Preparation and characterization of molecular weight standards of low polydispersity from oat and barley (1→3)(1→4)-β-d-glucan

Protective effects of sulfated polysaccharides from Enteromorpha intestinalis on oxidative stress, liver iron overload and Ferroptosis in Zebra fish exposed to ethanol

The study investigates the protective effects of sulfated polysaccharides extracted from Enteromorpha intestinalis (EIP) against oxidative stress, liver iron overload, and ferroptosis in zebrafish exposed to ethanol, a model for alcohol-related liver disease (ALD). The extracted polysaccharides were characterized for sulfate and sugar content, molecular weight, and functional groups. Adult male zebrafish were divided into three groups: control, ethanol-exposed (EE) (0.2 % ethanol (v/v) in the water), and ethanol-exposed with EIP supplementation (1 % EIP incorporated into the basal diet) (EE+EIP) for 30 days. The study measured liver oxidative stress indexes, serum enzymological indexes, liver and serum lipid profiles, liver iron ion content, and expression of ferroptosis-related genes. Histological analysis was conducted to assess lipid accumulation and iron deposition in liver tissues. The findings indicate that EIP supplementation significantly mitigates ethanol-induced liver damage. Specifically, EIP reduced malondialdehyde levels, increased antioxidant enzyme and non-enzymatic antioxidant activity, and decreased iron ion accumulation and the area of iron granules in the liver tissue. Additionally, EIP treatment lowered lipids levels and aminotransferase enzyme activity in the serum. In the ALD model, EIP inhibited ethanol-induced ferroptosis by modulating the expression of key genes: it decreased the expression of transferrin (tf), transferrin receptor (tfr), ferroportin (fpn), and ferritin heavy chain (fth), while increasing the expression of glutathione peroxidase 4 (gpx4) and solute carrier family 7 member 11 (slc7a11). EIP has protective effects against ethanol-induced liver injury in zebrafish, offering a foundation for further research into its hepatoprotective action and potential application in preventing and treating ALD.

Structural and Rheological Properties of Yanang Gum (Tiliacora triandra)

Plant polysaccharides are used in the food industry to improve the texture and stability of food. The viscosity of polysaccharides, which includes both thickening and gelling, is an important characteristic. Yanang, Tilaicora triandra (Colebr.) Diels., composed of polysaccharide gum in its leaves. In this research, Yanang gum’s structural and rheological properties were investigated. The gum’s structure is xylan, with a backbone made up mostly of mixed (1,3)- and (1,4)-D-xylan. The average molecular weight of Yanang gum is 3819 kDa, with a gyration radius of 120.4 nm and an intrinsic viscosity of 14.6 dL/g. The power-law model was found to be the best fit for Yanang gum flow curves. The consistency coefficient, k, increases significantly with concentration in both the forward and the reverse measurements, whereas the flow behavior index, n, decreased as concentration increased. Yanang gum exhibited shear-thinning flow behavior. Increasing the concentration results in heightened G′ and G″, and the cross-over point shifts toward lower frequencies. The results of this study show that Yanang gum may be beneficial as other natural gums for food products.

Seed coat mucilages: Structural, functional/bioactive properties, and genetic information

Seed coat mucilages are mainly polysaccharides covering the outer layer of the seeds to facilitate seed hydration and germination, thereby improving seedling emergence and reducing seedling mortality. Four types of polysaccharides are found in mucilages including xylan, pectin, glucomannan, and cellulose. Recently, mucilages from flaxseed, yellow mustard seed, chia seed, and so on, have been used extensively in the areas of food, pharmaceutical, and cosmetics contributing to stability, texture, and appearance. This review, for the first time, addresses the similarities and differences in physicochemical properties, molecular structure, and functional/bioactive properties of mucilages among different sources; highlights their structure and function relationships; and systematically summarizes the related genetic information, aiming with the intent to explore the potential functions thereby extending their future industrial applications.

The emulsifying and foaming properties of Amuniacum gum (Dorema ammoniacum) in comparison with gum Arabic

In this study, the emulsifying and foaming properties of a novel exudate gum from Dorema ammoniacum (AMG) were assessed in comparison with the well-known gum Arabic from Acacia tree (GAC). The sunflower oil-based emulsion (10% v/v) containing various concentrations (5%-15% w/v) of AMG and GAC was prepared. At all concentrations, AMG showed higher surface and interface activity than GAC. Increasing in AMG and GAC concentrations caused to increase and decrease in Z average, respectively. Overall, the GAC-stabilized emulsion showed lower Z average and PDI value than the AMG-stabilized emulsion during storage time. The sample containing AMG showed higher emulsion capacity and lower emulsion stability in comparison with the one containing GAC at all concentrations. The storage stability decreased and increased with increasing in AMG and GAC concentrations, respectively. After two-week storage, the emulsions containing 10 and 15% AMG showed higher phase separation than those containing GAC; however, this was opposite about sample containing 5% AMG. At thermal, centrifuge, and freezing conditions, the emulsion containing 5% AMG indicated significantly higher stability than GAC samples; however, at higher concentration, opposite effect could be observed. The foaming capacity of the samples containing AMG increased from 81% to 93% by increasing gum concentration from 5% to 15%. The solutions containing AMG showed higher foam capacity than control samples (without gum) and those containing GAC at all concentrations. Increasing in AMG and GAC concentrations slightly improved foam stability, and the highest value (92%) belonged to 15% AMG solution.

The effect of oat β-glucan on in vitro glucose diffusion and glucose transport in rat small intestine

BACKGROUND

Many previous studies have reported the role of oat β-glucan (OBG) in the reduction of postprandial glucose, and hypothesised that OBG may form a protective layer along the intestinal wall, acting as a viscous barrier to decrease glucose transportation. This study examined whether the molecular weight (MW) and concentration of OBG affected the diffusion of glucose in vitro. The effect of OBG on glucose transportation in vitro and sodium-potassium adenosine triphosphatase (Na(+)/K(+)-ATPase) activity in the everted small intestines of normal rats was also examined.

RESULTS

In vitro, higher MWs and concentrations of OBG increased the inhibitory effects on glucose diffusion and glucose adsorption. The transport of glucose by glucose transporters and Na(+)/K(+)-ATPase activity in the small intestinal mucosa of rats were significantly lower following the addition of OBG than those in the absence of OBG at the same time-points throughout glucose transportation (P < 0.05). In the OBG-treated group, the Na(+)/K(+)-ATPase activity decreased with increasing OBG MW. However, as the concentration of OBG in the solution increased, the Na(+)/K(+)-ATPase activity in the small intestine increased due to stronger gastrointestinal motility. We also found that higher MWs of OBG had a greater inhibitory effect on intestinal disaccharidase activities in vitro.

CONCLUSION

Oat β-glucan is able to adsorb glucose molecules, inhibit glucose transport, decrease the concentration of available glucose and suppress disaccharidase activities in the small intestine.

Characteristics and antioxidant of Ulva intestinalis sulphated polysaccharides extracted with different solvents

Ulva intestinalis, a tubular green seaweed, is a rich source of nutrient, especially sulphated polysaccharides. Sulphated polysaccharides from U. intestinalis were extracted with distilled water, 0.1N HCl, and 0.1N NaOH at 80°C for 1, 3, 6, 12, and 24h to study the effect of the extraction solvent and time on their chemical composition and antioxidant activity. Different types of solvents and extraction time had a significant influence on the chemical characteristics and antioxidant activity (p<0.05). Monosaccharide composition and FT-IR spectra analyses revealed that sulphated polysaccharides from all solvent extractions have a typical sugar backbone (glucose, rhamnose, and sulphate attached at C-2 or C-3 of rhamnose). Sulphated polysaccharides extracted with acid exhibited greater antioxidant activity than did those extracted with distilled water and alkali. The results indicated that solvent extraction could be an efficacious method for enhancing antioxidant activity by distinct molecular weight and chemical characteristic of sulphated polysaccharides.

Inter-laboratory evaluation of SEC-post-column calcofluor for determination of the weight-average molar mass of cereal β-glucan

Even though size exclusion chromatography (SEC) with post column addition of calcofluor (SEC-calcofluor) has been used for the determination of cereal β-glucan molar mass in foods for many years, there is a lack of systematic evaluation of the method. To address this issue a set of suitable β-glucan standards were generated by preparative SEC and their molar mass characteristics were determined by analytical multi-detection SEC (refractive index (RI), light scattering). Each standard was then analysed by SEC-calcofluor at three different labs. As a direct comparison, the analyses were repeated with a RI detector. For SEC-calcofluor accurate measurements of weight average molar mass (Mw) can be made for β-glucan populations within 10-500×10(3)g/mol. Above this molar mass threshold there is an increasing tendency for underestimation of Mw. Precipitation of some β-glucan-calcofluor complexes may have delayed their transport into the detector.

An unexpectedly lichenase-stable hexasaccharide from cereal, horsetail and lichen mixed-linkage β-glucans (MLGs): implications for MLG subunit distribution

Mixed-linkage (1→3),(1→4)-β-d-glucan (MLG) is a biologically and technologically important hemicellulose, known to occur in three widely separated lineages: the Poales (including grasses and cereals), Equisetum (fern-allies), and some lichens e.g. Iceland moss (Cetraria islandica). Lichenase (E.C. 3.2.1.73) is widely assumed to hydrolyse all (1→4) bonds that immediately follow (1→3) bonds in MLG, generating predominantly the tetrasaccharide β-d-Glcp-(1→4)-β-d-Glcp-(1→4)-β-d-Glcp-(1→3)-d-Glc (G4G4G3G; MLG4), the corresponding trisaccharide (G4G3G; MLG3), and sometimes also laminaribiose (G3G; MLG2). The ratio of the oligosaccharides produced characterises each polysaccharide. We report here that digestion of MLG from barley (Hordeum vulgare), Equisetum arvense and C. islandica by Bacillus subtilis lichenase also yields the unexpectedly stable hexasaccharide, β-d-Glcp-(1→3)-β-d-Glcp-(1→4)-β-d-Glcp-(1→4)-β-d-Glcp-(1→4)-β-d-Glcp-(1→3)-d-Glc (G3G4G4G4G3G, i.e. MLG2-MLG4), identified by thin-layer chromatography, gel-permeation chromatography, HPLC (HPAEC), β-glucosidase digestion, (1)H/(13)C-NMR spectroscopy and mass spectrometry. On HPLC, G3G4G4G4G3G is the major constituent of a peak previously ascribed solely to the nonasaccharide G4G4G4G4G4G4G4G3G. Because it was widely presumed that lichenase would cleave G3G4G4G4G3G to MLG2+MLG4, our data both redefine the substrate specificity of Bacillus lichenase and show previous attempts to characterise MLGs by HPLC of lichenase-digests to be flawed. MLG2 subunits are particularly underestimated; often reported as negligible, they are here shown to be an appreciable constituent of MLGs from all three lineages. We also show that there is no appreciable yield of water-soluble lichenase products with DP>9; potential identities of products previously labelled DP>9 are suggested. Finally, this discovery also provides a opportunity to investigate the spatial distribution of subunits along the MLG chain. We show that MLG2 subunits in barley and Cetraria MLG are not randomly distributed, but predominantly found at the non-reducing end of MLG4 subunits.

Increasing the viscosity of oat β-glucan beverages by reducing solution volume does not reduce glycaemic responses

The soluble fibre (1 → 3)(1 → 4)-β-d-glucan attenuates postprandial glycaemic responses when administered in solution. This attenuating effect is strengthened when solution viscosity is increased by increasing the β-glucan dose or molecular weight (MW). The effect of varying solution viscosity by changing solution volume, without changing the β-glucan dose or MW, on glycaemic responses was determined. A total of fifteen healthy subjects received six 50 g oral glucose beverages prepared with or without 4 g of high-MW (HMW, 580 000 g/mol) or low-MW (LMW, 145 000 g/mol) β-glucan, with a beverage volume of 250 or 600 ml. Postprandial plasma glucose concentration was measured over 2 h, and the peak blood glucose rise (PBGR) and the incremental area under the glycaemic response curve (AUC) were calculated. Subjects served as their own controls. The physico-chemical properties of the beverages were measured to examine their relationship with glycaemic response results. The HMW β-glucan beverage was more viscous and achieved greater reductions in PBGR than the glucose beverage with LMW β-glucan (P< 0·05). At the same MW, the 250 and 600 ml β-glucan beverages differed in viscosity (>9-fold difference) but not in PBGR (P>0·05). No differences in AUC were detected among the beverages (P= 0·147). The effects of β-glucan on glycaemic response were altered by changes in beverage viscosity achieved through changes in MW but not in volume. Therefore, β-glucan dose and MW are the most vital characteristics for optimising the bioactivity of β-glucan solutions with respect to glycaemic response.

Oat β-glucan increased ATPases activity and energy charge in small intestine of rats

Dietary oat or oat products may potentially help to fight against high risk of cardiovascular diseases and β-glucan in oat was considered as a central player. The present study aimed to investigate the effects of dietary oat whole meal or β-glucan on insulin sensitivity and energy metabolism of rats. Rats were fed with control diet, oat whole meal based diet, or control diet with supplemented β-glucan for 4 weeks. Oat whole meal and β-glucan increased insulin sensitivity index. Interestingly, supplementation of oat whole meal or β-glucan induced increases in intestinal Na(+)K(+)-ATPase activity, Ca(2+)Mg(2+)-ATPase activity, and energy charge, particularly in the distal part of small intestine (ileum). Furthermore, amounts of Bifidobacterium and Lactobacillus in colon contents were elevated by oat whole meal or β-glucan. These findings provide an insight into that β-glucan increased insulin sensitivity and benefited intestinal health.

β-Glucans

β-Glucans occur widely in plants, fungi and bacteria as structural components. The current chapter focused on β-glucans from cereals, mushrooms and some microorganism-produced β-glucans, such as curdlan, in terms of their sources, structural features, conformational and physicochemical properties, bioactivity and related health benefits. The effects of structure, molecular weight and conformation on the functionality of these β-glucans were discussed and their structure–function relationships were elucidated.

Fractionation, partial characterization and bioactivity of water-soluble polysaccharides and polysaccharide-protein complexes from Pleurotus geesteranus

Fractionation and purification of mushroom polysaccharides is a critical process for mushroom clinical application. After a hot-water treatment, the crude Pleurotus geesteranus (PG) was further fractionated into four fractions (PG-1, -2, -3, -4) using gradient precipitation with water and ammonia sulphate. By controlling the initial polymer concentration and ratio of solvents, this process produced PG fractions with high chemical uniformity and narrow Mw distribution without free proteins. Structurally, PG-1 and PG-2 are pure homopolysaccharide mainly composed of glucose; and PG-3 and PG-4 are heteropolysaccharide-protein complexes. PG-2, a high M(w) fraction mainly composed of glucose presented significant cytotoxicity at the concentration of 200 and 100 μg/ml to human breast cancer cells. Here, we report a new mushroom polysaccharides extraction and fractionation method, with which we produced four fractions of PG with PG-2 appearing effective anti-tumour activity.

Processing affects the physicochemical properties of beta-glucan in oat bran cereal

The tendency of mixed linkage oat beta-glucan to form viscous solutions is generally assumed to be related to its ability to lower serum cholesterol levels in humans. However, the association has not been clearly demonstrated. To conduct a clinical trial showing the relationship between LDL-cholesterol levels and viscosity, a series of extruded oat bran cereals were prepared in which the beta-glucan had a range of molecular weights and modified solubility. An extraction protocol using physiological enzymes at 37 degrees C was used to estimate the effect that the cereals would have on gut viscosity. By reducing the molecular weight from 1,930,000 to 251,000 g/mol, the apparent viscosity in the physiological extract dropped from 2900 to 131 mPa.s (at 30 s(-1)). Microscopic examination showed that as the extrusion conditions were made more severe, to cause depolymerization, the integrity of the cell walls was lost and beta-glucan dispersed throughout the cereal. Differences in the hardness and density of the extruded cereals were also evident as the molecular weight was reduced.

Carbanilation of cereal β-glucans for molecular weight determination and conformational studies

Cereal beta-glucans can form aggregates in aqueous solution. The presence of aggregates in cereal beta-glucan solutions led to inaccurate determination of molecular weights and it was believed that intermolecular hydrogen bonding caused the aggregation. To eliminate aggregates, a carbanilation method for molecular weight determination of cereal beta-glucans was developed. Wheat beta-glucan samples were selected for investigation. The carbanilation method can prevent intermolecular hydrogen bonding by blocking hydroxyl groups with phenyl carbamate groups. The carbanilates of cereal beta-glucans were prepared by the reaction of cereal beta-glucans with phenylisocyanate catalyzed by DMSO and pyridine. To avoid degradation during the carbanilation reaction, relatively mild conditions were used, which led to incomplete substitution (DS: approximately 2). However, after the carbanilation reaction, the carbanilates dissolved completely in 1,4-dioxane solution without any detectable aggregates, which allowed accurate molecular weight determination. The degree of substitution (DS) of carbanilates was determined by both a nitrogen content method and an FT-IR method. The FT-IR method proved to be the more effective for DS estimation. Using this method, the converted molecular weights of cereal beta-glucans were in good agreement with the results measured in 0.5M NaOH solution, which previously was shown to be a good solvent for cereal beta-glucans. After the carbanilation reaction, conformational changes of carbanilates were studied by static and dynamic light scattering techniques. The fractal dimension (d(f)=2.27) and the structure sensitive parameters (rho >2) suggested a porous globular structure for partially carbanilated beta-glucans.