels of lutein (57  4.6 g/g), zeaxanthin (11  0.1g/g) and -carotene (20  2 g/g) in moringa leaf powder support the notion that this plant material can be used as a source of provitamin A and non-provitamin A carotenoids. Phenolic analysis revealed the presence of substantial amounts of flavan-3-ols (1234  16 mg/100g) in baobab, anthocyanins (2001  56 mg/100g) in hibiscus, and flavonols (5352  139 mg/100g) in moringa leaf powder. Polysaccharide analysis demonstrated that the primary monosaccharide in baobab was found to be xyloglucan (47 %) which is in agreement with the tentative identification Xyloglucans (hemicellulosic polysaccharide) based on linkage analysis. Hibiscus was found to contain similar amounts of xylose (20%) and galactose (27%) supporting the presence of similar proportions of xyloglucans and pectic polysaccharides (type I, type II AG, RG I). The main monosaccharide in moringa was found to be galactose (36%) followed by glucose (23%) and linkage analysis revealed the presence of high proportions of pectic polysaccharides (type I, type II AG, RG I). These results provide insight into presence of potential enhancer or inhibitors of target micronutrient (provitamin A carotenoids or iron/zinc) bioavailability when used as functional and nutritional food ingredients.</p><p><br></p><p>Subsequently, the impact of mineral-rich baobab formulated at levels relevant for iron fortification on the bioaccessibility of provitamin A carotenoids (proVAC) from composite millet porridges containing dried carrot and mango was assessed using in vitro digestion. Proportions of millet flour and plant materials were dry blended to deliver ~25% of the RDA for vitamin A(VA) and iron(Fe) as follows: decorticated extruded millet (Senegalese Souna var.) (40-60%), dried proVA rich carrot and mango blend (30%), and dried Fe and ascorbic acid rich Adansonia digitata (baobab) (0-25%). While there were no significant differences in proVAC bioaccessibility from porridge formulations with 5 and 15% baobab (18.8+/-2.0 and 18.8±2.0% respectively) as compared to control containing no mineral-rich plant (23.8 +/- 1.2%), 25% baobab resulted in a significant decrease (p<0.05) in bioaccessibility of proVAC (13.3+/-1.6%). However, baobab inclusion did not impact intestinal uptake efficiency of provitamin A carotenoids by Caco-2 human intestinal cells</p><p><br></p><p>(3.3-3.6% -carotene and 3.7-4.5% for -carotene) across all formulation. These results suggest that any potential negative effects of baobab inclusion may be limited to food matrix interactions and digestion. This was confirmed in separate experiments that with experiments on baobab and carotenoid blends showing that digested baobab did not affect carotenoid absorption by Caco-2 cells. Overall these data support the notion that that modest inhibition of carotenoid bioaccessibility by baobab may not significantly limit carotenoid delivery from composite porridges. Furthermore, bioaccessible provitamin A content of a serving (200 g) of composite porridges can provide 27 - 48% of the RDA of vitamin A for children 1-3 years of age. </p><p><br></p><p>Finally, we evaluated the impact of long-term exposure to baobab and moringa digesta on Caco-2 cell differentiation biomarkers and provitamin A uptake to gain insight into how inclusion of these materials in to a daily diet may alter absorption and transport of nutrients or otherwise have potential negative effects on the intestine. Based on NMR analysis of intracellular metabolites in differentiating Caco-2 monolayers, significant alterations in specific osmotic pressure regulators, particularly glycerophosphocholine, taurine and myo-inositol were observed with repeated exposure to all treatment groups including the control (digested 0.9% saline solution). Changes in these metabolites levels have been linked with specific cellular function including protection against hyperosmotic stress and regulation of paracellular permeability of Caco-2 cells. Evaluation of carotenoid uptake comparing acute and acute on repeated exposure to treatment groups demonstrated that there was an overall significant reduction in carotenoid uptake with repeated exposure across all treatment groups including the control. Despite the reduction in carotenoid uptake, mRNA and protein levels of carotenoid transporters (CD-36, SR-B1 and FABP1) were not significantly altered with exposure through differentiation (except for SR-B1 protein levels). Decrease in SR-B1 levels may be due to bile acid accumulation from the digesta matrix which is known to regulate its own biosynthesis by a mechanism that involves the down-regulation SR-B1 expression to protect cells from cytotoxicity. Our results provide some insight into the impact of simulated gastrointestinal fluids alone on provitamin A uptake in this model system which are usually not taken into consideration in most Caco-2 cell studies. However, overall, these findings indicate that the introduction of baobab and moringa at levels relevant for delivery of meaningful levels of iron (15-23% RDA) should not have negative impacts on human intestinal function or carotenoid uptake over chronic use. </p><p>Taken together, our findings indicate that the three native Africa plant materials selected for investigation in these studies can be important sources of key micronutrients (iron, zinc and provitamin A carotenoids) and have potential as natural fortificants with application in staple foods such as cereal porridges. Incorporation of these plant materials, do not appear to negatively affect carotenoid bioavailability although there is a potential for their interaction during micellarization of carotenoids during normal digestion. While in vivo studies evaluating the bioavailability of provitamin A carotenoids from such composite formulations are required, these data support the further exploration of such natural fortification strategies in addressing micronutrient deficiencies in local African communities. </p><div><br></div><p><br></p>

University, Diss., 2003--Würzburg. / Erscheinungsjahr an der Haupttitelstelle: 2002.

PIRES, Kelma Maria dos Santos. Avaliação sazonal de carotenóides provitamina A (α– e β– caroteno) e vitamina E (α–tocoferol) em macroalgas marinhas pertencentes a família Caulerpacea (Divisão Chlorophyta). 2007. 94 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia de Pesca, Fortalezza-CE, 2007 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-18T14:11:47Z No. of bitstreams: 1 2007_dis_kmspires.pdf: 561534 bytes, checksum: 2fbf133b889f47da3a32efc273c3f7ec (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-18T14:12:01Z (GMT) No. of bitstreams: 1 2007_dis_kmspires.pdf: 561534 bytes, checksum: 2fbf133b889f47da3a32efc273c3f7ec (MD5) / Made available in DSpace on 2016-07-18T14:12:01Z (GMT). No. of bitstreams: 1 2007_dis_kmspires.pdf: 561534 bytes, checksum: 2fbf133b889f47da3a32efc273c3f7ec (MD5) Previous issue date: 2007 / Marine macroalgae are sources of a great variety of beneficial compounds such as minerals, dietary fibers and vitamins. The aim of this work was to verify seasonal variation upon both provitamin A carotenoids (α- and β-carotene) and vitamin E (α-tocopherol) contents in five species of the marine green macroalga Caulerpa both fresh and oven-dried at 40°C for 15 h. The contents in dried algae were compared to those in fresh algae to evaluate the losses after drying. Algal material was collected monthly from January to December 2006, in Pacheco Beach, Caucaia, Ceará. Analyses of α- and β-carotene and α-tocopherol were carried out in extracts 1:10 (p/v) for fresh alga and 1:20 (p/v) for dried alga using aqueous methanol (90:10, v/v). They were saponified with 5% KOH and partitioned into n-hexane, which was then evaporated. The residues were suspended in 1 mL methanol prior to HPLC analyses. Aliquots of 100 μL were injected in a HPLC system consisting of a Waters Spherisorb-Hichrom S5 ODS-2 column (4.6 x 250 mm) and a mobile phase of methanol:tetrahydrofurane (90:10, v/v), delivered at 1.5 mL min-1. The detector was set at 450 nm for α- and β-carotene and 290 nm for α-tocopherol. Chromatograms were registered at UnicornTM version 5.0. All samples showed α- and β-carotene and α-tocopherol, but their distribution along the year was variable. In general, the contents of α-carotene were greater than those of β-carotene. The losses of α- and β-carotene varied between 10% and 94%. In order to be considered an excellent source of vitamin A, the daily consumption would be 52 g to 689 g of fresh alga or 42 g to 469 g of dried alga. α-Tocopherol was detected in all samples except in dried C. racemosa collected in March. Similar to the distribution of α- and β-carotene along the year, α-tocopherol contents varied too. Losses varied from 22% to 91%. Daily portions to supply 50% of the Recommended Daily Allowance (RDA) would be 11 g to 168 g of fresh alga or 13 g to 70 g of dried alga. Amounts of vitamin A (retinol equivalents) and vitamin E (tocopherol equivalents) in all algae analyzed were not very different from most vegetables normally consumed / As algas marinhas são fontes de uma grande variedade de compostos benéficos para o homem, dentre os quais se destacam os minerais, as fibras dietárias e as vitaminas (A, B, C e E). O objetivo deste trabalho foi verificar a existência de variação sazonal nos teores de α- e β-caroteno (carotenóides provitamina A) e de α-tocoferol (vitamina E), em cinco espécies de macroalgas marinhas pertencentes ao gênero Caulerpa (Família Caulerpaceae, Divisão Chlorophyta), “in natura” e desidratada. Os conteúdos desses nutrientes nas algas desidratadas foram comparados com aqueles nas algas “in natura”, com o objetivo de verificar se houve alteração pelo processo de desidratação. As espécies de macroalgas marinhas foram coletadas mensalmente, de janeiro a dezembro de 2006, durante as marés baixas na Praia do Pacheco, Caucaia- CE. As análises de α- e β-caroteno e α-tocoferol foram realizadas a partir da extração da alga em metanol-água (90:10) nas proporções 1:10 (p/v), nas amostras “in natura”, e 1:20 (p/v), nas desidratadas, saponificação com hidróxido de potássio 5% por 30 min a 70°C e partição em n-hexano que foi evaporado sob corrente de ar. O resíduo foi suspenso em 1 mL de metanol no momento da análise cromatográfica e 100 μL foram injetados manualmente. O sistema cromatográfico consistiu em uma coluna Waters Spherisorb-Hichrom S5ODS-2 (4,6 x 250 mm) e uma fase móvel constituída de metanol:tetrahidrofurano (90:10, v/v), com fluxo de 1,5 mL min-1. O detector foi ajustado em 450 nm e 292 nm e os cromatogramas registrados através do sistema UnicornTM versão 5.0. Todas as espécies de Caulerpa “in natura” e desidratadas analisadas no presente trabalho apresentaram tanto α-caroteno quanto β-caroteno e as suas distribuições mostraram diferenças ao longo dos doze meses de coleta. De um modo geral, os teores de α-caroteno foram superiores aos de β-caroteno. As perdas nos conteúdos de carotenóides provitamina oscilaram entre 10% e 94%. Para que as algas analisadas neste trabalho fossem consideradas fontes excelentes de vitamina A seria necessário que as porções consumidas diariamente variassem de 52 g a 689 g, quando consumidas “in natura” ou de 42 g a 469 g, quando desidratadas. As cinco espécies analisadas neste trabalho apresentaram α-tocoferol, tanto nas amostras “in natura” quanto nas desidratadas, com exceção de C. racemosa coletada em março que após ser submetida a secagem não foi detectado α- tocoferol, e sua distribuição foi variável ao longo do ano. Nos teores de α- tocoferol foi observado perdas que variaram de 22 a 91%. As porções que deveriam ser consumidas diariamente para que as espécies de Caulerpa estudadas fossem capazes de fornecer 1/2 da IDR são relativamente pequenas, devendo oscilar entre 11 g e 168 g, quando “in natura”, ou entre 13 g e 70 g, quando desidratadas. As quantidades de retinol equivalente e α-tocoferol equivalente nas algas analisadas no presente trabalho não diferiram muito daquelas encontradas nos vegetais normalmente consumidos