Constituent Monosaccharides Research Articles

Crystal Structure of Methyl 3-O-α-d-Glucopyranosyl 2-Acetamido-2-Deoxy-α-d-Galactopyranoside Hydrate

Methyl 3-O-α-d-glucopyranosyl 2-acetamido-2-deoxy-α-d-galactopyranoside as a monohydrate, C15H27NO11·H2O, crystallizes in space group P212121, with four molecules in the unit cell. It constitutes the methyl glycoside of the carbohydrate part of the teichoic acid type polysaccharide from Micrococcus sp. A1, in which the disaccharides are joined through phosphodiester linkages. The conformation of the disaccharide is described by the glycosidic torsion angles ϕ = − 31° and ψ = + 1°, and the hydroxymethyl groups of the constituent monosaccharides are present in the gg and gt conformations for the sugar residues having the gluco- and galacto-configuration, respectively. For the N-acetyl group at C2 of the galactosamine residue the torsion angle τH = 147°, i.e., the amide proton has an antiperiplanar relationship to H2 of the sugar ring. The structure shows extensive hydrogen bonding along the a-direction, including the water molecule, and forms sheets with hydrophilic interactions within the sheets as a result of hydrogen bonding between disaccharides as well as hydrophobic interactions between the sheets, in particular, amongst methyl groups of the N-acetyl group of the α-d-GalpNAc residue in the disaccharides.Graphical The structure of the title disaccharide as a monohydrate, C15H27NO11·H2O, which shows extensive hydrogen bonding as well as hydrophobic interactions, was determined from minute crystals using synchrotron radiation and verified by solid state DFT calculations using plane waves.

Production of Asiatic Hybrid Lily ‘Beni no Mai’ with More than Two Flowers within One Year from Bulbils Influenced by Development Stage, Flower Bud Removal, and Temperature Manipulation

Background and objective: The objective of this study was to produce Asiatic hybrid lily with more than two flowers in one year starting from bulbils. This study was to force 'Beni no Mai' bulbils influenced by harvesting date, flower bud removal, and temperature manipulation and to evaluate dormancy and maturity by nuclear magnetic resonance imaging (NMRI) and carbohydrates analysis.Methods: In experiment 1, bulbils were harvested at 0-30 days after anthesis (DAA), and were divided into 7 stages. And, soluble monosaccharides and monosaccharide constituents of bulbils were analyzed. In experiment 2, flower buds of plants that flowered on 21 April were not removed or removed on 1, 13, and 25 April. Bulbils harvested were divided into four groups and planted after cold treatment. In experiment 3, bulbils received a sequential temperature (SEQ CD) treatments for three weeks at 2.5, 5.0, and 7.5°C, 1 week at 10, 12.5, and 15°C, and 3 weeks at 2.5, 5.0, and 7.5°C. In experiment 4, bulbils were harvested 0-70 DAA, and were subjected to spin-spin lattice relaxation time by NMRI.Results: The bulbils harvested at 30 DAA produced two flowers within 282 days, and were better in growth. The bulbils harvested at 30 DAA showed higher concentration of soluble glucose and lower concentration of non-cellulosic neutral glucose. Growth of bulbils removed flower buds before flowering were better than those of bulbils that flower bud was removed at anthesis and 13 Apr. However, the number of flowers of bulbils harvested from plants removed flower buds on 1 Apr. were less than 2. The SEQ CD treatment of 7.5°C/3W-15°C/1W-5°C/3W in bulbils could produce the plants with 2.2 flowers within 300 days after planting. When bulbils were harvested at 0-28 DAA, yellow color corresponding to T2 relaxation time of 15-20 ms was dominant, and bulbils harvested at 56-70 DAA showed T2 relaxation time of 35-50 ms and 50-100 ms.Conclusion: Considering the results of soluble carbohydrate content and T2 relaxation time of bulbils, it was found that the bulbils had a shallower dormancy and were more mature at 30-42 DAA than before 28 DAA. Also, when these bulbils were planted after SEQ CD treatment at 7.5°C/3W-15°C/1W-5°C/3W, plants with two or more flowers could be produced within one year.

Sweet Synthesis

Sweet Synthesis

Structural characteristics and in vitro fermentation patterns of polysaccharides from Boletus mushrooms.

The aim of this study was to investigate the structural characteristics and in vitro fermentation patterns of polysaccharides from Boletus mushrooms. Polysaccharides were solubilized from fruit bodies of selected mushrooms Boletus auripes, B. bicolor, and B. griseus using subcritical water extraction. Boletus polysaccharides were characterized for their general physicochemical pattern, constituent monosaccharides and molecular weight. A simulated in vitro fermentation model was used to study the utilization of Boletus polysaccharides by the gut microbiota and their consequent modulation of microbial communities. Results showed that the main constituent monosaccharides of Boletus polysaccharides were glucose, galactose and mannose, followed by fucose, xylose and rhamnose, with glucose being the most abundant. The polysaccharides from B. bicolor and B. griseus exhibited a relatively high proportion of galactose and mannose, respectively. Boletus polysaccharides exhibited a wide range of molecular weights (5 kDa to 2000 kDa), which covered multiple polysaccharide populations, but the proportions of these populations varied among the samples. Boletus polysaccharides were gradually utilized by the human fecal microbiota, promoting the production of SCFAs. Boletus polysaccharides contributed to a healthier gut microbiota composition by increasing the relative abundance of beneficial bacterial genera such as Bacteroides and Faecalibacterium and reducing the relative abundance of harmful bacterial genera such as Sutterella and Escherichia-Shigella. B. bicolor polysaccharides showed better fermentability and prebiotic effects than the other Boletus polysaccharide groups. Therefore, the consumption of select Boletus mushrooms, particularly B. bicolor, could be a potential approach to obtain polysaccharides for microbiota modulation and to support gut health.

Impact of sulfur-fumigation on carbohydrate components of Atractylodis Macrocephalae Rhizoma

Atractylodis Macrocephalae Rhizoma (AMR) is one of commonly used medicinal and edible herbs in China. It is often sulfur-fumigated during post-harvest processing. Carbohydrates are important active components of AMR. However, it is unknown whether sulfur-fumigation would induce changes on carbohydrates. Here, carbohydrates including polysaccharides, oligosaccharides and free monosaccharides were comprehensively analyzed to characterize the quality changes of sulfur-fumigated AMR. Determination of both homemade sulfur-fumigated AMR samples and commercial samples from market revealed that sulfur-fumigation did not affect molecular weight distribution of polysaccharides, but altered polysaccharides content and its ratios of constituent monosaccharides, especially glucose (Glc) and fructose (Fru), as well as the contents of oligosaccharides DP2–10 and free monosaccharide Fru. Moreover, the variations enhanced with the increasing of residual SO2 content. The potential transformation mechanisms could be due to the hydrolysis of polysaccharides. The research outcomes could provide a chemical basis for the safety and efficacy evaluations of sulfur-fumigated AMR.

Analysis of Oligosaccharides in Korean Fermented Soybean Products by the Combination of Mass Spectrometry and Gas Chromatography

Doenjang (fermented soybean paste) and ganjang (soy sauce) are traditional fermented foods that are widely consumed in Korea. The oligosaccharides found in soybean and its fermented foods have great potential to improve the quality of foods; however, their structural details have not been well studied. In this study, we used advanced mass spectrometry and gas chromatography to analyze oligosaccharides and their monomeric composition in two fermented soybean products. In both foods, oligosaccharides with a degree of polymerization ranging from 3 to 7 were found. Their constituent monosaccharides were characterized; galactose, xylose, arabinose, and rhamnose were the predominant constituents of the oligosaccharides, and fucose, fructose, mannose, glucose, and N-acetylglucosamine were also found. The great structural diversity of the oligosaccharides found suggests that soybean carbohydrates are hydrolyzed and/or transformed during fermentation and may yield novel oligosaccharides.

Characterization and in vitro anticancer potential of exopolysaccharide extracted from a freshwater diatom Nitzschia palea (Kütz.) W.Sm. 1856

Diatoms are photoautotrophic microalgae classified under class Bacillariophyceae, engulfed by hard silicate frustules, which give mechanical support and protection from bacterial infections. They exude polysaccharides extracellularly that help them with their gliding motion (locomotion). However, the bioactivity of such compounds was least explored from freshwater diatoms. In the present study, a single species of pennate diatom identified as Nitzschia palea was isolated and molecularly characterized by 18S rRNA smaller subunit gene (partial) sequencing and submitted to GenBank NCBI and accession number retrieved as ON360983. Based on logarithmic growth curve analysis, the exponential phase was obtained from 3rd to 4th day of diatom culture. The exopolysaccharide was extracted by the hot-water extraction method, and characterized by FT-IR. The total yield of exopolysaccharide from Nitzschia palea was estimated as 1.56 mg in 100 mL of culture after 7 days of incubation. The estimated carbohydrate content was 51.35 µg/100 µL. The monosaccharide constituents were determined by acid hydrolysis of exopolysaccharide, silylation (derivatization), followed by GC–MS analysis and tabulated. The extracted exopolysaccharide was evaluated for its anti-cancer potential against the Human Adenocarcinoma lung cancer cell line (A549) and the estimated IC50 value was 62.64 µg/mL. Acridine orange staining assay and DNA fragmentation assay also confirmed the apoptotic activity of exopolysaccharide derived from the diatom Nitzschia palea.

Mechanisms of the different effects of sucrose, glucose, fructose, and a glucose-fructose mixture on wheat starch gelatinization, pasting, and retrogradation.

The gelatinization, pasting, and retrogradation of starch influence texture, quality, and shelf-life attributes of many foods. The purpose of this work was to document the effects of a 50:50 glucose:fructose (glc:fru) mixture and sucrose solutions on these starch traits to provide a fundamental basis to explain the different texture and shelf-life attributes of baked goods formulated with these sugars. Differential scanning calorimetry, rapid visco analyzer, and oscillatory rheometry were used to quantify the effects of glucose, fructose, glc:fru mixture, and sucrose at different concentrations (0% to 60% w/w), on the gelatinization temperature, pasting, and retrogradation properties of wheat starch. Distinct differences were found between the effects of sucrose and those of the monosaccharides including the glc:fru mixture. Sucrose elevated Tgel and pasting temperature most and decreased other RVA parameters compared to the monosaccharides as concentration increased. Fructose and the glc:fru mixture promoted amylopectin retrogradation, while retrogradation was inhibited in sucrose and glucose solutions. The glc:fru mixture had similar effects on starch properties compared to fructose under static measurement conditions (DSC), and the effects were in between those of glucose and fructose under dynamic conditions when shear was applied (RVA and rheology). These effects are explained by the phase separation and/or solute partitioning of the monosaccharide constituents of the glc:fru mixture. Sugar solution physicochemical properties correlated strongly with starch gelatinization and retrogradation. The results substantiate the important relationship between sugar physicochemical properties and solution dynamics with starch thermal properties, which in turn affect the texture and structure of starch-containing food products. PRACTICAL APPLICATION: The quality attributes of starch-containing baked goods are influenced by how different amounts and types of sugars affect starch cooking properties. The underlying mechanisms of the different sugar effects involve solution viscosity, intermolecular hydrogen bonding, and phase separation. Substituting one sugar for another has less effect on these starch properties in products with lower sugar concentrations than in products with more sugar. Mixtures of sugars behave differently than single sugars in different conditions due to phase separation. Baked goods made with glucose:fructose mixtures in place of sucrose likely have higher amounts of gelatinized starch and increased firmness (i.e., staling or retrogradation) over time.

Unexpected High-Substrate-Dependent Ketonization of Aldose on Niobium Phosphate-Supported Magnesia: An Emphasis on Surface Chemisorption

A water-tolerant magnesia-based solid base was prepared by combining the use of a non-equilibrium and highly structured dual-porous niobium phosphate (NbP) as the support and high-temperature thermal treatment. The crystal growth of MgO changed, and the bond length of Mg–O was longer than that of pure MgO after it was supported on NbP, which led to the higher basic property of O2– on the surface of MgO/NbP to act as a solid base catalyst toward aldose ketonization. It was revealed that the prepared solid base MgO/NbP exhibited high substrate dependence for ketonization of saccharides, facilitating the use of glucose and glucose-containing aldo-disaccharides─including maltose, cellobiose, lactose, and melibiose─due to their lower free energy after chemisorption than that of pentose, and a moderate reverse reaction barrier in aqueous solution. It was demonstrated that ketonization mainly occurred on the solid surface, especially in the case of high substrate concentration, which was different from the conventional opinion. The type of glycosidic bond and the constituent monosaccharides also affected the yield and selectivity of rare keto-disaccharides. The high performance of the MgO/NbP catalyst toward ketonization of disaccharides was realized as the typical yield and the productivity of maltulose reached 14.2% and 42.6 g·kg-solution–1·h–1, respectively, when treated with 30.0 wt % maltose solution at 130 °C. Although deactivation issues, such as leaching of ions and coke deposition, still remain to be solved, the catalyst has potential to be used in synthesizing high-value rare keto-disaccharides.

Cell wall organic matrix composition and biomineralization across reef-building coralline algae under global change.

Crustose coralline algae (CCA) are one of the most important benthic substrate consolidators on coral reefs through their ability to deposit calcium carbonate on an organic matrix in their cell walls. Discrete polysaccharides have been recognized for their role in biomineralization, yet little is known about the carbohydrate composition of organic matrices across CCA taxa and whether they have the capacity to modulate their organic matrix constituents amidst environmental change, particularly the threats of ocean acidification (OA) and warming. We simulated elevated pCO2 and temperature (IPCC RCP 8.5) and subjected four mid-shelf Great Barrier Reef species of CCA to 2months of experimentation. To assess the variability in surficial monosaccharide composition and biomineralization across species and treatments, we determined the monosaccharide composition of the polysaccharides present in the cell walls of surficial algal tissue and quantified calcification. Our results revealed dissimilarity among species' monosaccharide constituents, which suggests that organic matrices are composed of different polysaccharides across CCA taxa. We also observed that species differentially modulate composition in response to ocean acidification and warming. Our findings suggest that both variability in composition and ability to modulate monosaccharide abundance may play a crucial role in surficial biomineralization dynamics under the stress of OA and global warming.

Degradation of water-soluble polysaccharides in pulp of litchi during storage

Water-soluble polysaccharides (WSP) were extracted from the pulp of litchi. Its main component was identified as arabinogalactan. The dominant monosaccharide constituents were arabinose and galactose. Galactose and mannose accumulated at the end of storage. ATP, ADP and AMP levels declined with increasing pulp breakdown index. WSP depolymerized which was characterized by a decrease in its content and molecular weight, while its structure remained stable during storage. Polygalacturonase and pectate lyase (PL) were active at the early storage time, and β-galactosidase (GAL) and α-l-arabinofuranosidase followed thereafter. Except for some pectin methylesterase (LcPME), LcPL, LcGAL and LcPME gene expression was downregulated. It was deduced that depolymerization of polysaccharides was mainly caused by the rupture of the branched side chain and glacturonic acid backbone to smaller repeating units, and both cell wall-degrading enzymes and nonenzymatic factors, such as energy level, participated in the degradation of polysaccharides, and consequently pulp breakdown of litchi.

Enthalpy-related parameters of interaction of sucrose, lactose and their monosaccharide constituents with the mebicar (N-tetramethylglycoluril) drug in an aqueous medium at 298.15 K

The molar enthalpies of dissolution of N-tetramethylglycoluril, a known psychotropically active pharmaceutical mebicar (Meb) (solute x), in aqueous solutions of d-monosaccharide glucose (Glu), fructose (Fru) and galactose (Gal) as well as disaccharide sucrose (Suc) and α-lactose (Lac) (cosolute y), were measured by the precision calorimetry method at T = 298.15 K and ambient pressure. Unlike the heat absorption in aqueous monosaccharides or Lac, the endothermicity of Meb dissolution in {water (W) + Suc} decreases as the sugar content becomes higher. The enthalpy-heterotactic coefficients for pair interactions between the solute and cosolute molecules, hxy, were determined using the McMillan-Mayer theory formalism. Similar to the homotactic parameters hyy, the hxy values (in J·kg·mol−2) were found to be positive, increasing in the series Suc (86) ≪ Lac (329) < Fru (456) < Glu (545) < Gal (663), despite the existing unusually large (in magnitude) negative hxx value, which is about −2000 J·kg·mol−2. Overall, the number of hydroxy groups and their axial(a)/equatorial(e) positions as well as the peculiarities of a glycoside bond and intramolecular H-bonding in cosolute saccharide molecules cause a stereospecificity of Meb hydration manifested in pair-interaction enthalpic coefficients hxy. So, the inequality hxy > hyy was found to be characteristic of monosaccharide containing aqueous Meb solutions (down to hyy ≈ 0.2hxy for Gal), and hxy < hyy – to be related to disaccharide containing aqueous Meb solutions. Thus, if hxy for (W + Lac + Meb) is ca. 0.65hyy, then it is only about 0.15hyy in the case of (W + Suc + Meb).

Artificial simulated saliva, gastric and intestinal digestion and fermentation in vitro by human gut microbiota of intrapolysaccharide from Paecilomyces cicadae TJJ1213

In this study, the in vitro digestion and fermentation of two intra-polysaccharide fractions (IPS1 and IPS2) from Paecilomyces cicadae TJJ1213 were investigated. The constituent monosaccharides of IPS1 and IPS2 were not changed after simulated saliva, gastric and small intestinal digestion. However, they can be hydrolyzed and utilized by gut microbiota, and short-chain fatty acids (SCFAs) level were increased after IPS1and IPS2 treatments. Furthermore, 16S rRNA sequencing analysis of fermentation samples were performed. Alpha-diversity, beta-diversity and taxonomic composition differences analysis revealed that IPS1 and IPS2 promoted the proliferation of beneficial bacteria and modulated the overall structure of gut microbiota. Taxonomic comparison analysis found that IPS1 increased the relative abundances of beneficial bacteria including Megamonas, Bifidobacterium and Lactobacillus, while IPS2 could increase the abundance of Bacteroides, Parabacteroides and Phascolarctobacterium. In addition, they can also decrease the levels of pathogenic bacteria containing Escherichia-Shigella, Klebsiella and Fusobacterium. These results indicated that IPS from P. cicadae TJJ1213 could be used as potential candidates for new functional foods.

Microwave-Assisted Deep Eutectic Solvent Extraction, Structural Characteristics, and Biological Functions of Polysaccharides from Sweet Tea (Lithocarpus litseifolius) Leaves.

The leaf of sweet tea (Lithocarpus litseifolius) is widely used as an edible and medicinal plant in China, which is rich in bioactive polysaccharides. In order to explore and promote the application of sweet tea polysaccharides in the functional food industry, the microwave-assisted deep eutectic solvent extraction (MDAE) of polysaccharides from sweet tea leaves was optimized, and the structural properties and biological functions of sweet tea polysaccharides prepared by MDAE (P-DM) were investigated and compared with that of hot water extraction (P-W). The maximum yield (4.16% ± 0.09%, w/w) of P-DM was obtained under the optimal extraction conditions (extraction time of 11.0 min, extraction power of 576.0 W, water content in deep eutectic solvent of 21.0%, and liquid–solid ratio of 29.0 mL/g). Additionally, P-DM and P-W possessed similar constituent monosaccharides and glycosidic bonds, and the homogalacturonan (HG) and arabinogalactan (AG) might exist in both P-DM and P-W. Notably, the lower molecular weight, higher content of total uronic acids, and higher content of conjugated polyphenols were observed in P-DW compared to P-W, which might contribute to its much stronger in vitro antioxidant, anti-diabetic, antiglycation, and prebiotic effects. Besides, both P-DW and P-W exhibited remarkable in vitro immunostimulatory effects. The findings from the present study indicate that the MDAE has good potential to be used for efficient extraction of bioactive polysaccharides from sweet tea leaves and P-DM can be developed as functional food ingredients in the food industry.

In vitro simulated digestion affecting physicochemical characteristics and bioactivities of polysaccharides from barley (Hordeum vulgare L.) grasses at different growth stages

In this study, three polysaccharides (BGPs: BGPs-Z21, BGPs-Z23, and BGPs-Z31) were successively extracted from barley (Hordeum vulgare L.) grasses (BG) at different growth stages, including seedling (Z21), tillering (Z23), and stem elongation (Z31). The effects of in vitro simulated saliva–gastrointestinal digestion on the physicochemical characteristics and biological activities of BGPs were investigated and compared. Results showed that the simulated saliva–gastrointestinal digestion had considerable influences on reducing sugar content, chemical components, monosaccharide constituents, and molecular weights of BGPs but hardly affected their preliminarily structural characteristics. Moreover, the antioxidant activities of BGPs were weakened after the simulated saliva–gastrointestinal digestion, but their bile acid-binding capacities were remarkably enhanced. The digested BGPs-Z31 by gastric juice possessed better antioxidant benefit, and bile acid-binding capacity (80.33 %) than other digested products. Overall, these results indicated that BGPs obtained from BG are valuable for functional foods as promising bioactive ingredients.

Comparison of physicochemical characteristics and biological activities of polysaccharides from barley (Hordeum vulgare L.) grass at different growth stages

Barley grass polysaccharides (BGPs) are some of the major bioactive constituents of barley (Hordeum vulgare L.) grass (BG). They exhibit favorable biological activities and health benefits. In this study, seven BGPs were extracted from BG, which was harvested at three different growth stages (e.g., seedling, tillering, and stem elongation), by alkaline-extraction method. Their physicochemical properties, structural characteristics, and biological activities were investigated and compared. Results demonstrated that the extraction yields, chemical compositions, monosaccharide constituents, and molecular weights of the seven BGPs obtained at different growth stages varied obviously. These BGPs had similar preliminary structural characteristics but different microstructures and thermal properties. Furthermore, the BGPs (BGP-Z12 and BGP-Z21) obtained at the seedling stage possessed stronger in vitro antioxidant potentials, cholic acid binding activity, and immunological activity than other BGPs. Therefore, these results indicated that that the seedling stage of BG was the preferable harvest time for preparing highly bioactive BGPs.

Preparation, physicochemical and structural characterizations, and bioactivities of polysaccharides from Corbicula fluminea industrial distillate

Corbicula fluminea distillate (CFD), as an industrial sub-product of the steaming process of C. fluminea, is rich in polysaccharides, proteins, and amino acids and has important developmental value. In this study, therefore, three water-soluble polysaccharides (CFDPs: CFDP-D, CFDP-U, and CFDP-T) were extracted and separated from CFD through direct ethanol precipitation, ultrasound-assisted extraction, and three-phase partitioning (TPP), respectively. Results demonstrated that the three extraction methods had important influences on extraction yields, chemical compositions, molecular weights, monosaccharide and amino acid constituents, structural characteristics, and microstructures as well as biological activities of CFDPs. Specifically, CFDP-T had higher yield (60.92% ± 3.58%), carbohydrate content (91.05% ± 1.22%), and uronic acid content (8.55% ± 0.18%) and lower protein content (7.15% ± 0.15%) than CFDP-D and CFDP-U. The three CFDPs were acidic proteoheteroglycans combined through O-glycosidic bonds and had high molecular weights of 1.93–2.41 × 107 Da and the same monosaccharide and amino acid compositions but different contents. Compared with CFDP-D and CFDP-U, CFDP-T exhibited more excellent free radical scavenging and stimulating (1.57 ± 0.03 μM, 500 μg/mL) activities on RAW264.7 macrophages in vitro. Therefore, our findings suggested that CFDP-T obtained from CFD by TPP had the potential to be a functional food ingredient in food industry.

Extraction Optimization, Structural Characterization, and Anti-Hepatoma Activity of Acidic Polysaccharides From Scutellaria barbata D. Don.

The Chinese medicinal herb Scutellaria barbata D. Don has antitumour effects and is used to treat liver cancer in the clinic. S. barbata polysaccharide (SBP), one of the main active components extracted from S. barbata D. Don, exhibits antitumour activity. However, there is still a lack of research on the extraction optimization, structural characterization, and anti-hepatoma activity of acidic polysaccharides from S. barbata D. Don. In this study, the optimal extraction conditions for SBP were determined by response surface methodology (RSM): the material-liquid ratio was 1:25, the extraction time was 2 h, and the extraction temperature was 90°C. Under these conditions, the average extraction efficiency was 3.85 ± 0.13%. Two water-soluble polysaccharides were isolated from S. barbata D. Don, namely, SBP-1A and SBP-2A, these homogeneous acidic polysaccharide components with average molecular weights of 1.15 × 105 Da and 1.4 × 105 Da, respectively, were obtained at high purity. The results showed that the monosaccharide constituents of the two components were fucose, galactosamine hydrochloride, rhamnose, arabinose, glucosamine hydrochloride, galactose, glucose, xylose, and mannose; the molar ratio of these constituents in SBP-1A was 0.6:0.3:0.6:30.6:3.3:38.4:16.1:8:1.4, and that in SBP-2A was 0.6:0.5:0.8:36.3:4.4:42.7:9.2:3.6:0.7. In addition, SBP-1A and SBP-2A contained uronic acid and β-glucan, and the residue on the polysaccharide was mainly pyranose. The in vitro results showed that the anti-hepatoma activity of SBP-2A was better than that of SBP-1A and SBP. In addition, SBP-2A significantly enhanced HepG2 cell death, as cell viability was decreased, and SBP-2A induced HepG2 cell apoptosis and blocked the G1 phase. This phenomenon was coupled with the upregulated expression of P53 and Bax/Bcl-2 ratio, as well as the downregulated expression of the cell cycle-regulating protein cyclinD1, CDK4, and Bcl-2 in this study. Further analysis showed that 50 mg/kg SBP-2A inhibited the tumour growth in H22 tumour-bearing mice, with an average inhibition rate of 40.33%. Taken together, SBP-2A, isolated and purified from S. barbata showed good antitumour activity in vivo and in vitro, and SBP-2A may be a candidate drug for further evaluation in cancer prevention. This study provides insight for further research on the molecular mechanism of the anti-hepatoma activity of S. barbata polysaccharide.

Identification of distinct capsule types associated with Serratia marcescens infection isolates.

Serratia marcescens is a versatile opportunistic pathogen that can cause a variety of infections, including bacteremia. Our previous work established that the capsule polysaccharide (CPS) biosynthesis and translocation locus contributes to the survival of S. marcescens in a murine model of bacteremia and in human serum. In this study, we determined the degree of capsule genetic diversity among S. marcescens isolates. Capsule loci (KL) were extracted from >300 S. marcescens genome sequences and compared. A phylogenetic comparison of KL sequences demonstrated a substantial level of KL diversity within S. marcescens as a species and a strong delineation between KL sequences originating from infection isolates versus environmental isolates. Strains from five of the identified KL types were selected for further study and electrophoretic analysis of purified CPS indicated the production of distinct glycans. Polysaccharide composition analysis confirmed this observation and identified the constituent monosaccharides for each strain. Two predominant infection-associated clades, designated KL1 and KL2, emerged from the capsule phylogeny. Bacteremia strains from KL1 and KL2 were determined to produce ketodeoxynonulonic acid and N-acetylneuraminic acid, two sialic acids that were not found in strains from other clades. Further investigation of KL1 and KL2 sequences identified two genes, designated neuA and neuB, that were hypothesized to encode sialic acid biosynthesis functions. Disruption of neuB in a KL1 isolate resulted in the loss of sialic acid and CPS production. The absence of sialic acid and CPS production also led to increased susceptibility to internalization by a human monocytic cell line, demonstrating that S. marcescens phagocytosis resistance requires CPS. Together, these results establish the capsule genetic repertoire of S. marcescens and identify infection-associated clades with sialic acid CPS components.

In vitro fecal fermentation properties of polysaccharides from Tremella fuciformis and related modulation effects on gut microbiota

Tremella fuciformis is an edible and medicinal mushroom. Polysaccharides from T. fuciformis have received increasing attention due to their diversely pharmacological activities. In this study, the digestive behavior and fermentation characteristics of T. fuciformis polysaccharides (TFP) were studied. The results revealed that the reducing sugar content, chemical composition, molecular weight, rheological property, constituent monosaccharide, and FT-IR spectrum of TFP were not altered after the in vitro simulated digestion, indicating that it was indigestible under different simulated digestion conditions. However, the physicochemical characteristics of TFP, including reducing sugar content, molecular weight, constituent monosaccharide, and free monosaccharide released, were obviously altered after the in vitro fermentation for 48 h, indicating that it was remarkably utilized by intestinal microbiota in human feces. Notably, TFP could obviously modulate the microbial composition via promoting the relative abundances of Phascolarctobacterium, Bacteroides, and Lachnoclostridium. Moreover, TFP could also increase the production of short-chain fatty acids, including acetic, propionic, n-butyric, and n-valeric acids, after the in vitro fermentation for 48 h. These results showed that TFP was stable under the simulated digestion conditions, but could be utilized by intestinal microbiota in human feces, and might possess the potential to improve intestinal health.