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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.
201

Bioacessibilidade, atividade antioxidante e antiproliferativa de compostos bioativos fenólicos de sucos de frutos da família Myrtaceae / Bioaccessibility, antioxidant and antiproliferative activity of bioactive phenolic compounds in juices from fruits of Myrtaceae family

Flávia Maria Beteto 16 November 2015 (has links)
Diversos estudos com compostos fenólicos têm demonstrado os efeitos benéficos destas substâncias frente a diversas patologias, incluindo alguns tipos de câncer. Considerando que os polifenóis da dieta, não absorvidos, podem permanecer no trato gastrointestinal por um período prolongado, e as células do epitélio intestinal podem ser regularmente expostas a estes compostos, é importante avaliar seu potencial efeito benéfico no trato gastrointestinal. Entretanto, é necessário determinar como o processo de digestão afeta a estabilidade e propriedades químicas destes compostos. O objetivo deste estudo foi avaliar a bioacessibilidade dos polifenóis de sucos de frutas da família Myrtaceae: cagaita (Eugenia dysenterica DC), camu-camu (Myrciaria dubia Mc Vaugh) e jaboticaba (Myrciaria cauliflora B.), o efeito da digestão gastrintestinal in vitro sobre sua atividade antioxidante, e a ação dos polifenóis dos sucos digeridos sobre a proliferação, ciclo celular e apoptose em células Caco-2 de adenocarcinoma de cólon humano. A digestão simulada in vitro causou perdas de alguns compostos, tais como os derivados de cianidina encontrados na jaboticaba, possivelmente devido às condições do pH intestinal. No entanto, o conteúdo de ácido elágico livre aumentou em todos os sucos analisados, indicando a ocorrência de hidrólise durante o processo de digestão in vitro, liberando ácido elágico a partir dos elagitaninos. A atividade antioxidante dos polifenóis foi afetada de forma diferente pela digestão in vitro, de acordo com o suco, provavelmente relacionado à composição de polifenóis. Quanto à proliferação, ciclo celular e apoptose, os polifenóis a partir da fração bioacessível do camu-camu apresentou aproximadamente 30% de inibição da proliferação, seguido pela cagaita com 24%, ambos na maior concentração testada (50 µg EAG/mL). Jaboticaba não apresentou efeito inibitório nas concentrações testadas, entretanto os compostos fenólicos de todas as frações bioacessíveis (50 µg EAG/mL) apresentaram parada no ciclo celular na fase G2/M sem induzir apoptose nas células Caco-2. Os resultados sugerem que os polifenóis das Myrtaceae podem modular a proliferação nas células Caco-2 por bloqueio da progressão do ciclo celular na fase G2/M e assim oferecer efeitos benéficos para a saúde do trato gastrointestinal. / Several studies with phenolic compounds have shown the beneficial effects of these substances across various diseases, including some types of cancer. Considering that most of the polyphenols and their conjugates, unabsorbed, can remain in the lumen for a prolonged period, and epithelial cells lining the intestine are regularly exposed to these compounds, it is important to evaluate their potential beneficial effects in the gastrointestinal tract. However it is necessary to evaluate how the digestion process affects the stability and chemical properties of these compounds. The aims of this study were to evaluate the bioaccessibility of polyphenols in juices from Brazilian native fruits of the Myrtaceae family (cagaita, camu-camu and jaboticaba), the effect of in vitro gastrointestinal digestion on their antioxidant activity, and the action of polyphenols from digested juices on proliferation, cell cycle and apoptosis in human colon cancer Caco-2 cells. The results showed that in vitro gastrointestinal digestion caused losses of some polyphenols, such as cyanidins derivatives from jaboticaba, possibly due to the exposure to conditions of intestinal pH. However, contents of free ellagic acid increased in all the juices analyzed, indicating the occurrence of hydrolysis during in vitro digestion process, releasing ellagic acid from the ellagitannins. The antioxidant activity was affected for different forms by the in vitro digestion, demonstrating be related to individual components present in each sample and the mechanisms by which they act as antioxidants. Regarding the evaluation of proliferation, cell-cycle and apoptosis, polyphenols from bioaccessible fractions of camu-camu showed about 30% of inhibition of proliferation, followed by cagaita with 24%, both at the highest concentration tested (50 µg GAE/mL). Jaboticaba did not show inhibitory effect at the concentrations tested but the phenolic compounds of all bioaccessible fractions (50 µg GAE/mL) showed arrest in G2/M phase of cell-cycle without inducing apoptosis in the Caco-2 cells. Results suggest that Myrtaceae polyphenols may modulate the proliferation of Caco-2 cells by blocking the progression of cell-cycle at G2/M phase, providing beneficial effects to gastrointestinal health.
202

Evidências da interação entre proteínas e taninos de feijão comum (Phaseolus vulgaris, L.) e seus efeitos na digestibilidade protéica / Evidence of proteins-tannins interaction in common bean (Phaseolus vulgaris L.) and their effects on protein digestibility

Karina Huber 02 February 2012 (has links)
O feijão constitui-se em um dos alimentos básicos da população brasileira e proporciona vários benefícios à saúde. No entanto, possui fatores antinutricionais que impedem parte do aproveitamento de alguns de seus nutrientes, destacando-se dentre esses fatores os polifenóis. Estes podem complexar com proteínas, diminuindo a sua digestibilidade e seu aproveitamento pelo organismo. Assim, esta pesquisa teve por objetivo avaliar o potencial antioxidante de feijão comum (Phaseolus vulgaris, L.) e, após a complexação de suas proteínas e polifenóis, avaliar os efeitos dos tratamentos dados e dessa ligação na digestibilidade protéica. Foi utilizado duas cultivares de feijão comum de duas diferentes cores, preto (Xamego) e marrom (BRS9435-Cometa), e uma linhagem de coloração branca (G2358). Os grãos foram analisados na forma crua e cozidos em autoclave, macerados ou não. Foram realizadas análises de: teor de taninos, fenólicos totais, atividade antioxidante, eletroforese, digestibilidade protéica in vitro, e ácidos fenólicos e flavonóides por CLAE. Nas análises dos grãos íntegros, a cultivar BRS9435-Cometa crua apresentou a maior atividade antioxidante e, apesar da maceração e da cocção terem reduzido teor de taninos, compostos fenólicos e atividade antioxidante da maior parte dos feijões, a maceração aumentou significativamente a quantidade de fenólicos totais em feijão preto. Houve alteração no perfil eletroforético da proteína dos grãos após a complexação com os polifenóis. As bandas com maior peso molecular, presentes nas faseolinas puras, apresentaram menor intensidade quando houve a complexação com polifenóis. A digestibilidade das faseolinas de feijões crus variou de 95,67 a 97,66% e a de feijões cozidos de 90,44 a 97,02%. Na digestibilidade de faseolinas puras a maceração seguida de cocção somente exerceu influência significativa em grãos brancos, reduzindo a digestibilidade da faseolina. De modo geral a complexação faseolinapolifenóis aumentou o percentual de digestibilidade. O efeito esperado da complexação faseolina-frações de polifenóis em reduzir a digestibilidade da faseolina foi muito discreto e muitas vezes inexistente, e o de aumento da digestibilidade pela cocção com ou sem maceração também foi limitado. Para os extratos brutos dos feijões, os resultados de DPPH variaram de 2,96 a 14,04 mg de TEAC.g-1 de extrato, e os de ABTS entre 13,70 e 29,51 mg de TEAC.g-1 de extrato. Em ambos os métodos de avaliação da atividade antioxidante, os resultados foram maiores para a maioria dos extratos das cultivares marrom e preta. Quanto às análises realizadas por CLAE, para ácidos fenólicos contatou-se que todos os extratos avaliados possuem os ácidos gálico, clorogênico, vanílico e sinápico, e que os dois primeiros foram os encontrados em maiores teores; praticamente todos os flavonóides foram detectados em quase todas as amostras, com exceção do Caempferol, que somente foi detectado nas amostras maceradas e cozidas. Para extratos de feijões brancos, os flavonóides encontrados em maiores concentrações foram a catequina e o caempferol-3-rutinosídeo; extratos de feijões marrons apresentaram predominantemente a catequina e o caempferol-3-glicosídeo; e em extratos de feijões pretos, predominantemente a catequina, caempferol-3-glicosídeo e quercetina-3-glicosídeo. De maneira geral, o efeito do tratamento térmico aumentou a atividade antioxidante, bem como a concentração dos compostos fenólicos avaliados nos extratos de feijões. / Common bean is one of the staples of the brazilian population and provides numerous health benefits. Nevertheless, it has antinutritional factors that prevent the use of some part of their nutrients, especially polyphenols. These can complex with proteins, decreasing their digestibility and utilization by the body. Thus, this research aimed to evaluate the antioxidant potential of common bean (Phaseolus vulgaris L.) and, after complexation of proteins and polyphenols, assess the effects of treatments given and of this complexation on protein digestibility. Was used two common bean cultivars in two different colors, black (Xamego) and brown (BRS9435-Comet), and a line of white color (G2358). The grains were analyzed as raw and cooked in an autoclave, soaked or not. The analyses that were performed are: content of tannins, total phenolics, antioxidant activity, electrophoresis, in vitro protein digestibility, and phenolic acids and flavonoids by HPLC. In the analyses of whole grains, raw BRS9435- Comet had the highest antioxidant activity and, despite soaking and cooking have shown low levels of tannins, phenolic compounds and antioxidant activity of most beans, soaking significantly increased the amount of total phenolic in black beans. There were changes in the electrophoretic profile of protein from grains by complexation with polyphenols. The bands with higher molecular weight, present in pure phaseolins, had a lower intensity when there was complexation with polyphenols. The digestibility of phaseolins from raw beans ranged from 95.67 to 97.66% and from cooked beans from 90.44 to 97.02%. Digestibility of pure phaseolins from soaked beans only exerted significant influence on white grains, reducing the digestibility of phaseolin. In general, the complexation of phaseolin and polyphenols increased percentage of digestibility. The expected effect of complexation of fractions of polyphenols and phaseolins in reduce the digestibility of phaseolins was very low and often non-existent, and the increase in the digestibility by cooking with or without soaking was also limited. For crude extracts of the beans, the results of DPPH ranged from 2.96 to 14.04 mg TEAC.g-1 extract, and of ABTS between 13.70 and 29.51 mg TEAC.g-1 extract. In both methods of assessing antioxidant activity, the results were higher for most of the extracts of brown and black cultivars. For analyses performed by HPLC it was found for phenolic acids that all extracts evaluated have the gallic acid, chlorogenic, vanillic and sinapic, and the first two were found at higher levels. Practically all flavonoids were detected in almost all samples, except for kaempferol, wich was only detected in soaked and cooked samples. For extracts from white beans, flavonoids found in highest concentrations were catechin and kaempferol-3-rutinoside; brown beans extracts showed mostly catechin and kaempferol-3- glucoside, and in extracts of black beans, mainly catechin, kaempferol-3-glucoside and quercetin-3-glucoside. In general, the effect of heat treatment increased the antioxidant activity and concentration of phenolic compounds evaluated in extracts of beans.
203

A blueberry-enriched diet may aid in the amelioration of bone loss in the ovariectomized rat model

Maria Maiz Rodriguez (6406343) 15 May 2019 (has links)
<div>Osteoporosis is the most common bone disease in older adults and is characterized by low bone mass and increased fragility. Women are at a higher risk for osteoporosis because of the rapid loss of bone during menopause. The decline of estrogen is accompanied by an increased bone resorption and a decreased bone formation which results in negative bone balance. Due to adverse effects on the uterus, breast and cardiovascular system, hormone replacement therapy has been discouraged. Nutritional strategies for osteoporosis prevention are being sought. It has been suggested that (poly)phenol-rich fruits may have bone protective effects. Blueberries are one of the richest sources of (poly)phenols, thus the aim of this dissertation was to determine whether a blueberry-enriched diet could aid in bone loss prevention in the ovariectomized rat model.</div><div><br></div><div>There are hundreds of blueberry varieties which differ in (poly)phenol profiles and content. Five blueberry varieties (Ira, Montgomery, SHF2B1-21:3, Onslow and Wild Blueberry) were chosen to assess the bioavailability of its individual (poly)phenols. Bioavailability of individual phenolic metabolites was determined through a pharmacokinetic study in ovariectomized rats. The results showed that Montgomery blueberry had significantly higher bioavailability of malvidin, cyanidin and myricetin metabolites, while Ira had significantly higher bioavailability of quercetin metabolites, thus suggesting that the absorption of blueberry polyphenols and their potential to reach target tissues differed between blueberry varieties.</div><div><br></div><div>It is important to assess what is the most appropriate dose of blueberry necessary to exert beneficial effects on bone. To determine the most adequate dose of wild blueberry to prevent bone loss in ovariectomized rats, a randomized crossover study was carried out to assess the effects of four different blueberry doses on net bone calcium retention over a 10-day treatment period. The results showed that the only dose to significantly increase net bone calcium retention by 25.6% (p = 0.0426) was the 5% blueberry diet (% w/w), while the higher doses of 10% and 15% had no effect on net bone calcium retention. This informed the last study where Montgomery blueberry and wild blueberry at a 5% dose (% w/w) were chosen to investigate the effects of an 8-week chronic feeding study on calcium metabolism, kinetics, bone microarchitecture and strength and polyphenol metabolism and distribution. A chronic consumption of the wild blueberry resulted in a trend towards minimal trabecular bone loss protection in comparison to the control diet (p=0.08). Kinetic modeling of calcium showed that the Montgomery blueberry had anabolic effects on bone through significantly increasing calcium absorption and bone deposition. The phenolic metabolism differed among blueberry varieties due to each berry’s polyphenol content and profiles and a chronic consumption of blueberry resulted in significant changes in absorption and metabolism of polyphenols. The bone marrow was investigated to determine whether there was any accumulation of phenolic acids in the tissue. Hippuric acid accumulation was significantly higher with the Montgomery blueberry treatments in comparison to control diet. Interestingly, hippuric acid content in the bone marrow was significantly and positively correlated with bone deposition calculated from kinetic modeling. Although no differences were observed on bone mineral density, strength, and microarchitecture, previous studies with a duration of 12-14 weeks have shown significant protection of a blueberry-enriched diet on bone mineral density. Because our study showed a trend for increased trabecular bone (p = 0.08) with the blueberry treatments, we conclude that an 8-week treatment was insufficient time to detect significant differences between the control and blueberry treatments. Since previous researchers before us have reported significant attenuation to bone loss immediately after OVX, it is possible that blueberry that in our study, blueberry was unable to rescue bone once lost after ovariectomy.<br></div><div><br></div><div>A blueberry-enriched diet resulted in a minimal protection to bone after stabilized to OVX, but showed significant increases in calcium absorption and bone turnover in ovariectomized rats. Colonic metabolite profiles from the chronic consumption of blueberry significantly changed over time, thus providing an insight into the effects of blueberry consumption on polyphenol metabolism.<br></div><div><br></div>
204

Vybrané alkoholové extrakty bezu černého pro využití v kosmetologii / Selected alcohol extracts of Sambucus nigra for use in cosmetology

Balonková, Daniela January 2019 (has links)
This thesis focuses on the preparation of selected alcohol extracts of elderberry and their use in cosmetology. In the theoretical part are described the botanical properties of the elderberry (Sambucus nigra). There are introduced and characterized bioactive compounds and toxic compounds contained in all vegetative parts of the plant. Attention is mostly focused on compounds with antioxidant properties. The theoretical part also contains a description of basic analytical methods, which are used in the practical part to characterize compounds contained in elder flowers. The practical part focuses on the optimization of the preparation of alcohol extracts with the aim to prepare the extract with the greatest possible content of polyphenols with respect to economy and production costs. Factors such as selection of the appropriate solvent, solvent to plant material ratio, solvent temperature, and extraction time are examined. Based on the total polyphenol concentration measured spectrophotometrically by the Folin-Ciocalteu method, the most suitable solvent is 60% ethanol, the ratio of plant material to solvent is 1:8, the laboratory temperature of solvent and the extraction time of 24 hours.Under these conditions, an ethanol extract is prepared, analyzed and determined selected properties, such as refractive index and density. Rutin, chlorogenic, caffeic and ferulic acids are identified by HPLC with a DAD detector. The pH value of alcohol extract is 5.743 ± 0.006, the refractive index is 1.365 ± 0.02 at 22.7 ° C and the density is 0.9288 gcm-3. By liquid chromatography the concentration of chlorogenic acids is quantified as 0.104 gl-1, caffeic acid as 0.086 gl-1 and ferulic acid as 0.060 gl-1. The extract is incorporated into cosmetic products, that are used in balneology. Prepared products are toilet soap and bath salt.
205

Izolace antibakteriálních sloučenin z kávové sedliny / Isolation of antimicrobial compounds from spent coffee grounds

Kurzová, Pavlína January 2020 (has links)
Coffee grounds are one of the very valuable lignocellulosic wastes that have been able to be processed and used for isolated phenolic substances. Many phenolic substances isolated from lignocellulosic wastes have antimicrobial properties. Aim of this thesis is isolation phenolic substances from spent coffee grounds extract and their available antimicrobial properties. Two isolation ways were applied to receive phenolic substances from spent coffee grounds: 1) solvent extraction (hexane, 75% ethanol, 70% acetone, diethyl ether, and ethyl acetate) and 2) release of active substances by alcoholic fermentation. All isolated materials were characterized by the viewpoint of concentration of reducing sugars, polyphenols and flavonoids. Subsequently, their antimicrobial activity was determined by using agar diffusion and broth dilution methods. Two gram-positive bacteria (Bacillus subtilis and Micrococcus luteus), one gram-negative bacteria (Serratia marcescens) and two yeasts (Candida glabrata and Saccharomyces cerevisiae) were used for antimicrobial testing. High-performance liquid chromatography (HPLC) was used to identify phenolic substances in the extracts. First, the results showed that the isolated sample with the highest antimicrobial activity was 70% acetone extract. This extract contained chlorogenic acid, gallic acid, caffeic acid and coumaric acid according to HPLC. The ethyl acetate extract showed the lowest antimicrobial activity. Second, after lyophilization, the isolated materials also revealed high antimicrobial activity. The highest antimicrobial activity displayed the materials obtained by the extraction with 70% ethanol. This sample contained chlorogenic acid, gallic acid and caffeic acids. Next, samples with phenolic compounds were obtained by the alcoholic fermentation of spent coffee grounds. These samples showed similarly to the previous solution extracts significant antimicrobial activity. Interestingly, the unfiltered samples received directly after alcoholic fermentation also showed antifungal properties. The characterization of phenolic compounds by HPLC showed similarly as in previous examples that chlorogenic, caffeic and gallic acids were present in these samples.
206

Stanovení aktivních látek v instantních nápojích určených pro dětskou výživu / Analysis of active substances in instant beverages for child´s nutrition

Jašková, Martina January 2011 (has links)
The aim of presented diploma thesis was to characterize baby beverages for early infant feeding. Theoretical part deals with baby foods and beverages including breast milk. Practical part is focused on analysis of active substances in 21 commercially available fruit and herbal instant granular baby beverages and in 3 packaged tea bags for infant and toddler age. To evaluation of antioxidant properties some group parameters were used - total polyphenols, total flavonoids, total antioxidant activity and anthocyanins. All of them were analysed by using spectrophotometrical methods. For identification and quantification of individual phenolic substances was used RP-HPLC/UV-VIS and HPLC/PDA/LC-MS, identification of individual mono- and disaccharides was performed by HPLC/RI. L-ascorbic acid supplemented to some children's drinks was analysed by HPLC-NH2/UV. Protein analysis was performed by Experion microfluidic electrophoresis system (BioRad) and protein concentration was verified by colorimetric method. In general, the highest content of phenolic compounds was shown in tea bags when compared with instant granular beverages that contain mostly added simple carbohydrates. Using contact microbial tests proved immediately after opening and also during manipulation with tea boxes was verified that analysed baby teas are in agreement with strict hygiene requirements for baby beverages.
207

Interaction between Polyphenols and Metalloproteins

Fu, Meiling 18 April 2022 (has links)
No description available.
208

Synthesis of Resveratrol Ester Derivatives Using Selective Enzymatic Hydrolysis.

Osei-Mensah, Marian 17 December 2011 (has links) (PDF)
Resveratrol, a naturally derived stilbene, is an interesting compound mostly talked about recently because for its anti-cancer properties. Unfortunately it has some shortcomings due to its low bioavailability and low solubility in water. For this reason, my research is to overcome resveratrol's drawbacks by improving its bioavailability and hydrophilicity. My research is focused on syntheses of novel derivatives of resveratrol such as 3, 5-di-O-isobutyroyl resveratrol and 3, 5-di-O-hexanoyl resveratrol using lipase catalyzed hydrolysis. Therefore, the tri-acylated resveratrols 3, 5, 4'-tri-O-isobutyroyl resveratrol and 3, 5,4'-tri-O-hexanoyl resveratrol were first synthesized. 3,5,4'-tri-O-isobutyroyl resveratrol and 3,5,4'-tri-O-hexanoyl resveratrol were then hydrolyzed using lipase (C. Antarctica) to obtain the products 3,5-di-O-isobutyroyl resveratrol and 3,5-di-O-hexanoyl resveratrol. The four compounds 3,5-di-O-isobutyroyl resveratrol, 3,5-di-O-hexanoyl resveratrol, 3,5,4'-tri-O-hexanoyl resveratrol, and 3,5-di-O-hexanoyl resveratrol were characterized by 1H NMR and 13C NMR.
209

Effect of Gut Microbiota Biotransformation on Dietary Tannins and Human Health Implications

Sallam, Ibrahim E., Abdelwareth, Amr, Attia, Heba, Aziz, Ramy K., Homsi, Masun Nabhan, von Bergen, Martin, Farag, Mohamed A. 05 May 2023 (has links)
Tannins represent a heterogeneous group of high-molecular-weight polyphenols that are ubiquitous among plant families, especially in cereals, as well as in many fruits and vegetables. Hydrolysable and condensed tannins, in addition to phlorotannins from marine algae, are the main classes of these bioactive compounds. Despite their low bioavailability, tannins have many beneficial pharmacological effects, such as anti-inflammatory, antioxidant, antidiabetic, anticancer, and cardioprotective effects. Microbiota-mediated hydrolysis of tannins produces highly bioaccessible metabolites, which have been extensively studied and account for most of the health effects attributed to tannins. This review article summarises the effect of the human microbiota on the metabolism of different tannin groups and the expected health benefits that may be induced by such mutual interactions. Microbial metabolism of tannins yields highly bioaccessible microbial metabolites that account for most of the systemic effects of tannins. This article also uses explainable artificial intelligence to define the molecular signatures of gut-biotransformed tannin metabolites that are correlated with chemical and biological activity. An understanding of microbiota–tannin interactions, tannin metabolism-related phenotypes (metabotypes) and chemical tannin-metabolites motifs is of great importance for harnessing the biological effects of tannins for drug discovery and other health benefits.
210

Probing Small Molecules and Membrane Protein Structures Utilizing Solid-state NMR Spectroscopy

Yu, Xueting 30 July 2012 (has links)
No description available.

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