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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

Fotoprotetores bioativos contendo extrato de mirtilo (Vaccinium myrtillus L.): caracterização físico-química e funcional / Bioactive sunscreens containing blueberry (Vaccinium myrtillus L.): physicochemical and funcional characterization

Ruscinc, Nadia 09 March 2018 (has links)
Os efeitos deletérios causados pela radiação ultravioleta (UV) e o aumento significativo no diagnóstico de câncer de pele, confirmam a necessidade de um progresso significativo na pesquisa de produtos fotoprotetores eficazes e seguros, para proteção eficaz da pele. As formulações atuais associam filtros UV, orgânicos e inorgânicos, com eficácia limitada e que podem acarretar reações cutâneas adversas. O extrato de Vaccinium myrtillus L. (EVM) apresenta em sua composição compostos fenólicos, como as antocianinas, que possuem atividade antioxidante. O objetivo deste estudo foi avaliar formulações fotoprotetoras contendo extrato de Vaccinium myrtillus L. com amplo espectro de ação e concentrações reduzidas de filtros UV. As emulsões contendo ou não EVM e filtros orgânicos (octocrileno e metileno bis-benzotriazolil tetrametilbutilfenol) e inorgânico (dióxido de titânio) foram avaliadas e consideradas estáveis perante parâmetros pré-definidos. O perfil de segurança foi determinado pelo método in vitro Hen´s Egg Test - Chorioallantoic Membrane (HET-CAM) e o potencial antirradicalar do EVM foi confirmado pelo teste de DPPH• A formulação fotoprotetora acrescida de 5,0% de EVM foi avaliada quanto à eficácia fotoprotetora in vivo e in vitro e não demonstrou aumento significativo no FPS quando comparada à formulação que continha somente os filtros solares e, no ensaio referente à hidratação da pele, não houve alteração nos dados, segundo teste de eficácia clínica. Os resultados obtidos sugeriram que mesmo não apresentando aumento no valor de FPS in vivo, a formulação fotoprotetora contendo o extrato, poderia atuar como agente antioxidante evitando os danos provocados pela radiação UV. / The deleterious effects caused by ultraviolet radiation (UV) and the significant increase in the diagnosis of skin cancer confirm the need for significant progress in researching effective and safe sunscreen products for effective skin protection. Current formulations associate UV, organic and inorganic filters with limited efficacy that can lead to adverse skin reactions. Vaccinium myrtillus extract (EVM) contains in its composition polyphenols compounds, such as anthocyanins, which have been antioxidant activity. The objective of this study was to evaluate sunscreens containing EVM with broad action spectrum and reduced concentrations of UV filters. Emulsions containing or not EVM and organic (octocrylene and methylene bis-benzotriazolyl tetramethylbutylphenol) and inorganic (titanium dioxide) filters were evaluated and considered stable under pre-defined parameters. The safety of the emulsion was assessed was determined by the in vitro Hen´s Egg Test - Chorioallantoic Membrane method (HET-CAM) and the antiradical potential of EVM was confirmed by the DPPH• test. The sunscreen formulation containing EVM 5.0% was photoprotective efficacy evaluated in vivo and in vitro and did not show a significant increase in SPF when compared the formulation only with UV filters and no improves skin hydration, according to clinical efficacy assay. The results of the study suggest that even without increase SPF in vivo, the sunscreen formulation containing the extract may show antioxidant activity avoiding damage caused by UV.
2

Fotoprotetores bioativos contendo extrato de mirtilo (Vaccinium myrtillus L.): caracterização físico-química e funcional / Bioactive sunscreens containing blueberry (Vaccinium myrtillus L.): physicochemical and funcional characterization

Nadia Ruscinc 09 March 2018 (has links)
Os efeitos deletérios causados pela radiação ultravioleta (UV) e o aumento significativo no diagnóstico de câncer de pele, confirmam a necessidade de um progresso significativo na pesquisa de produtos fotoprotetores eficazes e seguros, para proteção eficaz da pele. As formulações atuais associam filtros UV, orgânicos e inorgânicos, com eficácia limitada e que podem acarretar reações cutâneas adversas. O extrato de Vaccinium myrtillus L. (EVM) apresenta em sua composição compostos fenólicos, como as antocianinas, que possuem atividade antioxidante. O objetivo deste estudo foi avaliar formulações fotoprotetoras contendo extrato de Vaccinium myrtillus L. com amplo espectro de ação e concentrações reduzidas de filtros UV. As emulsões contendo ou não EVM e filtros orgânicos (octocrileno e metileno bis-benzotriazolil tetrametilbutilfenol) e inorgânico (dióxido de titânio) foram avaliadas e consideradas estáveis perante parâmetros pré-definidos. O perfil de segurança foi determinado pelo método in vitro Hen´s Egg Test - Chorioallantoic Membrane (HET-CAM) e o potencial antirradicalar do EVM foi confirmado pelo teste de DPPH• A formulação fotoprotetora acrescida de 5,0% de EVM foi avaliada quanto à eficácia fotoprotetora in vivo e in vitro e não demonstrou aumento significativo no FPS quando comparada à formulação que continha somente os filtros solares e, no ensaio referente à hidratação da pele, não houve alteração nos dados, segundo teste de eficácia clínica. Os resultados obtidos sugeriram que mesmo não apresentando aumento no valor de FPS in vivo, a formulação fotoprotetora contendo o extrato, poderia atuar como agente antioxidante evitando os danos provocados pela radiação UV. / The deleterious effects caused by ultraviolet radiation (UV) and the significant increase in the diagnosis of skin cancer confirm the need for significant progress in researching effective and safe sunscreen products for effective skin protection. Current formulations associate UV, organic and inorganic filters with limited efficacy that can lead to adverse skin reactions. Vaccinium myrtillus extract (EVM) contains in its composition polyphenols compounds, such as anthocyanins, which have been antioxidant activity. The objective of this study was to evaluate sunscreens containing EVM with broad action spectrum and reduced concentrations of UV filters. Emulsions containing or not EVM and organic (octocrylene and methylene bis-benzotriazolyl tetramethylbutylphenol) and inorganic (titanium dioxide) filters were evaluated and considered stable under pre-defined parameters. The safety of the emulsion was assessed was determined by the in vitro Hen´s Egg Test - Chorioallantoic Membrane method (HET-CAM) and the antiradical potential of EVM was confirmed by the DPPH• test. The sunscreen formulation containing EVM 5.0% was photoprotective efficacy evaluated in vivo and in vitro and did not show a significant increase in SPF when compared the formulation only with UV filters and no improves skin hydration, according to clinical efficacy assay. The results of the study suggest that even without increase SPF in vivo, the sunscreen formulation containing the extract may show antioxidant activity avoiding damage caused by UV.
3

Anthocyanins under drought and drought-related stresses in bilberry (<em>Vaccinium myrtillus</em> L.)

Tahkokorpi, M. (Marjaana) 07 June 2010 (has links)
Abstract The aim was to study the effects of drought and indirect drought-related stresses on anthocyanin content in bilberry (Vaccinium myrtillus L.). Anthocyanin content was also studied in relation to developmental stage (juvenile vs. mature leaves, previous vs. current-year stems). It was hypothesised that drought-stressed plants accumulate anthocyanins, but their direct role in osmotic regulation was questioned. Direct drought was created by preventing water supply. Freezing-induced dehydration was accomplished by removal of snow. Effects of summertime chilling (+2 °C during active growth, +5/0 °C during frost hardening) on water status were tested. The trace metal Nickel (Ni) was applied to the soil, as Ni may interfere with plant water relations at the rhizospheric level. Salt (Na+) was added to the soil to observe salt-induced disturbance in osmotic balance and ion homeostasis. Tissue water content (TWC) decreased and anthocyanin level increased under direct drought, especially in the mature leaves. The freezing-stressed plants contained the same TWC and anthocyanin levels in mid-winter compared to plants that overwintered below snow. The freezing-stressed plants had lower TWC and a similar anthocyanin level in early spring, and lower TWC and anthocyanin level in late spring than plants that overwintered below snow. In the summer and autumn following snow removal, current-year stems of freezing-stressed plants had the same TWC, but higher levels of anthocyanins than current-year stems of plants that overwintered below snow. New growth was thus affected by the freezing stress experienced by previous-year stems. Chilling had no effect on anthocyanins. Although TWC decreased and anthocyanin level increased from active growth to the beginning of frost hardening, no increase was observed during frost hardening. Ni did not cause drought stress in the aboveground shoots, but anthocyanin level decreased in the aboveground shoots along with Ni accumulation in the belowground stems. Na+ increased TWC in the belowground stems, but decreased TWC and anthocyanin level in the aboveground stems. It is proposed that anthocyanins do not have direct role in osmotic regulation, or in the development of freezing tolerance. It is suggested that the increase in anthocyanin level under direct drought stress is mainly due to the photoprotection of chlorophylls by anthocyanins. This is supported by two facts: (1) At increased anthocyanin level in the juvenile leaves, chlorophyll a was stabilized despite continuing drought stress, and (2) after the initial peak in the mature leaves, the accumulation of anthocyanins ceased although the drought became more severe. As chlorophyll a decreased in the mature leaves due to senescence, there was less demand for such high levels of anthocyanins.
4

Extraction, identification and antioxidant activity of the phenolic secondary metabolites isolated from the leaves, stems and fruits of two shrubs of the Ericaceae family / Extraction, identification et activité antioxydante des métabolites secondaires phénoliques isolés des feuilles, branches et fruits de deux arbrisseaux de la famille des Ericacées

Bujor, Oana-Crina 19 April 2016 (has links)
La myrtille et l’airelle rouge, deux arbrisseaux de la famille des Ericacées, sont consommées comme des aliments, boissons et suppléments alimentaires pour leur valeur nutritionnelle et leur richesse en polyphénols antioxydants. Dans les plantes, la qualité et la quantité de composés phénoliques sont influencées par les parties morphologiques de la plante à utiliser. En particulier, les composés phénoliques des végétaux exercent leur activité antioxydante dans la protection des lipides alimentaires et le compartiment gastrique a été proposé comme le site majeur pour le stress oxydatif lié au régime alimentaire. L’objectif général de cette thèse était d’étudier les variations saisonnières des composés phénoliques d’extraits de feuilles, branches et fruits de la myrtille et de l’airelle rouge ainsi que l’activité antioxydante de ces extraits. Pour cette étude, des extraits aqueux et hydroéthanoliques (fruits uniquement) des échantillons collectés en mai, juillet et septembre pendant les années 2013-2014 ont été obtenus par extraction assistée par microondes.Les analyses qualitatives et quantitatives par UPLC / MS des extraits de la myrtille ont montré la présence de dérivés de l’acide caféique et de l’acide p-coumarique et des glycosides de flavonols dans les feuilles tandis que des oligomères de flavanols étaient aussi présents dans les branches, et ce dans des quantités élevées. La thioacidolyse a révélé de faibles degrés de polymérisation (2-4) et l’(-)-épicatéchine comme unité principale des flavan-3-ols. Il existe une très bonne corrélation entre la Somme des Composés phénoliques par UPLC et la Teneur en Polyphenols Totaux ou l’activité antioxydante dans le test DPPH, excepté pour les feuilles du mois de mai. Ces dernières sont relativement riches en dérives de l’acide p-coumarique. Les effets de la saison apparaissent plus marqués pour les feuilles qui présentent une plus grande activité antioxydante et teneur en polyphénols en juillet et septembre. Ces paramètres sont optimaux en juillet pour les branches de myrtille. La période de de cueillette peut être définie en fonction des structures phénoliques désirées.Dans l’airelle rouge, la présence prédominante de monomères et oligomères de flavanols et de glycosides de quercétine a été identifiée dans toutes les parties morphologiques. Les proanthocyanidines contiennent la (+)-catéchine et la (-)-épicatéchine comme unités d'extension et terminale. De plus, la teneur en polyphénols totaux (méthode de Folin, UPLC) a montré une augmentation légère mais significative de mai à septembre pour les feuilles et les branches. Cette augmentation a été confirmée pour l'activité antioxydante dans le test DPPH pour les feuilles et les branches en 2014.L’activité antioxydante des extraits de myrtille et d’airelle rouge lors de l’inhibition de l’oxydation lipidique (accumulation de diènes conjugués) a été évaluée dans des conditions in vitro simulant la digestion. Tout d'abord, l'inhibition de l’oxydation lipidique a été conduite sur des émulsions huile de tournesol-dans-eau stabilisées par la sérum albumine bovine (BSA) ou des phospholipides d’œuf (PL), qui simulent l’état physique des lipides alimentaires lors de la digestion gastrique. L’oxydation a été initiée par la metmyoglobine, une forme de fer apportée par la viande rouge. Dans les deux modèles d’émulsions, les extraits aqueux des branches et des feuilles et l’extrait hydroethanolique de fruit de myrtille sont des inhibiteurs plus efficaces de l'oxydation lipidique durant la première phase de digestion (pH 5) que durant la seconde phase (pH 3). D’autre part, un extrait de feuilles de myrtille a été testé dans un modèle complet de digestion in vitro statique (étapes orale, gastrique et intestinale). L'oxydation lipidique, rapide lors de la l’étape gastrique (systèmes BSA et PL) et puis plus lente lors de l'étape intestinale (système PL), a été totalement inhibée par l'extrait de feuilles de myrtille. / Bilberry and lingonberry, two shrubs of the Ericaceae family, are consumed as food, beverage and dietary supplements due to their nutritional value and richness in antioxidant polyphenols. In plants, the quality and quantity of phenolic compounds are influenced by the parts of the plant to be used. In particular, plant phenolic compounds provide antioxidant activity in the protection of dietary lipids from oxidation and the gastric compartment has been proposed as a major site for diet-related oxidative stress. The aim of this thesis is to simultaneously assess the seasonal variations of phenolic compounds in leaves, stems, and fruits of bilberry and lingonberry extracts, as well as their antioxidant activity. For this study, aqueous and hydroethanolic (only fruits) extracts of bilberry and lingonberry samples collected in May, July and September during the years 2013-2014 were obtained under microwave-assisted extraction.In bilberry extracts, qualitative and quantitative analyses by UPLC/MS showed the presence of caffeoyl derivatives, p-coumaroyl derivatives, and flavonol glycosides in leaves whereas in stems, flavanol oligomers were additionally identified in significant amounts. Thioacidolysis revealed low degrees of polymerization (2-4) and (-)-epicatechin as the main flavan-3-ol unit. The sum of the phenolic compounds by UPLC was highly correlated with the Total Polyphenol Content and the antioxidant activity in the DPPH test for all the extracts except those of May leaves. The latter were relatively richer in p-coumaric acid derivatives. Seasonal effects were more marked for leaves which exhibited higher antioxidant activities and phenolic contents in July and September when these parameters were maximum in July for bilberry stems. The harvest period can be refined based on the desired phenolic structures. For lingonberry, the predominant presence of monomers and oligomers of flavanols and quercetin glycosides was found in all the morphological parts. Proanthocyanidins contain (+)-catechin and (-)-epicatechin as both extension and terminal units. The sum of the phenolic compounds by UPLC was less correlated with the Total Polyphenol Content and the antioxidant activity in the DPPH test than in bilberry. Furthermore, the total phenolic content (Folin method, UPLC) showed a slight but significant increase from May to September for both leaves and stems. This increase was confirmed for the antioxidant activity by the DPPH test for both leaves and stems in 2014.The antioxidant activity of bilberry and lingonberry extracts against lipid oxidation (formation of lipid-derived conjugated dienes) was evaluated under in vitro simulated digestion conditions. Firstly, the inhibition of lipid oxidation was performed using sunflower oil-in-water emulsions stabilized by bovine serum albumin (BSA) or egg yolk phospholipids (PL), both emulsifiers mimicking dietary components. Oxidation was initiated by metmyoglobin, a form of dietary iron from red meat. In both emulsion models, aqueous extracts from stems and leaves and the hydroethanolic fruit extract of bilberry proved to be more efficient inhibitors of lipid oxidation in the early phase of digestion (pH 5) than during the second phase (pH 3). Secondly, a bilberry leaf extract was tested in the inhibition of lipid oxidation in a complete static in vitro digestion model (oral, gastric and intestinal phases). The fast lipid oxidation in the gastric step (BSA and PL systems) and the slower lipid oxidation in the intestinal step (PL system) were totally inhibited by the bilberry leaf extract.

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