Arabinogalactans from Larix principis-rupprechtii: An investigation into the structure-function contribution of side-chain structures

Benzoylethynyl derivatives of arabinogalactan via acylation of its propargyl ethers

To introduce a highly reactive acetylenic ketone function into the polysaccharide structure, arabinogalactan propargyl ethers (AGPg) with degree of substitution 1 were modified via the benzoylation of residual hydroxyl groups followed by cross-coupling of propargyl ether groups with benzoyl chloride. In the first stage, mixed propargyl ethers/benzoic esters of AG (degrees of substitution 1 and 2, respectively) were obtained in a yield of up to 95 % at room temperature in pyridine. In the second stage, the synthesized AG derivatives were involved in a palladium/copper-catalyzed cross-coupling of propargyl groups with benzoyl chloride (60-65 оC, dioxane, Et3N) to afford arabinogalactans bearing benzoate and benzoylpropargyl ether groups in 87-96 % yield (degree of substitution up to 1.0). It was found that in dilute solutions containing a 5-10-fold excess of reagents relative to propargyl groups, the reaction of AGPg with benzoyl chloride prevails over the intermolecular cross-linking, giving organosoluble products with complete conversion of the terminal acetylenes. The addition of piperidine to the activated triple bond showed that the obtained AG derivatives are promising intermediates for design of new pharmacologically oriented polysaccharides. AGPg and the original arabinogalactan were benzoylated for the first time in a two-phase aqueous-organic system (37-60 % KOH aqueous solution/dioxane) to deliver the corresponding organosoluble benzoates in 54-81 % yields and a degree of substitution 1.2-2.8.

Dietary arabinogalactan modulates immunity and improves gut barrier in broilers via regulating metabolome and gut microbiome

The extraction of polysaccharides from wood by-products is recognized as a green re-utilization approach to shape a recycling-oriented society. In this research, we identified the structural properties of arabinogalactan (AG) extracted from Larix sibirica Ledeb wood chips and verified its efficacy as an additive in broiler framing. Results showed that the molecular weight of AG is 19.805 KDa. Methylation analysis and NMR spectra indicate that AG has a 1,6-linked Galp backbone, side residues mainly branched at C-1,3,6 on β-D-Galp. The Ara residues were substituted at C-3 of 1,6-linked Galp consisting of α-L-Araf-(1→3)-α-L-Araf-(1 → 3)-α-L-Araf (1→ and α-L-Araf-(1 → 4) β-D-Galp-(1 → 3)-β-D-Galp-(1→. As a dietary supplement in broiler model, AG treatment improved the body weight of broilers especially breast and leg muscle weight. Furthermore, AG could regulate host immune response, gut microbiota composition, and metabolic activity, especially promoting lipid metabolism. By means of serum non-targeted metabolomics analysis, enrichment of pantothenate and CoA biosynthesis and beta-alanine metabolism pathways could be determined. AG treatment led to a rise in bacteria that produce SCFAs, with elevated concentrations of acetic and butyric acids. In conclusion, AG can be considered as a potential dietary supplement to beneficially affect host's health status.

Prebiotics Beyond the Gut: Omics Insights, Artificial Intelligence, and Clinical Trials in Organ-Specific Applications

Prebiotics, traditionally linked to gut health, are increasingly recognized for their systemic benefits, influencing multiple organ systems through interactions with the gut microbiota. Compounds like inulin, fructooligosaccharides (FOS), and galactooligosaccharides (GOS) enhance short-chain fatty acid (SCFA) production, benefiting neurocognitive health, cardiovascular function, immune modulation, and skin integrity. Advances in biotechnology, including deep eutectic solvents (DES) for extraction and machine learning (ML) for personalized formulations, have expanded prebiotic applications. Integrating these innovations with "omics" technologies enables precise microbial modulation, fostering personalized nutrition and precision therapies. This review examines organ-specific effects of prebiotics, highlights findings from clinical trials, and explores biotechnological innovations that enhance prebiotic efficacy, laying the groundwork for future personalized therapeutic strategies.

Structural characterization of a polysaccharide from Scutellaria baicalensis Georgi and its immune-enhancing properties on RAW264.7 cells

A novel polysaccharide SPS01-2 (87.5 kDa) was isolated from the roots of Scutellaria baicalensis Georgi. Monosaccharide composition revealed that SPS01-2 consists of rhamnose, arabinose, galactose, galacturonic acid, and glucuronic acid in ratio of 4.4: 67.1: 22.2: 6.3: 1.2. Further investigations using methylation, NMR, and mass spectrometry indicated that SPS01-2 is classified as a type II arabinogalactan (AG-II) with a minor presence of type I rhamnogalacturonan (RG-I). The core structure alternates between 1,2/1,2,4-α-L-Rhap and 1,4-α-D-GalpA, with branches including 1,3,6-β-D-Galp, 1,3-β-D-Galp, T-β-D-Galp, and T-α-L-Rhap. The RG-I regions are linked to 1,6-β-D-Galp, and 1,3,6-β-D-Galp units. Numerous arabinan branches, featuring multiple branching points, are attached to the O-3 position of galactose. Additionally, T-β-D-Galp, 1,6-β-D-Galp, and T-β-D-4-OMe-GlcpA are also linked to galactose in the backbone. Furthermore, SPS01-2 demonstrated potential immune-enhancing properties by dose-dependently increasing proliferation, phagocytosis, and the production of nitric oxide and cytokines (TNF-α, IL-6, and IL-1β) in RAW264.7 cells. It also enhanced the expression of CD80, CD86, and MHC-II at concentrations ranging from 5 to 200 μg/mL. Moreover, the immunostimulatory activity of SPS01-2 was significantly reduced when branch linkages were removed through partial acid hydrolysis. Our findings indicate that SPS01-2 could serve as a natural immunostimulant in the food and pharmaceutical sectors.

Identification of an arabinogalactan with special structure from Moringa Oleifera leaf and exploration of its immunomodulatory activity

Arabinogalactan exhibits many biological activities, which is the candidate for functional food ingredients. However, there is limited research on the arabinogalactan from Moringa Oleifera leaf, and its structure needs to be more accurately characterized. This study investigated structural characteristics and immunomodulatory activity of a high-purity polysaccharide from Moringa oleifera leaf (i.e. MOLP-PE) to further explore arabinogalactan from Moringa Oleifera leaf and its potential application area. The results showed that MOLP-PE was a unique type II arabinogalactan: the main chain consisted of → 3, 4)-α-D-Galp-(1→, →3)-β-D-Galp-(1→ and →2, 4)-β-D-Rhap-(1→, with branches at the C-4 position of →3, 4)-α-D-Galp-(1→ and →2, 4)-β-D-Rhap-(1→, consisting of →5)-α-L-Araf-(1→, →3)-α-L-Araf-(1→, →6)-β-D-Galp-(1→ and →4)-β-D-GalpA-(1→. Compared with arabinogalactan from larch, galactan and arabinan, MOLP-PE exhibited stronger ability in stimulating proliferation, phagocytosis and cytokines release of macrophages and bound with Toll-like receptor 4 closer via more binding sites, which might be due to its higher contents of 1,3-linked-Galp and 1,5-linked-Araf. These findings elucidated that MOLP-PE, as type II arabinogalactan with a unique structure, could be exploited as an immunomodulatory food ingredient.

Comparison of structural characteristics and anti-tumor activity of two alkali extracted peach gum arabinogalactan

Two polysaccharides, PGP-90 and PGP-100 (molecular weights of 7.59 × 102 kDa and 10.48 × 102 kDa, respectively), were isolated from Peach gum using alkaline electrolyte water as an extraction solution. Structural characterization showed that PGP-90 and PGP-100 are AG-II arabinogalactans with β-D-(1 → 6)-Galp as the main chain and 1 → 3 Araf and 1 → 5 Araf branched chains at O-3 and O-4 positions. Animal experiments showed that PGP-90 and PGP-100 significantly improved immune function, enhance the proliferative capacity of lymphocytes and phagocytosis of peritoneal macrophages, and regulated the ratio of lymphocyte subpopulations in S180 tumor-bearing mice. Meanwhile, PGP-90 and PGP-100 promoted the secretion of cytokines (TNF-α, IFN-γ, and IL-2) by activated macrophages and blocked apoptosis at the G1 phase, resulting in tumor suppression rates of 40.80 % and 46.30 % (100 mg/kg), respectively, with PGP-100 demonstrating stronger in vivo anti-tumor activity. The above experimental results indicate that Peach gum polysaccharides have the potential to be functional anti-tumor agents.

The prebiotic impacts of galactose side-chain of tamarind xyloglucan oligosaccharides on gut microbiota

To explore the impacts of galactose side-chain on the prebiotic activity of xyloglucan oligosaccharides (XGOS), XGOS and de-galactosylated XGOS (DG-XGOS) were prepared from tamarind using an enzymatic method. The differences in structural features of XGOS and DG-XGOS were systematically analyzed. Their in vitro fermentation characteristics of human fecal microbiota were explored. These results indicated that both XGOS and DG-XGOS promoted short-chain fatty acids (SCFAs) production, decreased pH, and changed the microbiota composition of the fermentation broth. Comparatively, DG-XGOS was more effective than XGOS in producing SCFAs, inhibiting the phylum Proteobacteria prevalence, and promoting the phyla Bacteroidetes and Actinobacteria prevalence. In summary, the xyloglucan degradation products exert potential prebiotic activity. Removing the galactose side-chains further enhances oligosaccharide utilization by fecal microbiota, offering a valuable approach to improve the biological efficacy of oligosaccharides.

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.

Preparation, characterization and cytotoxicity assessment of a novel selenized polysaccharide from Morchella sextelata

Selenylation modification has been widely developed to improve the biological effects of natural polysaccharides. In this study, a purified new polysaccharide (MSP-4) was isolated from Morchella Sextelata, and selenized into SeMSP-4 using the HNO3-Na2SeO3 method. The selenium (Se) content of SeMSP-4 was 101.81 ± 9.90 mg/kg, and the molecular weight of SeMSP-4 was 1.23 × 105 Da. The FT-IR, XRD and AFM results showed that MSP-4 was successfully combined with the Se element. The structure characters of SeMSP-4 were analyzed by methylation analysis combined with 1D and 2D NMR spectroscopy. And, the radical scavenging test revealed that SeMSP-4 exhibited higher antioxidant capacities in vitro than MSP-4. The cytotoxicity analysis indicated that SeMSP-4 could dose-dependently inhibit the proliferation of HepG2 and HeLa cells, but did not show a cytotoxic effect on normal cells (HEK293). Furthermore, SeMSP-4 stimulation significantly increased the macrophage viability and enhanced NO production in macrophage cells. This study suggested that SeMSP-4 could be utilized as a potential selenium source with antioxidant, antitumor, and immunostimulatory activities.

Fine structure and hypoglycemic effect of a galactoglucan from the bulbs of Lanzhou lily

The present research aimed to further identify the fine structure, morphology, and thermal behaviors of a galactoglucan BHP-2 derived from Lanzhou lily bulbs through partial acid hydrolysis, methylation, 2D NMR (1H1H COSY, HSQC, and HMBC), scanning electron microscopy (SEM) and thermogravimetric-differential thermal analysis (TG-DTA). Additionally, the study assessed the potential in vitro hypoglycemic effect of BHP-2 by examining its inhibitory effect on α-glucosidase and α-amylase. The results indicated that the main backbone composition of BHP-2 consisted of →4)-α-D-Glcp-(1→, →3)-β-D-Glcp-(1 → and →6)-β-D-Galp-(1→, while the side chain composition predominantly featured →4)-α-D-Glcp-(1→, →3,5)-α-L-Araf-(1 → and →3)-β-D-Galp-(1→, attached to the C-2 and/or C-3 positions of →4)-α-D-Glcp-(1→. Terminal residues consisted of α-D-Glcp-(1 → and β-L-Araf-(1→. BHP-2 exhibited excellent thermal stability, with a microscopic surface characterized by tightly packed sheets and numerous spiral depressions, which might contribute to its remarkable in vitro hypoglycemic effect. BHP-2 showed competitive inhibition of α-amylase and mixed non-competitive inhibition of α-glucosidase, with respective IC50 values of 0.31 and 0.18 mg/mL, closely resembling to those of acarbose (0.27 and 0.12 mg/mL). These findings suggested that BHP-2 had potential as an additive for glycemic intervention.

Comparative Study on Anti-Inflammatory Effect of Polysaccharides from Vinegar-Baked Radix Bupleuri Using Different Methods

The impact of the extraction method on the physiochemical characteristics and anti-inflammatory effect of polysaccharides from vinegar-baked Radix Bupleuri (VBCPs) was studied. Five extraction methods were employed to obtain the VBCPs: hot water extraction (HW), ultrasound-assisted extraction (UA), enzyme-assisted extraction (EA), citric acid-assisted extraction (CA), and ammonia-assisted extraction (KA). The results showed that the extraction method affects the yield, characteristics, and anti-inflammatory effect of the polysaccharides significantly. KA produced the highest yield, Ara content, and the strongest effect of enhancing IL-10 secretion. VBCP-EA exhibited the largest molecular weight (Mw), the highest Man content, and the poorest effect on inhibiting NO, VBCP-UA possessed more Gal than other VBCPs, the lowest Mw, and a comparable effect on inhibiting NO and TNF-α with VBCP-KA and VBCP-CA. All VBCP self-assembled into nanoparticles in solutions, and VBCP-KA presented the lowest particle size. The structure-activity analysis showed that Mw and Man content are negatively correlated and Ara content is positively correlated with the NO inhibition and IL-10 secretion effects; Rha and Gal A content are positively correlated and Glu is negatively correlated with the TNF-α inhibiting effect. The above results indicated that KA is an efficient method for obtaining anti-inflammatory VBCP, which provides new insight into the extraction of VBCP.

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.

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

This work studies the extraction and purification of a novel arabinogalactan from pistachio external hull. It was extracted with a simple method from pistachio hull which is considered as unexploited waste. Based on the results of sugar analysis by GC-FID, glycosidic linkage by GC-MS, NMR spectroscopy, and molecular weight by Size Exclusion Chromatography, pistachio hull water soluble polysaccharides (PHWSP) were identified as a type II arabinogalactan (AG), with characteristic terminally linked α-Araf, (α1 → 5)-Araf, (α1 → 3,5)-Araf, terminally linked β-Galp, (β1 → 6)-Galp, and (β1 → 3,6)-Galp. DEPT-135, HSQC, HMBC and COSY NMR data suggested the presence of (β1 → 3)-Galp mainly branched at O-6 with (β1 → 6)-Galp chains, α-Araf chains, and terminally linked α-Araf. These AG from pistachio external hulls showed in vitro stimulatory activity for B cells, suggesting their possible use as an immunological stimulant in nutraceutical and biomedical applications.

The immunomodulatory activity of degradation products of Sesbania cannabina galactomannan with different molecular weights

Galactomannan (GM) is widely recognized as an immune enhancer; however, the underlying molecular mechanism is still unknown. Herein, four products with molecular weights in descending order, namely GM40, GM50, GM65, and GMOS, were separated from incomplete degradation products of Sesbania cannabina GM by ethanol precipitation, followed by their immunomodulatory activity. Through FTIR and XPS spectra, the amount of free hydroxyl groups was shown to decrease in the following order: GM > GM50 > GMOS > GM40 > GM65. Moreover, the immunomodulatory activity of different products decreased in abovementioned order. The TNF-α, IL-6 and TLR4 content in RAW 264.7 cells treated with different GM products in the presence or absence of TAK-242 (TLR4 inhibitor) suggested that the immunomodulatory activity of GM and its degradation products is TLR4-dependent. Overall, the preliminary relationship indicated here between the hydroxyl groups or the possible deeper structural changes of GM and the immunomodulatory activity need to be further investigated.

Pd-catalyzed cross-coupling of arabinogalactan propargyl ethers with 5-bromosalicylic acid

New salicylate derivatives of arabinogalactan have been synthesized in up to 90% yield by cross-coupling of propargyl ethers of arabinogalactan with 5-bromosalicylic acid salts. The reaction proceeds in the presence of the catalytic system Pd(PPh₃)₄/PPh₃ with CuBr (CuI), and piperidine or 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) as a base in DMSO at 70-95 °С. The propargyl groups of the starting arabinogalactan ethers are converted into propinylsalicylate ones with 35 and 50% conversion depending on the nature of the base used. Degree of arabinogalactan substitution with propynyl salicylate fragments reaches 1.0 and 0.7 in the reactions with piperidine and DBU, respectively. In the case of piperidine, along with the main process, intensive unprecedented (for Sonogashira reaction) hydroamination of propargyl groups is also observed, followed by hydrolysis of unstable enamines. The products have been characterized by IR, ¹Н and ¹³С NMR, UV spectroscopy as well as elemental analysis and gel permeation chromatography. Salicylate derivatives of arabinogalactan show high activity in prolonging the activated partial thromboplastin time (APTT), whereas neither the arabinogalactan nor propargyl ethers of arabinogalactan nor salicylic acid salts have obvious effects.

Effects of seleno-Sesbania canabina galactomannan on anti-oxidative and immune function of macrophage

Seleno-polysaccharides have become a major topic for research owing to their high anti-oxidative capacity and immune-enhancing activities. In this study, galactomannan (GM) was isolated from Sesbania cannabina, and next modified using HNO₃-Na₂SeO₃ method to obtain six varieties of seleno-galactomannans (SeGMs). FT-IR and GPC results showed the changes in chemical structure of SeGMs, indicating successful combination of selenium and GM. By measuring superoxide dismutase and malondialdehyde, the SeGMs showed a stronger protective effect against H₂O₂-induced oxidative damage in vitro than unmodified GM using macrophage RAW264.7 cell as a model, and the effect of SeGMs-14 was prominent. However, the selenylation modification did not show any obvious effect on the immunomodulatory activity of GM, as determined by the index of tumor necrosis factor-α, interleukin-6, and interleukin-1β. Overall, the prepared SeGMs from galactomannan could potentially serve as a dietary supplement of Se or an organic antioxidant.

Structural characteristics and enhanced biological activities of partially degraded arabinogalactan from larch sawdust

Larch arabinogalactan (AG), extracted from Larix gmelinii sawdust, was depolymerized by H₂O₂ oxidation and purified by gel column to yield a novel degraded fraction (AGD2). The structural analysis indicated AGD2 had lower arabinose content and molecular weight compared with AG, in which the ratio of galactose and arabinose was changed from 7:3 to 16:1, the molecular weight was decreased from 50.2 kDa to 3.7 kDa, and the chain conformation spread from highly branched structure to flexible strand. It was one kind of β-D-(1 → 3)-galactan with fewer β-D-(1 → 6)-Galp side branches at O-6 position. Further, the results of the Gal-3 binding and immunomodulatory assay suggested that the unbinding force of AGD2 onto Gal-3 was as twice as AG to be 76 ± 11 pN at the loading rate of 0.15 μm/s. It could better promote the secretion of pro-inflammatory cytokines (TNF-α, IL-6 and IL-1β) than AG in a dose-dependent manner.

Insight into anti-oxidative carbohydrate polymers from medicinal plants: Structure-activity relationships, mechanism of actions and interactions with bovine serum albumin

Recently, research associated with natural anti-oxidants leads to the chemical characterization of many compounds possessing strong anti-oxidant activity. Among these anti-oxidants, naturally occurring carbohydrate polymers containing pectic arabinogalactans esterified with phenolic acids in monomeric and dimeric forms are noteworthy. The presence of highly branched arabinogalactan type II side chains and sugar linked phenolic acid residues have been resolved as important parameters. The anti-oxidant activity of these compounds depend on their ability to convert free radicals into stable by-products and themselves oxidized to more stable and less reactive resonance stabilized radicals. Moreover, these carbohydrate polymers form water soluble stable complexes with protein. Such findings support their applications in a diversity of fields including food industry and pharmacy. This review highlights experimental evidences supporting that the carbohydrate polymers containing phenolic polysaccharides may become promising drug candidate for the prevention of aging and age related diseases.

Isolation, structural elucidation, and immunoregulation properties of an arabinofuranan from the rinds of Garcinia mangostana

In our search for bioactive polysaccharides as immunomodulatory agents, an arabinofuranan (GMP90-1) was purified and characterized from the rinds of Garcinia mangostana L. GMP90-1 (absolute molecular weight: 5.30 × 10³ g/mol) was found to be composed of arabinose, galactose, and rhamnose. The backbone of GMP90-1 was determined as (1→5)-linked α-l-Araf, (1→2,3,5)-linked α-l-Araf, (1→3,5)-linked α-l-Araf, (1→6)-linked β-d-Galp, and (1→2)-linked α-l-Rhap. Conformational analysis revealed GMP90-1 to exist as a rigid rod structure in sodium chloride solution. To explore its potential as immunomodulatory agents, an in vitro cell screening was performed and GMP90-1 was found to significantly enhance the phagocytic uptake of neutral red and improve the secreted level of nitric oxide (NO), interleukin (IL)-6, IL-1β, and tumor necrosis factor-α (TNF-α) of macrophages. Furthermore, the cellular immunomodulatory activities were confirmed by the in vivo zebrafish experiment, which suggested that GMP90-1 with immunomodulatory effects could be considered as a potential immunomodulatory for immune diseases.