Isolation and identification of an arabinogalactan extracted from pistachio external hull: Assessment of immunostimulatory activity

Structural characterization and human gut microbiota fermentation in vitro of a polysaccharide from Fucus vesiculosus

In this study, an acidic polysaccharide (FVP-7 A) was isolated from Fucus vesiculosus by DEAE-Sepharose™ fast flow. The chemical composition, glycosidic bonds and in vitro fecal fermentation characteristics of FVP-7 A were studied. Results shown that FVP-7 A was a homogenous polysaccharide with average molecular weight of 30.94 kDa. Combined with FT-IR, monosaccharide composition, methylation and NMR analysis, the glycosidic bonds of FVP-7 A mainly composed of →4)-β-D-Manp-(1→, →3)-α-L-Fucp-(1→, α-D-Manp-(1→, →3)-β-D-Manp-(1 → and →4,6)-α-D-Manp-(1→. The zeta potential and atomic force microscopy images indicated that FVP-7 A could exist stably as a single chain-like structure in dilute solution. After gut fermentation, FVP-7 A was utilized and promoted multiple short-chain fatty acids production, especially acetic acid, butyric acid and valeric acid. For prebiotics, FVP-7 A significantly increased the relative abundance of short-chain fatty acids producing bacteria such as Bacteroides, Lachnospira, Faecalibacterium, Ruminococcus, Oscillospira and Dialister, and inhiited the growth of the harmful bacteria Shigella. These results indicated that FVP-7 A could be used as a potential dietary supplement to improve intestinal health.

Structural elucidation and immunomodulatory activities in vitro of type I and II arabinogalactans from different origins of Astragalus membranaceus

Astragalus membranaceus polysaccharide (APS) possesses excellent immunomodulatory activity. However, there are several studies on the structural characterization of APS. Here, we aimed to elucidate the repeating units of polysaccharides (APS1, 106.5 kDa; APS2, 114.5 kDa) obtained from different Astragalus membranaceus origins and further investigated their immunomodulatory activities. Based on structural analysis, types of the two polysaccharides were identified as arabinogalactan-I (AG-I) and arabinogalactan-II (AG-II), and co-elution of arabinogalactans (AGs) and α-glucan was observed. The backbone of AG-I was 1,4-linked β-Galp occasionally substituted by α-Araf at O-2 and/or O-3. AG-II was a highly branched polysaccharide with long branches of α-Araf, which were attached to the O-3 of 1,6-linked β-Galp of the backbone. The presence of AGs in A. membranaceus was confirmed for the first time. The two polysaccharides could promote the expression of IL-6, IL-1β and TNF-α in RAW264.7 cells via MAPKs and NF-κB signaling pathways. The constants for APS1 and APS2 binding to Toll-like receptor 4 (TLR4) were 1.83 × 10-5 and 2.08 × 10-6, respectively. Notably, APS2 showed better immunomodulatory activity than APS1, possibly because APS2 contained more AGs. Hence, the results suggested that AGs were the vital components of APS in the immunomodulatory effect.

Bioactive arabinogalactan from Ferulopsis hystrix roots: characterization of gastroprotective and antioxidant potentials against drug-induced gastropathy

Bristled ferula (Ferulopsis hystrix (Bunge) Pimenov) is a perennial plant belonging to the Apiaceae family, and its aqueous extract is utilised in Eastern medicine to treat digestive system diseases. In this study, water-soluble polysaccharides from F. hystrix were isolated for the first time, and the basic polymer FH-3 was separated and characterised. FH-3 was found to contain arabinose and galactose in a 1:5 ratio, with a molecular weight of 52.3 kDa. Methylation analysis confirmed the structure of FH-3 to be arabino-3,6-galactan. Administration of FH-3 at 10 and 30 mg/kg doses in rats with drug-induced gastropathy effectively limited the development of large and strip-like erosions in the gastric mucosa. FH-3 prevented the development of oxidative stress, normalising malondialdehyde (MDA) and catalase (CAT) and reducing glutathione (GSH) serum levels. Arabinogalactan FH-3 is a new gastroprotective and antioxidant plant component in F. hystrix roots, offering promising prospects for treating stomach diseases.

Physicochemical Characterization, Antioxidant and Anticancer Activity Evaluation of an Acidic Polysaccharide from Alpinia officinarum Hance

AHP-3a, a triple-helix acidic polysaccharide isolated from Alpinia officinarum Hance, was evaluated for its anticancer and antioxidant activities. The physicochemical properties and structure of AHP-3a were investigated through gel permeation chromatography, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. The weight-average molecular weight of AHP-3a was 484 kDa, with the molar percentages of GalA, Gal, Ara, Xyl, Rha, Glc, GlcA, and Fuc being 35.4%, 21.4%, 16.9%, 11.8%, 8.9%, 3.1%, 2.0%, and 0.5%, respectively. Based on the results of the monosaccharide composition analysis, methylation analysis, and NMR spectroscopy, the main chain of AHP-3a was presumed to consist of (1→4)-α-D-GalpA and (1→2)-α-L-Rhap residues, which is a pectic polysaccharide with homogalacturonan (HG) and rhamnogalacturonan-I (RG-I) structural domains containing side chains. In addition, the results of the antioxidant activity assay revealed that the ability of AHP-3a to scavenge DPPH, ABTS, and OH free radicals increased with an increase in its concentration. Moreover, according to the results from the EdU, wound healing, and Transwell assays, AHP-3a can control the proliferation, migration, and invasion of HepG2 and Huh7 hepatocellular carcinoma cells without causing any damage to healthy cells. Thus, AHP-3a may be a natural antioxidant and anticancer component.

Extraction, structural characterization and immunoactivity of glucomannan type polysaccahrides from Lilium brownii var. viridulum Baker

Homogeneous polysaccharide (LBP) was extracted and purified from the bulblets of Lilium brownii var. viridulum Baker with a molecular weight of 312 kDa. The monosaccharides are composed of mannose and glucose, and the corresponding molar ratios are 0.582 and 0.418, respectively. FT-IR, LC-MS, NMR, GC-MS and HPAEC were used to analyze the functional groups, glycosidic linkages and chemical structure of LBP, which was a 1-4-linked glucomannan and contained a dodecasaccharide repeating units of →4)-β-D-Manp-(1 → 4)-β-D-Manp-(1 → 4)-β-D-Manp-(1 → 4)-β-D-Glcp-(1 → 4)-β-D-Manp-(1 → 4)-β-D-Manp-(1 → 4)-β-D-Glcp-(1 → 4)-α-D-Glcp-(1 → 4)-β-D-Glcp-(1 → 4)-β-D-Glcp-(1 → 4)-β-D-Manp-(1 → 4)-β-D-Manp-(1 → . In vitro experimental results showed that LBP had noble biocompatibility, and a low dose of 5 μg/mL LBP significantly up-regulated the mRNA expression of TNF-α, iNOS, IL-6, IL-1β and Toll-like receptors family (TLRs) in RAW 264.7 cells. In conclusion, LBP played an important role in immunomodulation, and further studies on the specific immunomodulatory mechanisms of LBP on RAW 264.7 cells are still needed.

Arabinogalactan Alleviates Lipopolysaccharide-Induced Intestinal Epithelial Barrier Damage through Adenosine Monophosphate-Activated Protein Kinase/Silent Information Regulator 1/Nuclear Factor Kappa-B Signaling Pathways in Caco-2 Cells

Intestinal epithelial barrier (IEB) damage is an important aspect in inflammatory bowel disease (IBD). The objective of this study was to explore the protective effects and mechanisms of arabinogalactan (AG) on lipopolysaccharide (LPS)-stimulated IEB dysfunction. The results show that AG (1, 2, and 5 mg/mL) mitigated 100 μg/mL LPS-stimulated IEB dysfunction through increasing transepithelial electrical resistance (TEER), reducing fluorescein isothiocyanate (FITC)-dextran (4 kDa) flux, and up-regulating the protein and mRNA expression of tight junction (TJ) proteins (Claudin-1, Zonula occludens-1 (ZO-1) and Occludin). In addition, AG ameliorated LPS-stimulated IEB dysfunction by reducing interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and IL-1β levels, decreasing the reactive oxygen species (ROS) level, increasing superoxide dismutase (SOD) activity, increasing the glutathione (GSH) level, and decreasing the levels of malondialdehyde (MDA) and intracellular calcium ([Ca2+]i). Furthermore, 2 mg/mL AG up-regulated the expression of silent information regulator 1 (SIRT1), the phosphorylated adenosine monophosphate-activated protein kinase (AMPK), and peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and inhibited the phosphorylation of nuclear factor kappa-B (NF-κB) and the inhibitor of NF-κBα (IκBα). Therefore, AG could maintain IEB integrity by activating AMPK/SIRT1 and inhibiting the NF-κB signaling pathway. In conclusion, AG can regulate the AMPK/SIRT1/NF-κB signaling pathway to reduce inflammation and oxidative stress, thus alleviating LPS-stimulated IEB damage.

Polysaccharides extracted with hot water from wild Prunus spinosa L. berries

Wild blackthorn berries represent an unexplored area in terms of the characterization of the natural biologically active polysaccharide complexes they contain. The antioxidant active fraction extracted from wild blackthorn fruits by hot water extraction (Hw) was subjected to ion-exchange chromatography and yielded six fractions by successive elution with salts. The purified fractions differed in the content of neutral sugars, uronic acids, proteins and phenolics. About 62% of the applied material was recovered from the column, with a higher yield of the fractions eluted with 0.25 M NaCl. Based on the sugar composition of the eluted fractions, several polysaccharide types were observed. The dominant components of Hw are the fractions eluted with 0.25 M NaCl (∼70%), which represent highly esterified homogalacturonan, containing up to 70-80% of galacturonic acids with a low content of rhamnogalacturonan associated with arabinan, galactan or arabinogalactan side chains, but no phenolics. Further, a dark brown polysaccharide material with a yield of ∼17% and with a high content of phenolic compounds, was eluted with alkali (1.0 M NaOH). It mainly represents an acidic arabinogalactan.

Preparation and Characterization of di- and Tricarboxylic Acids-Modified Arabinogalactan Plasticized Composite Films

To ensure the high quality of water, it is necessary to remove toxic pollutants. At present, purification of water is implemented using various sorbents. The efficient sorption materials are modified polysaccharides. In this study, we report on a new environmentally friendly method for modifying larch hemicellulose-arabinogalactan (AG)-with polybasic carboxylic acids (citric, succinic, oxalic, and adipic) to obtain composite materials. The synthesized AG derivatives have been explored by a complex of physicochemical methods, including gel permeation chromatography (GPC), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffractometry (XRD), scanning electron microscopy (SEM), and sorption capacity investigations. It is shown that the heat treatment results in the formation of additional inter- and intramolecular bonds between carboxylic acids and polysaccharide molecules. The formation of ester bonds has been confirmed by the appearance of absorption bands in the IR spectra in the range of 1750-1690 cm^-1. It has been found, using the TGA study, that the most thermally stable (up to 190 °C) sample is arabinogalactan oxalate obtained under heat treatment. The SEM study of the synthesized AG films has shown that the modified samples have the homogeneous film surface ensured by cross-linking. It has been established, when studying the sorption properties of the AG derivatives, that AG succinate (82.52%) obtained by lyophilization has the highest sorption capacity, due to the developed mesoporous surface, which, in turn, makes the synthesized films promising eco-friendly materials for use as drug carriers, sorbents, and water treatment agents.

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.

Structural characterization and immunomodulatory activity of an arabinogalactan from Jasminum sambac (L.) Aiton tea processing waste

An arabinogalactan named JSP-1a was isolated from Jasmine tea processing waste by DEAE Sepharose FF and Sephacryl S-200 HR chromatography. Polysaccharide JSP-1a, with an average molecular weight of 87.5 kDa, was composed of galactose (59.60 %), arabinose (33.89 %), mannose (4.81 %), and rhamnose (1.70 %). JSP-1a was found to be a type II arabinogalactan comprising the main backbone of 1, 6-linked Galp residues, and the side chain containing α-T-Araf, α-1,5-Araf, β-T-Galp, β-1,3-Galp, and β-1,4-Manp residues was attached to the O-3 position of β-1,3,6-Galp residues. Evidence from bioactivity assays indicated that JSP-1a possessed potent immunomodulatory effects on RAW264.7 macrophages: treatment with JSP-1a increased phagocytosis, activated NF-κB p65 translocation, and promoted the production of NO, reactive oxygen species (ROS), the tumor necrosis factor (TNF)-α, and interleukin (IL)-6. Furthermore, inhibition of Toll-like receptor 4 caused the suppression of NO release and cytokines secretion, which indicated that TLR-4/NF-κB pathway might play a significant role in JSP-1a-induced macrophages' immune response. The results of this study could provide a theoretical basis of JSP-1a as a safe immunostimulatory functional foods or a treatment for immunological diseases.

Rheological characterization of the exopolysaccharide produced by Alteromonas macleodii Mo 169

Rheology modifiers are essential additives in numerous products in a variety of industries. Due to environmental awareness, consumer-oriented industries are interested in novel natural rheological agents that can replace synthetic chemicals. In this study, the chemical composition and rheological properties of a novel exopolysaccharide (EPS) produced by Alteromonas macleodii Mo 169 were investigated. It was mainly composed of uronic acids (50 mol%) and total carbohydrates were 17 % sulfated. The EPS viscosity increased with concentration, and a non-Newtonian shear thinning behavior was found for concentrations above 0.1 wt%. The elastic and viscous moduli indicated a weak gel-like structure above 0.4 wt%. It maintained its shear thinning behavior and viscoelastic properties in the presence of NaCl and CaCl₂ for pH range 5-7 and temperatures up to 55 °C. Though the apparent viscosity decreased at pH 3 and 9 and temperatures above 65 °C, the shear thinning behavior was retained. The viscous and viscoelastic properties were recovered after heating (95 °C) and cooling (0 °C), indicating a good thermal stability and recoverability. After high shear force, the solution recovered original rheological properties within few seconds, demonstrating self-healing properties.

Protease-Assisted Mild Extraction of Soluble Fibre and Protein from Fruit By-Products: A Biorefinery Perspective

By-products from the fruit supply chain, especially seeds/kernels, have shown great potential to be valorised, due to their high content of macronutrients, such as lipids, protein, and fibre. A mild enzymatic assisted extraction (EAE) involving the use of a protease was tested to evaluate the feasibility of a cascade approach to fractionate the main fruit by-products components. Protease from Bacillus licheniformis (the enzyme used in the AOAC 991.43 official method for dietary fibre quantification) was used, and besides protein, the conditions of hydrolysis (60 °C, neutral pH, overnight) allowed us to dissolve a portion of soluble fibres, which was then separated from the solubilized peptide fraction through ethanol precipitation. Good protein extraction yields, in the range 35-93%, were obtained. The soluble fibre extraction yield ranged from 1.6% to 71% depending on the by-product, suggesting its applicability only for certain substrates, and it was found to be negatively correlated with the molecular weight of the fibre. The monosaccharide composition of the soluble fibres extracted was also diverse. Galacturonic acid was present in a low amount, indicating that pectin was not efficiently extracted. However, a predominance of arabinose and galactose monomers was detected in many fractions, indicating the isolation of a fruit soluble fibre portion with potential similarity with arabinogalactans and gum arabic, opening up perspectives for technological applications. The residual solid pellet obtained after protease assisted extraction was found to be an excellent fibre-rich substrate, suitable for being subjected to more "hard" processing (e.g., sequential pectin and hemicellulose extraction) with the objective to derive other fractions with potential great added economic value.