Exercícios intensos resultam em depleção acentuada de glicogênio muscular e aumento da lactacidemia, associados ao aumento do cortisol circulante e seus efeitos catabólicos, como a proteólise muscular, ocasionando em menor desempenho físico e comprometendo a qualidade de treinamento do atleta. Diante disso, o presente estudo avaliou o efeito agudo da suplementação de carboidrato sobre o desempenho físico e a resposta hormonal durante e após uma sessão de exercícios intermitentes de alta intensidade. Participaram do estudo 16 corredores com, idade média de 26 ± 5. Os atletas realizaram, em dois momentos distintos [experimental: carboidrato (CHO) e controle: placebo (PLA)], exercícios intermitentes: 12x800 m pausa 1\'30\" a 100% da velocidade média (Vm) 3.000 m. Com relação aos parâmetros de desempenho físico não foram observados efeitos benéficos com a administração de CHO. Os voluntários realizaram o teste em 28,32±1 ,52 min (CHO) e 28,32±1,38 min (PLA). Observou-se aumento significativo da glicemia durante o exercício em ambos grupos, retornando aos valores pré-exercício durante o período de recuperação, indicando acentuada velocidade de captação da glicose após esforços intensos. Quanto à lactacidemia, houve aumento significativo durante o exercício (CHO: 3, 75±1,62 mmol/L PLA: 2, 79±1,69 mmol/L) quando comparado às concentrações pré-exercício (p<0,05). Essas concentrações estiveram significativamente aumentadas durante o exercício no grupo CHO devido a maior disponibilidade de substrato (p<0,05). Entretanto, a suplementação de CHO não diminuiu as concentrações plasmáticas de cortisol durante o exercício. No experimento PLA a concentração de insulina esteve significativamente maior no período de recuperação, como resultado de uma intensa glicogenólise hepática, superando possivelmente o aumento da glicemia no grupo CHO. / Intense exercises result in accentuated depletion of muscular glycogen and increase of the lactacidemy, which are associated to the increase of the circulating cortisol and its catabolic effects like the muscular proteolysis, causing in shorter physical acting, risking the quality of the athlete\'s training. Because of that, the present study evaluated the acute effect of the carbohydrate supplementation on the physical performance and the hormonal response during and after a session of intermittent exercises of high intensity. Sixteen runners, at the average age of 26 ± 5 have participated in the study. The athletes have accomp1ished, in two different trials [(experimental: carbohydrate (CHO) and control: placebo (PLA)], intermittent exercises: 12x800 m pause 1 \'30\" at 100% mean velocity (Vm) 3000 m. ln relation to the physical performance parameters, no beneficial effects were observed at the CHO administration. The athletes have accomplished the test in 28,32±1,52 min (CHO) and 28,32±1,38 min (PLA). A significant increase of the glycemia was observed in both trials during the exercise, going back to the pre-exercising values during the recovery period, indicating an accentuated speed of glucose captation after intense efforts. As to the lactacidemy, there was a significant increase during the exercise (CHO: 3, 75±1,62 mmol/L PLA: 2,79±1,69 mmol/L) when compared to the pre exercising concentrations (p < 0,05). Those concentrations were significantly increased during the exercise in CHO trial due to larger substratum readiness (p < 0,05). However, the CHO supplementation didn\'t reduce the plasmatic concentrations of cortisol during the exercise. In the PLA trial, the insulin concentration was significantly larger in the recovery period as a result of an intense hepatic glycogenolysis possibly overcoming the increase of glycemia in the CHO trial.

Thesis (M.Sc. (Biochemistry)) -- University of Limpopo, 2013 / Diabetes mellitus is one of the fast growing chronic metabolic disorders throughout the world. It has become a life threatening disease and health burden. So far it can only be managed with commercial therapeutic agents, proper diet and exercise. People particularly from developing countries use medicinal plants to treat this condition. According to WHO, about 80% of the population in developing countries are dependable on medicinal plants. This prompted many researchers to explore the effectiveness and safety of these plants. In the current study ten medicinal plants were randomly chosen, screened for antidiabetic activity by testing their ability to inhibit α-amylase and α-glucosidase enzymes. The plants were tested using in vitro assays. The finely powdered leaves of each plant were extracted with hexane, chloroform, acetone and ethyl acetate. Phytoconstituents of each plant extracts were analyzed using both qualitative and quantitative methods. All plant extracts tested positive for phenols, flavonoids and all negative for starch. Their compounds were better separated in the TEA mobile system on the TLC plates. All plant extracts had more of total phenolics ranging between 0.1-400 GAE/mg than total flavonoids and condensed tannins. Antioxidant activity of the plant extracts was tested quantitatively at various concentrations using DPPH. Most plant extracts were able to scavenge the radicals produced by DPPH at highest concentration of 2.5 mg/mℓ. Not all plant extracts with the highest number of total phenolics had the highest antioxidant activity. For antidiabetic in vitro assays, plant extracts inhibited various percentages of both α-amylase and α-glucosidase activity at concentrations ranging between 0.019- 2.5 mg/mℓ. The best overall activity against both enzymes was observed in acetone and ethyl acetate plant extracts. Cassia abbreviata and Helinus integrifolius were even more active than acarbose which was used as positive control. These plant extracts inhibited both the enzymes in a dose dependent and non-competitive manner. Seeing that both extracts of C. abbreviata and H. integrifolius were consistent when inhibiting both enzymes, they were further evaluated for their effect on glucose uptake by the C2C12 muscle and H-II-4-E liver cells. All the plant extracts tested were able to increase glucose uptake in the muscle cells. However optimal increase was seen in the liver cells when treated with 250 µg/mℓ of acetone and ethyl acetate extracts of C. abbreviata. The cytotoxicity effects of both acetone and ethyl acetate of C. abbreviata and H. integrifolius was tested using the xCelligence system on RAW 264.7 cells. Different cell indexes were obtained after treating the cells with different concentrations (0.05,0.1 and 0.25 mg/mℓ) of each plant extracts respectively. The system was run for three days but the toxic effects of plant extracts were analyzed for the first ten hours. The results obtained shows that cell index decreased as the concentration of the plant extracts was increased. All the plant extracts were less toxic as compared to positive control, Actinomycin D. The leaves of H. integrifolius were further exhaustively extracted with hexane, dichloromethane, acetone, ethyl acetate and methanol respectively. Since the DCM extracts yielded the highest mass in quantity, it was further used for isolation of active compounds. Column chromatography and bioassay guided fraction led to isolation of a mixture of triterpenes identified as α and β-amyrin. The structure was elucidated using nuclear magnetic resonance technique. The inhibitory capability of the isolated compound against α-amylase enzyme was less than the crude extract which inhibited more than 50% of the activity at a concentration of 1 mg/mℓ.Based on the enzymes assays and cell culture work it can be concluded that C. abbreviata and H. integrifolius species are the best inhibitors of carbohydrate digesting enzymes, and therefore be used to manage postprandial hyperglycemia in the people with type 2 diabetes. However more work still need to be conducted for further isolation of more active compounds.

Earnest carbohydrate research was initiated in the nineteenth century by several talented organic chemists. Carbohydrates, now known to play essential roles in a range of fundamental biological processes, are presently studied by a throng of scientists from many fields, including: biochemistry, molecular biology, immunology, structural biology, medicine, agriculture, pharmacology and, of course, chemistry. Organic chemistry remains as relevant to carbohydrate research as it has ever been; its practitioners, with their skills in synthesis and fundamental understanding of molecules, are truly indispensable. This thesis details various synthetic endeavours within the field of carbohydrate chemistry. It describes four projects with goals as diverse as natural product synthesis, rational inhibitor design and the development of new reagents in organic synthesis. The first chapter provides an account of the synthesis of compound 1, a potent germination stimulant present in smoke, from D-xylose. Many analogues of 1 were prepared from carbohydrates and evaluated as germination stimulants, which permitted the dissemination of several structure-activity relationships. Subsequent chapters describe the design and preparation of inhibitors for various carbohydrate-processing enzymes. Compounds 55 and 56 were sought after as putative synergistic inhibitors of a Vitis vinifera (grape) uridine diphospho-glucose:flavonoid 3-O-glucosyltransferase (VvGT1). It was hoped that crystallographic investigations of VvGT1-UDP-2/3 complexes by a collaborator, structural biologist Professor Gideon Davies, would aid in clarifying mechanistic aspects of this enzyme.Compounds 114, 115 and 118 were prepared as putative arabinanase inhibitors. Once again, this work was undertaken to assist in crystallographic studies that might provide a better understanding of how these enzymes operate. The thesis concludes by describing the development of compound 152.HCl, a novel reagent for the diazotransfer reaction. Previously, this reaction utilised trifluoromethanesulfonyl azide (TfN3), an expensive and explosive liquid with a poor shelf-life, to convert a primary amine directly into an azide. Reagent 152.HCl was developed to replace TfN3 in this useful synthetic transformation. A one-pot procedure enabled the simple and inexpensive preparation of 152.HCl, which was demonstrated to be shelf-stable, crystalline and, crucially, effective in the diazotransfer reaction.

[Truncated abstract] Obesity is now a major public health problem worldwide. More than half the Australian population is now overweight. This is an important public health concern primarily because of the impact of overweight and obesity on risk of diabetes, hypertension and cardiovascular disease. Many strategies have been proposed to fight the obesity epidemic. One possible strategy involves understanding of the role of dietary components in the control of food intake. In this regard, dietary protein and fibre appear to be the most satiating nutrients. Foods enriched in protein, replacing energy from carbohydrate, or dietary fibre can increase satiety and reduce energy intake in the short-term. Longer-term trials suggest benefits of increasing protein or fibre intake on weight loss and features of the metabolic syndrome. The effects of dietary approaches which increase both protein and fibre at the expense of refined carbohydrate are uncertain. A practical approach to increasing both protein and fibre content of processed foods is to incorporate high protein and fibre ingredients into high carbohydrate foods. Lupin kernel flour is a novel food ingredient derived from the endosperm of lupin. It contains 40 to 45% protein, 25 to 30% fibre, and negligible sugar and starch. Lupin kernel flour can be incorporated into refined carbohydrate rich foods such as bread to increase protein and fibre content at the expense of refined carbohydrate. ... Body weight was measured every 2 weeks throughout the 16 week intervention, and these data were analysed to determine whether there was any between group difference in the rate of change in weight over 16 weeks. Over 16 weeks, lupin bread compared to white bread resulted in a significant increase in protein (13.7 (2.3, 25.0) g/d) and fibre (12.5 (8.8, 16.2) g/d) intakes, and a decrease in carbohydrate intake (-19.9 (-45.2, 5.5) g/d). There was a significant difference between groups in the rate of weight change over the 16 weeks (P=0.05). However, at 16 weeks there was no significant effect on body weight (-0.4 (-1.3, 0.6) kg), fat mass (-0.5 (-1.2, 0.2) kg) or fat free mass (0.2 (-0.5, 0.8) kg). Plasma adiponectin and leptin were not altered. Mean 24 hour systolic blood pressure (-2.4 (-3.4, -1.3) mm Hg) and pulse pressure (-3.1 (-3.9, -2.3) mm Hg) were lower for lupin relative to white bread, but diastolic blood pressure was not significantly different between groups. Apart from a lower HDL cholesterol for lupin relative to white bread (-0.09 (-0.17, -0.01) mmol/L), there were no significant differences in other blood lipids and glucose and insulin concentrations. Interpretation of the results was not influenced after adjustment for potential confounding factors. These studies assessed effects of bread enriched in lupin kernel flour relative to white bread, resulting in a higher protein and fibre intake and lower refined carbohydrate intake. This increased satiety and reduced energy intake acutely, but did not significantly influence body weight over 16 weeks. Systolic blood pressure and pulse pressure were significantly reduced. There were no significant improvements in blood lipids or glucose and insulin concentrations. Therefore, increasing protein and fibre intake at the expense of refined carbohydrate using lupin kernel flour may benefit satiety and blood pressure. Longer-term trials incorporating weight loss may be needed to observe benefits on body weight.

It is currently accepted that the most appropriate diet in the treatment of non-insulin-dependent diabetes mellitus &quoteNIDDM&quote is high in carbohydrates, high in fibre and low in fat. Dietary fibre reduces the rate of carbohydrate absorption, which may have a beneficial effect on insulin action. Furthermore, high fibre diets also increase the amount of carbohydrates which are not absorbed from the small intestine. These malabsorbed carbohydrates are fermented by the bacterial population in the large intestine, producing short chain fatty acids &quoteSCFA&quote, including propionate, which has been shown to alter liver carbohydrate metabolism. This thesis investigated the actions of slowed carbohydrate absorption and carbohydrate malabsorption in streptozotocin-induced &quoteSTZ&quote diabetic rats. High carbohydrate diet supplemented with guar gum, a soluble dietary fibre, fed to STZ diabetic rats improved insulin sensitivity. investigation of the alterations in the stomach and small intestine demonstrated that guar increased the viscosity of the meal in the intestine. The action of increased fermentation, producing more propionate, was investigated by supplementing propionate into the diets of STZ diabetic rats or when perfused into isolated rat livers. No changes in insulin action or liver glucose metabolism were measured. in addition, it was shown that guar gum reduces food intake in STZ diabetic rats. Mild reductions in food intake in STZ diabetic rats were shown to increase insulin action. In summary, STZ diabetic rats fed high carbohydrate, high fibre diets reductions in food consumption and slowed carbohydrate absorption are important factors which may lower blood glucose concentrations and increase insulin action. increased SCFA production is unlikely to contribute significantly to the improvements in insulin action.

Aydat est un petit lac eutrophe et dimictique du Massif Central (France), en environnement volcanique. L'étude de la diagenèse des sédiments actuels (trappes) et récents (carottes) de ce lac, a été abordée selon les méthodes classiques de la sédimentologie, de la géochimie minérale, ainsi que par l'analyse d'une famille de constituants organiques majeurs : les polysaccharides. Les sédiments actuels ont été collectés mensuellement d'octobre 1995 à septembre 1996 à l'aide de 3 trappes réparties dans la colonne d'eau, dans la partie centrale du lac. Les carottes sédimentaires, de 50 cm de long, ont été prélevées à l'aplomb de la ligne de trappes. La fraction minérale des sédiments est dominée par des particules authigènes. Les frustules de diatomées, qui représentent plus de 80% des sédiments, contribuent de façon stable à l'enregistrement sédimentaire. En revanche, des minéraux autochtones tels que la calcite et les oxy-hydroxydes de fer et manganèse, sont fortement impliqués dans la dynamique biogéochimique lacustre, essentiellement régie par les processus redox induits par l'activité biologique. Ainsi, le comportement des éléments les plus mobiles des sédiments de fond anoxiques, qu'ils soient solubles, échangeables et/ou complexables, a pu être précisé par le biais d'attaques chimiques séquentielles. L'ensemble des données géochimiques acquises sur la phase solide des sédiments, combinées avec les analyses des éléments en solution réalisées par l'équipe du Laboratoire de Géochimie des Eaux (Université Paris VII), a permis d'établir un bilan annuel des éléments chimiques dans le lac d'Aydat. Ce bilan a notamment permis d'identifier 5 types de comportements différents des divers éléments suivis tout au long de l'année d'étude et a également permis de quantifier l'intensité du recyclage des éléments réactifs tels que Fe, Mn, Co, Ba et As, dans le réservoir lacustre. La dynamique de la matière organique, qui est essentiellement régie par les processus géochimiques lacustres via l'activité biologique, a été suivie grâce à l'analyse des polysaccharides, composés ubiquistes majeurs du règne végétal, aisément recyclés. Malgré un flux de matière organique autochtone abondant dans le lac d'Aydat, la composition des sucres neutres reflète mal la production planctonique primaire (diatomées, cyanobactéries), mais plutôt celle de la flore microbienne. L'intense activité bactérienne au sein de la colonne d'eau et surtout au niveau de l'interface eau-sédiment, qui se signale particulièrement par l'abondance d'un désoxyhexose, le rhamnose, empêche les sucres de participer significativement à l'enregistrement sédimentaire. Ainsi, ces composés métabolisables contribuent via les bactéries, aux processus diagénétiques, et donc à l'entretien des cycles biogéochimiques dans lesquels les éléments minéraux les plus réactifs sont périodiquement impliqués.

<p>Lichens are fascinating symbiotic systems, where a fungus and a unicellular alga, most often green (bipartite green algal lichens; 90% of all lichens), or a fi lamentous cyanobacterium (bipartite cyanobacterial lichens; 10% of all lichens) form a new entity (a thallus) appearing as a new and integrated organism: in about 500 lichens the fungus is associated with both a cyanobacterium and an alga (tripartite lichens). In the thallus, the lichen bionts function both as individual organisms, and as a symbiont partner. Hence, in lichens, the participating partners must both be able to receive and acquire resources from the other partner(s) in a controlled way.</p><p>Lichens are particularly successful in harsh terrestrial environments. In part this is related to their poikilohydric nature and subsequent ability to repeatedly become desiccated and hydrated. Metabolic activity, i.e. photosynthesis, respiration, and for cyanobacterial lichens N2-fixation, is limited to periods when the thallus is suffi ciently hydrated. Mineral nutrients are mainly acquired from dry or wet deposition directly on the thallus. Taken together it then appears that lichens are to a large extent passively controlled by their environment, making their control over resource allocation and acquisition particularly challenging.</p><p>The aim of this thesis was to investigate resource acquisition and allocation processes in different lichens, and to see how these respond to changes in resource availability. This was done by following lichen growth in the fi eld during manipulation of water, light, and nutrient supply, and by assessing the responses of both the integrated thallus as well as the individual bionts. As a fi rst step, resource allocation and acquisition was investigated for a broad range of lichens aiming to determine the magnitude of metabolic variation across lichens. Seventy-fi ve lichen species were selected to cover as broad a spectrum as possible regarding taxonomy, morphology, habitat, and nitrogen requirements. The lichens had invested their nitrogen resources so that photosynthetic capacity matched respiratory carbon demand around a similar equilibrium across the contrasting species. Regulation of lichen growth was investigated in another study, using the two tripartite species <i>Nephroma arcticum</i> and <i>Peltigera aphthosa</i>, emphasizing the contribution of both internal and external factors. The empirical growth models for the two lichens were similar, showing that weight gain is to a higher extent dependent on those external factors that regulate their photosynthesis, whilst area gain is more controlled by internal factors, such as their nitrogen metabolism. This might be inferred from another study of the same species, where nitrogen manipulations resulted in an undisturbed weight gain, a similar resource allocation pattern between the bionts, but a distorted area gain. </p><p>Aiming to investigate lichen nitrogen relations even further, lichens’ capacities to assimilate combined nitrogen in the form of ammonium, nitrate and amino acids were assessed using 14 contrasting boreal species. All these had the capacity to assimilate all the three nitrogen forms, with ammonium absorption being more passive, and nitrate uptake being low in bipartite cyanobacterial lichens. Differences in uptake capacities between species were more correlated to photobiont than to morphology or substrate preferences. Finally, to investigate intra-specifi c plasticity in relation to altered nutrient supply, resource investments between photo- and mycobiont were investigated in the two bipartite green algal lichens <i>Hypogymnia physodes </i>and and <i>Platismatia glauca</i> in a low and a high nutrient environ- in a low and a high nutrient environ- ment. In both species, more of the resources had been directed to the photobiont in the high nutrient environment also increasing their overall carbon status. Taken together, my studies indicate that in spite of the apparent passive environmental control on lichen metabolism, these symbiotic organisms are able to both optimize and control their resource acquisition and allocation processes.</p>

<p>An efficient and versatile non-destructive method to analyze the progress of solid-phase glycoconjugate synthesis with gel-phase ¹⁹F NMR spectroscopy is described. The method relies on use of fluorinated linkers and building blocks carrying fluorinated protective groups. Commercially available fluorinated reagents have been utilized to attach the protective groups. </p><p>The influence of resin structures for seven commercial resins upon resolution of gel-phase ¹⁹F NMR spectra was investigated. Two different linkers for oligosaccharide synthesis were also developed and successfully employed in preparation of α-Gal trisaccharides and a n-pentenyl glycoside. Finally, reaction conditions for solid-phase peptide glycosylations were established.</p>

<p>The glycaemic responses to various carbohydrate-rich foods are partly dependent on the rate at which the carbohydrate is digested and absorbed. The glycaemic index (GI) is a way of ranking foods according to their glycaemic response and is recommended as a useful tool in identifying starch-rich foods that give the most favourable glycaemic response. This investigation was undertaken to determine whether carbohydrate-rich foods with a low GI and a high content of dietary fibre (DF) could have beneficial metabolic effects in the insulin resistance syndrome. This question was addressed both in single-meal studies and in randomised controlled clinical trials. Starch-rich foods with low GI values incorporated into composite meals resulted in lower postprandial responses of both glucose and insulin than foods with a high GI in meals with an identical macronutrient and DF composition, in subjects with type 2 diabetes. After three weeks on a diet including low GI starchy foods metabolic profile was improved in subjects with type 2 diabetes, compared with a corresponding high GI diet. The glucose and insulin responses throughout the day were lower, the total and low density lipoprotein cholesterol was decreased, and the fibrinolytic activity was normalised. In subjects with impaired insulin sensitivity and diabetes low GI foods rich in soluble DF for breakfast gave a more favourable metabolic profile, with smaller glucose fluctuations from baseline during the day, than a breakfast with high GI foods low in DF. A low GI breakfast high in DF also resulted in lower responses of insulin and C-peptide after breakfast and a lower triacylglycerol response after a standardised lunch. However, none of the tested breakfasts improved the glucose and insulin responses after lunch. Similar results were obtained in obese subjects after including a breakfast with a low GI high in soluble DF for a period of four weeks in comparison with a breakfast with a high GI and low content of DF.</p><p>These results support the therapeutic potential of a diet with a low GI in the treatment of diabetes and also in the treatment of several of the metabolic disturbances related to the insulin resistance syndrome.</p>

Carbohydrates are abundant in nature and have functions ranging from energy storage to acting as structural components. Analysis of carbohydrate structures is important and can be used for, for instance, clinical diagnosis of diseases as well as in bacterial studies. The complexity of glycans makes it difficult to determine their structures. NMR spectroscopy is an advanced method that can be used to examine carbohydrates at the atomic level, but full assignments of the signals require much work. Reliable automation of this process would be of great help. Herein studies of Escherichia coli O-antigen polysaccharides are presented, both a structure determination by NMR and also research on glycosyltransferases which assemble the polysaccharides. The computer program CASPER has been improved to assist in carbohydrate studies and in the long run make it possible to automatically determine structures based only on NMR data. Detailed computer studies of glycans can shed light on their interactions with proteins and help find inhibitors to prevent unwanted binding. The WaaG glycosyltransferase is important for the formation of E. coli lipopolysaccharides. Molecular docking analyses of structures confirmed to bind this enzyme have provided information on how inhibitors could be composed. Noroviruses cause gastroenteritis, such as the winter vomiting disease, after binding human histo-blood group antigens. In one of the projects, fragment-based docking, followed by molecular dynamics simulations and binding free energy calculations, was used to find competitive binders to the P domain of the capsid of the norovirus VA387. These novel structures have high affinity and are a very good starting point for developing drugs against noroviruses. The protein targets in these two projects are carbohydrate binding, but the techniques are general and can be applied to other research projects. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 5: Manuscript. Paper 6. Manuscript.