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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Citrus limonoids and flavonoids: extraction, antioxidant activity and effects on hamster plasma cholesterol distribution

Yu, Jun 01 November 2005 (has links)
Four in vitro models were used to measure the antioxidant activity of 11 citrus phytochemicals. The citrus limonoids and bergapten showed very weak antioxidant activity. The flavonoids demonstrated mild, to moderate, to strong antioxidant activity. In addition to some other commonly accepted structural features our data indicated that the hydroxyl group in position 6 of ring A could also increase the antioxidant activity of flavonoids. Compared with the active flavonoids, limonoids are highly oxygenated triterpenoids, with fewer hydroxyl groups to stabilize unpaired electrons (or scavenge free radicals). Bergapten lacks a hydroxyl group. This is the first report on the antioxidant activity of limonoids and neoeriocitrin. A feeding study using Syrian hamsters was followed to determine the effect of citrus limonoids and flavonoids on plasma cholesterol. Hamsters fed with limonin, limonin 17-Beta-D-glucopyranoside and grapefruit pulp significantly inhibited the increase of LDL/HDL-cholesterol (36.6%, 52.9% and 57% respectively) compared with the basal control (65.8%) and the pectin control (70%). Furthermore, hamsters fed with limonin had significantly larger LDL particle size (21.21 nm) compared with the control group (19.96 nm). Further studies demonstrated that LDLs from hamsters fed with limonin and limonin 17-Beta-D-glucopyranoside were less susceptible to oxidation. These data suggest that limonin, limonin 17-Beta-D-glucopyranoside and grapefruit pulp have potential inhibitory effects against atherogenesis. Supercritical CO2 (SC-CO2) was attempted to extract limonoids from grapefruit seeds and molasses. Limonin aglycone was successfully extracted with SC-CO2 directly from grapefruit seeds with the yield of 6.3 mg/g seeds at 48.3 MPa, 50˚C and 60 min with CO2 top feeding; and the limonin glucoside was extracted using SC-CO2 and ethanol as co-solvent from the defatted seeds with the yield of 0.73 mg/g seeds at 42 MPa, 52˚C, 45% ethanol (XEth=0.45) and 40 min with CO2 top feeding; and limonin glucoside also was extracted using SC-CO2 and ethanol with the yield of 0.61mg/g grapefruit molasses at 48.3 MPa, 50˚C and 10% ethanol (XEth=0.1), 40 min with CO2 top feeding. CO2 flow rate was around~5 l/min in experiments. The results demonstrated SC-CO2 extraction of limonoids from citrus juice industry byproducts has practical significance for future commercial production.
2

Lipossomas contendo ácido caurenoico ou extrato de Copaifera langsdorffii: desenvolvimento, caracterização e atividades antitumoral e tripanocida / Loaded liposomes with kaurenoic acid or Copaifera langsdorffii extract: development, characterization, antitumor and tripanocide activities

Costa, Ana Rita de Mello 18 April 2016 (has links)
A Copaifera langsdorffii é uma das plantas de incentivo governamental para pesquisas científicas e possui diversas atividades biológicas. Em especial, as atividades antitumoral e tripanocida foram abordadas neste estudo tendo o ácido caurenoico (AC) como marcador. Devido à escassa literatura sobre a extração do AC e à sua baixa solubilidade, sua extração foi estudada com solvente orgânico e por fluido supercrítico. A extração por fluido supercrítico é vantajosa já que não fornece extratos com resíduos de solventes orgânicos e é ecologicamente correta. Visto as atividades antitumoral e tripanocida do AC e estas atividades serem objeto de estudo nacional e mundial, o AC foi inserido em lipossomas convencionais e furtivos com a finalidade de torná-lo mais biodisponível, permitir seu alcance ao sítio-alvo e diminuir seus efeitos adversos. Assim, os objetivos deste trabalho foram segmentados em três vertentes: a) realizar o estudo e otimização da extração do ácido caurenoico a partir das folhas de C. langsdorffii, b) obter lipossomas convencionais, secá-los pelos métodos de secagem liofilização (FD), spray drying (SD) e spray freeze drying (SFD), comparar suas características físico-químicas e avaliar suas atividade antitumoral e tripanocida, c) obter lipossomas furtivos e avaliar sua seletividade tumoral. De maneira geral, os resultados das extrações sólido-líquido e por fluido supercrítico apresentaram boa seletividade e eficiência visto que foram capazes de fornecer extratos com aproximadamente 20% de AC. A extração por fluido supercrítico foi mais eficaz extraindo 26,2% de AC. Já os lipossomas convencionais secos por SD e SFD apresentaram-se mais semelhantes entre si quanto à propriedade de fluxo e morfologia, à interação do AC com os componentes da bicamada lipídica e à dissolução/ liberação que quando secos por FD. Os três métodos de secagem foram capazes de prolongar em seis meses a estabilidade do AC nos lipossomas quando comparado com a dispersão aquosa. Os lipossomas convencionais secos apresentaram citotoxicidade maior frente a células tumorais e menor frente a células normais quando carregados com o AC e comparados com os lipossomas convencionais vazios (sem AC). Foi possível sintetizar com sucesso o lipídeo ligado ao polietilenoglicol e ao ácido fólico com o intuito de preparar os lipossomas furtivos. Entretanto, estes lipossomas não apresentaram ação antitumoral seletiva quando comparados às células normais. / Copaifera langsdorffii is one of the Brazilian plants which receives governmental support for scientific researches and also presents several biological activities. The kaurenoic acid (KA) is a diterpenic acid constituent of this specie that presents, in special, antitumoral and tripanocide activities which were taken into account in this study. Due to the lack of KA extraction from C. langsdorffii leaves in the literature and to KA low solubility, its extraction was studied using solid-liquid and supercritical fluid extraction methods. The supercritical fluid extraction is advantageous since provides solvent-free extracts and is an environment friendly method. Since KA is antitumoral and tripanocide and both activities are subject of national and internacional studies, in this study, KA was added in conventional and stealth liposomes in order to increase its biodiponibility, to allow it reaching the target tissue and decrease its adverse effects. So, this work was divided in three segments: a) study and optimize the KA extraction from C. langsdorffii leaves by solid-liquid (SLE) and supercritical fluid (SFE) extraction methods, b) obtain conventional liposomes, dry them by freeze drying (FD), spray drying (SD) and spray freeze drying (SFD), compare their physico-chemical features and evaluate their antitumor and tripanocide activities, c) obtain stealth liposomes and evaluate their selective tumor activity. In a general way, the extraction methods result in high KA selective extraction by both SLE and SFE since they were able to extract nearly 20% of KA. The SFE was a bit more efficacious than SLE providing 26,2% of KA. Conventional liposomes dried by SD and SFD were more similar in fluidity and morphology, KA and liposome lipid compounds interaction and dissolution/ release than liposomes dried by FD. The three drying methods provided more stable liposomes than the aqueous solution liposomes. Dried conventional liposomes presented higher cytotoxicity to tumor cells and lower one to normal cells when loaded with KA than unloaded conventional liposomes. The lipid linked to poliethyleneglycol and to folic acid to prepare stealth liposomes were successfully synthesized. However, the stealth liposomes did not presented selective antitumor action in relation to normal cells.
3

Lipossomas contendo ácido caurenoico ou extrato de Copaifera langsdorffii: desenvolvimento, caracterização e atividades antitumoral e tripanocida / Loaded liposomes with kaurenoic acid or Copaifera langsdorffii extract: development, characterization, antitumor and tripanocide activities

Ana Rita de Mello Costa 18 April 2016 (has links)
A Copaifera langsdorffii é uma das plantas de incentivo governamental para pesquisas científicas e possui diversas atividades biológicas. Em especial, as atividades antitumoral e tripanocida foram abordadas neste estudo tendo o ácido caurenoico (AC) como marcador. Devido à escassa literatura sobre a extração do AC e à sua baixa solubilidade, sua extração foi estudada com solvente orgânico e por fluido supercrítico. A extração por fluido supercrítico é vantajosa já que não fornece extratos com resíduos de solventes orgânicos e é ecologicamente correta. Visto as atividades antitumoral e tripanocida do AC e estas atividades serem objeto de estudo nacional e mundial, o AC foi inserido em lipossomas convencionais e furtivos com a finalidade de torná-lo mais biodisponível, permitir seu alcance ao sítio-alvo e diminuir seus efeitos adversos. Assim, os objetivos deste trabalho foram segmentados em três vertentes: a) realizar o estudo e otimização da extração do ácido caurenoico a partir das folhas de C. langsdorffii, b) obter lipossomas convencionais, secá-los pelos métodos de secagem liofilização (FD), spray drying (SD) e spray freeze drying (SFD), comparar suas características físico-químicas e avaliar suas atividade antitumoral e tripanocida, c) obter lipossomas furtivos e avaliar sua seletividade tumoral. De maneira geral, os resultados das extrações sólido-líquido e por fluido supercrítico apresentaram boa seletividade e eficiência visto que foram capazes de fornecer extratos com aproximadamente 20% de AC. A extração por fluido supercrítico foi mais eficaz extraindo 26,2% de AC. Já os lipossomas convencionais secos por SD e SFD apresentaram-se mais semelhantes entre si quanto à propriedade de fluxo e morfologia, à interação do AC com os componentes da bicamada lipídica e à dissolução/ liberação que quando secos por FD. Os três métodos de secagem foram capazes de prolongar em seis meses a estabilidade do AC nos lipossomas quando comparado com a dispersão aquosa. Os lipossomas convencionais secos apresentaram citotoxicidade maior frente a células tumorais e menor frente a células normais quando carregados com o AC e comparados com os lipossomas convencionais vazios (sem AC). Foi possível sintetizar com sucesso o lipídeo ligado ao polietilenoglicol e ao ácido fólico com o intuito de preparar os lipossomas furtivos. Entretanto, estes lipossomas não apresentaram ação antitumoral seletiva quando comparados às células normais. / Copaifera langsdorffii is one of the Brazilian plants which receives governmental support for scientific researches and also presents several biological activities. The kaurenoic acid (KA) is a diterpenic acid constituent of this specie that presents, in special, antitumoral and tripanocide activities which were taken into account in this study. Due to the lack of KA extraction from C. langsdorffii leaves in the literature and to KA low solubility, its extraction was studied using solid-liquid and supercritical fluid extraction methods. The supercritical fluid extraction is advantageous since provides solvent-free extracts and is an environment friendly method. Since KA is antitumoral and tripanocide and both activities are subject of national and internacional studies, in this study, KA was added in conventional and stealth liposomes in order to increase its biodiponibility, to allow it reaching the target tissue and decrease its adverse effects. So, this work was divided in three segments: a) study and optimize the KA extraction from C. langsdorffii leaves by solid-liquid (SLE) and supercritical fluid (SFE) extraction methods, b) obtain conventional liposomes, dry them by freeze drying (FD), spray drying (SD) and spray freeze drying (SFD), compare their physico-chemical features and evaluate their antitumor and tripanocide activities, c) obtain stealth liposomes and evaluate their selective tumor activity. In a general way, the extraction methods result in high KA selective extraction by both SLE and SFE since they were able to extract nearly 20% of KA. The SFE was a bit more efficacious than SLE providing 26,2% of KA. Conventional liposomes dried by SD and SFD were more similar in fluidity and morphology, KA and liposome lipid compounds interaction and dissolution/ release than liposomes dried by FD. The three drying methods provided more stable liposomes than the aqueous solution liposomes. Dried conventional liposomes presented higher cytotoxicity to tumor cells and lower one to normal cells when loaded with KA than unloaded conventional liposomes. The lipid linked to poliethyleneglycol and to folic acid to prepare stealth liposomes were successfully synthesized. However, the stealth liposomes did not presented selective antitumor action in relation to normal cells.
4

Valorisation fonctionnelle et antioxydante des épidermes de pommes Golden Delicious / Functional and antioxidant valorization of apple peels Golden Delicious

Duchêne-Massias, Audrey 20 May 2015 (has links)
Les pommes sont considérées comme bénéfiques pour la santé, de part leur teneur en polyphénols qui leur confèrent l’étiquette "d’aliment santé". Les procédés de transformation agroalimentaire des fruits et légumes génèrent des coproduits qui sont considérés comme sans valeur par les industriels. Or, au regard des volumes générés, ce sont des sources abondantes de nutriments.Une voie possible de valorisation de ces coproduits est la réintroduction dans des produits alimentaires en tant qu’ingrédient, de façon à proposer des aliments enrichis en molécules fonctionnelles. Pour ce faire, deux voies ont été explorées: l’utilisation de poudres d’épidermes de pommes pour stabiliser une émulsion et l’extraction des polyphénols au moyen de la technologie à base de CO2 supercritique. Ce travail examine également des solutions pour remédier au problème de brunissement enzymatique, comme le traitement thermique et l’addition de poudres de fruits naturellement riches en agents antibrunissement.Les phases de préparation des pommes sont de réelles étapes de transformation qu’il faut optimiser et maîtriser afin de préserver toutes les propriétés antioxydantes des coproduits végétaux. Nos travaux ont également permis de mettre en évidence des propriétés plus fonctionnelles des pelures de pommes, comme agent stabilisant d’émulsions. L’impact des paramètres d’extraction a été mis en évidence par l’exploration de plusieurs conditions telles que la masse chargée, le broyage, le protocole ainsi que la température et la composition du fluide extractant. / Apples are considered beneficial to health, because of their content of phenolic compounds that confer the label "health food". Fruits and vegetables food processes generate byproducts that are considered worthless by industrial. However, given the volumes generated, they are rich sources of nutrients.One possible way of valorization of these byproducts is the reintroduction of food as ingredient, to propose fortified foods with functional molecules. To do this, two approaches have been explored: the use of apple peels powders to stabilize an emulsion and the extraction of phenolic compounds by supercritical CO2+ethanol. This work also discusses solutions to remedy the enzymatic browning, such as heat treatment and the addition of naturally rich fruit powders as anti-browning agents.Apples preparation phases are real transformation steps which it’s necessary to optimize and master to preserve all the antioxidant properties of fruits and vegetables byproducts. Our works also highlight more functional properties of apple peels as a stabilizing emulsions agent. The impact of extraction parameters was demonstrated by the exploration of several conditions such as the loaded weight, the grinding, the protocol as well as the temperature and composition of supercritical fluids.

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