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[Recent research progress of selenium polysaccharides from medicinal plants].
Liang, H, Huang, J, Wang, L, Chen, J, Tian, ML
Zhongguo Zhong yao za zhi = Zhongguo zhongyao zazhi = China journal of Chinese materia medica. 2018;(15):3080-3092
Abstract
Selenium polysaccharides (Se polysaccharides) are a kind of organic selenium compounds which obtain the activities from Se and polysaccharides. Comparing to Se or polysaccharides, Se polysaccharides exhibit improved biological activities and are more prone to be absorbed by human bodies, therefore, they have been widely used in medical applications, such as immunomodulation, anti-tumor, anti-oxidation, anti-aging. Due to their unique pharmacological activities, Se polysaccharides from medicinal plants have gradually become a research hotspot. However, only a few of Se polysaccharides have been separated and purified in recent years. The structure of polysaccharides is also very complex, therefore, determination of the chemical structure and mechanism of bioactivity of Se polysaccharide in vivo remain to be further studied. This article systematically introduced the main source and biological activities of Se polysaccharides from medicinal plants. The purpose of this review is to provide a basis for the further research of Se polysaccharides.
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Unusual polysaccharide rheology of aqueous dispersions of soft phytoglycogen nanoparticles.
Shamana, H, Grossutti, M, Papp-Szabo, E, Miki, C, Dutcher, JR
Soft matter. 2018;(31):6496-6505
Abstract
Phytoglycogen is a natural polysaccharide produced in the form of dense, 35 nm diameter nanoparticles by some varieties of plants such as sweet corn. The highly-branched, dendrimeric structure of phytoglycogen leads to interesting and useful properties such as softness and deformability of the particles, and a strong interaction with water. These properties make the particles ideal for use as unique additives in personal care, nutrition and biomedical formulations. In the present study, we describe rheology measurements of aqueous dispersions of phytoglycogen nanoparticles. The viscosity of the dispersions remained Newtonian up to large concentrations (∼20% w/w). For higher concentrations, the zero-shear viscosity increased dramatically, reaching values that exceeded that of the water solvent by six orders of magnitude at a concentration of 30% w/w and were well described by the Vogel-Fulcher-Tammann relation of glassy dynamics. The very large values of the zero-shear viscosity are coupled with significant deformation of the soft nanoparticles. We quantified the softness of the particles by performing osmotic pressure measurements on concentrated dispersions, obtaining a value of 15 kPa for the compressional modulus. For the most concentrated samples, we observed flow at stresses less than the apparent yield stress value determined by fitting the high strain rate data to the Herschel-Bulkley model. This behavior, similar to that of star polymer glasses, suggests the possibility of a hairy colloid particle geometry. Remarkably, phytoglycogen nanoparticles dispersed in water provide a very simple experimental realization of glass-forming dispersions of soft colloidal particles that can be used to validate theoretical models in detail.
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A Polysaccharide-Based Antibacterial Coating with Improved Durability for Clear Overlay Appliances.
Park, S, Kim, HH, Yang, SB, Moon, JH, Ahn, HW, Hong, J
ACS applied materials & interfaces. 2018;(21):17714-17721
Abstract
Clear overlay appliances (COAs) are widely used in orthodontic fields because they offer many advantages, such as cost-effectiveness, good formability, and good optical characteristics. However, it is necessary to frequently replace COAs because the thermoplastic polymers that are used to fabricate COAs have poor abrasion resistance and have a tendency to induce bacterial accumulation. Here, we have developed polysaccharide-based antibacterial multilayer films with enhanced durability, intended for COA applications. First, multilayer films composed of carboxymethylcellulose (CMC) and chitosan (CHI) were fabricated on polyethylene terephthalate glycol-modified (PETG), which was preferred material for COA fabrication, via a layer-by-layer (LbL) technique. Next, chemical cross-linking was introduced within the LbL-assembled multilayer films. The LbL-assembled CMC/CHI film, which was made porous and rough by the cross-linking, formed a superhydrophilic surface to prevent the adhesion of bacteria and exhibited a bacterial reduction ratio of ∼75%. Furthermore, the cross-linking of the multilayer film coated on the PETG also improved the chemical resistance and mechanical stability of the PETG under simulated intraoral conditions with artificial saliva, by increasing the bond strength between the polysaccharide chains. We attempted to accumulate datasets using our experimental design and to develop sophisticated methods to assess nanoscale changes through large-scale measurements.
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Postexercise Fructose-Maltodextrin Ingestion Enhances Subsequent Endurance Capacity.
Maunder, E, Podlogar, T, Wallis, GA
Medicine and science in sports and exercise. 2018;(5):1039-1045
Abstract
PURPOSE Restoring skeletal muscle and hepatic glycogen content during short-term (<6 h) recovery from prolonged exercise is pertinent for athletes seeking to maximize performance in repeated exercise bouts. Previous research suggests that coingestion of fructose-glucose carbohydrate sources augments hepatic and has equivalent effects on skeletal muscle glycogen storage during short-term recovery from prolonged exercise compared with isocaloric glucose ingestion. The aim of the present investigation was to determine whether this has a discernible effect on subsequent exercise capacity. METHODS Eight trained endurance runners and triathletes performed two experimental trials in a single-blind, randomized, and counterbalanced crossover design. Trials involved treadmill running to exhaustion at 70% V˙O2max, a 4-h recovery with 90 g·h of glucose-maltodextrin (GLU + MAL) or fructose-maltodextrin (FRU + MAL) ingestion (1:1.5 ratio), and a second bout of treadmill running to exhaustion at 70% V˙O2max. RESULTS Exercise capacity in bout 2 was significantly greater with FRU + MAL (81.4 ± 22.3 vs 61.4 ± 9.6 min, P = 0.02), a large magnitude effect (effect size = 1.84 ± 1.12, 32.4% ± 19.9%). Total carbohydrate oxidation rates were not significantly different during bout 1 or 2 between trials, although total carbohydrate oxidized in bout 2 was significantly greater with FRU + MAL (223 ± 66 vs 157 ± 26 g, P = 0.02). Ingested carbohydrate oxidation rates were greater during bout 2 with FRU + MAL (P = 0.001). Plasma glucose and nonesterified fatty acid concentrations were not significantly different between trials. Plasma lactate concentrations were significantly greater during recovery before bout 2 with FRU + MAL (P = 0.001). Self-reported nausea and stomach fullness during bout 2 were marginally in favor of FRU + MAL. CONCLUSION Short-term recovery of endurance capacity was significantly enhanced with FRU + MAL versus GLU + MAL ingestion during recovery.
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Glycan-metabolizing enzymes in microbe-host interactions: the Streptococcus pneumoniae paradigm.
Hobbs, JK, Pluvinage, B, Boraston, AB
FEBS letters. 2018;(23):3865-3897
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Abstract
Streptococcus pneumoniae is a frequent colonizer of the upper airways; however, it is also an accomplished pathogen capable of causing life-threatening diseases. To colonize and cause invasive disease, this bacterium relies on a complex array of factors to mediate the host-bacterium interaction. The respiratory tract is rich in functionally important glycoconjugates that display a vast range of glycans, and, thus, a key component of the pneumococcus-host interaction involves an arsenal of bacterial carbohydrate-active enzymes to depolymerize these glycans and carbohydrate transporters to import the products. Through the destruction of host glycans, the glycan-specific metabolic machinery deployed by S. pneumoniae plays a variety of roles in the host-pathogen interaction. Here, we review the processing and metabolism of the major host-derived glycans, including N- and O-linked glycans, Lewis and blood group antigens, proteoglycans, and glycogen, as well as some dietary glycans. We discuss the role of these metabolic pathways in the S. pneumoniae-host interaction, speculate on the potential of key enzymes within these pathways as therapeutic targets, and relate S. pneumoniae as a model system to glycan processing in other microbial pathogens.
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Oxygen Activation by Cu LPMOs in Recalcitrant Carbohydrate Polysaccharide Conversion to Monomer Sugars.
Meier, KK, Jones, SM, Kaper, T, Hansson, H, Koetsier, MJ, Karkehabadi, S, Solomon, EI, Sandgren, M, Kelemen, B
Chemical reviews. 2018;(5):2593-2635
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Abstract
Natural carbohydrate polymers such as starch, cellulose, and chitin provide renewable alternatives to fossil fuels as a source for fuels and materials. As such, there is considerable interest in their conversion for industrial purposes, which is evidenced by the established and emerging markets for products derived from these natural polymers. In many cases, this is achieved via industrial processes that use enzymes to break down carbohydrates to monomer sugars. One of the major challenges facing large-scale industrial applications utilizing natural carbohydrate polymers is rooted in the fact that naturally occurring forms of starch, cellulose, and chitin can have tightly packed organizations of polymer chains with low hydration levels, giving rise to crystalline structures that are highly recalcitrant to enzymatic degradation. The topic of this review is oxidative cleavage of carbohydrate polymers by lytic polysaccharide mono-oxygenases (LPMOs). LPMOs are copper-dependent enzymes (EC 1.14.99.53-56) that, with glycoside hydrolases, participate in the degradation of recalcitrant carbohydrate polymers. Their activity and structural underpinnings provide insights into biological mechanisms of polysaccharide degradation.
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Medium-chain Triglycerides with Maltodextrin Increase Fat Oxidation during Moderate-intensity Exercise and Extend the Duration of Subsequent High-intensity Exercise.
Nosaka, N, Suzuki, Y, Suemitsu, H, Kasai, M, Kato, K, Taguchi, M
Journal of oleo science. 2018;(11):1455-1462
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Abstract
Medium-chain triglycerides (MCT) are useful for increasing fat utilization during exercise. The highest rate of fat oxidation during submaximal exercise tends to precede the lactate threshold in untrained adults. In our previous study, blood lactate concentration was more than 4 mmol/L (onset of blood lactate) in recreational athletes during exercise at a workload corresponding to 60% peak O2 uptake (V・o2), which was below ventilation threshold. In the present study, we investigated the effect of 2 week of ingestion of food containing 6 g MCT on substrate oxidation during moderate-intensity (50% peak V・o2) exercise and high-intensity (70% peak V・o2) exercise in recreational athletes. For comparison, two experimental trials were conducted after participants had been administered isoenergic test foods (MCT-supplemented food with mainly maltodextrin-containing carbohydrate (MCT + CHO) or CHO) for 2 weeks, with a washout period between trials. Participants were instructed to perform cycle ergometer exercise at a workload corresponding to 50% peak V・o2 for 40 min followed by a workload corresponding to 70% peak V・o2 until exhaustion. Fat oxidation was significantly increased in the MCT + CHO trial (13.3 ± 2.7 g/40 min, mean ± SD, p < 0.05) during moderate-intensity exercise and the duration was extended significantly (23.5 ± 19.4 min, p < 0.05) during subsequent high-intensity exercise, compared with that observed in the CHO trial (fat oxidation; 11.7 ± 2.8 g/40 min, duration; 17.6 ± 16.1 min). In conclusion, continuous ingestion of 6 g MCT with maltodextrin could increase fat oxidation during moderate-intensity exercise and extend the duration of subsequent high-intensity exercise in recreational athletes, compared with the ingestion of isoenergic maltodextrin alone.
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A caffeine-maltodextrin mouth rinse counters mental fatigue.
Van Cutsem, J, De Pauw, K, Marcora, S, Meeusen, R, Roelands, B
Psychopharmacology. 2018;(4):947-958
Abstract
INTRODUCTION Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity that has negative implications on many aspects in daily life. Caffeine and carbohydrate ingestion have been shown to be able to reduce these negative effects of mental fatigue. Intake of these substances might however be less desirable in some situations (e.g., restricted caloric intake, Ramadan). Rinsing caffeine or glucose within the mouth has already been shown to improve exercise performance. Therefore, we sought to evaluate the effect of frequent caffeine-maltodextrin (CAF-MALT) mouth rinsing on mental fatigue induced by a prolonged cognitive task. METHODS Ten males (age 23 ± 2 years, physical activity 7.3 ± 4.3 h/week, low CAF users) performed two trials. Participants first completed a Flanker task (3 min), then performed a 90-min mentally fatiguing task (Stroop task), followed by another Flanker task. Before the start and after each 12.5% of the Stroop task (eight blocks), subjects received a CAF-MALT mouth rinse (MR: 0.3 g/25 ml CAF: 1.6g/25 ml MALT) or placebo (PLAC: 25 ml artificial saliva). RESULTS Self-reported mental fatigue was lower in MR (p = 0.017) compared to PLAC. Normalized accuracy (accuracy first block = 100%) was higher in the last block of the Stroop in MR (p = 0.032) compared to PLAC. P2 amplitude in the dorsolateral prefrontal cortex (DLPFC) decreased over time only in PLAC (p = 0.017). CONCLUSION Frequent mouth rinsing during a prolonged and demanding cognitive task reduces mental fatigue compared to mouth rinsing with artificial saliva.
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Multiple stable states in microbial communities explained by the stable marriage problem.
Goyal, A, Dubinkina, V, Maslov, S
The ISME journal. 2018;(12):2823-2834
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Abstract
Experimental studies of microbial communities routinely reveal that they have multiple stable states. While each of these states is generally resilient, certain perturbations such as antibiotics, probiotics, and diet shifts, result in transitions to other states. Can we reliably both predict such stable states as well as direct and control transitions between them? Here we present a new conceptual model-inspired by the stable marriage problem in game theory and economics-in which microbial communities naturally exhibit multiple stable states, each state with a different species' abundance profile. Our model's core ingredient is that microbes utilize nutrients one at a time while competing with each other. Using only two ranked tables, one with microbes' nutrient preferences and one with their competitive abilities, we can determine all possible stable states as well as predict inter-state transitions, triggered by the removal or addition of a specific nutrient or microbe. Further, using an example of seven Bacteroides species common to the human gut utilizing nine polysaccharides, we predict that mutual complementarity in nutrient preferences enables these species to coexist at high abundances.
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Interactions between cell wall polysaccharides and polyphenols.
Zhu, F
Critical reviews in food science and nutrition. 2018;(11):1808-1831
Abstract
In plant-based food systems such as fruits, vegetables, and cereals, cell wall polysaccharides and polyphenols co-exist and commonly interact during processing and digestion. The noncovalent interactions between cell wall polysaccharides and polyphenols may greatly influence the physicochemical and nutritional properties of foods. The affinity of cell wall polysaccharides with polyphenols depends on both endogenous and exogenous factors. The endogenous factors include the structures, compositions, and concentrations of both polysaccharides and polyphenols, and the exogenous factors are the environmental conditions such as pH, temperature, ionic strength, and the presence of other components (e.g., protein). Diverse methods used to directly characterize the interactions include NMR spectroscopy, size-exclusion chromatography, confocal microscopy, isothermal titration calorimetry, molecular dynamics simulation, and so on. The un-bound polyphenols are quantified by liquid chromatography or spectrophotometry after dialysis or centrifugation. The adsorption of polyphenols by polysaccharides is mostly driven by hydrophobic interactions and hydrogen bonding, and can be described by various isothermal models such as Langmuir and Freundlich equations. Quality attributes of various food and beverage products (e.g., wine) can be significantly affected by polysaccharide-polyphenol interactions. Nutritionally, the interactions play an important role in the digestive tract of humans for the metabolism of both polyphenols and polysaccharides.