La consommation d'aliments riches en ellagitannins (ETs) pourrait être associée principalement à la prévention des maladies cardiovasculaires et la régulation des cancers hormono-dépendants. Néanmoins, les ETs ne sont pas biodisponibles en tant que tel et, après avoir été partiellement transformés en acide ellagique (EA) dans le tractus gastro-intestinal (GI) supérieur, ils sont métabolisés dans le côlon par la flore intestinale en urolithines, un groupe de molécules plus biodisponibles et bioactives qui peuvent persister jusqu'à 4 jours à des concentrations relativement élevées dans le plasma et l'urine. La variabilité de l'excrétion des urolithines dans l'urine est importante et à partir d'un échantillon de population de 26 volontaires sains, trois groupes principaux d'individus ont pu être distingués : "faible ou non-excréteur d'urolithin », « Excréteur prédominant d'UA et dérivés» et « Excréteur prédominant d'UB et dérivés»". Ces groupes ont également été observés en considérant la cinétique totale d'excrétion sur une période de 4 jours après ingestion du jus et à des périodes différentes tout au long d'une année. Bien que les variabilités inter-et intra-individuelles soient relativement élevées, les individus conservent leur statut au cours des différentes périodes d'intervention même en modifiant les quantités d'ETs ingérées. L'analyse par UPLC-PDA/ESI-Q-TOF/MS2 a permis d'attribuer hypothétiquement une identité à 15 autres métabolites d'ETs dans l'urine, mais le profilage métabolomique n'a pas permis de discriminer d'autres composés exceptés les dérivés d'UA ou d'UB. La fermentation in-vitro des ETs et EA, par les matières fécales a montré une voie métabolique spécifique qui débouche sur la production d'UA. Néanmoins, les métabolites excrétés in vivo sont beaucoup plus complexes ce qui met en évidence de fortes interactions entre le système excréteur de l'hôte et la composition du microbiote intestinal. La recirculation hépatique suivie par une re-conversion des métabolites de phase II dans le côlon permettrait d'expliquer l'excrétion d'UB chez certains volontaires. L'écologie spécifique de la flore intestinale évaluée par la méthode des empreintes PCR-DGGE a permis d'identifier quelques microorganismes associés à une plus grande capacité de bioconversion des ETs en urolithins / Consumption of dietary ellagitannins (ETs) could be associated mainly with prevention of cardiovascular diseases and regulation of hormone-dependent cancers. Nonetheless, ETs are not bioavailable as such; therefore, after being partially converted into ellagic acid (EA) in the upper gastrointestinal (GI) tract, they undergo sequential bioconversion in the colon by gut microbiota into urolithins, a more bioavailable and bioactive group of molecules that persist up to 4 days at relatively high concentrations in urine. Variability of urolithin excretion in urine is high and three main groups, “no or low urolithin excreters,” “predominantly UA derivatives excreters” and “predominantly UB derivatives excreters,” were observed on a cohort of 26 healthy volunteers. These categories were also unambiguously observed following the total excretion of main ETs' metabolites over a 4 day period after ingesting one shot of juice, and at different periods of time along one year. Although relatively high inter- and intra-individual variabilities were observed, individuals preserved their status during various intervention periods with different amounts of ETs ingested. UPLC-PDA and ESI-Q-TOF/MS1 and MS2 allowed the tentative assignment of an identity to 15 other ETs metabolites in urine, but this profiling did not allow the discrimination of any other compounds aside from UA or UB derivatives. In-vitro fermentation of ETs and EA with fecal stools showed a specific metabolic pathway ending in the production of UA. Nonetheless, metabolites excreted in-vivo are much more complex, highlighting strong interactions between host excretory system and composition of gut microbiota. Hepatic recirculation and additional bioconversion of Phase II metabolites in the colon may explain predominant excretion of UB in some volunteers. Microbiota ecology assessed by PCR-Denaturing Gradient Gel Electrophoresis (DGGE) fingerprint method allowed the association of some microorganism species to higher capacity of bioconversion of dietary ETs into urolithins.Key words: Ellagitannins, blackberry, urolithin, colonic metabolites, ETs degradation patterns, gut microbiota, gastrointestinal tract,

Humic substances, such as the closely related humic and fulvic acids are ubiquitous, naturally occurring organic macromolecules of complex but undefined structure. These compounds are known complexing agents due to their supramolecular like structures and are capable of binding a wide variety of compounds. Numerous studies have confirmed that humic and fulvic acids exhibit diverse medicinal and therapeutic properties. For this reason, alternative or “natural” medicinal preparations rich in these substances are being self-administered, often concomitantly with conventional drugs. The possibility exists that these humic substances, found in the alternative medicinal products, may result in drug-drug interactions and bind to simultaneously ingested drugs. Complex formation may affect absorption and alter overall bioavailability. Changes in these parameters may lead to reduced therapeutic effect or toxic side effects of prescribed drugs in patients. Similarly, these humic substances may bind to and alter the uptake of ingested nutrients, such as vitamins and minerals, obtained from food sources as well as dietary supplements. Changes in absorption may result in a loss of proper physiological functioning in the body or in unwanted effects of overdose. This study investigated the effect of fulvic and humic acids on the absorption of commonly administered classes of drugs, vitamins and minerals using the everted mouse gut model that was successfully used to assess the membrane transport of the test compounds. This model made use of everted segments of excised intestinal tissue placed in Krebs Ringer Buffer (pH7.4), where physiological functioning of the tissue is maintained for up to two hours after excision. The amount of test compound which crossed through the intestinal membrane without and in the presence of each humic substance was quantified using LC-MS/MS methods developed for each of the drugs and vitamins, and ICP-MS, in the case of the minerals. The amount of test compound absorbed alone was compared to the amount absorbed when in the presence of each humic substance. Changes in the uptake, for each test compound was noted, the extent of the absorption increase or decrease was compound specific. The changes in absorption observed could be attributed to changes in compound solubility and mechanism of transport across the intestinal membrane once in complex. Drugs and vitamins were seen to be more prone to decreases in absorption in the presence of the humic substances, whereas the majority of the minerals showed significantly increased absorption. Binding of the minerals to the humic substances through chelation, and not complex formation, could have a greater effect on compound solubility. Health care professionals, as well as individuals ingesting these and other substances concurrently, should be aware of the potential effects on absorption that may occur due to drug-drug interactions in order to avoid a loss of therapeutic/physiological activity or negative toxic symptoms. / Dissertation (MSc)--University of Pretoria, 2015. / tm2015 / Pharmacology / MSc / Unrestricted

Orientadores: Jaime Amaya-Farfan, Fernanda de Pace / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-27T12:05:55Z (GMT). No. of bitstreams: 1 Roquetto_AlineRissetti_M.pdf: 2148135 bytes, checksum: 6a59bf58e9dbc6285574497bb9558141 (MD5) Previous issue date: 2015 / Resumo: A obesidade é um dos maiores problemas de saúde pública no mundo, sendo associada a diversas doenças metabólicas como inflamação, resistência insulínica, dislipidemia, esteatose hepática, entre outras. Recentemente, tem sido demonstrado que alterações nas proporções dos filos que compõem a microbiota intestinal repercutem negativamente sobre o metabolismo e processos fisiológicos do hospedeiro. A dieta moderna é apontada como um dos fatores capazes de modular as bactérias intestinais e desencadear respostas inflamatórias. Diante deste cenário e tendo conhecimento de que a própolis, resina produzida por abelhas que possui ação anti-inflamatória e antimicrobiana, a presente pesquisa teve como objetivo avaliar o efeito da suplementação da própolis em camundongos tratados com dieta hiperlipídica sobre a microbiota intestinal e biomarcadores inflamatórios. Quarenta camundongos da linhagem C57BL/6 foram divididos em 4 grupos (n=10) aleatoriamente: grupo controle ¿ dieta baseada na AIN-93G; grupo hiperlipídico (HF) ¿ dieta com 37% de gordura; e grupos HFP2 e HFP5 tratados com dieta hiperlipídica, seguida de suplementação com própolis 0,2% nas duas e cinco semanas que antecederam ao sacrifício respectivamente. Foram coletadas amostras de sangue e músculo para determinações bioquímicas e indicadores de inflamação, o conteúdo cecal foi extraído para sequenciamento do DNA da microbiota intestinal. Os resultados não mostraram diferenças no ganho de peso entre os grupos experimentais, mas o tratamento com própolis por 5 semanas foi efetivo em reverter a disbiose causada pela dieta HF, com relação aos filos Firmicutes, e Proteobacteria. Os níveis de lipopolissacarídeos (LPS) no soro, bem como a expressão de toll-like receptor-4 (TLR4) e de citocinas pró-inflamatórias no músculo foram reduzidos pelo tratamento prolongado com própolis. Além disso, esta intervenção melhorou os níveis séricos de glicose e triacilgliceróis. Estes resultados sugerem a possibilidade de que a própolis exerça ação benéfica modificando o microbioma que limita a permeabilização da parede intestinal, regulando a translocação de componentes bacterianos para a corrente sanguínea e, consequentemente, conduzindo a uma menor expressão de citocinas inflamatórias / Abstract: Obesity is a major world-wide public health problem and is associated with metabolic disorders as generalized inflammation, insulin resistance, dyslipidemia, hepatic steatosis, among others. Recently, it has been demonstrated that changes in the proportions of phyla that make up the gut microbiota have a profound effect on the metabolism and physiology of the host. The modern diet has been identified as one of the factors that modulate the intestinal bacteria and trigger inflammatory responses. Considering this state of affairs and knowing that propolis, a resin present in bee honey, has anti-inflammatory and anti-microbial action, the present study was designed to evaluate the effect of propolis supplementation on the intestinal microbiome and inflammatory biomarkers of mice pre-conditioned with a high-fat diet. Forty mice of the C57BL/6 strain were randomly divided into four groups (n = 10): control group ¿ diet based on the AIN 93-G; high-fat group ¿ diet with 37% fat; and two other groups treated with high-fat, HFP2 and HFP5, that were supplemented with 0.2% propolis during two and five weeks preceding sacrifice, respectively. Blood and muscle samples were collected for biochemical analyses and inflammation markers, the cecal contents were extracted for DNA sequencing of the intestinal microbiota¿s genome. The results showed no differences in weight gain among the experimental groups, but treatment with propolis for 5 weeks effectively reverted the dysbiosis caused by the HF diet with respect to the Firmicutes and Proteobacteria phyla. The levels of serum lipopolysaccharide (LPS), and Toll-like receptor-4 (TLR4) expression, and proinflammatory cytokines in muscle were reduced by the longer propolis treatment. In addition, this intervention improved serum glucose and serum triacylglycerol levels. The present results suggest that ingested propolis exerts its beneficial action, first modifying the intestinal microbiota, which limits intestinal wall permeability and controls the translocation of bacterial components into the bloodstream and thus averting inflammatory cytokine overexpression / Mestrado / Nutrição Experimental e de Alimentos / Mestra em Alimentos e Nutrição

Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the second leading cause of cancer death in the United States. Aldo-keto reductase 1 B10 (AKR1B10) is highly expressed in colon and small intestine of normal humans, but its expression is lost or markedly down-regulated in tissues of patients with ulcerative colitis (UC) and CRC. AKR1B10 is a monomeric cytosolic enzyme with strong enzymatic activity to α, β-unsaturated carbonyl compounds, protecting cells from carbonyl lesions; AKR1B10 also mediates de novo synthesis of long chain fatty acids and membrane lipids, such as phosphatidylinositol 4,5-bisphosphate (PIP2). To study the etiopathogenic role of AKR1B10 in UC and CRC, our lab generated AKR1B8 deficient (AKR1B8 -/-) mice. AKR1 B8 is the orthologue in mice of human AKR1B10,

La fermentation des fibres alimentaires est l’une des fonctions majeures du microbiote intestinal humain. Les bactéries fibrolytiques synthétisent un grand nombre d’enzymes, appelées Glycoside Hydrolases (GH), indispensables à la déconstruction de la grande variété structurelle des polysaccharides pariétaux que nous ingérons. Au cours de ce travail, nous avons exploré, grâce à une approche de métagénomique fonctionnelle, l’organisation et les propriétés des systèmes enzymatiques bactériens impliqués dans la dégradation des glycanes de parois végétales dans l’intestin humain.En premier lieu, nous avons cherché à déterminer si les bactéries de la muqueuse iléale étaient capables de dégrader les fibres pariétales dans un contexte sain. Cette fonction étant généralement décrite pour le microbiote colique par extrapolation de travaux menés à partir de selles humaines, nos connaissances de la dégradation des fibres dans la partie haute du tractus digestif sont donc très limitées. Un total de 20 000 clones issus du métagénome bactérien d’une partie saine de la muqueuse iléale d’un individu a été criblé pour des activités de dégradation de la carboxymethylcellulose et du xylane, deux substrats modèles des polysaccharides pariétaux. Douze clones métagénomiques positifs nous ont permis de mettre en évidence un arsenal de gènes bactériens codant pour des GH et d’autres protéines impliquées dans le métabolisme des fibres alimentaires dont certains organisés en PUL (Polysaccharide Utilization Loci), des clusters de gènes spécialisés dans la dégradation des polysaccharides complexes. Ces gènes proviennent de chromosomes bactériens assignés au genre Bacteroides ou à des espèces de Clostridiales, et codent pour des enzymes capables de dégrader également des β-glucanes à liaisons mixtes. L’étude de la prévalence de ces gènes dans les métagénomes de référence indique que plusieurs d’entre eux proviendraient de souches bactériennes plutôt spécifiques de la muqueuse iléale. De plus, certaines enzymes présentent des propriétés inédites potentiellement intéressantes dans le domaine biotechnologique. Nos recherches ont donc permis de revisiter la fonction fibrolytique du microbiote intestinal chez l’Homme et de proposer une localisation de cette fonction dès l’intestin grêle.Dans un second temps, en utilisant une approche méthodologique similaire, nous avons étudié la capacité du microbiote fécal d’un individu obèse à dégrader des polysaccharides pariétaux complexes, en général moins consommés par les individus obèses. Au total, nous avons identifié 50 clones appartenant à 14 espèces bactériennes des phyla suivants : Bacteroidetes, Firmicutes et Actinobacteria. Les inserts métagénomiques portent des gènes codant pour différentes familles de GH, impliquées dans la dégradation des polysaccharides d’intérêt. Les premières analyses de la prévalence de ces gènes chez plus d’une centaine d’individus (obèses ou non), par interrogations des catalogues de gènes microbiens de référence, suggèrent des associations avec le statut phénotypique « obèse ». / Among the crucial functions of the intestinal microbiota, extracting energy from food such as dietary fibres is of major importance. Facing the huge diversity of incoming complex carbohydrates, the fibrolytic bacteria synthesize a set of diversified Carbohydrate-Active Enzymes (CAZymes) including Glycoside Hydrolases (GH) that specifically disrupt complex polysaccharides. Here, using functional metagenomic approaches, we explored the organization and properties of bacterial enzymatic systems involved in the breakdown of plant cell wall (PCW) glycans in the intestinal tract.Firstly, we investigated the capacity of the microbiota associated to the human ileum mucosa to degrade complex non-starch polysaccharides in a healthy context. This function has never been investigated in this part of the intestine, but it has been rather associated to microorganisms inhabiting the colon, due to more accessible fecal samples. Using a fosmid library derived from a healthy part of the human ileal mucosa, we screened 20,000 metagenomic clones for their activities against carboxymethylcellulose and xylan chosen as models of the major PCW polysaccharides from dietary fibres. Twelve positive clones revealed a broad range of CAZyme encoding genes from Bacteroides to Clostridiales species, as well as Polysaccharide Utilization Loci (PUL). Functional GH genes were identified and break-down products examined from different polysaccharides including mixed-linkage β-glucans. Revealed CAZymes and PUL were also examined for their prevalence in human gut microbiomes. Part of them belongs to unidentified strains rather specifically established in the ileum. Others were enzymes unclassified in identified GH families or with original properties addressing novel candidates for biotechnological applications. Thus, we evidenced for the first time that the ileal mucosa associated-microbiota encompasses the enzymatic potential for PCW complex polysaccharide degradation that might start in the small intestine.In a second time, by using the same methodology, we harvested the enzymatic capacities of the fecal microbiota from an obese person to disrupt complex polysaccharides from dietary fibres usually consumed in lower quantity in obese people. This study aimed at examining the links between genes encoding enzymes specifically dedicated to PCW complex carbohydrates and the obese phenotypic status using reference microbial gene catalogs. We screened a fecal metagenomic library from an obese individual on representative PCW substrates and identified 50 clones belonging to 14 different species from the Bacteroidetes, Firmicutes and Actinobacteria phyla. The metagenomic inserts harbor genes encoding enzymes from GH families specific from complex carbohydrate degradation. First querying of the prevalence of these genes in hundreds individuals (obese and control), using catalogs of reference microbial genes, suggest associations with the "obese" phenotypic status.

Clostridium difficile est une bactérie enteropathogène responsable d'infections intestinales dont les manifestations cliniques varient d’une simple diarrhée à une colite pseudomembraneuse parfois mortelle. L’une des problématiques majeures rencontrées dans la prise en charge des infections à C. difficile (ICD) est la survenue de récidives. Chez de nombreuses espèces bactériennes, la formation de biofilm est associée à la chronicité de l’infection. Le biofilm est un mode de vie dans lequel les bactéries sont engluées dans une substance polymérique qu'elles secrètent elles-mêmes. L’aptitude de C. difficile à former un biofilm in vitro a été clairement établie depuis 2012. Cependant aucune étude n’a montré jusqu’ici s’il est capable de former un biofilm in vivo. L’objectif de cette thèse était d’une part d’étudier différents paramètres impliqués dans la formation du biofilm in vitro et d’autre part de déterminer si C. difficile est capable de former un biofilm in vivo. Dans un premier temps, nous avons analysé la capacité de différentes souches de C. difficile (souches cliniques et souches de laboratoires modifiées génétiquement) à former un biofilm in vitro. Parmi ces dernières, la souche mutée pour le gène cwp84, codant une protéase de surface responsable de la maturation de la couche S de C. difficile, présente un biofilm particulièrement robuste et épais comparé à la souche parentale 630∆erm. L’activité protéolytique de Cwp84 est donc impliquée dans la formation du biofilm et module certaines propriétés de surface de la bactérie telles que l’hydrophobicité. Nous avons également étudié la composition en sucre de la matrice du biofilm, après une étape de mise au point qui a permis de déterminer les conditions permettant d’obtenir suffisamment de matériel. Les conditions retenues ont été les suivantes : formation de biofilm sur un support en verre, en présence de glucose et en milieu renouvelé. La présence d’un sucre qui possède un profil proche du PSII (polysaccharide associé à la surface des cellules planctoniques de C. difficile) dans la matrice du biofilm a été détecté par spectroscopie infrarouge. Dans un second temps, afin d’étudier l’aptitude de C. difficile à former un biofilm in vivo, différents modèles animaux ont été utilisés : un modèle de souris monoxéniques dans lequel plusieurs souches de C. difficile ont été testées (souches 630∆erm, mutant cwp84, R20291, P30) et un modèle de souris dixénique pour étudier la formation de biofilm mixte (C. difficile/Finegoldia magna et C. difficile/Clostridium scindens). Dans le modèle monoxénique, quelles que soient les souches testées, C. difficile est distribué de manière hétérogène tout au long de la surface du tissu intestinal. Les bactéries sont majoritairement retrouvées isolées sauf pour la souche R20291 qui forme le plus souvent des petits agrégats. Pour cette souche, différents marquages immunohistochimiques réalisés sur des coupes de cecum et de colon ont montré que la majorité des bactéries sont enchâssées dans de petites structures en 3 dimensions adhérentes à la couche du mucus. Le polysaccharide PSII est détecté en grande quantité à l'intérieur de cette structure. Ce composé étant présent dans la matrice de biofilm de C. difficile formé in vitro, ces résultats suggèrent que la souche R20291 pourrait s’organiser en biofilm dans le modèle de souris monoxénique. En modèle de souris dixéniques, nous avons montré que la présence de F. magna n’influe pas sur le niveau de colonisation de C. difficile, alors que l'association avec C. scindens semble être bénéfique aux deux bactéries puisqu'une augmentation de la population globale de deux espèces est observée comparé à la population présente dans chaque modèle mono-espèce. En conclusion, une souche productrice de biofilm in vitro semble être capable de s’organiser en une structure biofilm in vivo. Le rôle du biofilm dans l'étape de colonisation du colon par C. difficile et les rechutes des ICD devra être analysé. / Clostridium difficile is an enteropathogenic bacterium responsible for intestinal infections, the clinical symptoms vary from moderate diarrhea to pseudomembranous colitis, sometimes fatal. One of the major problems encountered in the management of C. difficile infections (DCI) is the occurrence of recurrences. In many bacterial species, biofilm formation is associated with the chronicity of infection. Biofilm is a way of life in which bacteria are entrapped in a polymeric substance secreted by the bacteria themselves. The ability of C. difficile to form an in vitro biofilm has been clearly established since 2012. However, no study has so far shown whether it is capable of forming a biofilm in vivo. The objective of this thesis was to analyze different parameters involved in the formation of biofilm in vitro and to determine whether C. difficile is able to form a biofilm in vivo.We first analyzed the ability of different strains of C. difficile to form a biofilm in vitro (clinical strains and strains genetically modified laboratories). Among the latter, the mutant strain for the cwp84 gene, encoding a surface-associated protease responsible for the maturation of the S layer of C. difficile, forms a particularly robust and thick biofilm compared to the 630Δerm parental strain. The proteolytic activity of Cwp84 is involved in the formation of biofilm and modulates certain surface properties of the bacterium such as hydrophobicity. We have also studied the polysaccharide composition of the biofilm matrix, after a development stage that allowed us to determine the optimal conditions for obtaining sufficient material. The conditions retained were the following: formation of biofilm on a glass support in the presence of glucose and in a renewed medium. We were able to determine by infrared spectroscopy the presence of a sugar which has a similar profile than the PSII (polysaccharide associated with the surface of C. difficile planktonic cells) in the matrix of the biofilm.Second, in order to study the ability of C. difficile to form a biofilm in vivo, different animal models were used: a monoxenic mouse model in which we tested several strains of C. difficile (strains 630Δerm, mutant cwp84, R20291, P30) and a dixenic mouse model to study the formation of mixed biofilm (C .difficile/Finegoldia magna and C. difficile/Clostridium scindens). In the monoxenic model, regardless of the strains tested, C. difficile is distributed heterogeneously throughout the intestinal tissue surface. The bacteria are mostly found isolated except for C. difficile R20291 which usually forms small aggregates. For this strain we have shown, thanks to various immunohistochemical labeling performed on cecum and colon sections, that the majority of the bacteria are embedded in a small 3-dimensional structures overlaying the mucus layer. The PSII polysaccharide is present in a large amount in this structure. As this compound has been detected in the in vitro C. difficile biofilm matrix, these results suggest strongly that the R20291 strain could be organized into biofilm structures in the monoxenic mouse model. In the dixenic mouse model, we have shown that the presence of F. magna does not influence the level of colonization of C. difficile, whereas the association with C. scindens seems to be beneficial to both bacteria since an increase of the global population is observed in this model compared to the population present in each single-species model.To conclude, an in vitro biofilm producing strain appears to be able to organize in a biofilm structure in vivo. The role of biofilm in the colonization step of the intestinal tract by C. difficile and in the occurrence of recurrences should be further analyzed.

abstract: The Human Gut Microbiome (GM) modulates a variety of structural, metabolic, and protective functions to benefit the host. A few recent studies also support the role of the gut microbiome in the regulation of bone health. The relationship between GM and bone health was analyzed based on the data collected from a group of twenty-three adolescent boys and girls who participated in a controlled feeding study, during which two different doses (0 g/d fiber and 12 g/d fiber) of Soluble Corn Fiber (SCF) were added to their diet. This analysis was performed by predicting measures of Bone Mineral Density (BMD) and Bone Mineral Content (BMC) which are indicators of bone strength, using the GM sequence of proportions of 178 microbes collected from 23 subjects, by building a machine learning regression model. The model developed was evaluated by calculating performance metrics such as Root Mean Squared Error, Pearson’s correlation coefficient, and Spearman’s rank correlation coefficient, using cross-validation. A noticeable correlation was observed between the GM and bone health, and it was observed that the overall prediction correlation was higher with SCF intervention (r ~ 0.51). The genera of microbes that played an important role in this relationship were identified. Eubacterium (g), Bacteroides (g), Megamonas (g), Acetivibrio (g), Faecalibacterium (g), and Paraprevotella (g) were some of the microbes that showed an increase in proportion with SCF intervention. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2020

<p>In this study, structural specificity of flavonoids was investigated toselectively inhibit starch digestive enzymes to stimulate the ileal-brake by triggering glucagon-like peptide-1 (GLP-1) through distal small intestine starch digestion which can regulate food intake and appetite. The double bond between C2 and C3 on flavonoid’s chemical structure plays a critical role to inhibit human pancreatic α-amylase, leading to π-staking interaction. Meanwhile, the hydroxyl group at C3 on the backbone benzopyran ring is intimately related to inhibition of the mucosal α-glucosidases. This selective inhibition is likely the result of fundamental differences in the protein structures of α-amylase and α-glucosidases, as they belong to different glycosyl hydrolase Families 13 and 31 (GH13 and GH31). α-Amylase has the catalytic active siteslocated in wide and shallow grooves on the protein structure, while α-glucosidases possess the narrow and deep catalytic pocket. In an acute study done on mice, luteolin, which had thehigher degree of selectivity toward α-amylase, showed a slow and sustained postprandial glycemic response with a reduced blood glucose peak and extended high glucose profile, compared to 3’,4’-dihydroxylflavonol as the selective α-glucosidases specific inhibitor. Quercetin was inhibitory of both α-amylase and α-glucosidases.Glycemic profiles in mice confirmed in vitro analysis of the inhibitory selectivity of the flavonoids tested. Additionally, the extended glycemic response with luteolin was accompaniedthe higher secretion of GLP-1 at extended postprandial times by delivering more starch portion into the distal small intestine where the ileal-brake and gut-brain axis activation takes place. Overall, selective inhibition of α-amylase by flavonoids potentially could be considered as a key approach to control glucose release from starch with slow and extended, but still complete, digestion for improved glycemic response and minimized adverse side effects that result from severely restricting or even shutting down starch digestion by pharmaceutical grade inhibitors.<br></p>

Hajj, the annual Islamic pilgrimage to Makkah, Saudi Arabia, is a unique mass gathering event that brings more than 2 million individuals from around the world. Several public health considerations, such as the spread of infectious diseases, must be taken into account with this large temporary influx of people. Gastrointestinal diseases, such as diarrhea, are common at Hajj, yet little is known about the etiology. The human gut microbiome, collection of organisms residing within the intestinal tract, has been under intense study recently, since next generation DNA sequencing technologies allow for extensive surveying of genetic material found in complex biological samples, such as those containing many different organisms. Thus, using 16S rRNA and metagenomic shotgun sequencing, we have characterized the gut microbiome of over 612 pilgrims with and without diarrhea. Several metadata factors, such as hospitalization and different comorbidities, were found to have significant effects on the overall gut microbiome composition. Metagenomic shotgun sequencing efforts revealed the presence of antimicrobial resistance genes originating from disparate regions from around the world. This study provides a snapshot of information concerning the health status of the gut microbiome of Hajj pilgrims and provides more context to the investigation of how to best prepare for mass gathering events.

Insulin resistance and obesity are major public health concerns. The impact of diet and genetics on insulin resistance and obesity is well accepted. Additionally, the gut microbiota has been shown to influence obesity and metabolic disorders. However, much remains to be understood about the role of gut microbiota in the development of insulin resistance and obesity. We utilized a mouse model lacking PAS kinase, a protein involved in cellular metabolism, in order to better understand the relationship between diet, genetics and the gut microbiota. Previous research has shown that mice lacking PAS kinase were protected from the effects of a high fat diet, gaining less weight and showing a better response to insulin. Surprisingly, when PAS-kinase deficient mice were placed on a western-style, high fat, high sugar (HFHS) diet, they became obese and had an impaired response to insulin, much like wild type mice on the same diet. Mutant mice did, however, show more resistance to the effects of the unhealthy diet in one aspect-they maintained normal levels of claudin-1 in the colon, suggesting that they were less likely to develop excessive gut permeability (leaky gut). While significant differences in gut microbial composition were seen in response to the HFHS diet, with shifts in the ratio of Firmicutes/Bacteroidetes and increases in the levels of Actinobacteria, none of the differences correlated with genotype. Unexpectedly, however, within the mice on the HFHS diet and regardless of genotype, the composition of the gut microbiota diverged into two clusters. The mice in one cluster showed more resistance to obesity and their glucose response was like that of wild type mice on a healthy normal chow diet (NCD), while mice in the other cluster showed more weight gain and impaired glucose response. No similar gut microbiota divergence occurred in mice on the NCD, suggesting that the HFHS diet made mice vulnerable to (but did not cause) the development of a harmful gut microbiota, whereas the healthy NCD protected against spontaneous harmful shifts in the composition of the gut microbiota.