Polysaccharide Research Articles

1H-NMR, HPSEC-RID, and HPAEC-PAD Characterization of Polysaccharides Extracted by Hydrodynamic Cavitation from Apple and Pomegranate By-Products for Their Valorization: A Focus on Pectin

Several chemical analytical methods were applied to characterize the chemical structure of polysaccharides extracted from discarded apples and pomegranate peels using hydrodynamic cavitation methods in a circular economy perspective. In particular, the purity of the polysaccharides and the degrees of acetylation and methylation were evaluated by proton Nuclear Magnetic Resonance (1H-NMR) analysis; simple sugars and galacturonic acid were analyzed simultaneously by High-Performance Anion Exchange Chromatography—Pulsed Amperometric Detector (HPAEC-PAD); the molecular weight of the extracted polysaccharides was determined by High-Performance Size Exclusion Chromatography-Refractive Index Detector (HPSEC-RID). The results showed a negligible presence of co-precipitated proteins/tannins, easily removed by dialysis, as well as other co-precipitated molecules such as monosaccharides and organic acids. Polysaccharides from apples consisted mainly of pectic material with a prevalence of homogalacturonans. Polysaccharides from pomegranate peels showed greater compositional variability with significant amounts of arabinose and galactose, a lower content of pectin, and the presence of rhamnogalacturonans I. Both polysaccharides were highly methylated and differed in the degree of acetylation, which could lead to different properties. Polysaccharides from apples presented two main molecular weights (>805 kDa and 348–805 kDa, respectively), while those from pomegranate peel showed a major fraction at 348 kDa and minor fractions < 23 kDa. In conclusion, the research tools proposed by this study have allowed defining the macrostructure of polysaccharides in a quick and efficient way to valorize these food by-products.

Impact of Thermal Processing on the Structure, Antioxidant Properties and Hypoglycemic Activities of Sweet Potato Polysaccharides.

In this study, three kinds of thermal treatments were applied to sweet potatoes: steaming (100 °C, 20 min), frying (150 °C, 10 min), and baking (200 °C, 30 min). We analyzed the changes in the physicochemical structure, antioxidant properties, and hypoglycemic activities of sweet potato polysaccharides between untreated and heat-treated samples. The results showed that the polysaccharides of all sweet potatoes (untreated and heat-treated) were composed of pyranose structures, had low protein content, and shared the same monosaccharide composition. Infrared spectra showed that the three thermal processing treatments had no significant effect on the functional groups or chemical bonding of sweet potato polysaccharides. In addition, all four polysaccharides exhibited dose-dependent antioxidant and hypoglycemic activities. The above experimental results suggest that thermal processing did not affect the physicochemical, antioxidant, or hypoglycemic activities of sweet potato polysaccharides.

Structural characterization of polysaccharides from Panax ginseng C. A. Meyer root and their triggered potential immunoregulatory and radioprotective activities

With people's increasing awareness of healthy diet, the diverse health-promoting functions of ginseng have been widely recognized. As one of the key functional components, ginseng polysaccharides have attracted increasing research interest. Here, three purified polysaccharide fractions, GPS-1a, GPS-1b, and GPS-2, were obtained from the root extract of Panax ginseng C. A. Meyer. Structurally, GPS-1a and GPS-1b were both linked in a → 6)-α-D-Glcp-(1 → pattern but composed of glucose and galactose in molar ratios of 9.76:0.24 and 9.81:0.19. In contrast, GPS-2 was composed of glucose, galactose, arabinose, rhamnose, and galacturonic acid in a molar ratio of 1.82:1.94:0.79:0.52:4.93. The main backbone consisted of →4)-α-D-GalpA-(1→, →4)-α-D-GalpA-6OMe-(1→, →3, 4)-α-D-GalpA-(1→, →3)-α-L-Rhap-(1 → linages, and its branches are composed of →5)-α-L-Araf-(1→, →4)-β-D-Galp-(1→, →2)-β-D-Glcp-(1→, α-D-GalAp-(1→. Benefitting from this structural variance, GPS-2 exhibited the most significant immunoregulatory and radioprotective efficacies. Specifically, GPS-2 promoted TLR2, NF-κB, and TRAF6 protein expression levels, thereby significantly improving macrophage phagocytosis, splenic lymphocyte proliferation, and stimulation of NO, IL-1β, IL-6, and TNF-α secretion, which activated RAW264.7 and splenic lymphocytes. The following radioprotection activity tests unveiled that GPS-2 increased the organ index, number of peripheral blood cells, cellularity of splenocytes, and bone marrow cell numbers in irradiated mice. This investigation revealed the contribution of polysaccharide structure characteristics to the bioactive expression and elucidated the potential utilization of GPS-2 as a radioprotective agent or immunomodulator.

Study on the Structural Features of Eight Dendrobium Polysaccharides and Their Protective Effects on Gastric Mucosa.

This study aimed to analyze the structure of polysaccharides from eight different Dendrobium species and their protective effects on gastric mucosa. Ultraviolet (UV) analysis showed that the contents of eight polysaccharides ranged from 51.89 ± 6.91% to 80.57 ± 11.63%; the degree of acetylation ranged from 0.17 ± 0.03 to 0.48 ± 0.03. High-performance liquid chromatography (HPLC) results showed that these polysaccharides were mainly composed of mannose (Man) and glucose (Glc) with a small amount of galactose (Gal) and arabinose (Ara), and the monosaccharide ratios of different Dendrobium species were different. High-performance size exclusion chromatography-multi angle light scattering-refractive index detector (HPSEC-MALS-RID) showed that the molecular weight (Mw) of all Dendrobium polysaccharides was >1 × 105 Da; D. huoshanense had the lowest molecular weight. Subsequently, an ethanol injured GES-1 cell model was constructed to evaluate the gastric mucosal protective potential of polysaccharides from eight different Dendrobium species. The results showed that the protective effect of the low concentration 50 μg/mL DHP treatment group was similar to that of the control group (p > 0.05), and the cell viability could reach 97.32% of that of the control group. Based on the polysaccharide composition, different kinds of Dendrobium have different degrees of migration and repair effects on GES-1 damaged cells, and the effect of DHP is slightly better than that of other varieties (83.13 ± 1.05%). Additionally, Dendrobium polysaccharides alleviated ethanol-induced oxidative stress and inflammatory response in gastric mucosal cells by enhancing the activity of antioxidant enzymes (superoxide dismutase, glutathione peroxidase, catalase) and reducing the levels of malondialdehyde and reactive oxygen species. Overall, DHP can most effectively protect gastric mucosa. These findings enhance our understanding of the relationship between the structure and biological activity of Dendrobium polysaccharides, providing a foundation for the quality control of Dendrobium. Furthermore, these findings offer theoretical support for the development of Dendrobium polysaccharides as nutraceuticals to treat digestive system diseases.

Various steaming durations alter digestion, absorption, and fermentation by human gut microbiota outcomes of Polygonatum cyrtonema Hua polysaccharides.

Different steaming durations dramatically alter the structure of Polygonatum cyrtonema polysaccharides (PCPs). This study aimed to compare characteristics of digestion, absorption, and fermentation by gut microbiota across four representative PCPs from different steaming durations (0, 4, 8, and 12 h), each with unique molecular weights and monosaccharide profiles. Chemical composition of the four PCPs was analyzed. Digestibility was evaluated using an in vitro saliva-gastrointestinal digestion model. Absorption characteristics were assessed with a Caco-2 monolayer model, and impacts on gut microbiota composition and short chain fatty acid (SCFA) levels were analyzed using in vitro fermentation with human gut microbiota. Longer steaming durations altered the chemical profiles of PCPs, reducing carbohydrate content (84.87-49.58%) and increasing levels of uronic acid (13.99-19.61%), protein (1.07-5.43%), and polyphenols (0.05-2.75%). Four PCPs were unaffected by saliva digestion but showed enhanced gastrointestinal digestibility, with reducing sugar content rising from 4.06% (P0) to 38.5% (P12). The four PCPs showed varying absorption characteristics, with P0 having the highest permeability coefficient value of 9.59 × 10-8 cm/s. However, all PCPs exhibited poor permeability, favoring gut microbiota fermentation. The four PCPs altered gut microbiota composition and elevated SCFA production, but levels declined progressively with longer steaming durations. All PCPs significantly increased the abundance of Bacteroidota, Firmicutes, and Actinobacteriota, making them the dominant bacterial phyla. Additionally, all PCPs significantly increased the abundance of Bifidobacterium, Prevotella, and Faecalibacterium compared to the control group, which, along with Bacteroides, became the dominant microbiota. Increasing the steaming duration led to a reduction in Prevotella levels, with PCPs from raw rhizomes showing the highest relative abundance at 24.90%. PCPs from moderately steamed rhizomes (4 h) led to a significant rise in Faecalibacterium (7.73%) among four PCPs. P8 and P12, derived from extensively steamed rhizomes (≥8 h), exhibited similar gut microbiota compositions, with significantly higher relative abundances of Bacteroides (20.23-20.30%) and Bifidobacterium (21.05-21.51%) compared to P0 and P4. This research highlights the importance of adjusting steaming durations to maximize the probiotic potential of P. cyrtonema polysaccharides, enhancing their effectiveness in modulating gut microbiota and SCFA levels.

Integrated Valorization of Fucus spiralis Alga: Polysaccharides and Bioactives for Edible Films and Residues as Biostimulants.

Fucus spp. seaweeds thrive in the cold temperate waters of the northern hemisphere, specifically in the littoral and sublittoral regions along rocky shorelines. Moreover, they are known to be a rich source of bioactive compounds. This study explored the valorization of Fucus spiralis through the extraction of bioactives and polysaccharides (PSs) for food applications and biostimulant use. The bioactives were extracted using microwave hydrodiffusion and gravity (MHG), where the condition of 300 W for 20 min resulted in the highest total phenolic content and antioxidant activity of the extract. Cellular assays confirmed that the extract, at 0.5 mg/mL, was non-cytotoxic to HaCat cells. Polysaccharides (PSs) were extracted from the remaining biomass. The residue from this second extraction contained 1.5% protein and 13.35% carbohydrates. Additionally, the free amino acids and minerals profiles of both solid residues were determined. An edible film was formulated using alginate (2%), PS-rich Fucus spiralis extract (0.5%), and F. spiralis bioactive-rich extract (0.25%). The film demonstrated significant antioxidant properties, with ABTS and DPPH values of 221.460 ± 10.389 and 186.889 ± 36.062 µM TE/mg film, respectively. It also exhibited notable physical characteristics, including high water vapor permeability (11.15 ± 1.55 g.mm.m-2.day-1.kPa-1) and 100% water solubility. The residues from both extractions of Fucus spiralis exhibited biostimulant (BS) effects on seed germination and seedling growth. BSs with PSs enhanced pea germination by 48%, while BSs without PSs increased the root dry weight of rice and tomato by 53% and up to 176%, respectively, as well as the shoot dry weight by up to 38% and up to 74%, respectively. These findings underscore the potential of Fucus spiralis within the framework of a circular economy, wherein both extracted bioactives and post-extraction by-products can be used for sustainable agriculture and food applications.

The anti-angiogenic, anti-inflammatory and anticoagulant potential of a polysaccharide extracted from the brown alga Cystoseira humilis

The present study aimed to evaluate the properties of a sulfated polysaccharide (PSCH) extracted from the brown alga Cystoseira humilis. We analyzed the chemical composition, anti-angiogenesis activities, anticoagulant, and anti-inflammatory effects of the PSCH, using various techniques encompassing UV–visible spectroscopy, fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (X-RD), scanning electron microscopy (SEM), steric exclusion chromatography (SEC) and high-performance liquid chromatography coupled to refractive index detector (HPLC-RID). The study found that PSCH was a sulfated heteropolysaccharide consisting of glucuronic acid, arabinose, galacturonic acid, xylose and fructose, and has a semi-crystalline nature with a molecular weight of about 379.44 kDa. The PSCH contains 41.77 % carbohydrates, 12.33 % proteins, and 4.59 % sulfates. The PSCH fraction has anti-angiogenic potential highlighted through assays on the chorioallantoic membrane, where vascular branching was inhibited by about 41.65 % and 61.38 % at concentrations of 50 and 100 μg/egg, respectively, compared to the untreated group. PSCH displayed an anti-edematous effect in vivo by reducing malondialdehyde and advanced oxidation protein products in paw tissue after five hours of carrageenan injection. When rats were co-treated with PSCH, there was evidence of a significant increase in antioxidant enzyme activity (superoxide dismutase, glutathione peroxidase, and glutathione) in edematous paw tissues compared to untreated rats. Furthermore, PSCH significantly influenced hematological parameters and the rate of anti-inflammatory serum protein fractions compared to the inflamed group. Interestingly, PSCH may exhibit anticoagulant properties by extending activated partial thrombosis time, thrombin time and prothrombin time. The present study has shown that Cystoseira humilis polysaccharides have antioxidant, anti-angiogenic, anti-inflammatory, and anti-coagulant properties, making them suitable for therapeutic purposes.

PP1 phosphatase controls both daughter cell formation and amylopectin levels in Toxoplasma gondii.

Virulence of apicomplexan parasites is based on their ability to divide rapidly to produce significant biomass. The regulation of their cell cycle is therefore key to their pathogenesis. Phosphorylation is a crucial posttranslational modification that regulates many aspects of the eukaryotic cell cycle. The phosphatase PP1 is known to play a major role in the phosphorylation balance in eukaryotes. We explored the role of TgPP1 during the cell cycle of the tachyzoite form of the apicomplexan parasite Toxoplasma gondii. Using a conditional mutant strain, we show that TgPP1 regulates many aspects of the cell cycle including the proper assembly of the daughter cells' inner membrane complex (IMC), the segregation of organelles, and nuclear division. Unexpectedly, depletion of TgPP1 also results in the accumulation of amylopectin, a storage polysaccharide that is usually found in the latent bradyzoite form of the parasite. Using transcriptomics and phospho-proteomics, we show that TgPP1 mainly acts through posttranslational mechanisms by dephosphorylating target proteins including IMC proteins. TgPP1 also dephosphorylates a protein bearing a starch-binding domain. Mutagenesis analysis reveals that the targeted phospho-sites are linked to the ability of the parasite to regulate amylopectin steady-state levels. Therefore, we show that TgPP1 has pleiotropic roles during the tachyzoite cell cycle regulation, but also regulates amylopectin accumulation.

An arabinan from Citrus grandis fruits alleviates ischemia/reperfusion-induced myocardial cell apoptosis via the Nrf2/Keap1 and IRE1/GRP78 signaling pathways

Citrus grandis fruit is a famous traditional Chinese medicine with various bioactivities, including cardioprotective effects. Polysaccharides are one of the key active ingredients responsible for its cardioprotective effects. This study aimed to investigate the structure and cardioprotective effect of a homogeneous polysaccharide from C. grandis fruit (CGP80-1) and explore its mechanism against myocardial ischemia-reperfusion (MI/R) injury. Structure analysis showed that CGP80-1 (11,917 Da) is an arabinan with compact coil chain conformation, containing →5)-α-L-Araf-(1→, →3,5)-α-L-Araf-(1→, and →2,3,5)-α-L-Araf-(1→ as the backbone, as well as →5)-α-L-Araf-(1→ and t-α-L-Araf as side-chains substituted at the C2 and C3 positions. Pharmacological experiments showed that pre-treatment with CGP80-1 could effectively alleviate MI/R injury by improving endogenous antioxidant enzymes and cardiac enzymes, reducing reactive oxygen species levels, and regulating apoptosis-related proteins such as caspase-3, Bax, and Bcl-2. The protective effects were correlated with the Nrf2/Keap1 and IRE1/GRP78 signaling pathways. Further analysis of structure-activity relationships revealed that the myocardial protection effects of CGP80-1 might be attributed to its appropriate molecular weight, high arabinose content, and unique compact coil chain conformation. Overall, our results provide insight into the chemical structure of CGP80-1 and its mechanism of action, suggesting that CGP80-1 could be a candidate drug for myocardial protection.

Structure and anticoagulant activity of a galactoarabinan sulfate polysaccharide and its oligosaccharide from the green algae, Codium fragile

A polysaccharide, CZS-0-1, was obtained from the marine green algae Codium fragile using ion-exchange and size-exclusion chromatography. Composition and characteristics analyses showed CZS-0-1 was a sulfated galactoarabinan consisting of arabinose, galactose and a small amount of glucose in a ratio of 9:2:1 with 21% sulfate content and a molecular weight of 810 kDa. Structural properties were determined using desulfation and methylation analyses combined with instrument analysis. The results showed that the backbone of CZS-0-1 was (1 → 3)-β-L-Arap. Its O-4 and/or O-2 positions showed sulfate modification; additionally, it had 10% of (1 → 3)-β-D-Galp branches at the O-4 position of the (1 → 3)-β-L-Arap. The galactose side chains also had sulfate modification at the O-4 or O-6 position. The structure of CZS-0-1 was further confirmed by Top-down analysis of the oligosaccharides after oxidated hydrolysis by mass spectrometry. CZS-0-1 exhibited significant heparin-like anticoagulant activity. It exerted anticoagulant effects by inhibiting FIIa and FXa activities with the presence of heparin cofactors. The anticoagulant activity of CSZ-0-1 was closely related to the molecular weight, and the reduction of molecular weight may lead to a significant decrease in the anticoagulant activity. This study demonstrated that the green algae, Codium fragile can be considered as a useful resource for bioactive polysaccharides.

Schizophyllum commune fruiting body polysaccharides inhibit glioma by mediating ARHI regulation of PI3K/AKT signalling pathway

Glioma poses a serious threat to human health and has a high mortality rate. Therefore, developing natural anti-tumour drugs for cancer treatment is an urgent priority. Schizophyllum commune is an edible and medicinal fungus, with polysaccharides as its main active components, which may have anti-tumour properties. Herein, we characterised S. commune fruiting body polysaccharides (SCFP) structure and evaluated its anti-glioma activity in vitro and in vivo. UV and FTIR spectra, high-performance gel chromatography, and monosaccharide composition analyses demonstrated that SCFP was a heteropolysaccharide with a molecular weight of 290.92 kDa. Among the monosaccharide compositions, mannose, galactose, and glucose were the most abundant. SCFP significantly inhibited the survival of the glioma cell lines U251 and U-87MG. U251 xenograft tumours treated with SCFP via gavage showed a 47.39 % inhibition, with no significant toxic side effects observed. SCFP upregulated aplasia Ras homologue member I (ARHI) expression, thereby regulating PI3K/AKT signalling, inhibiting tumour migration, and inducing apoptosis, to inhibit tumour growth. Furthermore, SCFP treatment increased the relative abundance of beneficial bacteria, including Akkermansia muciniphila, Ligilactobacillus murinus, and Parabacteroides goldsteinii, in tumour-bearing mice and restored the gut microbiota structure to that of the normal group (NG group) mice without tumours. Thus, SCFP has the potential for application as a natural anticancer drug.

Long-term effect of phenol, quinoline, and pyridine on nitrite accumulation in the nitrification process: performance, microbial community, metagenomics and molecular docking analysis

Phenol, quinoline, and pyridine, commonly found in industrial wastewater, disrupt the nitrification process, leading to nitrite accumulation. This study explores the potential mechanisms through which these biotoxic organic compounds affect nitrite accumulation, using metagenomic and molecular docking analyses. Despite increasing concentrations of these compounds from 40 to 160 mg/L, ammonia nitrogen removal was not hindered, and stable nitrite accumulation rates exceeding 90 % were maintained. Additionally, these compounds inhibited nitrite-oxidizing bacteria (NOB) and enriched ammonia-oxidizing bacteria (AOB) in situ. As the concentration of these compounds rose, protein (PN) and polysaccharide (PS) concentrations also increased, along with a higher PN/PS ratio. Metagenomic analysis further revealed an increase in hao relative abundance, while microbial community analysis showed increased Nitrosomonas abundance, which contributed to nitrite accumulation stability. Molecular docking indicated that these compounds have lower binding energy with hydroxylamine oxidoreductase (HAO) and nitrate reductase (NAR), theoretically supporting the observed sustained nitrite accumulation.

Isolation, purification, and structural elucidation of a water-soluble polysaccharide derived from Phellinus baumii Pilát mycelia

This study involved the successful production of mycelial polysaccharides by optimizing submerged culture conditions of Phellinus baumii Pilát. Then, the investigation focused on the composition and chemical structure of the water-soluble polysaccharide from P. baumii Pilát mycelia (PBMP) by extraction and purification. Specifically, this study indicated that a water-soluble PBMP fraction 1 (PBMP1) was isolated from PBMP. Moreover, this study discovered a PBMP1 isolated from PBMP, which was found to have the monosaccharide compositions comprised of fucose (Fuc), glucose (Glc), and galactose (Gal) despite the absence of proteins. Subsequently, the composition and structure of PBMP1 were characterized using Fourier transform infrared (FT-IR) spectroscopy, periodate oxidation, Smith degradation, methylation reaction, gas chromatography-mass spectrometer (GC-MS), and Nuclear magnetic resonance (NMR). The composition and structure of PBMP1 were characterized in this study, revealing an α-glycosidic bond conformational linkage with 1,4-Glc residues and 1,6-Gal residues forming the backbone. Additionally, a highly branched hetero-polysaccharide was identified with a non-reducing terminus of Fuc containing 1,3,4- and 1,4,6-Glc branching. The findings of this study offer valuable insights and information that can be utilized by researchers, manufacturers, and other stakeholders to advance the field of P. baumii Pilát product development. Moreover, these results have significant implications for future large-scale mass production and functional applications of PBMP1 products.

Effect of cations on aerobic granulation for sidestream treatment

Aerobic granular sludge (AGS) represents an aggregate of sludge formed through the self-immobilization of microorganisms under aerobic conditions. It is currently under scrutiny for its potential as a technology to reduce carbon emissions and promote sustainability. The practicality of AGS stems from its ability to encourage granule formation and enhance structural stability. In this study, a total of five cations (K+, Ca2+, Mg2+, Al3+, Fe3+) were introduced to facilitate stable structuring and the formation of granules for treating high-strength wastewater, such as side-stream treatment. As a result of the experiment, the loosely bound extracellular polymeric substances (LB-EPS) content in the cation-enhanced sludge witnessed a significant increase, leading to elevated total EPS content under all experimental conditions. Furthermore, the protein (PN)/polysaccharide (PS) ratio, a pivotal component of EPS influencing AGS's hydrophobicity and structural stability, exhibited a collective increase, with Mg2+ reaching the highest value of 1.7. The relationship between relative hydrophobicity and the PN/PS ratio was found to strongly impact sludge adhesion, with noteworthy results observed particularly for Mg2+, Al3+, and Fe3+. The viability of attached cells reached 96.8 %, the highest recorded in the case of Mg2+. In the context of treating high-strength wastewater, Mg2+ emerged as the optimal cation for accelerating AGS formation and enhancing structural stability.

Pectin-like heteroxylans in the early-diverging charophyte Klebsormidium fluitans.

The cell walls of charophytic algae both resemble and differ from those of land plants. Cell walls in early-diverging charophytes (e.g. Klebsormidiophyceae) are particularly distinctive, in ways that may enable survival in environments that are incompatible with land-plant polymers. This study therefore investigates the structure of Klebsormidium polysaccharides. The 'pectin' fraction (defined by extractability) of Klebsormidium fluitans, solubilised by various buffers from alcohol-insoluble residues (AIRs), was digested with several treatments that (partially) hydrolyse land-plant cell-wall polysaccharides. Products were analysed by gel-permeation and thin-layer chromatography. The Klebsormidium pectic fraction made up ~30-50% of its AIR, was optimally solubilised at pH 3-4 at 100°C, and contained residues of xylose ≈ galactose > rhamnose > arabinose, fucose, mannose, glucose. Uronic acids were undetectable and the pectic fraction was more readily solubilised by formate than by oxalate, suggesting a lack of chelation. Some land-plant-targeting hydrolases degraded the Klebsormidium pectic fraction: digestion by α-l-arabinanase, endo-β-(1⟶4)-d-xylanase, and α-d-galactosidase suggests the presence of β-(1⟶4)-xylan with terminal α-l-arabinose, α-d-galactose and (unexpectedly) rhamnose. 'Driselase' released oligosaccharides of xylose and rhamnose (~1:1) and graded acid hydrolysis of these oligosaccharides indicated a 'rhamnoxylan' with rhamnose side-chains. Partial acid hydrolysis of Klebsormidium pectic fraction released rhamnose plus numerous oligosaccharides, one of which comprised xylose and galactose (~1:2 Gal/Xyl), suggesting a galactoxylan. Lichenase was ineffective, as were endo-β-(1⟶4)-d-galactanase, endo-β-(1⟶4)-d-mannanase, β-d-xylosidase and β-d-galactosidase. Klebsormidium pectic fraction possesses many land-plant-like linkages but is unusual in lacking uronic acid residues and in containing rhamnoxylan and galactoxylan domains. Uronic acids allow land-plant and late-diverging charophyte pectins to form Ca2+-bridges, facilitating cell-wall polymer association; their absence from Klebsormidium suggests that neutral heteroxylans rely on alternative cross-linking mechanisms. This lack of dependency on Ca2+-bridges may confer Klebsormidium's ability to grow in the acidic, metal-rich environments which it tolerates.

Pleurocinus ostreatus Polysaccharide Alleviates Cyclophosphamide-Induced Immunosuppression through the Gut Microbiome, Metabolome, and JAK/STAT1 Signaling Pathway.

This study investigated the structure of Pleurocinus ostreatus polysaccharide (POP-1) and its effect on immunocompromised mice induced by cyclophosphamide (CY). Novel POP-1 was α- and β-glucopyranose, its molecular weight was 4.78 × 104 Da, it was mainly composed of glucose (88.9%), and it also contained galactose (2.97%), mannose (5.02%), fucose (0.3%), arabinose (0.21%), ribose (0.04%), galactose acid (0.17%), and glucose acid (1.45%). After POP-1 was administered to immunosuppressed mice, results showed that POP-1 increased the body weight, spleen, and thymus index and enhanced T lymphocyte proliferation in mice. POP-1 up-regulated the expression of CD3+, CD4+, and CD8+ lymphocytes and the ratio of CD4+/CD8+ in the mouse spleen to increase immunoglobulin (IgM, IgG, and IgA) and secrete cytokines (IL-2, IL-6, TNF-α, and IFN-γ) through activation of the JAK/STAT1 signaling pathway. Moreover, POP-1 remarkably reversed the gut-microbiota dysbiosis in immunosuppressed mice by increasing the abundance of Muribaculaceae, Lactobacillaceae, Blautia, and Ligilactobacillus and altered the fecal metabolites by increasing hexahomomethionine, DG(8:0/20:4(5Z, 8Z, 11Z, 14Z)-OH(20)/0:0, 2-((3-aminopyridin-2-yl)methylene)hydrazinecarbothioamide, Ginkgoic acid, and carboxy-ethyl-hydroxychroman, which is closely related to the immunity function. This study indicates that P. ostreatus polysaccharide effectively restores immunosuppressive activity and can be a functional ingredient in food and pharmaceutical products.

The dissolution of galactomannans in type II/III deep eutectic solvents: Effect of polysaccharide structure and interaction mechanism

Deep eutectic solvents (DESs) have garnered increasing attention as sustainable solvents for natural polysaccharides. Galactomannans (especially guar and locust bean gums) are abundant natural compounds used in food, medicine, agriculture and daily chemical products, whereas their high molecular weight and randomly distributed non-linear structures remain a huge challenge in solubilization and high value-added utilization. In this study, the dissolution of galactomannans in type II/III DESs was comprehensively investigated using density functional theory (DFT) calculation, experimental results, and molecular dynamics simulation (MD). The results indicated that immense anionic and neutral H-bonds supported by type II DESs (consisting of a quaternary ammonium salt and a metal chloride hydrate) could break and rebuild galactomannan H-bond networks, thereby exhibiting remarkable physical solubilization. A large number of active acid sites in type III DESs (consisting of a quaternary ammonium salt and a hydrogen bond donor) greatly improved solubility and cleaved the glycosidic bond, enabling the recovery of polysaccharides with a target molecular weight. Furthermore, significant correlations between solubility and the structure of galactomannans had been established, which meant that high molecular weight and rich galactose side-chains produced repulsive interactions with DESs, directly hindering dissolution. Overall, this work not only offered a framework for enhancing the dissolution of polysaccharides, but also proposed a promising strategy for development of task specific DESs promoting green chemistry and the use of sustainable bioresources.

Quantitative study on the selective depressing effect of polysaccharides on some polar minerals

This study presents a systematic summary on the depressing effect of polysaccharides on some polar minerals, revealing that the order of their depressing strength on some polar minerals was primarily associated with the surface properties of the minerals, showing a limited correlation with the structure of polysaccharides. Subsequently, the selective depressing mechanism of polysaccharides on polar minerals was quantitatively explained from the perspective of acid–base interaction mechanism, and a criterion system for determining the depressing effect of polysaccharide on minerals was proposed. Specifically, it was found that the hydroxylation reaction of metal sites on mineral surface was a prerequisite for polysaccharide adsorption. Under the above–mentioned conditions, the selective depressing effect of polysaccharides on these minerals with different metal sites could be assessed through a parameter system in which the ion potential φ of surface metal sites served as the primary determinant, and the solubility product constant of metal hydroxides played a secondary role. In cases where minerals shared identical surface metal sites, the selective depressing effect of polysaccharides was analyzed by comparing the coordination numbers of these sites. Specifically, minerals with a higher number of coordinated surface metal sites tend to show a weaker response to depressing effect of polysaccharide. Consequently, this study theoretically elucidated the selective depressing effect of polysaccharides on polar minerals, and the criterion system proposed in this study outperforms the prediction results based on the isoelectric point (pHiep). These research findings have important guiding significance for a deeper understanding of the selective depressing mechanism of polysaccharides and the regulation of flotation.

Resolving Atomic-Level Dynamics and Interactions of High-Molecular-Weight Hyaluronic Acid by Multidimensional Solid-State NMR.

High-molecular-weight (HMW) hyaluronic acid (HA) is a highly abundant natural polysaccharide and a fundamental component of the extracellular matrix (ECM). Its size and concentration regulate tissues' macro- and microenvironments, and its upregulation is a hallmark feature of certain tumors. Yet, the conformational dynamics of HMW-HA and how it engages with the components of the ECM microenvironment remain poorly understood at the molecular level. Probing the molecular structure and dynamics of HMW polysaccharides in a hydrated, physiological-like environment is crucial and also technically challenging. Here, we deploy advanced magic-angle spinning (MAS) solid-state NMR spectroscopy in combination with isotopic enrichment to enable an in-depth study of HMW-HA to address this challenge. This approach resolves multiple coexisting HA conformations and dynamics as a function of environmental conditions. By combining 13C-labeled HA with unlabeled ECM components, we detect by MAS NMR HA-specific changes in global and local conformational dynamics as a consequence of hydration and ECM interactions. These measurements reveal atom-specific variations in the dynamics and structure of the N-acetylglucosamine moiety of HA. We discuss possible implications for interactions that stabilize the structure of HMW-HA and facilitate its recognition by HA-binding proteins. The described methods apply similarly to the studies of the molecular structure and dynamics of HA in tumor contexts and in other biological tissues as well as HMW-HA hydrogels and nanoparticles used for biomedical and/or pharmaceutical applications.

Orientation of Chitin Nanofibers Dispersed in a Thermoplastic Polymer Matrix Through Dry Thermal Stretching

AbstractNanostructures derived from structural polysaccharides, such as cellulose and chitin, are notable for their sustainability, lightweight properties, and superior mechanical attributes. The macroscopic performance of these materials largely depends on the orientation of nanostructures. This study explores the preferential orientation of chitinous nanofibers (NFs) within a thermoplastic polymer matrix (PM) comprising poly(N‐vinylpyrrolidone) and glycerol, achieved through dry thermal stretching techniques. Altering the PM composition enables the modulation of the system's glass transition temperature (Tg). Chitin NFs are effectively dispersed within the PM, with their orientation enhanced by stretching at temperatures ≈30 °C above the Tg of the composites, resulting in an elongation at rupture (ε) of 105%. Under similar temperature conditions, composites with chitosan NFs show strong interactions with the PM, hindering the stretching process (ε = 10%). In contrast, composites with acetylated chitin NFs demonstrate increased stretchability (ε = 170%) but have insufficient interactions to stabilize their orientation. These interactions, identified as hydrogen bonds through FTIR, vary significantly based on the functional groups present on the NF surfaces. This variation is supported by DSC and dynamic mechanical analysis. Oriented ChNFs hold potential for bioactive applications.