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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

An Assessment of Integrated Weed Management Strategies for Purple Threeawn-Dominated Rangelands

Dufek, Nickolas Alois January 2013 (has links)
Purple threeawn (Aristida purpurea Nutt.) is a native bunch grass that is avoided by grazers. It is capable of dominating old cropland and overgrazed pastures, limiting livestock carrying capacity, and degrading wildlife habitat. Traditional management tools have had little impact on threeawn dominance in semiarid regions of the west. Our objectives were to: 1) assess fire and nitrogen treatment effects on threeawn forage quality at various phenological stages to test their potential as pretreatments in a grazing strategy and 2) examine a threeawn-dominated plant community’s response to prescribed fire, nitrogen addition, and clipping. Fire improved threeawn forage quality with greater improvements in early phenological stages. Nitrogen had little effect on forage quality. Fire and nitrogen reduced threeawn while increasing cool season grasses. Light and moderate clipping following fire did not improve the efficacy of fire. Fire appears to an effective preliminary treatment to improve the chance of herbivory.
2

Fibre fermentation in the pig intestine : effect on metabolite production and nitrogen excretion

Jha, Rajesh 10 May 2010
Fine tuning a nutritional strategy by incorporating dietary fibre (DF) in pig diets can help to improve gut health. Fermentation of DF, especially the soluble fraction, in pig intestines yields short-chain fatty acids (SCFA) and lactic acid, which have been found to improve gut health by favouring the growth of health-promoting bacteria such as <i>Lactobacilli</i> and <i>Bifidobacteria</i>, at the expense of pathogenic ones like <i>Clostridium</i> or <i>Salmonella</i>, which may enhance the health of host species. The presence of fermentable fibre in the pig diet can also contribute to reducing nitrogen (N) excretion, which can have a positive impact on the environmental footprint, one of the main concerns of a modern commercial pork production.<p> The overall objective of this thesis project was to evaluate the fermentation characteristics of a selection of feedstuffs in the pig intestines and their potential impact on the gut environment and nitrogen excretion. The evaluation was performed by executing two projects using both <i>in vitro</i> and in <i>vivo studies</i>.<p> The first project focused on the fermentation characteristics of hulless barley in comparison to hulled barley and oats and their effects on the gut environment, especially the production of fermentation metabolites. The rate of fibre fermentation in the intestines was first studied by means of an in vitro gas production technique. The results demonstrated that hulless barleys have higher fermentability and produce higher amounts of SCFA than hulled barley and oats. An experiment carried out on pigs confirmed that the fermentation of the soluble fibre fraction of hulless barley in the gut leads to increased production of SCFA and lactic acid, which in turn contribute to the growth of potentially beneficial microbiota and decrease potentially harmful bacteria, an indicator of improved gut health. This finding shows that gut health parameters may be modulated. Thus gut health could potentially be improved through feed formulation by a judicious selection of feed ingredients with specific fibre fractions, not only by the addition of isolated fibres, which is commonly recommended at present.<p> The second project was executed to study the effect of some feedstuffs differing in their DF and protein content on fermentation characteristics and N excretion in pigs. The feedstuffs included wheat bran, wood cellulose, peas, pea hulls, pea inner fibre, sugar beet pulp, flax seed meal and corn distiller's dried grains with solubles. The results showed that peas and pea fibre-based diets produced higher amounts of SCFA and reduced N excreted, compared to others. In a parallel <i>in vitro</i> study, fermentation characteristics and bacterial protein synthesis was also studied using the same feed ingredients. The findings of the <i>in vitro</i> study corraborated the results of the <i>in vivo</i> experiment. These studies showed that peas and pea fibres have the potential to be used in pig diets in order to gain gut health-benefits and reduce N excretion.<p> From this thesis, it can be concluded that sources and type of dietary fibre have a significant effect on the production of fermentation metabolites in the pig intestine and on N excretion. Among the feed ingredients studied, hulless barley and pea fibres seem to have the greatest potential to be included in pig diets as a source of fermentable fibre to modulate the gut environment, which in turn, extend possibly health-promoting properties and reduce N excretion from pigs. However, further research is needed to understand the specific health benefits of these fibre sources and to quantify the specific fibre components required to achieve these benefits.
3

Fibre fermentation in the pig intestine : effect on metabolite production and nitrogen excretion

Jha, Rajesh 10 May 2010 (has links)
Fine tuning a nutritional strategy by incorporating dietary fibre (DF) in pig diets can help to improve gut health. Fermentation of DF, especially the soluble fraction, in pig intestines yields short-chain fatty acids (SCFA) and lactic acid, which have been found to improve gut health by favouring the growth of health-promoting bacteria such as <i>Lactobacilli</i> and <i>Bifidobacteria</i>, at the expense of pathogenic ones like <i>Clostridium</i> or <i>Salmonella</i>, which may enhance the health of host species. The presence of fermentable fibre in the pig diet can also contribute to reducing nitrogen (N) excretion, which can have a positive impact on the environmental footprint, one of the main concerns of a modern commercial pork production.<p> The overall objective of this thesis project was to evaluate the fermentation characteristics of a selection of feedstuffs in the pig intestines and their potential impact on the gut environment and nitrogen excretion. The evaluation was performed by executing two projects using both <i>in vitro</i> and in <i>vivo studies</i>.<p> The first project focused on the fermentation characteristics of hulless barley in comparison to hulled barley and oats and their effects on the gut environment, especially the production of fermentation metabolites. The rate of fibre fermentation in the intestines was first studied by means of an in vitro gas production technique. The results demonstrated that hulless barleys have higher fermentability and produce higher amounts of SCFA than hulled barley and oats. An experiment carried out on pigs confirmed that the fermentation of the soluble fibre fraction of hulless barley in the gut leads to increased production of SCFA and lactic acid, which in turn contribute to the growth of potentially beneficial microbiota and decrease potentially harmful bacteria, an indicator of improved gut health. This finding shows that gut health parameters may be modulated. Thus gut health could potentially be improved through feed formulation by a judicious selection of feed ingredients with specific fibre fractions, not only by the addition of isolated fibres, which is commonly recommended at present.<p> The second project was executed to study the effect of some feedstuffs differing in their DF and protein content on fermentation characteristics and N excretion in pigs. The feedstuffs included wheat bran, wood cellulose, peas, pea hulls, pea inner fibre, sugar beet pulp, flax seed meal and corn distiller's dried grains with solubles. The results showed that peas and pea fibre-based diets produced higher amounts of SCFA and reduced N excreted, compared to others. In a parallel <i>in vitro</i> study, fermentation characteristics and bacterial protein synthesis was also studied using the same feed ingredients. The findings of the <i>in vitro</i> study corraborated the results of the <i>in vivo</i> experiment. These studies showed that peas and pea fibres have the potential to be used in pig diets in order to gain gut health-benefits and reduce N excretion.<p> From this thesis, it can be concluded that sources and type of dietary fibre have a significant effect on the production of fermentation metabolites in the pig intestine and on N excretion. Among the feed ingredients studied, hulless barley and pea fibres seem to have the greatest potential to be included in pig diets as a source of fermentable fibre to modulate the gut environment, which in turn, extend possibly health-promoting properties and reduce N excretion from pigs. However, further research is needed to understand the specific health benefits of these fibre sources and to quantify the specific fibre components required to achieve these benefits.
4

Effects of condensed tannin on in vitro ruminal fermentation

McKiearnan, Allison Nicole January 1900 (has links)
Master of Science / Department of Animal Sciences and Industry / KC Olson / Condensed tannins (CT) in plants are phenolic compounds with relatively high binding affinities for proteins. In ruminants, dietary CT limit DM intake and digestibility, and ruminal protein degradation by forming CT-protein complexes. Effects of dietary CT, animal species, prior dietary CT exposure, and antimicrobial inclusion on 48-h rate and extent of digestion were measured in two in vitro experiments. Cattle, sheep, and goats (n = 3 / species) were used in a 2-period, randomized complete-block experiment with a 2 × 3 × 2 × 3 factorial arrangement of treatments. Factor 1 was substrate: tannin-free or high-CT. Factor 2 was source of ruminal fluid inoculum: cattle, sheep, or goat. Factor 3 was prior animal exposure to a high-CT diet: non-exposed or exposed. Factor 4 was inclusion of antimicrobials: no antimicrobial, penicillin + streptomycin to suppress bacterial activity, or cycloheximide to suppress fungal activity in the fermentation. Tannin-free or high-CT substrates were incubated in vitro using ruminal fluid from animals either not exposed (period 1) or exposed to dietary CT (period 2). Periods consisted of an adaptation to tannin-free (10 d) or high-CT diets (21 d) and a 15-d period of ruminal-fluid collection via stomach tube. The presence of CT or penicillin + streptomycin in in vitro fermentation reduced (P < 0.001) total gas pressure, DM disappearance, and total VFA, acetate, propionate, butyrate, valerate, and branched-chain VFA concentrations. We concluded that: 1) CT had negative effects on fermentation, 2) prior exposure to dietary CT attenuated some but not all negative effects, and 3) CT effects were similar to the effects of penicillin + streptomycin.
5

Bioengineered Wheat Arabinoxylan: Fostering Next-Generation Prebiotics Targeting Gut Microbiome and Depression Inversely-Linked Microbes

Njoku, Emmanuel Nnabuike 20 April 2023 (has links)
Various disorders closely linked to gut dysbiosis have been associated with poor dietary patterns. Dietary prebiotic fibers play an essential role in modulating the gut microbiome by enhancing the abundance of beneficial microorganisms and improving the production of short-chain fatty acids. Arabinoxylan (AX) is a major component of most dietary fibers and has been shown to exhibit potential prebiotic properties and modulate gut microbiome composition. This study aimed to investigate the in vitro impact of bioengineered wheat arabinoxylan on depression-inversely linked gut microbes and human gut microbiome diversity and metabolism. This study demonstrates the ability of bioengineered AX to stimulate the growth of depression-inversely linked gut bacterial species (Faecalibacterium prausnitzii and Lacticaseibacillus rhamnosus LGG). On the microbiome composition, the bioengineered AX induced an increased abundance of beneficial bacterial taxa (Bacteroides, Bifidobacterium, Anaerofustis, and Eubacterium) compared to the control and native AX. These effects on microbes translated into significant metabolic activity and produced primary SCFAs (acetate, butyrate, and propionate). The findings from this study suggest that bioengineered wheat arabinoxylan could be considered a promising strategy for fostering next-generation prebiotics targeting depression-inversely linked gut microbes and also supports the structure-function relationship between AX and the human gut microbiome.
6

Avaliação das propriedades nutricionais de barras de cereais elaboradas com farinha de banana verde / Evaluation of the nutritional properties of cereal bars produced with unripe banana flour

Santos, Juliana Ferreira dos 22 November 2010 (has links)
Muitas alternativas têm sido propostas para melhorar as características nutricionais dos alimentos, algumas delas utilizando fontes de fibra alimentar ainda pouco conhecidas. Entre estas fontes de fibra alimentar (FA), a farinha de banana verde (FBV) tem se mostrado uma boa alternativa por sua alta concentração de amido resistente (AR) que pode melhorar o valor nutricional de diferentes preparações. Neste trabalho foram estudadas barras de cereal elaboradas com FBV, com o objetivo de avaliar in vivo e in vitro as propriedades nutricionais desses produtos. As amostras consistiam em dois tipos de barras de cereais, uma delas elaborada com FBV (barras FBV) e outra sem este ingrediente (barras controle). A composição centesimal e perfil de carboidratos das barras foram avaliados. A fermentabilidade da fração não-disponível das barras foi avaliada através de testes in vitro utilizando inóculo de ratos. A resposta glicêmica das barras foi avaliada após sua ingestão por voluntários saudáveis (n=16), sendo determinados o índice glicêmico (IG) e carga glicêmica (CG). A principal característica que pôde ser observada é que as barras FBV possuem maior conteúdo de AR que as barras controle (7,22 g/100g e 2,11 g/100g na base integral), resultado da adição de FBV. Esta adição reflete na concentração de carboidratos não-disponíveis (soma de FA e AR) das barras FBV, que é de 18,19 g/100g na base integral. As barras FBV apresentam maior fermentabilidade in vitro em relação às barras controle (p<0,05) de acordo com a produção de ácidos graxos de cadeia curta (AGCC), produzindo 4,04 mmol/g de substrato, enquanto as barras controle produzem apenas 3,51 mmol/g de substrato. As barras FBV apresentam baixo IG (em relação à glicose) (41%) e CG (4), enquanto as barras controle apresentam IG médio (60%) e CG baixa (5). A partir dos resultados apresentados, é possível concluir que a adição de FBV às barras de cereal aumenta seu conteúdo de carboidratos não-disponíveis, representados pelo AR e FA, resultando num produto de alta fermentabilidade e de baixa resposta glicêmica pós-prandial. / Several alternatives have been proposed to improve the nutritional characteristics of foods, some of them using sources of dietary fiber that are still underused. Among these sources of dietary fiber (DF), unripe banana flour (UBF) has been considered a good alternative for its high concentration of resistant starch (RS), which can improve the nutritional value of different preparations. The aim of this study was to evaluate, in vivo and in vitro, the nutritional properties of cereal bars made with UBF. The samples consisted of two types of cereal bars, one made with UBF (UBF bars) and the other one without this ingredient (control bars). The chemical composition and carbohydrate profile of the bars were evaluated. The fermentability of the non-available fraction of bars was assessed in vitro using cecal contents of mice. The glycemic response of the bars was assessed after its ingestion by healthy volunteers (n = 16), being determined the glycemic index (GI) and glycemic load (GL). The main feature that could be observed is that the UBF bars have higher RS content than the control bars (7.22 g/100g and 2.11 g/100g wet weight), a result of the addition of UBF. This addition reflects on the concentration of non-available carbohydrates (sum of DF and RS) in UBF bars, which is 18.19 g/100g wet weight. The UBF bars presented better in vitro fermentability in relation to control bars (p <0.05) according to the production of short chain fatty acids (SCFA), yielding 4.04 mmol / g substrate, while the control bars produce only 3.51 mmol / g substrate. The UBF bars have a low GI (based on glucose) (41%) and CG (4), while the control bars show medium GI (60%) and low CG (5). According to these results, it is possible to conclude that the addition of UBF to cereal bars increases their non-available carbohydrate content, represented by RS and DF, resulting in a product of high fermentability and low postprandial glycemic response.
7

GLUTEN - FREE FOOD SYSTEM: SCREENING OF POLYPHENOLS AND THEIR BIO ACCESSIBILITY THROUGH IN VITRO GASTROINTESTINAL PROCESSES AND METABOLOMICS - BASED STUDIES

ROCCHETTI, GABRIELE 03 April 2019 (has links)
Circa l’1% della popolazione mondiale è colpita da celiachia. I celiaci sono costretti a seguire una dieta priva di glutine e molto spesso quest’ultima risulta essere sbilanciata e/o carente in molti nutrienti. Recentemente, l’uso di matrici alternative al frumento, come pseudocereali, legumi e cultivar di riso pigmentate sta riscuotendo grande interesse a causa del loro elevato quantitativo di composti bioattivi (polifenoli). Quindi, considerando l’importanza attuale dei polifenoli sia nella formulazione tecnologica che nella promozione di aspetti salutistici degli alimenti senza glutine, lo scopo di questa tesi è stata basata su: 1) profilazione dei polifenoli in matrici prive di glutine (farine non di frumento, legumi, pseudocereali e frutta secca) e loro proprietà antiossidanti in vitro; 2) valutazione dell’impatto di trattamenti termici e di fermentazioni microbiche sul profilo fenolico di queste matrici prive di glutine; 3) valutazione del ruolo dei polifenoli come inibitori degli enzimi amilolitici; e 4) valutazione del destino dei polifenoli caratterizzanti alimenti senza glutine durante processi in vitro simulanti digestione gastrointestinale e fermentazione fecale. I polifenoli sono stati analizzati sfruttando tecniche di metabolomica mirata/non-mirata. / Around 1% of world population is affected by coeliac disease. Coeliac people are constrained to follow a strict gluten free (GF) diet and very often this latter is unbalanced and lacks in many nutrients. In the last years, the exploitation of alternative crops or underutilized species, such as pseudocereals, legumes and pigmented cereal cultivars, is gaining interest because of their amount and profile of bioactive compounds, such as polyphenols. Therefore, considering the actual importance of polyphenols for both the formulation of GF foods and their health-promoting properties, the current PhD thesis was based on: 1) the profiling of polyphenols in GF raw materials (such as non-wheat flours, legumes, pseudocereals and nuts) and their in vitro antioxidant activities; 2) the evaluation of the impact of different heat treatments and microbial fermentations on the phenolic profile of GF raw materials; 3) the investigation of polyphenols in GF foods as inhibitors of digestive enzymes; and 4) the assessment of the fate of polyphenols characterizing GF foods during simulated in vitro gastrointestinal and fermentation processes. Polyphenols were analysed by means of targeted/untargeted metabolomics-based approaches (i.e., high resolution chromatography and mass spectrometry platforms).
8

Avaliação das propriedades nutricionais de barras de cereais elaboradas com farinha de banana verde / Evaluation of the nutritional properties of cereal bars produced with unripe banana flour

Juliana Ferreira dos Santos 22 November 2010 (has links)
Muitas alternativas têm sido propostas para melhorar as características nutricionais dos alimentos, algumas delas utilizando fontes de fibra alimentar ainda pouco conhecidas. Entre estas fontes de fibra alimentar (FA), a farinha de banana verde (FBV) tem se mostrado uma boa alternativa por sua alta concentração de amido resistente (AR) que pode melhorar o valor nutricional de diferentes preparações. Neste trabalho foram estudadas barras de cereal elaboradas com FBV, com o objetivo de avaliar in vivo e in vitro as propriedades nutricionais desses produtos. As amostras consistiam em dois tipos de barras de cereais, uma delas elaborada com FBV (barras FBV) e outra sem este ingrediente (barras controle). A composição centesimal e perfil de carboidratos das barras foram avaliados. A fermentabilidade da fração não-disponível das barras foi avaliada através de testes in vitro utilizando inóculo de ratos. A resposta glicêmica das barras foi avaliada após sua ingestão por voluntários saudáveis (n=16), sendo determinados o índice glicêmico (IG) e carga glicêmica (CG). A principal característica que pôde ser observada é que as barras FBV possuem maior conteúdo de AR que as barras controle (7,22 g/100g e 2,11 g/100g na base integral), resultado da adição de FBV. Esta adição reflete na concentração de carboidratos não-disponíveis (soma de FA e AR) das barras FBV, que é de 18,19 g/100g na base integral. As barras FBV apresentam maior fermentabilidade in vitro em relação às barras controle (p<0,05) de acordo com a produção de ácidos graxos de cadeia curta (AGCC), produzindo 4,04 mmol/g de substrato, enquanto as barras controle produzem apenas 3,51 mmol/g de substrato. As barras FBV apresentam baixo IG (em relação à glicose) (41%) e CG (4), enquanto as barras controle apresentam IG médio (60%) e CG baixa (5). A partir dos resultados apresentados, é possível concluir que a adição de FBV às barras de cereal aumenta seu conteúdo de carboidratos não-disponíveis, representados pelo AR e FA, resultando num produto de alta fermentabilidade e de baixa resposta glicêmica pós-prandial. / Several alternatives have been proposed to improve the nutritional characteristics of foods, some of them using sources of dietary fiber that are still underused. Among these sources of dietary fiber (DF), unripe banana flour (UBF) has been considered a good alternative for its high concentration of resistant starch (RS), which can improve the nutritional value of different preparations. The aim of this study was to evaluate, in vivo and in vitro, the nutritional properties of cereal bars made with UBF. The samples consisted of two types of cereal bars, one made with UBF (UBF bars) and the other one without this ingredient (control bars). The chemical composition and carbohydrate profile of the bars were evaluated. The fermentability of the non-available fraction of bars was assessed in vitro using cecal contents of mice. The glycemic response of the bars was assessed after its ingestion by healthy volunteers (n = 16), being determined the glycemic index (GI) and glycemic load (GL). The main feature that could be observed is that the UBF bars have higher RS content than the control bars (7.22 g/100g and 2.11 g/100g wet weight), a result of the addition of UBF. This addition reflects on the concentration of non-available carbohydrates (sum of DF and RS) in UBF bars, which is 18.19 g/100g wet weight. The UBF bars presented better in vitro fermentability in relation to control bars (p <0.05) according to the production of short chain fatty acids (SCFA), yielding 4.04 mmol / g substrate, while the control bars produce only 3.51 mmol / g substrate. The UBF bars have a low GI (based on glucose) (41%) and CG (4), while the control bars show medium GI (60%) and low CG (5). According to these results, it is possible to conclude that the addition of UBF to cereal bars increases their non-available carbohydrate content, represented by RS and DF, resulting in a product of high fermentability and low postprandial glycemic response.
9

Effect of Bran Particle Size on Gut Microbiota Community Structure and Function

Riya D Thakkar (6632180) 14 May 2019 (has links)
With the advent of industrialization and food processing techniques the sizes of the cereal bran have been drastically reduced. In my thesis, I have tested the effect, if any, of wheat bran and maize bran particle size, in vitro, on the gut microbiota community structure by 16S rRNA sequencing and their function, by Short chain fatty acids (acetate, propionate, butyrate) production. In turn, we also linked the microbiota and SCFA differences to different chemical composition amongst variously sized fractions of wheat and maize bran.
10

Structural-dependent effects of dietary fibers in colon cancer: Focus on dietary fiber naturally changed by the papaya ripening / Efeitos estrutura-dependente das fibras alimentares no câncer de cólon: foco na fibra alimentar naturalmente modificada durante o amadurecimento do mamão papaia

Prado, Samira Bernardino Ramos do 06 May 2019 (has links)
Dietary fiber (DF) consumption is related with several healthy benefits such as the decreasing risk of colon cancer development. The DF is not digested by the digestive enzymes and reach to colon where is fermented by the colonic microbiota. The fermentation process releases metabolites as short chain fatty acids (SCFA) such as butyrate, propionate and acetate. Besides the fermentation process, the DF can directly interact with intestinal epithelial cells inducing mechanism that can also be related with the associated DF consumption benefits. The lack of information regarding DF and colon cancer are due to the complexity of both the cancer and the DF structure. The papayas DF are derived from the fruit cell wall, and they are probably naturally modified during ripening through a massive polysaccharide hydrolysis, because papayas show a very fast pulp softening. Due to the lack of information about DF and their beneficial effects to human health as well as the possibility of the natural papaya ripening to modifying the DF presented in the fruit pulp, the present thesis had as the primary objectives: 1) to evaluate how the cell-wall degrading enzymes affect the fruit cell wall solubilization and molecular weight; 2) to investigate the direct effects of the papaya pectin derived from unripe to ripe papayas in cancer cell lines, in galectin-3 interaction and in HEK cells expressing pattern recognition receptors (PRR); 3) to evaluate the human colonic in vitro fermentation using DF from unripe and ripe papayas as substrates; 4) to conduct an in vivo experiment using rats with pre-neoplastic colon lesions while receiving a diet with DF from unripe and ripe papayas. The endopolygalacturonases were the main enzymes acting on the solubilizing papaya cell wall pectin affecting both the papaya firmness and pectin structure. Overall, the papayas DF showed a ripening dependent structureeffects. In the cancer cell lines experiments, the ripe papayas pectin showed a more pronounced effects in inducing cancer cell death, inhibiting cancer cells migration and aggregation, activating PRR as toll-like receptors and inhibiting the pro-metastatic protein galectin-3. The DF from papayas also showed different aspects in colonic in vitro fermentation regarding the DF utilization by the bacteria and the bacteria abundance profile. Lastly, the animals receiving the diet with the DF from ripe papayas had less aberrant crypt foci in colon than the animals that received the DF from unripe papayas or cellulose (AIN-93G DF). Therefore, the study of papaya DF was carried out both during papaya ripening and its biological effects in vitro and in vivo, generating unprecedented results relating the endogenous biochemical changes of the fruits during maturation with the possible beneficial effects of their ingestion for health human. / O consumo de fibras alimentares (FA) está relacionado com vários benefícios à saúde como a diminuição no risco do desenvolvimento de câncer de cólon. A FA não é digerida pelas enzimas digestivas do trato gastrointestinal sendo fermentada pela microbiota intestinal do cólon. Como subproduto do processo de fermentação há a liberação de ácidos graxos de cadeia curta (SCFA) - como o butirato, o propionato e o acetato. Além do processo de fermentação, a FA pode interagir diretamente com as células epiteliais do intestino, induzindo mecanismos que também podem estar relacionados com os benefícios associados ao consumo de FA. A falta de informação sobre a FA e o câncer de cólon é, em partes, devido à complexidade de ambos, tanto do câncer quanto da estrutura da FA. As FA do mamão papaia são derivadas da parede celular da fruta apresentando diferentes estruturas dependendo do ponto de amadurecimento do fruto. Esse fato ocorre, pois, durante o amadurecimento do mamão papaia, existe uma extensa hidrólise dos polissacarídeos presentes na parede celular, diminuindo rapidamente a firmeza da polpa do fruto. Devido à falta de informações sobre FA e seus efeitos benéficos à saúde humana que são dependentes da sua estrutura, bem como a possibilidade do amadurecimento do mamão papaia naturalmente modificar as FA presentes na polpa dos frutos, a presente tese teve como principais objetivos: 1) avaliar como as enzimas que degradam a parede celular do mamão papaia afetam a solubilização e o peso molecular da parede celular do fruto; 2) investigar os efeitos diretos da pectina derivada de mamões verdes e maduros em linhagens de células de câncer, na interação com a galectina-3, e em células do tipo HEK que expressam receptores de reconhecimento de padrões (RRP); 3) avaliar a fermentação colônica humana in vitro utilizando as FA de mamões verdes e maduros; 4) avaliar em ratos com lesões pré-neoplásicas no cólon o efeito do consumo de ração com ou sem FA de mamões papaias verdes e maduros. As endopoligalacturonases foram relacionadas como as principais enzimas que atuam solubilizando a pectina da parede celular do mamão, afetando tanto a firmeza da polpa do fruto quanto a solubilização da pectina durante o amadurecimento. De modo geral, as FA dos mamões exerceram um efeito estruturadependente de acordo com a maturação do fruto. Nos experimentos utilizando linhagens de células de câncer, a pectina do mamão papaia maduro apresentou efeitos mais pronunciados na indução da morte e na inibição da migração e da agregação das células, bem como ativando os RRP, como por exemplo, os receptores do tipo toll-like, além de inibir a proteína pró-metastática galectina-3. As FA dos mamões também apresentaram diferentes resultados na fermentação colônica in vitro quanto à utilização das FA pelas bactérias do intestino, e também no perfil de crescimento dessas bactérias. Por fim, os animais que receberam a dieta com as FA dos mamões maduros apresentaram menor incidência de focos de criptas aberrantes do que os animais que receberam as FA provenientes de mamões verdes ou de celulose (FA da ração AIN-93G). Portanto, o estudo das FA dos mamões foi efetuado tanto durante o amadurecimento dos mamões quanto dos seus efeitos biológicos in vitro e in vivo, tendo gerado resultados inéditos relacionando as alterações bioquímicas endógenas dos frutos durante o amadurecimento com os possíveis efeitos benéficos da sua ingestão para a saúde humana.

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