An improved procedure for the methylation analysis of oligosaccharides and polysaccharides

Refined linkage analysis of the sulphated marine polysaccharide fucoidan of Cladosiphon okamuranus with a focus on fucose

Methylation followed by depolymerization and gas chromatography (GC) is an effective methodology for the linkage analysis of polysaccharides, including fucoidan, a sulphated algal polysaccharide. However, this sample material demands attention to experimental details to prevent aberrations in the analytical result. The use of deficient bases for methylation, the presence of water, analyte degradation during hydrolysis, and coelution of the target analytes during gas chromatography create doubts about published results. We therefore investigated critical parameters of the method and carefully optimized the steps of the protocol to ensure the integrity of the results for the fucose monomers. Fucoidan from Cladosiphon okamuranus was used as reference sample to determine the glycosidic bonds, and sulphate positions in the monomer. Fucoidan in protonated form was methylated in a strictly water-free environment using lithium dimsyl as base and methyl iodide for methylation. The methylated polymer was isolated by solid phase extraction, which was crucial to recover also the highly sulfated fraction. Hydrolysis was conducted with trifluoroacetic acid. To separate all target analytes in GC-FID/MS, a stationary phase with high cyanopropyl content (HP-88) was required, as the commonly employed phenyl siloxane phases result in co-elution, which distorts the result severely.

The study of galactomannans with different molecular weights and their ability to form microparticles suitable for pulmonary delivery

The influence of locust bean gum (LBG) galactomannans (GMs) molecular weight (Mw) to assemble microparticulate systems was evaluated, and carriers for deep lung delivery were developed. A commercial batch of LBG with a mannose/galactose (M/G) ratio of 2.4 (batch 1) was used to study the influence of different microwave partial acid hydrolysis conditions on carbohydrate composition, glycosidic linkages, and aqueous solutions viscosity. The microwave treatment did not affect the composition, presenting 4-Man (36-42 %), 4,6-Man (27-35 %), and T-Gal (24-25 %) as the main glycosidic linkages. Depolymerization led to a viscosity reduction (≤0.005 Pa·s) with no major impact on polysaccharide debranching. The structural composition of the LBG galactomannans were further elucidated with sequence-specific proteins using carbohydrate microarray technologies. A second batch of LBG (M/G 3.3) was used to study the impact of GMs with different Mw on microparticle assembling, characteristics, and insulin release kinetics. The low-Mw GMs microparticles led to a faster release (20 min) than the higher-Mw (40 min) ones, impacting the release kinetics. All microparticles exhibited a safety profile to cells of the respiratory tract. However, only the higher-Mw GMs allowed the assembly of microparticles with sizes suitable for this type of administration.

RG-I pectin-like polysaccharide from Rosa chinensis inhibits inflammation and fibrosis associated to HMGB1/TLR4/NF-κB signaling pathway to improve non-alcoholic steatohepatitis

A novel RG-I pectin-like polysaccharide, YJ3A1, was purified from the flowers of Rosa chinensis and its structure and hepatoprotective effect in vivo and in vitro were investigated. The backbone of this polysaccharide is mainly composed of 1, 4-galactan, 1, 4-linked α-GalpA and 1, 2-linked α-Rhap disaccharide repeating unit attached by 1, 6-linked β-Galp or 1, 5-linked α-Araf on C-4 of the Rhap. Interestingly, oral administration of YJ3A1 significantly ameliorates NASH-associated inflammation, oxidative stress and fibrosis and does not affect the liver morphology of normal mice at a dose of 50 mg/kg. The mechanism study suggests that the biological activity may associate to inactivating of high-mobility group box 1 protein (HMGB1)/TLR4/NF-κB and Akt signaling pathways by restraining the expression and release of HMGB1, thereby impeding the effect of NASH. The current findings outline a novel leading polysaccharide for new drug candidate development against NASH.

Immune-enhancing activity of compound polysaccharide on the inactivated influenza vaccine

Traditional Chinese medicine polysaccharides have numerous biological activities with broad applications in the biomedical industries. However, a clear understanding of the pharmacological activities of compound polysaccharides with multi-component structures remain challenging. This study aimed to investigate the immune boosting effect of compound polysaccharides on the influenza vaccine and assess the preliminary structure-activity relationship. The compound polysaccharide (CP) was isolated from the combined Chinese herbs lentinan, pachymaran and tremellan, and purified by gradient ethanol precipitation to obtain its subcomponents of CP-20, CP-40, CP-60, and CP-80 with decreasing molecular weights. These polysaccharides were mainly composed of glucans with different linkage patterns, including α-(1 → 3)-glucan, α-(1 → 4)-glucan and β-(1 → 6)-glucan. A significant improvement was observed in the survival of mice vaccinated with inactivated (IAV) vaccine and the isolated polysaccharides as adjuvants. A reduction in the pulmonary virus titer and weight loss were also observed. Moreover, CP-40 and CP-60, as well as the original CP, significantly enhanced the serum anti-IAV antibody titers and interleukin IL-2, IL-5, and IL-6 concentrations. These preliminary results indicate the immune boosting effect of the compound polysaccharides is highly relevant to the specific structural properties of the subcomponent, and CP-40 is worthy of further exploration as a glycan adjuvant for the IAV vaccine.

Ulvans are not equal - Linkage and substitution patterns in ulvan polysaccharides differ with Ulva morphology

Ulva are hardy green seaweeds that contain the sulfated polysaccharide ulvan and grow in two distinct morphologies: foliose and tubular. The authors hypothesise that ulvan from tubular species are more structurally complex than ulvans from foliose species. Herein, using standardised methods, the glycosyl linkage positions and sulfate ester substitutions of constituent monosaccharides of ulvan isolated from foliose (U. lacinulata and U. stenophylloides) and tubular (U. prolifera and U. ralfsii) species of Ulva were investigated. Comparison of native ulvans with 80 and 100 °C desulfated counterparts indicated that 4-linked rhamnose is predominantly 3-O-sulfated in all four ulvans. Ulvans from the foliose species predominantly contained →3,4)-Rhap-(1→, →4)-GlcAp-(1→ and →4)-IdoAp-(1→, collectively accounting for 67 to 81 mol% of the total linkages. In contrast, these same linkages in ulvans from the tubular species only collectively accounted for 29 to 36 mol%. Instead, ulvan from tubular species contained a combination of →2,3,4)-Rhap-(1→, terminal Rhap-(1→, →4)-GlcAp-(1→, →4)-Xylp-(1→, and/or →4)-Galp-(1→ in high proportions; some of the latter three residues were also likely O-2 sulfated. The results presented here suggest that ulvan from foliose species are predominantly unbranched polysaccharides composed of repeat disaccharides while ulvans from tubular species contain a greater diversity of branch and sulfate substitution locations.

Alleviative effects of sulfated polysaccharide from Ishige Okamurae against DSS-induced ulcerative colitis via inhibiting inflammation and modulating gut microbiota

A water-soluble polysaccharide from the brown alga Ishige Okamurae, designated IOP-0, was obtained by preparative anion-exchange and size-exclusion chromatography. Chemical and spectroscopic investigations revealed that IOP-0 was a sulfated fucoidan with a backbone primarily composed of 3-linked and 4-linked-L-fucose with sulfate groups at C-2/C-4 of the 3-linked-L-fucose. The protective effect of IOP-0 on ulcerative colitis was evaluated in this work. The results showed that IOP-0 could significantly alleviate the symptoms of ulcerative colitis by preventing weight loss, preserving the structure of intestinal tissues, and ameliorating the dysregulation of inflammatory cytokines (TNF-α, IL-6, and IL-10). Meanwhile, IOP-0 protected the colonic mucosal barrier by promoting the tight junction protein ZO-1 and occludin expression. In addition, IOP-0 was able to maintain intestinal homeostasis and improve intestinal function by regulating the gut microbiota and their metabolites, such as short-chain fatty acids (SCFAs). These results suggest that IOP-0 might be a potential dietary supplement for the prevention and treatment of ulcerative colitis.

Methylation-GC-MS/FID-Based Glycosidic Linkage Analysis of Unfractionated Polysaccharides in Red Seaweeds

Glycosidic linkage analysis was conducted on the unfractionated polysaccharides in alcohol-insoluble residues (AIRs) prepared from six red seaweeds (Gracilariopsis sp., Prionitis sp., Mastocarpus papillatus, Callophyllis sp., Mazzaella splendens, and Palmaria palmata) using GC-MS/FID analysis of partially methylated alditol acetates (PMAAs). The cell walls of P. palmata primarily contained mixed-linkage xylans and small amounts of sulfated galactans and cellulose. In contrast, the unfractionated polysaccharides of the other five species were rich in galactans displaying diverse 3,6-anhydro-galactose and galactose linkages with varied sulfation patterns. Different levels of cellulose were also observed. This glycosidic linkage method offers advantages for cellulose analysis over traditional monosaccharide analysis that is known for underrepresenting glucose in crystalline cellulose. Relative linkage compositions calculated from GC-MS and GC-FID measurements showed that anhydro sugar linkages generated more responses in the latter detection method. This improved linkage workflow presents a useful tool for studying polysaccharide structural variations across red seaweed species. Furthermore, for the first time, relative linkage compositions from GC-MS and GC-FID measurements, along with normalized FID and total ion current (TIC) chromatograms without peak assignments, were analyzed using principal component analysis (PCA) as a proof-of-concept demonstration of the technique's potential to differentiate various red seaweed species.

Development and Application of a High-Throughput Method for the Purification and Analysis of Surface Carbohydrates from Klebsiella pneumoniae

Klebsiella pneumoniae (Kp) is a Gram-negative bacterium, and a leading cause of neonatal sepsis in low- and middle-income countries, often associated with anti-microbial resistance. Two types of polysaccharides are expressed on the Kp cell surface and have been proposed as key antigens for vaccine design: capsular polysaccharides (known as K-antigens, K-Ags) and O-antigens (O-Ags). Historically, Kp has been classified using capsule serotyping and although 186 distinct genotypes have been predicted so far based on sequence analysis, many structures are still unknown. In contrast, only 11 distinct OAg serotypes have been described. The characterization of emerging strains requires the development of a high-throughput purification method to obtain sufficient K- and O-Ag material to characterize the large collection of serotypes and gain insight on structural features and potential cross-reactivity that could allow vaccine simplification. Here, this was achieved by adapting our established method for the simple purification of O-Ags, using mild acetic acid hydrolysis performed directly on bacterial cells, followed by filtration and precipitation steps. The method was successfully applied to purify the surface carbohydrates from different Kp strains, thereby demonstrating the robustness and general applicability of the purification method developed. Further, antigen characterization showed that the purification method had no impact on the structural integrity of the polysaccharides and preserved labile substituents such as O-acetyl and pyruvyl groups. This method can be further optimized for scaling up and manufacturing to support the development of high-valency saccharide-based vaccines against Kp.

A pyruvylated and sulfated galactan from the green alga Dictyosphaeria cavernosa: Structure, anticoagulant property and inhibitory effect on zebrafish thrombosis

A pyruvylated and sulfated galactan from the green alga Dictyosphaeria cavernosa, designated PSG, was obtained by dilute alkali extraction, ion-exchange and gel filtration chromatography. The backbone of PSG was composed of 3-linked β-d-Galp units with partial sulfation on C-4 and C-6. Pyruvate ketals were linked to O-3 and O-4 of nonreducing terminal β-d-Galp, as well as O-4 and O-6 of 3-linked β-d-Galp. The branches consisting of 6-linked β-d-Galp(4SO4) and β-d-Galp(3,4-Pyr)-(1→ units were located at C-6 of 3-linked β-d-Galp unit. PSG possessed obvious anticoagulant effect in vitro as assessed by the tests of activated partial thromboplastin time and thrombin time. The assay of anticoagulant mechanism showed that PSG promoted thrombin inactivation mediated by heparin cofactor-II and antithrombin-III (ATIII), and could effectively potentiate factor Xa inactivation by ATIII. The antithrombotic activity of PSG in vivo was assessed by phenylhydrazine (PHZ)-induced zebrafish thrombotic model. The results indicated that PSG obviously reduced peripheral erythrocytes aggregation, enhanced cardiac blood flow and improved peripheral platelet circulation, and PSG possessed a marked inhibitory effect on the PHZ-induced zebrafish thrombosis. Thus, PSG is a hopeful anticoagulant and antithrombotic polysaccharide.

Streptococcus pneumoniae serotype 33G: genetic, serological, and structural analysis of a new capsule type

IMPORTANCE

Streptococcus pneumoniae (the pneumococcus) is a bacterial pathogen with the greatest burden of disease in Asia and Africa. The pneumococcal capsular polysaccharide has biological relevance as a major virulence factor as well as public health importance as it is the target for currently licensed vaccines. These vaccines have limited valency, covering up to 23 of the >100 known capsular types (serotypes) with higher valency vaccines in development. Here, we have characterized a new pneumococcal serotype, which we have named 33G. We detected serotype 33G in nasopharyngeal swabs (n = 20) from children and adults hospitalized with pneumonia, as well as healthy children in Mongolia. We show that the genetic, serological, and biochemical properties of 33G differ from existing serotypes, satisfying the criteria to be designated as a new serotype. Future studies should focus on the geographical distribution of 33G and any changes in prevalence following vaccine introduction.

Novel 4-O-β-d-xylopyranosyl-3,6-anhydro-l-galactopyranosyl disaccharide units in a polysaccharide from the red alga Pyrophyllon subtumens

Thalli of the endemic epiphytic New Zealand red seaweed Pyrophyllon subtumens are known to contain a high level of xylose and a notable amount of arabinose but the extracted polysaccharide has not been characterised. The linkage/substitution of individual sugars within the water-soluble polysaccharide extract and various derivatives were determined by chemical and spectroscopic methods. No 3-linked sugars nor any d-galactose were found, which excluded agar-, carrageenan- or mixed 3-linked/4-linked β-d-xylan-type polysaccharides found in many other red macroalgae. Instead, the polysaccharide backbone contained predominantly 4-linked β-d-xylopyranosyl, 4-linked 3,6-anhydro-l-galactopyranosyl and 4-linked l-galactopyranosyl units. Some of each type of sugar were sulfated at various positions. Some xylosyl units were substituted at the 2- or 3-position with l-arabinosyl units. The polysaccharide is complex and likely contains a range of structures. However, partial sequencing was successfully used to recover and identify a novel disaccharide 4-O-d-xylopyranosyl-3,6-anhdydro-l-galactopyranose, which indicates a unique →4)-β-d-Xylp-(1 → 4)-3,6-anhydro-l-Galp-(1 → repeat unit in the polysaccharide.

The cell walls of different Chara species are characterized by branched galactans rich in 3-O-methylgalactose and absence of AGPs

Streptophyte algae are the closest relatives to land plants; their latest common ancestor performed the most drastic adaptation in plant evolution around 500 million years ago: the conquest of land. Besides other adaptations, this step required changes in cell wall composition. Current knowledge on the cell walls of streptophyte algae and especially on the presence of arabinogalactan-proteins (AGPs), important signalling molecules in all land plants, is limited. To get deeper insights into the cell walls of streptophyte algae, especially in Charophyceae, we performed sequential cell wall extractions of four Chara species. The three species Chara globularis, Chara subspinosa and Chara tomentosa revealed comparable cell wall compositions, with pectins, xylans and xyloglucans, whereas Chara aspera stood out with higher amounts of uronic acids in the pectic fractions and lack of reactivity with antibodies binding to xylan- and xyloglucan epitopes. Search for AGPs in the four Chara species and in Nitellopsis obtusa revealed the presence of galactans with pyranosidic galactose in 1,3-, 1,6- and 1,3,6-linkage, which are typical galactan motifs in land plant AGPs. A unique feature of these branched galactans was high portions of 3-O-methylgalactose. Only Nitellopsis contained substantial amounts of arabinose A bioinformatic search for prolyl-4-hydroxylases, involved in the biosynthesis of AGPs, revealed one possible functional sequence in the genome of Chara braunii, but no hydroxyproline could be detected in the four Chara species or in Nitellopsis obtusa. We conclude that AGPs that is typical for land plants are absent, at least in these members of the Charophyceae.

Influence of ultrasonication and hydrolysis conditions in methylation analysis of bacterial homoexopolysaccharides

Homoexopolysaccharides (HoEPS) such as α-glucans and β-fructans are synthesized by lactic and acetic acid bacteria. Methylation analysis is an important and well-established tool for the structural analysis of these polysaccharides, however, multiple steps are required for polysaccharide derivatization. Because ultrasonication during methylation and the conditions during acid hydrolysis may influence the results, we investigated their role in the analysis of selected bacterial HoEPS. The results reveal that ultrasonication is crucial for water insoluble α-glucan to swell/disperse and deprotonate prior to methylation whereas it is not necessary for water soluble HoEPS (dextran and levan). Complete hydrolysis of permethylated α-glucans requires 2 M trifluoroacetic acid (TFA) for 60/90 min at 121 °C while levan is hydrolyzed in 1 M TFA for 30 min at 70 °C. Nevertheless, levan was also detectable after hydrolysis in 2 M TFA at 121 °C. Thus, these conditions can be used to analyze a levan/dextran mixture. However, size exclusion chromatography of permethylated and hydrolyzed levan showed degradation and condensation reactions at harsher hydrolysis conditions. Application of reductive hydrolysis with 4-methylmorpholine-borane and TFA did not lead to improved results. Overall, our results demonstrate that conditions used for methylation analysis have to be adjusted for the analysis of different bacterial HoEPS.

Fern cell walls and the evolution of arabinogalactan proteins in streptophytes

Significant changes have occurred in plant cell wall composition during evolution and diversification of tracheophytes. As the sister lineage to seed plants, knowledge on the cell wall of ferns is key to track evolutionary changes across tracheophytes and to understand seed plant-specific evolutionary innovations. Fern cell wall composition is not fully understood, including limited knowledge of glycoproteins such as the fern arabinogalactan proteins (AGPs). Here, we characterize the AGPs from the leptosporangiate fern genera Azolla, Salvinia, and Ceratopteris. The carbohydrate moiety of seed plant AGPs consists of a galactan backbone including mainly 1,3- and 1,3,6-linked pyranosidic galactose, which is conserved across the investigated fern AGPs. Yet, unlike AGPs of angiosperms, those of ferns contained the unusual sugar 3-O-methylrhamnose. Besides terminal furanosidic arabinose, Ara (Araf), the main linkage type of Araf in the ferns was 1,2-linked Araf, whereas in seed plants 1,5-linked Araf is often dominating. Antibodies directed against carbohydrate epitopes of AGPs supported the structural differences between AGPs of ferns and seed plants. Comparison of AGP linkage types across the streptophyte lineage showed that angiosperms have rather conserved monosaccharide linkage types; by contrast bryophytes, ferns, and gymnosperms showed more variability. Phylogenetic analyses of glycosyltransferases involved in AGP biosynthesis and bioinformatic search for AGP protein backbones revealed a versatile genetic toolkit for AGP complexity in ferns. Our data reveal important differences across AGP diversity of which the functional significance is unknown. This diversity sheds light on the evolution of the hallmark feature of tracheophytes: their elaborate cell walls.

Structural characterization of a sulfated polysaccharide from Ishige okamurae and its effect on recovery from immunosuppression

A sulfated polysaccharide from the brown alga Ishige okamurae Yendo, designated IOY, was successfully isolated by anion-exchange and size-exclusion chromatography. Chemical and spectroscopic analyses demonstrated that IOY was a fucoidan, that consisted of →3)-α-l-Fucp-(1→, →4)-α-l-Fucp-(1→, →6)-β-d-Galp-(1 → and →3)-β-d-Galp-(1 → residues with sulfate groups at C-2/C-4 the of (1 → 3)-α-l-Fucp and C-6 the of (1 → 3)-β-d-Galp residues. IOY possessed a potent immunomodulatory effect in vitro as measured by lymphocyte proliferation assay. The immunomodulatory effect of IOY was further investigated in vivo using immunosuppressed mice induced by cyclophosphamide (CTX). The results showed that IOY significantly increased the spleen and thymus indexes and alleviated CTX-induced spleen and thymus damage. Furthermore, IOY had a significant effect on hematopoietic function recovery and promoted the secretion of interleukin-2 (IL-2) and tumor necrosis factor (TNF-α). Notably, IOY reversed CD4+ and CD8+ T cell reduction and improved immune response. These data indicated that IOY had vital in immunomodulatory function and could be used as drug or functional food to lessen chemotherapy-induced immunosuppression.

Anti-Diabetic Activity of a Novel Exopolysaccharide Produced by the Mangrove Endophytic Fungus Penicillium janthinellum N29

Marine microorganisms often produce exopolysaccharides with novel structures and diverse biological activities due to their specific marine environment. The novel active exopolysaccharides from marine microorganisms have become an important research area in new drug discovery, and show enormous development prospects. In the present study, a homogeneous exopolysaccharide from the fermented broth of the mangrove endophytic fungus Penicillium janthinellum N29, designated as PJ1-1, was obtained. The results of chemical and spectroscopic analyses showed that PJ1-1 was a novel galactomannan with a molecular weight of about 10.24 kDa. The backbone of PJ1-1 was composed of →2)-α-d-Manp-(1→, →4)-α-d-Manp-(1→, →3)-β-d-Galf-(1→ and →2)-β-d-Galf-(1→ units with partial glycosylation at C-3 of →2)-β-d-Galf-(1→ unit. PJ1-1 had a strong hypoglycemic activity in vitro, evaluated using the assay of α-glucosidase inhibition. The anti-diabetic effect of PJ1-1 in vivo was further investigated using mice with type 2 diabetes mellitus induced by a high-fat diet and streptozotocin. The results indicated that PJ1-1 markedly reduced blood glucose level and improved glucose tolerance. Notably, PJ1-1 increased insulin sensitivity and ameliorated insulin resistance. Moreover, PJ1-1 significantly decreased the levels of serum total cholesterol, triglyceride and low-density lipoprotein cholesterol, enhanced the level of serum high-density lipoprotein cholesterol and alleviated dyslipidemia. These results revealed that PJ1-1 could be a potential source of anti-diabetic agent.

A sulfated polysaccharide from Dictyosphaeria cavernosa: Structural characterization and effect on immunosuppressive recovery

A homogeneous sulfated polysaccharide DCS1 was obtained from Dictyosphaeria cavernosa by alkali extraction and chromatography purification. On the basis of chemical and spectroscopic analyses, DCS1 was a novel mannan-type sulfated polysaccharide and had a molecular weight of 15.48 kDa. DCS1 consisted of a main chain of (1 → 4)-α-d-Manp units with partial sulfate substitution at C-2 and branches at C-2/C-6. DCS1 possessed a potent immune-enhancing effect in vitro evaluated by the assays of lymphocytes proliferation and macrophage phagocytosis. The immunomodulatory effect of DCS1 in vivo was further investigated using immunosuppressed mice induced by cyclophosphamide (Cy). The data showed that DCS1 markedly increased the spleen and thymus indexes, and ameliorated the Cy-induced damage to spleen and thymus. Moreover, DCS1 had a significant effect on hematopoietic function recovery, and promoted the secretion of the interleukin-2 and tumor necrosis factor-α. Notably, DCS1 reversed the reduction of CD4+ T cells, improved the disorder of CD4+/CD8+ T cells and enhanced the immune response. The investigation demonstrated that the sulfated polysaccharide DCS1 with novel structure could be a hopeful immunomodulatory agent.

Structure-function relationships of pectic polysaccharides from broccoli by-products with in vitro B lymphocyte stimulatory activity

To study structure-function relationships of pectic polysaccharides with their immunostimulatory activity, broccoli by-products were used. Pectic polysaccharides composed by 64 mol% uronic acids, 18 mol% Ara, and 10 mol% Gal, obtained by hot water extraction, activated B lymphocytes in vitro (25-250 μg/mL). To disclose active structural features, combinations of ethanol and chromatographic fractionation and modification of the polysaccharides were performed. Polysaccharides insoluble in 80 % ethanol (Et80) showed higher immunostimulatory activity than the pristine mixture, which was independent of molecular weight range (12-400 kDa) and removal of terminal or short Ara side chains. Chemical sulfation did not promote B lymphocyte activation. However, the action of pectin methylesterase and endo-polygalacturonase on hot water extracted polysaccharides produced an acidic fraction with a high immunostimulatory activity. The de-esterified homogalacturonan region seem to be an important core to confer pectic polysaccharides immunostimulatory activity. Therefore, agri-food by-products are a source of pectic polysaccharide functional food ingredients.

The Bep gene cluster in Burkholderia cenocepacia H111 codes for a water-insoluble exopolysaccharide essential for biofilm formation

Burkholderia cenocepacia is an opportunistic pathogen isolated from cystic fibrosis patients where it causes infections that are extremely difficult to treat with antibiotics, and sometimes have a fatal outcome. Biofilm is a virulence trait of B. cenocepacia, and is associated with infection persistence and increased tolerance to antibiotics. In biofilms exopolysaccharides have an important role, conferring mechanical stability and antibiotic tolerance. Two different exopolysaccharides were isolated from B. cenocepacia H111 biofilms: a water-soluble polysaccharide rich in rhamnose and containing an L-Man residue, and a water-insoluble polymer made of glucose, galactose and mannose. In the present work, the product encoded by B. cenocepacia H111 bepA-L gene cluster was identified as the water-insoluble exopolysaccharide, using mutant strains and NMR spectroscopy of the purified polysaccharides. It was also demonstrated that the B. cenocepacia H111 wild type strain produces the water-insoluble exopolysaccharide in pellicles, thus underlining its potential importance in in vivo infections.

Anticoagulant Property of a Sulfated Polysaccharide with Unique Structural Characteristics from the Green Alga Chaetomorpha aerea

Sulfated polysaccharides from marine algae have attracted a great amount of attentions for the development of marine drugs due to their unique structural features, and they are great potential sources of naturally occurring anticoagulant agents. The genus Chaetomorpha is one of the largest genera in green algae and has a worldwide distribution. In the present study, a homogeneous polysaccharide from Chaetomorpha aerea, designated as PCA, was obtained by alkali extraction, anion-exchange and size-exclusion chromatography. Based on the results of chemical and spectroscopic analyses, PCA was a sulfated galactoarabinan which was mainly constituted of a backbone of →4)-β-l-Arap-(1→ unit, partially sulfated at C-3 of →4)-β-l-Arap-(1→ and C-4 of →6)-α-d-Galp-(1→. The side chains consisting of →6)-α-d-Galp-(1→ and →5)-α-l-Araf-(1→ residues were in C-2 of →4)-β-l-Arap-(1→ unit. PCA had a strong anticoagulant activity in vitro as evaluated by the assays of activated partial thromboplastin time, thrombin time and fibrinogen level. The obvious anticoagulant activity in vivo of PCA was also found. PCA significantly inhibited the activities of the intrinsic coagulation factors XII, XI, IX and VIII, and exhibited weak inhibition effects on the common coagulation factors II and X. The anticoagulant mechanism of PCA was attributed to strong thrombin inhibition potentiated by heparin cofactor II or antithrombin III, and it also possessed an apparent inhibition effect on coagulation factor Xa mediated by antithrombin III. The investigation demonstrated that PCA could be a promising anticoagulant agent for health promotion and the treatment of thrombotic diseases.

An arabinogalactan isolated from Pollen Typhae induces the apoptosis of RKO cells by promoting macrophage polarization

An arabinogalactan (PTPS-1-2) was isolated and characterized from Pollen Typhae, and its potential antitumor effects on activating macrophages to produce immunomodulatory factors and promoting apoptosis in colorectal cancer cells were investigated. Structural characterization showed that PTPS-1-2 had a molecular weight of 59 kDa and was composed of rhamnose, arabinose, glucuronic acid, galactose, and galacturonic acid with a molar ratio of 7.6: 17.1: 6.5: 61.4: 7.4. Its backbone was predominantly composed of T-β-D-Galp, 1,3-β-D-Galp, 1,6-β-D-Galp, 1,3,6-β-D-Galp, 1,4-α-D-GalpA, 1,2-α-L-Rhap, additionally, branches contained 1,5-α-L-Araf, T-α-L-Araf, T-β-D-4-OMe-GlcpA, T-β-D-GlcpA and T-α-L-Rhap. PTPS-1-2 activated RAW264.7 cell by triggering the NF-kB signaling pathway and M1 macrophage polarization. Furthermore, the conditioned medium (CM) of Mφ pretreated with PTPS-1-2 exerted marked antitumor effects by inhibiting RKO cell proliferation and suppressing cell colony formation. Collectively, our findings suggested that PTPS-1-2 might be a therapeutic option for the prevention and treatment of tumors.

Genetic and Structural Variation in the O-Antigen of Salmonella enterica Serovar Typhimurium Isolates Causing Bloodstream Infections in the Democratic Republic of the Congo

Salmonella enterica serovar Typhimurium causes a devastating burden of invasive disease in sub-Saharan Africa with high levels of antimicrobial resistance. No licensed vaccine is available, but O-antigen-based candidates are in development, as the O-antigen moiety of lipopolysaccharides is the principal target of protective immunity. The vaccines under development are designed based on isolates with O-antigen O-acetylated at position C-2 of abequose, giving the O:5 antigen. Serotyping data on recent Salmonella Typhimurium clinical isolates from the Democratic Republic of the Congo (DRC), however, indicate increasing levels of isolates without O:5. The importance and distribution of this loss of O:5 antigen in the population as well as the genetic mechanism responsible for the loss and chemical characteristics of the O-antigen are poorly understood. In this study, we Illumina whole-genome sequenced 354 Salmonella Typhimurium isolates from the DRC, which were isolated between 2002 and 2017. We used genomics and phylogenetics combined with chemical approaches (¹H nuclear magnetic resonance [NMR], high-performance anion-exchange chromatography with pulsed amperometric detection [HPAEC-PAD], high-performance liquid chromatography–PAD [HPLC-PAD], and HPLC-size exclusion chromatography [HPLC-SEC]) to characterize the O-antigen features within the bacterial population. We observed convergent evolution toward the loss of the O:5 epitope predominantly caused by recombination events in a single gene, the O-acetyltransferase gene oafA. In addition, we observe further O-antigen variations, including O-acetylation of the rhamnose residue, different levels of glucosylation, and the absence of O-antigen repeating units. Large recombination events underlying O-antigen variation were resolved using long-read MinION sequencing. Our study suggests evolutionary pressure toward O-antigen variants in a region where invasive disease by Salmonella Typhimurium is highly endemic. This needs to be taken into account when developing O-antigen-based vaccines, as it might impact the breadth of coverage in such regions.

Rapid generation of Shigella flexneri GMMA displaying natural or new and cross-reactive O-Antigens

Generalized modules for membrane antigens (GMMA) are exosomes released from engineered Gram-negative bacteria and represent an attractive vaccine platform for the delivery of the O-Antigen (OAg), recognized as the key target for protective immunity against several pathogens such as Shigella. Shigella is a major cause of disease in Low- and Middle-Income countries and the development of a vaccine needs to deal with its large serotypic diversity. All S. flexneri serotypes, except serotype 6, share a conserved OAg backbone, corresponding to serotype Y. Here, a GMMA-producing S. flexneri scaffold strain displaying the OAg backbone was engineered with different OAg-modifying enzymes, either individually or in combinations. This strategy rapidly yielded GMMA displaying 12 natural serotypes and 16 novel serotypes expressing multiple epitopes combinations that do not occur in nature. Importantly, a candidate GMMA displaying a hybrid OAg elicited broadly cross-bactericidal antibodies against a large panel of S. flexneri serotypes.

Antidiabetic-activity sulfated polysaccharide from Chaetomorpha linum: Characteristics of its structure and effects on oxidative stress and mitochondrial function

A water-soluble polysaccharide from the green alga Chaetomorpha linum, designated CHS2, was obtained by water extraction, preparative anion-exchange and size-exclusion chromatography. Results of chemical and spectroscopic analyses showed that CHS2 was a sulfated rhamnogalactoarabinan, and its backbone was mainly constituted by 4-linked and 3,4-linked β-l-arabinopyranose with sulfate groups at C-2/C-3 of 4-linked β-l-arabinopyranose. The branching contained 4-linked, 6-linked β-d-galactopyranose and terminal rhamnose residues. Based on the inhibition of human islet amyloid polypeptide (hIAPP) aggregation and morphology change of hIAPP aggregates in in vitro tests, it was proved that CHS2 effectively inhibited the hIAPP aggregation and possessed strong antidiabetic activity. CHS2 was nearly no toxicity in NIT-1 cells and could attenuate hIAPP-induced cytotoxicity. CHS2 may significantly reduce the generation of intracellular reactive oxygen species and hIAPP aggregation-induced oxidative stress in NIT-1 cells. CHS2 was co-localized with mitochondria, and largely protected mitochondria function from hIAPP aggregation-induced damage through stabilizing mitochondrial membrane potential and enhancing the mitochondrial complex I, II or III activity and ATP level. The data demonstrated that CHS2 could have potential prospect to become an antidiabetic drug for type 2 diabetes mellitus treatment.

Purification, Chemical Characterization and Immunomodulatory Activity of a Sulfated Polysaccharide from Marine Brown Algae Durvillaea antarctica

An immunomodulatory polysaccharide (DAP4) was extracted, purified, and characterized from Durvillaea antarctica. The results of chemical and spectroscopic analyses demonstrated that the polysaccharide was a fucoidan, and was mainly composed of (1→3)-α-l-Fucp and (1→4)-α-l-Fucp residues with a small degree of branching at C-3 of (1→4)-α-l-Fucp residues. Sulfate groups were at C-4 of (1→3)-α-l-Fucp, C-2 of (1→4)-α-l-Fucp and minor C-6 of (1→4)-β-d-Galp. Small amounts of xylose and galactose exist in the forms of β-d-Xylp-(1→ and β-d-Gal-(1→. The immunomodulatory activity of DAP4 was measured on RAW 264.7 cells, the results proved that DAP4 exhibited excellent immunomodulatory activities, such as promoted the proliferation of spleen lymphocytes, increased NO production, as well as enhanced phagocytic of macrophages. Besides, DAP4 could also produce better enhancement on the vitality of NK cells. For the high immunomodulatory activity, DAP4 might be a potential source of immunomodulatory fucoidan with a novel structure.

Structural characterization of a P-selectin and EGFR dual-targeting fucoidan from Sargassum fusiforme

In this study, we obtained fucoidans SFP, SHP, STP, and FVP from Sargassum fusiforme, Sargassum horneri, Sargassumthunbergii, and Fucus vesiculosus, respectively. Chitosan/fucoidan nanoparticles (Cs/F NPs) were prepared using the fucoidans mentioned above. SFP NPs and SHP NPs showed strong binding abilities to P-selectin and epithelial growth factor receptor (EGFR). Given the yields from the alga, SFP was first selected to explore the structural characteristics of the P-selectin and EGFR dual-targeting fucoidan. SFP had an estimated molecular weight of 739 kDa and was mainly composed of galactose (26.57%, mol%) and fucose (66.81%), with minor amounts of mannose (2.54%), glucosamine (0.42%), and glucose (3.66%). Galactose and fucose accounted for thevast majority. Further investigation, including methylation analysis, one- and two-dimensional nuclear magnetic resonance, and mass spectroscopy, was performed to reveal the fine structure of SFP. The results indicated that SFP mainly consisted of → 3)-α-l-Fucp-(1→, →4)-α-l-Fucp-(1→, →3,4)-α-l-Fucp-(1→, →3)-β-d-Galp-(1→, and minor → 6)-β-d-Galp-(1→, partially sulfated at the C-4 of → 3)-α-l-Fucp-(1→, C-3 of → 4)-α-l-Fucp-(1→, C-3 of → 6)-β-d-Galp-(1→, and C-6 of → 3)-β-d-Galp-(1 → . Sulfated fuco- and galactofuco-segments formed the branches.

Anti-diabetic activity of a sulfated galactoarabinan with unique structural characteristics from Cladophora oligoclada (Chlorophyta)

The polysaccharide from green alga Cladophora oligoclada, OHSS2, was a sulfated galactoarabinan which was constituted by a backbone of (1 → 4)-β-l-arabinopyranose units with partial sulfate at C-3 of (1 → 4)-β-l-arabinopyranose units. The side chains containing (1 → 4)-β-l-arabinopyranose, (1 → 4)-β-d-galactopyranose and/or (1 → 4,6)-β-d-galactopyranose units were in C-2/C-3 of (1 → 4)-β-l-arabinopyranose units. OHSS2 had strong anti-diabetic activity in vitro assessed by inhibition of human islet amyloid polypeptide (hIAPP) aggregation. The mechanism analysis of anti-diabetic activity showed that OHSS2 diminished the production of intracellular reactive oxygen species and alleviated hIAPP aggregation-induced oxidative stress in NIT-1 cells. OHSS2 stabilized mitochondrial membrane potential, and enhanced the mitochondrial complex I, II or III activity and ATP level. Thus, OHSS2 effectively protected mitochondria from hIAPP aggregation-induced damage. Furthermore, OHSS2 was co-localized with mitochondria and could have a direct influence on mitochondrial function. These results revealed that OHSS2 had potential as a novel anti-diabetic agent.

Search for evolutionary roots of land plant arabinogalactan-proteins in charophytes: presence of a rhamnogalactan-protein in Spirogyra pratensis (Zygnematophyceae)

Charophyte green algae (CGA) are assigned to be the closest relatives of land plants and therefore enlighten processes in the colonization of terrestrial habitats. For the transition from water to land, plants needed significant physiological and structural changes, as well as with regard to cell wall composition. Sequential extraction of cell walls of Nitellopsis obtusa (Charophyceae) and Spirogyra pratensis (Zygnematophyceae) offered a comparative overview on cell wall composition of late branching CGA. Because arabinogalactan-proteins (AGPs) are considered common for all land plant cell walls, we were interested in whether these special glycoproteins are present in CGA. Therefore, we investigated both species with regard to characteristic features of AGPs. In the cell wall of Nitellopsis, no hydroxyproline was present and no AGP was precipitable with the β-glucosyl Yariv's reagent (βGlcY). By contrast, βGlcY precipitation of the water-soluble cell wall fraction of Spirogyra yielded a glycoprotein fraction rich in hydroxyproline, indicating the presence of AGPs. Putative AGPs in the cell walls of non-conjugating Spirogyra filaments, especially in the area of transverse walls, were detected by staining with βGlcY. Labelling increased strongly in generative growth stages, especially during zygospore development. Investigations of the fine structure of the glycan part of βGlcY-precipitated molecules revealed that the galactan backbone resembled that of AGPs with 1,3- 1,6- and 1,3,6-linked Galp moieties. Araf was present only in small amounts and the terminating sugars consisted predominantly of pyranosidic terminal and 1,3-linked rhamnose residues. We introduce the term 'rhamnogalactan-protein' for this special AGP-modification present in S. pratensis.

"Neptune Balls" Polysaccharides: Disentangling the Wiry Seagrass Detritus

Each year, high amounts of dead seagrass material are washed ashore at beaches world-wide. In the Mediterranean region, the seagrass Posidonia oceanica is responsible for huge agglomerates of ball-like seagrass litter. As these are often removed due to touristic reasons, a reuse method would be a step towards a more ecologically oriented society. In this study, the main polysaccharide components were analyzed, in order to propose possible usage options. To do this, different aqueous fractions were extracted, analyzed by classical carbohydrate analysis methods (GC-FID/MS, colorimetric assay and elemental analysis), and purified by ion-exchange chromatography, as well as selective precipitation with a detecting agent for highly glycosylated glycoproteins. The obtained purified fractions were analyzed in detail and a linkage-type analysis of the most promising extract was conducted via permethylation. Only low amounts of glycoproteins, as well as medium amounts of the characteristic apiogalacturonan were likely to be present, while xylan seemed to be the most abundant polysaccharide in most fractions. A partial structural proposal showed general accordance with land plant xylans, presenting reuse options in the field of biofuel and bioplastic generation.

Pharmacological Investigations in Traditional Utilization of Alhagi maurorum Medik. in Saharan Algeria: In Vitro Study of Anti-Inflammatory and Antihyperglycemic Activities of Water-Soluble Polysaccharides Extracted from the Seeds

The anti-inflammatory and antihyperglycemic effects of polysaccharides extracted from Alhagi maurorum Medik. seeds, spontaneous shrub collected in Southern of Algerian Sahara were investigated. Their water extraction followed by alcoholic precipitation was conducted to obtain two water-soluble polysaccharides extracts (WSPAM1 and WSPAM2). They were characterized using Fourier transform infrared, ¹H/¹³C Nuclear Magnetic Resonance, Gas Chromatography-Mass Spectrometry and Size Exclusion Chromatography coupled with Multi-Angle Light Scattering. The capacity of those fractions to inhibit α-amylase activity and thermally induced Bovine Serum Albumin denaturation were also investigated. WSPAM1 and WSPAM2 were galactomannans with a mannose/galactose ratio of 2.2 and 2.4, respectively. The SEC-MALLS analysis revealed that WSPAM1 had a molecular weight of 1.4 × 10⁶ Da. The investigations highlighted antinflammatory and antihyperglycemic effects in a dose-dependant manner of WSPAM1 and WSPAM2.

Chemical Structure and Anticoagulant Property of a Novel Sulfated Polysaccharide from the Green Alga Cladophora oligoclada

Marine macroalgae are efficient producers of sulfated polysaccharides. The algal sulfated polysaccharides possess diverse bioactivities and peculiar chemical structures, and represent a great potential source to be explored. In the present study, a heparinoid-active sulfated polysaccharide was isolated from the green alga Cladophora oligoclada. Results of chemical and spectroscopic analyses indicated that the sulfated polysaccharide was composed of →6)-β-d-Galp-(1→, β-d-Galp-(1→, →6)-α-d-Glcp-(1→ and →3)-β-d-Galp-(1→ units with sulfate esters at C-2/C-4 of →6)-β-d-Galp-(1→, C-6 of →3)-β-d-Galp-(1→ and C-3 of →6)-α-d-Glcp-(1→ units. The branches consisting of β-d-Galp-(1→ and →6)-β-d-Galp-(1→ units were located in C-3 of →6)-β-d-Galp-(1→ units. The sulfated polysaccharide exhibited potent anticoagulant activity in vitro and in vivo as evaluated by activated partial thromboplastin time (APTT), thrombin time, and the fibrinogen level. For the APTT, the signal for clotting time was more than 200 s at 100 μg/mL in vitro and at 15 mg/kg in vivo. The obvious thrombolytic activity of the sulfated polysaccharide in vitro was also found. The mechanism analysis of anticoagulant action demonstrated that the sulfated polysaccharide significantly inhibited the activities of all intrinsic coagulation factors, which were less than 1.0% at 50 μg/mL, but selectively inhibited common coagulation factors. Furthermore, the sulfated polysaccharide strongly stimulated the inhibition of thrombin by potentiating antithrombin-III (AT-III) or heparin cofactor-II, and it also largely promoted the inhibition of factor Xa mediated by AT-III. These results revealed that the sulfated polysaccharide from C. oligoclada had potential to become an anticoagulant agent for prevention and therapy of thrombotic diseases.

Linkage Analysis of Oligosaccharides and Polysaccharides: A Tutorial

Polysaccharides and oligosaccharides are a diverse group of natural polymers with important biological functions. The diversity of carbohydrate polymers is vast, ranging from small oligosaccharides of defined composition decorating proteins, to large, complex heteropolymers comprising integral cell wall components of plants, fungi and bacteria. An important step in the elucidation of unknown carbohydrate structures in a sample is the assessment of the various linkages present. This is accomplished by performing linkage analysis of the sample. The analysis proceeds as a successive series of chemical steps in which unlinked carbohydrate hydroxyls are marked with methyl groups, the sample is hydrolyzed into monosaccharides and reduced to alditols, and finally free hydroxyls are acetylated. Gas chromatography-mass spectrometry (GC-MS) analysis is employed to analyze the resultant partially methylated alditol acetates (PMAAs). The following paper reviews the major literature pertaining to the specific protocol for linkage analysis of carbohydrates outlined herein. The review details additional steps necessary for the completion of uronic acid linkage analysis, as well as analysis of chitin containing polymers. It also gives chromatographic examples of common erroneous results which the first time practitioner will want to be aware of. Our hope is that this protocol will serve as a definitive guide, allowing novice researchers to perform linkage analysis of carbohydrates in their own lab.

Impact of grape variety, berry maturity and size on the extractability of skin polyphenols during model wine-like maceration experiments

BACKGROUND

Skin cell walls modulate anthocyanin and tannin extraction from grape skins. However, relationships between the composition of alcohol-insoluble cell wall solids (AIS) and extraction are still unclear. Our objectives were to characterize the impact of variety, berry size and ripeness on skin AIS composition (polysaccharides, proteins) and polyphenol extraction during maceration.

RESULTS

Grape skin composition and its impact on polyphenol extraction was compared for two varieties - Carignan and Grenache - with skins of berries sorted according to their size and density. Extractions were performed under model wine-like maceration conditions. Fresh skins had similar content of polymeric tannins, but strongly differed in their anthocyanin content (higher in Carignan and in the ripest berries) and composition (higher proportions in coumaroylated anthocyanins in Carignan). Anthocyanin extraction was proportionally much higher in Grenache, which was not just related to the Carignan's higher levels in coumaroylated anthocyanins. Chemical reactions decreased anthocyanin concentrations in solution for both varieties. Tannin extraction for Grenache was slightly higher and faster than for Carignan. Skin AISs differed slightly between the two varieties in their carbohydrate composition and protein content, but not between modalities. Polyphenol analyses in the precipitates evidenced at the end of the maceration and in residual skins highlighted differences between the two varieties and between berries with different ripeness.

CONCLUSION

Structural information on the cell wall network and on its changes during maceration, along with a better understanding of the chemical reactions of anthocyanins and tannins, is needed to better relate grape and wine polyphenol composition. © 2020 Society of Chemical Industry.

Arabinogalactan-proteins from non-coniferous gymnosperms have unusual structural features

Arabinogalactan-proteins (AGPs), important signalling molecules of the plant cell wall, are structurally extensively investigated in angiosperms, but information on AGPs in gymnosperms is still limited. We characterized AGPs from the gymnosperms Ginkgo biloba, Ephedra distachya, Encephalartos longifolius and Cycas revoluta. The protein contents are comparable to that of angiosperm AGPs. Hydroxyproline is the site of linking the carbohydrate part and was detected in all AGPs with highest concentration in Cycas AGP (1.1 % of the AGP). Interestingly, with the exception of Cycas, all AGPs contained the monosaccharide 3-O-methylrhamnose not present in angiosperm polysaccharides. The carbohydrate moieties of Cycas and Ephredra showed the main components 1,3,6-linked galactose and terminal arabinose typical of angiosperm AGPs, whereas that of Ginkgo AGP was unique with 1,4-linked galactose as dominant structural element. Bioinformatic search for glycosyltransferases in Ginkgo genome also revealed a lower number of galactosyltransferases responsible for biosynthesis of the 1,3-Gal/1,6-Gal AGP backbone.

Lyophilized alginate-based microspheres containing Lactobacillus fermentum D12, an exopolysaccharides producer, contribute to the strain's functionality in vitro

Lactobacillus (Limosilactobacillus) fermentum D12 is an exopolysaccharide (EPS) producing strain whose genome contains a putative eps operon. Whole-genome analysis of D12 was performed to disclose the essential genes correlated with activation of precursor molecules, elongation and export of the polysaccharide chain, and regulation of EPS synthesis. These included the genes required for EPS biosynthesis such as epsA, B, C, D and E, also gt, wzx, and wzy and those involved in the activation of the precursor molecules galE, galT and galU. Both the biosynthesis and export mechanism of EPS were proposed based on functional annotation. When grown on MRS broth with an additional 2% w/v glucose, L. fermentum D12 secreted up to 200 mg/L of a mixture of EPSs, whose porous structure was visualized by scanning electron microscopy (SEM). Structural information obtained by ¹HNMR spectroscopy together with composition and linkage analyses, suggested the presence of at least two different EPSs, a branched heteropolysaccharide containing t-Glcp and 2,6-linked Galf, and glycogen. Since recent reports showed that polysaccharides facilitate the probiotic-host interactions, we at first sought to evaluate the functional potential of L. fermentum D12. Strain D12 survived simulated gastrointestinal tract (GIT) conditions, exhibited antibacterial activity against enteropathogenic bacteria, adhered to Caco-2 cells in vitro, and as such showed potential for in vivo functionality. The EPS crude extract positively influenced D12 strain capacity to survive during freeze-drying and to adhere to extracellular matrix (ECM) proteins but did not interfere Caco-2 and mucin adherence when added at concentrations of 0.2, 0.5, and 1.0 mg/mL. Since the viable bacterial count of free D12 cells was 3 logarithmic units lower after the exposure to simulated GIT conditions than the initial count, the bacterial cells had been loaded into alginate for viability improvement. Microspheres of D12 cells, which were previously analyzed at SEM, significantly influenced their survival during freeze-drying and in simulated GIT conditions. Furthermore, the addition of the prebiotic substrates mannitol and lactulose improved the viability of L. fermentum D12 in freeze-dried alginate microspheres during 1-year storage at 4 °C compared to the control.

The development and characterization of an E. coli O25B bioconjugate vaccine

Extraintestinal pathogenic Escherichia coli (ExPEC) cause a wide range of clinical diseases such as bacteremia and urinary tract infections. The increase of multidrug resistant ExPEC strains is becoming a major concern for the treatment of these infections and E. coli has been identified as a critical priority pathogen by the WHO. Therefore, the development of vaccines has become increasingly important, with the surface lipopolysaccharide constituting a promising vaccine target. This study presents genetic and structural analysis of clinical urine isolates from Switzerland belonging to the serotype O25. Approximately 75% of these isolates were shown to correspond to the substructure O25B only recently described in an emerging clone of E. coli sequence type 131. To address the high occurrence of O25B in clinical isolates, an O25B glycoconjugate vaccine was prepared using an E. coli glycosylation system. The O antigen cluster was integrated into the genome of E. coli W3110, thereby generating an E. coli strain able to synthesize the O25B polysaccharide on a carrier lipid. The polysaccharide was enzymatically conjugated to specific asparagine side chains of the carrier protein exotoxin A (EPA) of Pseudomonas aeruginosa by the PglB oligosaccharyltransferase from Campylobacter jejuni. Detailed characterization of the O25B-EPA conjugate by use of physicochemical methods including NMR and GC-MS confirmed the O25B polysaccharide structure in the conjugate, opening up the possibility to develop a multivalent E. coli conjugate vaccine containing O25B-EPA.

The biofilm of Burkholderia cenocepacia H111 contains an exopolysaccharide composed of l-rhamnose and l-mannose: Structural characterization and molecular modelling

Burkholderia cenocepacia belongs to the Burkholderia Cepacia Complex, a group of 22 closely related species both of clinical and environmental origin, infecting cystic fibrosis patients. B. cenocepacia accounts for the majority of the clinical isolates, comprising the most virulent and transmissible strains. The capacity to form biofilms is among the many virulence determinants of B. cenocepacia, a characteristic that confers enhanced tolerance to some antibiotics, desiccation, oxidizing agents, and host defenses. Exopolysaccharides are a major component of biofilm matrices, particularly providing mechanical stability to biofilms. Recently, a water-insoluble exopolysaccharide produced by B. cenocepacia H111 in biofilm was characterized. In the present study, a water-soluble exopolysaccharide was extracted from B. cenocepacia H111 biofilm, and its structure was determined by GLC-MS, NMR and ESI-MS. The repeating unit is a linear rhamno-tetrasaccharide with 50% replacement of a 3-α-L-Rha with a α-3-L-Man. [2)-α-L-Rhap-(1→3)-α-L-[Rhap or Manp]-(1→3)-α-L-Rhap-(1→2)-α-L-Rhap-(1→]_n Molecular modelling was used to obtain information about local structural motifs which could give information about the polysaccharide conformation.

Structural characterization and effect on leukopenia of fucoidan from Durvillaea antarctica

Fucoidans from brown seaweed shows various bioactive properties and promising prospects in biomedical field. Here, a novel fucoidan (F-4) was extracted and purified from Durvillaea antarctica. The structure of F-4 was characterized by HPLC, HPGPC, GC-MS, together with IR and NMR spectral analysis. F-4 is a sulfated polysaccharide mainly composed of fucose (Fuc), galactose (Gal), and glucose (Glc) in a molar ratio of 26.4: 7.1: 1.0. The backbone of F-4 is composed of (1→3) and (1→4)-linked-α-L-Fucp residues, which sulfated at C-4 or C-2 positions and branched with α-L-Fuc, β-D-Gal, and β-D-Glc residues. Furthermore, F-4 can effectively promote the growth of leukocyte in a mouse model induced by cyclophosphamide, possibly by activating hematopoietic progenitor cells and regulating the hematopoietic microenvironment of bone marrow. Our data provide useful information for further investigation of fucoidan in the treatment of chemotherapy-induced leukopenia.

Migration of Tannins and Pectic Polysaccharides from Natural Cork Stoppers to the Hydroalcoholic Solution

Ellagitannins, condensed tannins, and pectic-derived polysaccharides were removed from natural cork stoppers using hydroalcoholic solution. Two main populations of migrated compounds were determined; the major one with molecular weight (MW) between 0.2 and 1 kDa and the second with 2.1 kDa and polydispersity of 1.3. Two residual populations mainly composed of condensed tannins were also observed between 2.5 and 4.5 kDa and higher than 15 kDa. Simple, C-glycosidic, complex, and oligomeric ellagitannins were identified by high-performance liquid chromatography-diode array detection/electrospray ionization-mass spectrometry (HPLC-DAD/ESI-MS). Ellagitannins linked to condensed tannins and some pectic-derived polysaccharides were also tentatively identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF-MS). This preliminary work opens an opportunity for the cork stoppers industry due to the relevance of this type of compounds on the astringency and bitterness of wines.

Helicobacter pylori lipopolysaccharide structural domains and their recognition by immune proteins revealed with carbohydrate microarrays

The structural diversity of the lipopolysaccharides (LPSs) from Helicobacter pylori poses a challenge to establish accurate and strain-specific structure-function relationships in interactions with the host. Here, LPS structural domains from five clinical isolates were obtained and compared with the reference strain 26695. This was achieved combining information from structural analysis (GC-MS and ESI-MSⁿ) with binding data after interrogation of a LPS-derived carbohydrate microarray with sequence-specific proteins. All LPSs expressed Lewis^x/y and N-acetyllactosamine determinants. Ribans were also detected in LPSs from all clinical isolates, allowing their distinction from the 26695 LPS. There was evidence for 1,3-d-galactans and blood group H-type 2 sequences in two of the clinical isolates, the latter not yet described for H. pylori LPS. Furthermore, carbohydrate microarray analyses showed a strain-associated LPS recognition by the immune lectins DC-SIGN and galectin-3 and revealed distinctive LPS binding patterns by IgG antibodies in the serum from H. pylori-infected patients.

Study on structure characterization of pectin from the steamed ginseng and the inhibition activity of lipid accumulation in oleic acid-induced HepG2 cells

Two acid polysaccharides were obtained from steamed ginseng (GPS-1 and GPS-2) through water extraction, ion-exchange chromatography and gel chromatography. The structural features and ability of the polysaccharides to inhibit lipid accumulation in oleic acid-induced HepG2 cells were studied. GPS-1 consisted of type I arabinogalactans (AG-I), arabinogalactans-II (AG-II) and rhamnogalacturonan I (RG-I) domains. GPS-2 was a pectin-like polysaccharide consisting mainly of the homogalacturonan (HG) domain and a small amount of AG domain. Both GPS-1 and GPS-2 had branches attaching on O-3 of (1 → 6)-GalA or O-4 of (1 → 2)-Rha and terminated by either Ara or Gal. An in vitro experiment revealed that GPS-1 treatment at 50-400 μg/ml could dose-dependently decrease intracellular lipid accumulation and cholesterol (TC) and triglycerides (TG) levels. GPS-1 exerted a more serious hypolipidemic effect than GPS-2 did. Moreover, GPS-1 considerably increased the phosphorylation of AMP-activated protein kinase (AMPK) and affected the expression of AMPK downstream targets, including the inhibition of the protein expression of sterol regulatory element-binding protein 1c (SREBP-1c) and activation of Acetyl-CoA carboxylase (ACC). Results suggest that GPS-1 could inhibit lipid accumulation via the AMPK the signalling pathway.

Anticoagulant-active sulfated arabinogalactan from Chaetomorpha linum: Structural characterization and action on coagulation factors

A sulfated polysaccharide from the green alga Chaetomorpha linum, designated CLS4, was isolated by water extraction, anion-exchange and size-exclusion chromatography. Chemical and spectroscopic analyses demonstrated that CLS4 was a sulfated arabinogalactan, which was constituted by (1→6)-β-d-galactopyranose and (1→5)-α-l-arabinofuranose residues with sulfate groups at C-2/ C-3 of (1→5)-α-l-arabinofuranose and C-2/C-4 of (1→6)-β-d-galactopyranose. CLS4 possessed strong anticoagulant activity in vitro or in vivo as evaluated by activated partial thromboplastin time and thrombin time assays. CLS4 largely inhibited the activities of the coagulation factors XII, XI, IX and VIII. CLS4 was a potent thrombin inhibitor mediated by antithrombin III (ATIII) or heparin cofactor II, and it also effectively stimulated the factor Xa inhibition by potentiating ATIII. Moreover, CLS4 had a high thrombolytic activity in vitro as assessed by clot lytic rate assay. The results suggested that CLS4 could be a promising source of anticoagulant agent.

Arabinogalactan-proteins of Zostera marina L. contain unique glycan structures and provide insight into adaption processes to saline environments

Seagrasses evolved from monocotyledonous land plants that returned to the marine habitat. This transition was accomplished by substantial changes in cell wall composition, revealing habitat-driven adaption to the new environment. Whether arabinogalactan-proteins (AGPs), important signalling molecules of land plants, are present in seagrass cell walls is of evolutionary and plant development interest. AGPs of Zostera marina L. were isolated and structurally characterised by analytical and bioinformatics methods as well as by ELISA with different anti-AGP antibodies. Calcium-binding capacity of AGPs was studied by isothermal titration calorimetry (ITC) and microscopy. Bioinformatic searches of the Z. marina proteome identified 9 classical AGPs and a large number of chimeric AGPs. The glycan structures exhibit unique features, including a high degree of branching and an unusually high content of terminating 4-O-methyl-glucuronic acid (4-OMe GlcA) residues. Although the common backbone structure of land plant AGPs is conserved in Z. marina, the terminating residues are distinct with high amounts of uronic acids. These differences likely result from the glycan-active enzymes (glycosyltransferases and methyltransferases) and are essential for calcium-binding properties. The role of this polyanionic surface is discussed with regard to adaption to the marine environment.

Burkholderia cenocepacia H111 Produces a Water-Insoluble Exopolysaccharide in Biofilm: Structural Determination and Molecular Modelling

Biofilms are a multicellular way of life, where bacterial cells are close together and embedded in a hydrated macromolecular matrix which offers a number of advantages to the cells. Extracellular polysaccharides play an important role in matrix setup and maintenance. A water-insoluble polysaccharide was isolated and purified from the biofilm produced by Burkholderiacenocepacia strain H111, a cystic fibrosis pathogen. Its composition and glycosidic linkages were determined using Gas–Liquid Chromatography–Mass Spectrometry (GLC–MS) on appropriate carbohydrate derivatives while its complete structure was unraveled by 1D and 2D NMR spectroscopy in deuterated sodium hydroxide (NaOD) aqueous solutions. All the collected data demonstrated the following repeating unit for the water-insoluble B. cenocepacia biofilm polysaccharide: [3)-α-d-Galp-(1→3)-α-d-Glcp-(1→3)-α-d-Galp-(1→3)-α-d-Manp-(1→]_n Molecular modelling was used, coupled with NMR Nuclear Overhauser Effect (NOE) data, to obtain information about local structural motifs which could give hints about the polysaccharide insolubility. Both modelling and NMR data pointed at restricted dynamics of local conformations which were ascribed to the presence of inter-residue hydrogen bonds and to steric restrictions. In addition, the good correlation between NOE data and calculated interatomic distances by molecular dynamics simulations validated potential energy functions used for calculations.

Recent progress in the research of yam mucilage polysaccharides: Isolation, structure and bioactivities

Yam (Dioscorea spp.), known as an edible and medicinal tuber crop in China, has been used historically for the treatment of diabetes, diarrhea, asthma, and other ailments in traditional Chinese medicine. Moreover, it has been consumed as starchy food for thousands of years in China. Modern phytochemistry and pharmacological experiments have been proved that non-starch polysaccharide is one of the main bioactive substances of yam. Many studies have been focused on the isolation and identification of polysaccharides and their bioactivities of Chinese yam. However, due to the difference in the variety of raw materials and the method of polysaccharides extracting, the structure and biological activity of the obtained polysaccharides also differ. It has been demonstrated that Chinese yam polysaccharide has various important biological activities, such as hypoglycemia, immunomodulatory, antioxidant, and antitumor activities. This paper is aimed at summarizing previous and current references of the isolation processes, structural features and bioactivities of yam polysaccharides. The review will serve as a useful reference material for further investigation and application of yam polysaccharides in functional foods and medicine fields.

Arabinogalactan-Proteins from the Liverwort Marchantia polymorpha L., a Member of a Basal Land Plant Lineage, Are Structurally Different to Those of Angiosperms

The thalloid liverwort Marchantia polymorpha as a member of a basal land plant lineage has to cope with the challenge of terrestrial life. Obviously, the plant cell wall has been strongly involved in the outstanding evolutionary process of water-to-land-transition. AGPs are signaling glycoproteins of the cell wall, which seem to be ubiquitous in seed plants and might play a role in adaption to abiotic and biotic stress situations. Therefore, we investigated the cell wall composition of Marchantia polymorpha with special focus on structural characterization of arabinogalactan-proteins. The Marchantia AGP shows typical features known from seed plant AGPs like precipitation with β-glucosyl-Yariv's reagent, a protein moiety with hydroxyproline and a carbohydrate part with 1,3,6-linked galactose and terminal arabinose residues. On the other hand, striking differences to AGPs of angiosperms are the occurrence of terminal 3-O-methyl-rhamnose and a highly branched galactan lacking appreciable amounts of 1,6-linked galactose. Binding of different AGP-antibodies (JIM13, KM1, LM2, LM6, LM14, LM26, and MAC207) to Marchantia AGP was investigated and confirmed structural differences between liverwort and angiosperm AGP, possibly due to deviating functions of these signaling molecules in the different taxonomic groups.

Molecular properties and structural characterization of an alkaline extractable arabinoxylan from hull-less barley bran

An alkaline extractable arabinoxylan (HBAX-25) was fractionated from crude arabinoxylan (HBAX) obtained optimally in hull-less barley (Hordeum vulgare L. var. nudum Hook. f.) bran. Molecular properties and structural characterization of HBAX-25 were investigated thoroughly based on chemical composition of 8.31% (w/w) moisture and 87.57% (w/w) sugar with specifically few proteins (1.08%, w/w) and high arabinoxylans (82.46%, w/w). Data from monosaccharide composition indicated that HBAX-25 mainly consisted of arabinose (30.13 mol%) and xylose (51.55 mol%) with A/X ratio of 0.58, representative for arabinoxylans, which coincided with FT-IR results and was corroborated by methylation and NMR analyses, i.e., a relatively low-branched arabinoxylan composed of un-substituted (1,4-linked β-D-Xylp, 71.19%), mono-substituted (1,3,4-linked β-D-Xylp, 14.78%) and di-substituted (1,2,3,4-linked β-D-Xylp, 10.76%) xylose units as backbone via β-(1→4) linkages, with six possible branches or individuals included. Hence, a structural basis of HBAX-25 was established, which could have potential in food and other value-added applications capable of interpreting their physicochemical, functional and technological characteristics.

Structure of the capsular polysaccharide of the KPC-2-producing Klebsiella pneumoniae strain KK207-2 and assignment of the glycosyltransferases functions

Klebsiella pneumoniae strain KK207-2 was isolated in 2010 from a bloodstream infection of an inpatient at an Italian hospital. It was previously found to produce the KPC-2 carbapenemase and to belong to clade 1 of sequence type 258. Genotyping of the conserved wzi and wzc genes from strain KK207-2 yielded contrasting results: the wzc-based method assigned the cps_207-2 to a new K-type, while the wzi-based method assigned it to the known K41 K-type. In order to resolve this contradiction, the capsular polysaccharide of K. pneumoniae KK207-2 was purified and its structure determined by using GLC-MS of appropriate carbohydrate derivatives, ESI-MS of both partial hydrolysis and Smith degradation derived oligosaccharides, and NMR spectroscopy of oligosaccharides, and the lithium degraded, native and de-O-acetylated polysaccharide. All the collected data demonstrated the following repeating unit for the K. pneumoniae KK207-2 capsular polysaccharide: The polysaccharide contains about 0.60 acetyl groups per repeating unit on C6 of the Gal residue. The reactions catalyzed by each glycosyltransferase in the cps_KK207-2 gene cluster were assigned on the basis of structural homology with other Klebsiella K antigens.

The impact of distillation process on the chemical composition and potential prebiotic activity of different oligosaccharidic fractions extracted from grape seeds

The study was designed to evaluate how the distillation process is able to affect the composition and bioactivity of oligosaccharides contained in the grape seeds. Different oligosaccharidic fractions have been extracted both before and after grape pomace distillation in order to valorize this by-product. A multistep solid-phase extraction approach (C-18 and carbograph cartridges) has been applied to purify and fractionate the oligosaccharidic compounds. Chemical characterization of the fractions was performed using a UPLC-ESI-MSⁿ method. Complex oligosaccharides consist principally of neutral oligosaccharides rich in arabinose and glucose. Then, the oligosaccharides contained in the different fractions as potential functional ingredients with prebiotic activity toward well-known probiotic bacteria, such as Lactobacillus acidophilus and Lactobacillus plantarum, were evaluated. Data showed how, in some combination, oligosaccharidic fractions obtained may be considered a novel "functional ingredient" with potential prebiotic activity mainly towards L. acidophilus.