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Background: Natural killer cells play important roles in tumor immune surveillance, and cancer cells must resist this surveillance in order to progress and metastasise. Introduction: The study aimed to explore the mechanism of how breast cancer cells become resistant to the cytotoxicity of NK cells. Methods: We established NK-resistant breast cancer cells by exposing MDA-MB-231 cells and MCF-7 cells to NK92 cells. Profiles of lncRNA were compared between the NK-resistant and parental cell lines. Primary NK cells were isolated by MACS, and the NK attacking effect was tested by non-radioactive cytotoxicity. The change in lncRNAs was analyzed by Gene-chip. The interaction between lncRNA and miRNA was displayed by Luciferase assay. The regulation of the gene was verified by QRT-PCR and WB. The clinical indicators were detected by ISH, IH, and ELISA, respectively. Results: xUCA1 was found to be significantly up-regulated in both NK-resistant cell lines, and we confirmed such up-regulation on its own to be sufficient to render parental cell lines resistant to NK92 cells. We found that UCA1 up-regulated ULBP2 via the transcription factor CREB1, while it up-regulated ADAM17 by “sponging” the miR-26b-5p. ADAM17 facilitated the shedding of soluble ULBP2 from the surface of breast cancer cells, rendering them resistant to killing by NK cells. UCA1, ADAM17, and ULBP2 were found to be expressed at higher levels in bone metastases of breast cancer than in primary tumors. Conclusion: Our data strongly suggest that UCA1 up-regulates ULBP2 expression and shedding, rendering breast cancer cells resistant to killing by NK cells.

Polysaccharides were extracted by hot water and alkali in sequence from Dolichos lablab L. hull, and further purified by ion-exchange and gel columns. Hot water extracted D. lablab hull polysaccharide (DLHP) was rich in glucuronoxylan and pectin, and alkali extracted polysaccharide (DLHAP) mostly embraced glucuronoxylan. The structures of purified glucuronoxylans from DLHP and DLHAP were mainly analyzed by HPAEC-PAD, methylation combined with GC–MS, NMR and SEC-MALLS. DLHP-1 was identified as acetylated glucuronoxylan containing →4)-β-Xylp-(1→ backbone with substitution at O-2 site by α-GlcpA/4-O-methyl-α-GlcpA. The molar ratio of β-Xylp to α-GlcpA was 6.9:1, and acetylation was mainly at O-3 site of β-Xylp with acetylation degree of 21.5%. DLHP-1 and DLHP-2 had similar physicochemical properties, except for molecular weight (Mw). DLHAP-1 was the non-methylated glucuronoxylan almost without acetylation, and it had the molar ratio of β-Xylp to α-GlcpA of 5.6:1. Besides, DLHP-1 (Mw of 20.0 × 103 g mol−1) adopted semi-flexible chain, while DLHAP-1 (Mw of 15.4 × 103 g mol−1) showed flexible chain. These results provided a structural basis for study on polysaccharides from D. lablab hull, which was benefit for understanding biological activities and developing functional food or pharmaceuticals of D. lablab.

Polysaccharides are important constituents in Dolichos lablab hull. Herein, pectin-glucuronoxylan complex from D. lablab hull designated as DLHP-3 (D. lablab hull polysaccharide,) was prepared by ion exchange and gel permeation chromatography, and further characterized by acid degradation and enzymatic hydrolysis, methylation combined with GC-MS, NMR and MALDI-TOF-MS analysis. Both of pectin and glucuronoxylan regions were found in DLHP-3. The glucuronoxylan region consisted of a →4)-β-Xylp-(1→ backbone with branches of α-GlcpA-(1→ substituted at O-2 site, and the ratio of xylose to glucuronic acid was about 5:1. Acetyl groups were mainly attached to O-3 site of →2,4)-β-Xylp-(1→ residues. The main chain of pectin region could be represented by →4)-α-GalpA-(1→4)-α-GalpA-(1→ and →2)-α-Rhap-(1→4)-α-GalpA-(1→ with partial methyl-esterification. The side chains were deduced to embrace arabinan and arabinogalactan linked to rhamnogalacturonan-I region. Pectin was probably covalently bound to glucuronoxylan. Our findings uncovered the molecular structure of pectin-glucuronoxylan complex from D. lablab hull.

Background Glucomannans (GMs) are a group of hydrophilic polysaccharides, which have been produced from different parts of natural plants. Studies on plant-derived GMs contribute to wide applications of GMs or GMs-added products that have desirable quality and health characteristics. Among those popular GMs, konjac glucomannan (KGM) and acemannan are the most famous ones that have been widely reviewed from various points in recent years. However, there is a lack of a comprehensive review to introduce the sources, extraction and purification methods, structural features, and other aspects of GMs from common natural plants such as Aloe, Dendrobium, Bletilla, and so on. Scope and approach This review firstly presents the extraction and purification technologies of GMs from different plant sources, aiming at optimizing more effective production methods with specific treatments for special plant origins. After that, structural features, biological properties, as well as structure-function relationship are summarized. Key findings and conclusions GMs have been widely isolated from different sectors (leaf, stem, and roots) of many plant resources. A general extraction and purification procedure together with several suggestions is put forward to prepare GMs. Although the β-(1 → 4)-linked main chain has been confirmed, detailed structural characteristics of GMs such as side chain and functional group related properties need further studies. Molecular weights, monosaccharide composition, and acetyl group of GMs are key factors that have been identified to affect plentiful biological properties such as immunomodulatory, anti-tumor, anti-diabetic activities. However, the inherent action mechanisms remain unclear. Several research interests in the future are recommended.

Background Food-derived natural polysaccharides are attracting increasing attention in fields of food and healthy product, and the purification of polysaccharide is indispensable for the study. Currently, purification process mostly focuses on crude polysaccharide, while the importance of polysaccharide purification in the processes of raw material and polysaccharide extraction are easily ignored. Scope and approach This review aims to develop an understanding and practical suggestions on polysaccharide purification. Numerous methods on polysaccharide purification were summarized, and their advantages and disadvantages have been discussed. Finally, current challenges and perspectives on polysaccharide purification were pointed out. Key findings and conclusions Polysaccharide purification should be emphasized and performed based on three consecutive and progressive stages: polysaccharide in raw material, polysaccharide in crude extract and the crude polysaccharide. Besides, the purification of crude polysaccharide comprises the enrichment of polysaccharide and isolation of fractions having different structural or conformational characteristics. However, how to prepare polysaccharide with high purity in large scale and simultaneously preserving its native structure and bioactivity, remains a demanding and important task for future work.

Polysaccharide derived from natural products has a wide range of sources and mild properties, and exhibit various bioactivities. Ascorbic acid is one of the most important nutrients in fruits and vegetables, as well as their products. Ascorbic acid and polysaccharide coexist in many systems during food production and processing. Many studies have found that ascorbic acid at low concentrations degrades polysaccharide derived from natural products via hydroxyl radical. In this paper, the research progress on ascorbic acid induced polysaccharide degradation is summarized from four aspects: mechanism of action, analytical methods, influencing factors and bioactivity of degradation products. It is expected to provide a theoretical basis for further research.

This study was to assess the anti-inflammatory potential of exopolysaccharide (EPS) produced by a medicinal fungus Cordyceps sinensis Cs-HK1. The EPS was isolated from the Cs-HK1 mycelial fermentation broth by ethanol precipitation and purified by deproteinization and dialysis. The EPS had a total sugar content of 74.8% and a maximum average molecular weight (MW) over 107 Da, and consisted mainly of glucose and mannose, and a small amount of galactose and ribose. In THP-1 and RAW264.7 cell cultures, EPS significantly inhibited lipopolysaccharide (LPS)-induced inflammatory responses of the cells including the release of NF-κB and several pro-inflammatory factors such as NO, TNF-α and IL-1β. In the murine model of LPS-induced acute intestinal injury, the oral administration of EPS to the animals effectively suppressed the expression of major inflammatory cytokines TNF-α, IL-1β, IL-10 and iNOS and alleviated the intestinal injury. The results suggest that the Cs-HK1 EPS has notable anti-inflammatory activity and can be a potential candidate for further development of new anti-septic therapeutics. To the best of our knowledge, this is the first report on the anti-inflammation of an EPS from C. sinensis fungal fermentation.

This study aimed at investigating gastroprotective activity of Hericium erinaceus polysaccharide (HEP) and characterizing one of its bioactive fractions. Acetic acid-induced gastric ulcer (GU) rat model was used to evaluate the gastroprotective activity of HEP, while H

Probiotic-fermented carrot juice (PFCJ) is a functional food, for which colloidal stability during storage is essential. The water-soluble polysaccharides (WSPs) it contains provide this stability as colloidal stabilizers; they are pectinic, mainly containing galacturonic acid, galactose and arabinose as monosaccharide units. The particle-size distribution, ζ potential, centrifugal sediment ratio, soluble solids content, total acid and structural features of these WSPs were evaluated as functions of storage time. The PFCJ displayed pseudoplastic fluid behavior. Molecular weight and solid morphology of WSPs did not change significantly with storage, although the molecular weights of WSPs showed a slight decrease. The storage stability is ascribed to its WSPs acting as electrosteric stabilizers (which are very robust colloidal stabilizers) by adsorbing onto the insoluble plant cell wall polysaccharides which comprise the dispersed phase in the suspension. Viscosity and particle size remained relatively stable when stored at 4 °C and 25 °C, while centrifugal sediment ratio, soluble solids content and total acid all increased significantly; these can also be explained in terms of the structure of the WSPs. This can provide guidance to choosing ingredients which improve storage stability and other properties of importance to consumers by using the precepts of electrosteric colloidal stabilization: e.g. the presence of water-soluble polysaccharides with long hydrophilic moieties.

Plants in Amorphophallus genus are rich in soluble dietary fibres and have long been used as food and traditional medicine in Asian countries. In the present investigation, natural O-acetyl-glucomannans were extracted from tubers of Amorphophallus rivirei (konjac), A. albus and two local types of A. bulbifer (wild type M and wild type B), which were designated as KGM, AGM, MGM, and BGM, successively. Comparative studies were conducted on their physicochemical properties and primary structures. The four AcGMs had about 90% (w/w) neutral sugar, 11% (w/w) moisture, and 1%–2% (w/w) ash. Relatively high contents of acetyl groups (17%–24%, w/w) were detected. Mannose and glucose as the main components existed in molar ratios of 1.41, 1.41, 1.21, and 1.58 for KGM, AGM, MGM, and BGM, respectively. Relative molecular weights of AcGMs increased in the order of: KGM

Aloe barbadensis Miller (Aloe vera) has long been used in food, cosmetic and pharmaceutical industries. The solid wastes such as the spikes and the outer green skins are usually separated from the inner gel and discarded during the process of Aloe vera leaves. Three kinds of polysaccharides (designated as ASP-4N, ASP-6N and ASP-8N) were successfully purified from the leaf skin of Aloe vera in our previous work. The present study aimed to analyze the structural and molecular features of ASP-6N and ASP-8N using methylation and GC-MS, NMR, high performance size-exclusion chromatography coupled with multi-angle laser light scattering (HPSEC-MALLS) and scanning electron microscopy (SEM) techniques. Results showed that ASP-6N and ASP-8N were β-(1→4)-glucomannans with acetyl groups, which may attach to O-2, O-3 or O-6 of mannopyranosyl residues in the backbone as mono-, di-, or tri-acetylated forms. HPSEC-MALLS analysis indicated that the polysaccharide fractions from Aloe leaf skin adopted various conformations in the aqueous solution depending on their molecular mass. The polysaccharides had fibrous, ribbon-like and spherical morphology by SEM observation.

High intake of dietary fibers was found to be inversely associated with type-2 diabetes (T2D), whereas the difference among different dietary fibers on T2D remains unclear. Therefore, we have investigated the effects of different dietary fibers on T2D. Nine types of dietary fibers were used to investigate and evaluate their effects on type-2 diabetic rats via physiology, genomics, and metabolomics. We found that supplementation with β-glucan, arabinogalactan, guar gum, apple pectin, glucomannan, and arabinoxylan significantly reduced the fasting blood glucose, whereas carrageenan, xylan, and xanthan gum did not affect glycemic control in diabetic rats. Also, bioactive dietary fibers (β-glucan, arabinogalactan, guar gum, and apple pectin) associated with the increased butyric acid level and abundance of beneficial bacteria (Lachnobacterium, Parabacteroides, Faecalibacterium, Akkermansia, and some butyric acid-producing bacteria), as well as improved host metabolism by decreasing 12α-hydroxylated bile acids, acylcarnitines, and amino acids (leucine, phenylalanine, citrulline, etc.), thereby exert beneficial effects on T2D. It was also found that β-glucan might attenuate insulin resistance via downregulation of Prevotella copri-mediated biosynthesis of branched-chain amino acids in T2D. Together, our study uncovered the effects of different dietary fibers on T2D, along with their potential mechanism.

Macrolepiota albuminosa (Berk.) Pegler is abundant in active polysaccharides, but little is known about their structures and solution properties. In this study, water-extracted polysaccharides from M. albuminosa (MAWP) were purified into three fractions with structural heterogeneity, which was attributed to the diversity in molecular weight, monosaccharide composition and linkage patterns, further affecting their solution properties. Methylation and NMR analysis revealed MAWP-60p and MAWP-70 were a 3-O-methylated glucomannogalactan and a previously unreported glucomannogalactan, whereas MAWP-80 was elucidated as a branched galactoglucan. Besides, three fractions exhibited random coil conformation in aqueous solution, while MAWP-60p had the highest viscosity due to its highest molecular weight, mean square radius of gyration (Rg) and O-methyl group attached to the backbone. The molecular weight, monosaccharide composition and glycosidic linkages might be the major contributors to the flexibility, molecular size and stereochemistry of mushroom polysaccharide chains.

Three water-soluble pectic polysaccharides (WKBP-P2, P3 and P4) were isolated from white kidney bean by ion exchange combined with size-exclusion methods. The structural features were characterized by GC–MS, NMR spectroscopy and HPSEC-MALLS-RI. It was found that three pectic polysaccharides were the major water-extracted polysaccharides in white kidney bean. All the WKBP-P2, P3 and P4 were probably composed of various structural regions including homogalacturonan (HG), xylogalacturonan (XGA), rhamnogalacturonan I (RG-I) regions in backbone, and arabinan region mainly as side chain. However, these pectic polysaccharides were significantly different in molar ratios of these structural regions and molecular size. WKBP-P2 was HG-predominant pectin (partially methyl-esterified) with weight-average molecular weight (Mw) of 1.2 × 104 g/mol, and contained minor RG-I, arabinan and probable XGA regions. WKBP-P3 (Mw of 4.0 × 104 g/mol) primarily embraced XGA, HG, arabinan regions and minor RG-I region. WKBP-4 with highest Mw (4.5 × 105 g/mol) had the most arabinan region (51.3%), which was probably the side chain linked to the backbone composed of RG-I, HG and slight XGA regions. These findings provided a structural basis for study on polysaccharides from white kidney bean, which was benefit for development of functional food.

Type 2 diabetes (T2D) is a worldwide epidemic associated with metabolic disorders and intestinal microbiota alterations. Polysaccharides have been considered to be beneficial to the prevention and alleviation of T2D. In the present study, ultra-performance liquid chromatography-triple-time-of-flight-based metabolomics and proteomics and 16S rRNA sequencing methods were employed to evaluate the effects of glucomannans from Dendrobium officinale stem, konjac, and Aloe vera leaves on host metabolism and intestinal microbiota regulation in type 2 diabetic rats and potential mechanisms. The metabolism of amino acids was significantly disturbed in the type 2 diabetic rats, especially the upregulated branched-chain amino acid (BCAA) metabolism. Host-derived BCAA metabolism was significantly decreased in type 2 diabetic rats. However, the levels of BCAAs in host circulation and gene abundance of BCAA biosynthesis in gut microbiota were significantly increased in diabetic rats, which suggested that the disturbed intestinal microbiota might be responsible for the increased circulation of BCAAs in T2D. Glucomannan treatment decreased the abundance of microbial BCAA biosynthesis-related genes and ameliorated the host BCAA metabolism. Also, glucomannan with a higher molecular weight and a lower ratio of mannose/glucose possessed better antidiabetic effects. In summary, the antidiabetic effects of glucomannans might be associated with the amelioration of BCAA metabolism by modulating intestinal microbiota.

Glucomannans (GMs) from abundant natural resources have excellent processing properties and plentiful bioactivities. In current study, functional properties of GMs with different structural characteristics, including KGM from konjac, DOP from dendrobium, AGP40, ASP-4N, ASP-6N, & ASP-8N from aloe were determined. Results suggested that molecular weights (Mw) of GMs were positively correlated with their water absorption capacity, fat absorption capacity, and viscosity, while ratio of mannose/glucose showed negative effect. Higher degree of acetylation (DA) mainly corresponded to higher values of solubility and ζ-potential. Then, effects of the six GMs on general health status, serum biochemicals, and intestinal SCFAs production in mice were evaluated in vivo. Analysis of general health status and levels of serum biochemicals revealed that mice with consecutive supplementation of GMs for 14 days performed normally compared with those in control group. Interestingly, the productions of SCFAs (mainly acetate and butyrate) in the cecal and colonic contents were significantly promoted. Generally, higher concentrations of SCFAs were produced when mice were treated with GMs having higher Mw, ratio of glucose, and DA. The current investigation suggested that both functional and intestinal fermentation property of GMs were jointly determined by the monosaccharide composition, molecular weight, and degree of acetylation.

Osteosarcoma (OS) has high heterogeneity and poor prognosis. In order to explore the molecular mechanism of OS and the tumor micro-environment (TME) on OS, we employed single-cell RNA-sequencing (scRNA-seq) on 110,745 individual cells from OS primary lesion, recurrent focal and metastatic tissues. We identified 5 main malignant subpopulations of OS cells, 3 clusters of osteoclast(OC) and 2 types of cancer-associated fibroblasts (CAFs). Further we found that the progenitor OC and, antigen presenting CAF (apCAF) were lower in lung metastatic and recurrent tumor tissues than in primary tumor tissue. M2-like macrophages were predominant in the TME myeloid cells. Inactivation state of tumor-infiltrating T cells, mainly the CD4-/CD8-T and Treg cells, existed in lung metastatic tissues. T-cell immunoreceptor with Ig and ITIM domains (TIGIT) expressed in 11 samples. We then blocked TIGIT which significantly enhancd the cytotoxic effects of primary T cells on OS cell lines. Our report represents the first use of scRNA-seq for the transcriptomic profiling of OS cells. Thus, the findings in this study will serve as a valuable resource for deciphering the intra-tumoral heterogeneity in OS and provide potential therapeutic strategies for OS in clinic.

A homogeneous galactoglucan was purified from the alkali-extracted polysaccharides from the basidioma of Macrolepiota albuminosa by gradient ethanol precipitation, whose proposed structure was given for the first time. Results showed it had a molecular weight of 210 kDa, and mainly consisted of glucose and galactose. There were abundant filaments, randomly distributed sheet-like and flaky appearance in its surface by SEM observation. Its backbone comprised β-(1 → 6)-Glcp, α-(1 → 6)-Galp and β-(1 → 3,6)-Glcp residues at 4:1:1, terminated by β-(1 → 3)-Glcp and T-Glcp residues. Rheological measurements suggested its steady flow behavior was highly dependent on concentrations. Newtonian behavior was evident at low concentrations, whereas pseudoplastic behavior was observed at high concentrations. Besides, the X-ray diffraction patterns proved the presence of amorphous structure. The conformational parameters were detected by HPSEC-MALLS-RI, revealing a random coil conformation in NaNO3 aqueous solution. This work provides a theoretical basis for the application of polysaccharides from M. albuminosa in food- and drug-based therapies.

Aloe barbadensis Miller (Aloe vera) is a kind of popular medicinal and horticultural crops widely cultivated around the world. Polysaccharides with different structural features and bioactivities have been isolated from the pulp of Aloe vera. In the current study, a novel polysaccharide fraction (AGP40) isolated and purified from gel juice of Aloe vera was subjected to structural and conformational analysis. AGP40 had a backbone consisting of major →4)-β-Manp-(1 → residues and minor →3)-β-Manp-(1 → and →4)-β-Glcp-(1 → residues. Low degree of branches distributed at O-6 of 4-linked mannose in the main chain. The acetyl groups in AGP40 presented as mono- or di-substituents (O-2, O-3, O-6, O-2,3, O-2,6 and O-3,6). AGP40 performed as random coil conformation in 0.1 M NaNO3 solution, and had fibrous filaments and irregular spherical structures in solid state. Detailed structural and conformational analysis of AGP40 in the present study may greatly improve the bioactive function investigation and mechanism explanation of acetyl glucomannans in the future.

Hericium erinaceus (H. erinaceus), an edible mushroom with medicinal value, has a long history of usage in China and other oriental countries. Polysaccharide is supposed to be one of the major bioactive compounds in H. erinaceus, which possesses immunomodulating, anti-cancer, antioxidant, gastroprotection and intestinal health promotion, neuroprotective, hepatoprotective, antihpyerglycemic and hypolipidemic activities. In this review, the current advancements on extraction, purification, structural characteristics and biological activities of polysaccharide from different sources (fruiting body, mycelium and culture broth) of H. erinaceus were summarized. Among these aspects, summaries of the structural characteristics focused on the purified polysaccharides. Meanwhile, comparisons on the structural characteristics among the purified polysaccharides obtained from above three sources were made. Moreover, their biological activities were introduced on the basis of in vivo and in vitro experiments, and some possible action mechanisms were listed. Furthermore, the structure-activity relationship of the polysaccharide was discussed. New perspectives for the future work of Hericium erinaceus polysaccharide were also proposed. HIGHLIGHTS Extraction, purification, structural characteristics and biological activities of Hericium erinaceus polysaccharide (HEP) were summarized. Structural characteristics of the purified polysaccharides from different sources (fruiting body, mycelium and culture broth) of Hericium erinaceus were summarized and compared. Structure-activity relationship of HEP was discussed, and new perspectives for the future work of this polysaccharide were proposed.

Dictyophora indusiata and many other Dictyophora mushrooms distribute widely around the world. They have long been used as edible mushroom in China. Owing to the outstanding healthy benefits, various bioactive substances from Dictyophora indusiata , including polysaccharide, amino acid, vitamin and protein, have been studied in recent years. Polysaccharide is one of the most important substances reported through out years. This review outlines recent progress on the extraction, purification, structural features and biological activities of polysaccharide from Dictyophora indusiata .

The fine structure and conformational properties of neutral polysaccharide isolated from the whole seeds of Cassia obtusifolia (CP-30) were systematically investigated for the first time, by 1D and 2D NMR, size exclusion chromatography coupled with multiple detectors (SEC-MALS), dynamic light scattering (DLS), and static light scattering (SLS). The structure of CP-30 was elucidated to be a galactomannan, consisting of 1,4-linked-Manp backbone with side chains (T-Galp) attached to O-6 of 1,4-linked-Manp. DLS and SLS results showed that 0.6 M NaNO3 was a good solvent for CP-30. The structure sensitive parameter ρ (1.33–1.80), the Mark-Houwink exponent α (0.59), and the conformational parameter ν (0.51 from z vs Mw, and 0.52 from Rh vs Mw) suggested a random coil conformation of CP-30 in solution. The molar mass per unit of contour length (356.6 nm−1), persistent length (5.3 nm), and characteristic ratio (24.0) obtained by the wormlike cylinder model further indicated a dense random coil conformation of CP-30. By scanning electron microscopy, the linear chain shape of CP-30 in water was observed. The present research provided systematic information on structural and conformational properties of CP-30, which was important for elucidating the physicochemical characteristics of cassia polysaccharide and meaningful for its further application in food and medicinal industry.

Enzymatic hydrolysis was proposed for the first time to purify the sub-fraction of water-extracted cassia polysaccharide (CP-40), and a homogeneous polysaccharide CP-40-M was obtained with relatively high yield. The structural features of CP-40-M were characterized using size-exclusion chromatography equipped with multiple detectors (SEC-MALLS), high-performance anion-exchange chromatography (HPAEC), methylation and gas chromatography-mass (GC-MS), as well as nuclear magnetic resonance (NMR) spectra. The weight-average molecular weight for CP-40-M was determined to be 0.29×105Da, and the molar ratio of xylose to glucuronic acid was 4.62. The structure of CP-40-M was elucidated to be glucuronoxylan, with glucopyranosyluronic acid group terminally attached to O-2 of the →4)-β-Xylp-(1→ backbone. It was the first time to obtain this type of xylan from the water extract of Cassia obtusifolia seeds. The structure elucidation of CP-40-M was meaningful for better understanding the natural characteristics of cassia polysaccharide and important for their potential use in food industry and folk medicine.

This study aims at investigating physical–chemical properties of a water-soluble heteropolysaccharide from Plnatago asiatica L. leaves, and its immunomodulatory effects on macrophages RAW264.7 cells. Hot water-extracted crude polysaccharide from the plant leaves (PLLCP) was fractionated into four fractions by DEAE Sepharose Fast Flow eluted with 0.1–0.5 M NaCl solutions. The most abundant fraction (0.3 M NaCl elution), designated PLLP-2, was identified as a heteropolysaccharide with an average molecular weight (Mw) of 3.54 × 104 and composed mainly of Gal (34.4%), GalA (36.5%), Ara (10.1%) and Rha (8.4%). PLLP-2 was an acidic polysaccharide exhibiting inflaky curly aggregation with smooth surface. PLLCP and its main subfraction PLLP-2 displayed immunomodulatory activities by stimulating the production of pro-inflammatory cytokines, including TNF-α and IL-1β in macrophage RAW264.7 cells. These results indicate that the main polysaccharide fraction purified from P. asiatica L. leaves is probably pectin, and have potential immunomodulatory function.

Plantago (Plantaginaceae) is an herbal plant, which is used in folk medicine, functional food, and dietary supplement products. Recent pharmacological and phytochemical studies have shown that polysaccharides isolated from Plantago have multiple medicinal and nutritional benefits, including improve intestinal health, hypoglycemic effect, immunomodulatory effect, etc. These health and pharmacological benefits are of great interest to the public, academia, and biotechnology industries. This paper provides an overview of recent advances in the physicochemical, structural features, and biological effects of Plantago polysaccharides and highlights the similarities and differences of the polysaccharides from different species and in different parts, including leaves, seeds, and husks. The scientific support for its use as a prebiotic is also addressed. The purpose of this review is to provide background as well as useful and up-to-date information for future research and applications of these polysaccharides.

In this study, okra (Abelmoschus esculentus (Linn.) Moench) pods (pericarp) obtained after removing seeds and flesh were applied for polysaccharide extraction. The 60 °C water extract polysaccharide (OPW-60) was obtained from okra peel at 60 °C, and then 100 °C water extract polysaccharide (OPW-100) was obtained from the residue at 100 °C. Acid extraction at 60 °C was finally used to obtain the polysaccharide by acid leaching at 60 °C (OPA-60). Then, structural characteristics and antioxidant activities investigations were performed on the extracted polysaccharides. The results showed that monosaccharide composition of three polysaccharides was different. OPW-60 was mainly type I rhamnogalacturonan (RG-I) pectin, while OPW-100 and OPA-60 consist of RG-I and homogalacturoan (HG) pectins. 1H NMR analysis confirmed the existence of rhamnose and acetyl group among them. The structure diversity resulted in the difference of viscosity, molecular weight, surface morphology and antioxidant activities. OPW-60 exhibited the highest apparent viscosity, which might be attributed to the differences in molecular weight distribution and monosaccharide composition. OPW-60 was most effective in scavenging 2,2-Diphenyl-1-picrylhydrazyl radicals and chelating ferrous ion ability, while OPW-100 exhibited the highest hydroxyl radical scavenging activity. The results showed that polysaccharides with different structure and antioxidant ability could be obtained from okra under different extraction conditions.

Monosaccharide composition analysis is indispensable for the structural characterization and bioactive studies of polysaccharides. Besides, it is also helpful for the quality control of functional polysaccharides. The process is usually carried out by hydrolyzing the polysaccharides into monosaccharides, and then detecting liberated monosaccharides or their derivatives. However, the accuracy is not guaranteed owing to improper experimental methods that result in the incomplete cleavage of glycosidic linkages, the instability of released monosaccharides and the deviation of detection. A main challenge of monosaccharide composition analysis is the lack of generally applicable hydrolysis and detection methods. Therefore, practical suggestions on how to determine monosaccharide composition of polysaccharides should be proposed. In this review, the hydrolysis conditions and detection methods, along with their usability and limitation, are thoroughly compared and summarized. Finally, future perspectives and remaining challenges in this field were outlined. This review will provide guidelines for monosaccharide composition analysis of polysaccharides from natural sources.

The water-extracted polysaccharide from Portulaca oleracea L. mainly consisted of two pectic polysaccharides designated as POWP-H and POWP-L. The POWP-L was rich in linear homogalacturonan with GalA content of 77.6%, while POWP-H might be a rhamnogalacturonan I (RG-I) pectin composed of Rha (15.7%), Ara (31.7%), Gal (42.5%) and GalA (10.1%). The structure of POWP-H was elucidated by partial degradation, methylation analysis combined with GC-MS method and NMR spectroscopy. It had a weight-average molecular weight of 1.2 × 106 g/mol and high degree of branch of 0.57. The presence of abundant arabinogalactan-II and certain galactan side chains in POWP-H was verified by the T-Araf (17.4%), 1,3,6-Galp (11.8%), 1,3-Galp (8.1%), T-Galp (13.4%) and 1,4-Galp (14.3%). The evidence for the RG-I backbone of POWP-H was demonstrated by the structure analysis of its degraded product POWP-H-H, which had the backbone of →4)-α-GalpA-(1 → 2)-α-Rhap-(1 → 4)-α-GalpA-(1 → 2,4)-α-Rhap-(1→ substituted by short side chain of β-Galp-(1 → 4)-β-Galp-(1→ at O-4 position of →2,4)-α-Rhap-(1 → . Moreover, the POWP-H-H was mainly O-acetylated at O-3 position of α-Rhap with 24.8% acetylation degree. In conclusion, POWP-H was mainly the highly branched and acetylated RG-I pectin with relative short RG-I backbone and abundant arabinogalactan II and certain galactan side chains. Besides, it adopted a flexible chain conformation in 0.1 M NaNO3 solution.

Aloe barbadensis Miller ( Aloe vera ) is widely used for healthy foods, medical and cosmetic products, while its leaf skin is usually treated as industrial waste. To have a profound understanding of the polysaccharides in the leaf skin of Aloe vera , crude polysaccharide was extracted from the leaf skin of Aloe vera and purified into three fractions, designated as ASP-4N, ASP-6N and ASP-8N, using gradient ammonium sulfate precipitation. The physicochemical properties and structural characteristics of ASP-4N were systematically investigated by methylation analysis and 1D/2D NMR spectroscopy. Results showed that decreasing contents of neutral sugar (79%–74%) were detected among the three fractions, with the concentration increasing of ammonium sulfate used for precipitation. Small amounts of protein and uronic acid were also detected by colorimetric method. Homogeneity identified by high performance gel permeation chromatography (HPGPC) indicated that the three fractions were highly purified. The relative weight average molecular weights for ASP-4N, ASP-6N and ASP-8N were 339, 130 and 67.6 kDa, successively. Monosaccharide compositions and characteristic FT-IR spectra of these fractions suggested the presence of typical acetylated glucomannan and the ratios of mannose/glucose were 19.13, 8.97 and 2.96, successively. Further structural analysis of ASP-4N suggested that it was a highly acetylated (1 → 4)-β-glucomannan. There was also some (1 → 3)-β-Man p mixed in the backbone.

Pomelo albedo was extracted with water to obtain the high methoxyl pectin, labeled as PAP. The physicochemical and rheological properties of PAP were determined. The effects of PAP addition on rheological property and thermal stability of konjac glucomannan (KGM) were evaluated. Results indicated that PAP was composed of arabinose, glucose and galacturonic acid with a relative mass percentage of 7.2%: 9.5%: 83.3%, and exhibited an average molecular weight of 56.6 kDa. The degree of esterification of PAP was 65.5%, showing PAP was a kind of high methoxyl pectin. Apparent viscosity of PAP was concentration-dependently increased, while it was slightly enhanced with salt (NaCl or CaCl2) addition. Moreover, the addition of PAP declined the apparent viscosity, elastic property and thermal stability of KGM. It can be concluded that interaction was occurred between KGM and PAP. Meanwhile, the interaction mechanism between KGM and PAP has been preliminarily proposed. The present study can provide some references for the application of PAP and support the combination usage of this pectin and KGM in food and other industries.

It has been found that probiotic-fermented carrot pulp has a beneficial effect in reducing blood glucose, more so than unfermented pulp. This paper explores the reason for this by looking at fermentation-induced changes in nutritional components and hypoglycemic effects of its polysaccharides. Micronutrient content showed minor changes, except for titratable acidity. Fat and protein decreased, while total carbohydrates increased. These polysaccharides are pectinic, and the number of total polysaccharides rose after fermentation. Scanning electron microscopy showed that the morphology changed from filamentous solid to spiral. The molecular weight of water-soluble polysaccharide (WSP) diminished after fermentation, while those of acid- and alkali-soluble polysaccharides increased. WSP had stronger hydroxyl radical scavenging activity in vitro, and WSP from probiotic-fermented carrot pulps showed better hypoglycemic effects than WSP from non-fermented carrot pulps in animal experiments. Thus, the fermentation-induced improvement in diabetes control from fermented carrot pulp probably arises from its WSP.

While polysaccharides are the most abundant biomacromolecules widely distributed in nature, little is known in their chemical structures and functional mechanism. Compared with DNA and protein, polysaccharides possess more complex structures and composition with various molecular size, conformational shape and charge characteristic. Currently, the lack of a uniform and clear consensus of polysaccharide purity leads to low accuracy of structural analysis. In the present study, a new theory on polysaccharide purification named as “relative ordered structure” was proposed, which was used to purify the water-extracted polysaccharides from Hypsizygus marmoreus (SHMP), successfully giving five purified sub-fractions. Results showed that their major chemicals were similar, while molecular weights, monosaccharide compositions, surface morphology, solution properties as well as their structural features enormously varied. Methylation and 1D/2D NMR analysis indicated the presence of α-glucans, fucomannogalactans and galactoglucan in SHMP, further confirming the feasibility of this theory in isolation and purification of natural polysaccharides. Based on the results and previous reports, this work aims to introduce and generalize the “relative ordered structure” theory. Altogether, structural characterization of polysaccharides cannot simply “copy” the techniques on protein, more theories and methodology applicable to polysaccharide itself should be established.

β-Glucans are widely found in plants and microorganisms, which has a variety of functional activities. During production and application, interactions with other components have a great influence on the structure and functional properties of β-glucan. In this paper, interactions (including non-covalent interaction and free-radical reaction) between natural product derived β-glucan and ascorbic acid, polyphenols, bile acids/salts, metal ion or other compounds were summarized. Besides, the mechanism and influence factors of interactions between β-glucan and small-molecule compounds, and their effects on the functional properties of β-glucan were detailed. This review aims to develop an understanding and practical suggestions on interactions between β-glucan and small-molecule compounds, which is expected to provide a useful reference for processing and application.

Arabinoxylan (HBAX-60) was fractioned from alkaline-extracted arabinoxylan (HBAX) in the whole grain of hull-less barley (Hordeum vulgare L. var. nudum Hook. f. Poaceae) by 60% ethanol precipitation, which was studied for physicochemical properties and structure elucidation. Highly purified HBAX-60 mainly composed of arabinose (40.7%) and xylose (59.3%) was created. The methylation and NMR analysis of HBAX-60 indicated that a low-branched β-(1→4)-linked xylan backbone possessed un-substituted (1,4-linked β-Xylp, 36.2%), mono-substituted (β-1,3,4-linked Xylp, 5.9%), and di-substituted (1,2,3,4-linked β-Xylp, 12.1%) xylose units as the main chains, though other residues (α-Araf-(1→, β-Xylp-(1→, α-Araf-(1→3)-α-Araf-(1→ or β-Xylp-(1→3)-α-Araf-(1→) were also determined. Additionally, HBAX-60 exhibited random coil conformation in a 0.1 M NaNO3 solution. This work provides the properties and structural basis of the hull-less barley-derived arabinoxylan, which facilitates further research for exploring the structure–function relationship and application of arabinoxylan from hull-less barley.

Nuclear magnetic resonance (NMR) has been widely used as an analytical chemistry technique to investigate the molecular structure and conformation of polysaccharides. Combined with 1D spectra, chemical shifts and coupling constants in both homo- and heteronuclear 2D NMR spectra are able to infer the linkage and sequence of sugar residues. Besides, NMR has also been applied in conformation, quantitative analysis, cell wall in situ, degradation, polysaccharide mixture interaction analysis, as well as carbohydrates impurities profiling. This review summarizes the principle and development of NMR in polysaccharides analysis, and provides NMR spectra data collections of some common polysaccharides. It will help to promote the application of NMR in complex polysaccharides of biochemical interest, and provide valuable information on commercial polysaccharide products.

Polysaccharide from Agrocybe cylindracea has been demonstrated to exhibit excellently biological functions, but insufficient understanding of its physicochemical property and fine structure limits its wide application and development. In the present study, two water-soluble heteroglycans, a high molecular weight (SACP-40) and a low molecular weight (SACP-80), were isolated from the fruit bodies of A. cylindracea by hot water extraction and gradient ethanol precipitation. There was little difference in their physicochemical properties, including major chemicals and monosaccharide compositions. Rheological measurements revealed SACP-80 was a typical pseudoplastic fluid with shear thinning behavior at the concentration of 3.0%, whereas exhibited a near-Newtonian fluid at lower concentration. SEM observation suggested SACP-80 showed micro-spherical shapes loosely attached to fibrous filament in its surface. Besides, methylation and 1D/2D NMR analysis indicated that SACP-80 was a branched heteroglycan with a backbone composed of β-(1 → 6)-glucopyranosyl, α-(1 → 6)-galactopyranosyl and α-(1 → 2,6)-glucopyranosyl residue at a ratio of 3:1:1. This work provides a theoretical basis for gaining insight into the relationship between the fine structure and viscosity of polysaccharide from A. cylindracea, which could further guide its functional studies and advance the potential application in food and biomedicine industries.

Glucans of multiple architecture and bioactivities are widely distributed in cereals. In our previous study, the barley water-soluble fiber (BSF) has been proved to possess hypoglycaemic and hypolipidaemic effects. A further attempt in the present study is to comprehensively demonstrate the structures and solution properties of main constituents in BSF. Two mainly homogeneous fractions (BSF-20 and BSF-80r) were purified from BSF, and their physicochemical and structural characterization were investigated. Methylation and 1D/2D NMR experiments indicated that BSF-20 was a linear β-glucan, composed of β-D-Glcp residues via (1 → 4)-linkages, and occasionally single (1 → 3)-linkage. The high performance size-exclusion chromatography coupled with multiangle laser light scattering, X-ray diffraction, rheological measurements and scanning electron microscopy were further conducted to analyze its solution property and morphology. BSF-20 adopted a linear flexible chain in aqueous solution, and exhibited high viscosity and strong gelling properties. Intertwined fibrous filaments were visualized by SEM observation. Besides, BSF-80r was a limit dextrin, which was an artefact caused by the incomplete hydrolysis of starch during the isolation of barley soluble fiber. Therefore, the highly viscous β-glucan is the main biomacromolecule occurring in BSF. This work lays the groundwork for the potential application of barley soluble fiber in beverages and other liquid products as new thickeners and stabilizers.

Previous studies have suggested that water-soluble polysaccharides from fermented carrot pulp (WSP-p) have stronger anti-diabetic effects than those from un-fermented carrot pulp (WSP-n). This study aimed to improve understanding of these functional differences by comparing their molecular structures. Weight-average molecular weights of WSP-p fractions were lower than those of the corresponding WSP-n fractions. While both WSPs had similar functional groups, more fragmented particles were observed on the surface of large particles of WSP-n than WSP-p. Monosaccharide composition and methylation analysis confirmed that both WSP-p and WSP-n were pectic polysaccharides, containing rhamnogalacturonan-I-type polysaccharides with 1,4-linked α-d-galacturonic acid residues and homogalacturonan regions with 1,4-GalpA linkages. 1H and 13C NMR showed that they had similar linkage patterns. These findings suggested that probiotic fermentation of WSP mainly cleaved the linkages between repeating units, and resulted in less polydisperse molecular size distributions.

Polysaccharide from seeds of Plantago asiatica L. is rich in Ara and Xyl. However, it contains small amounts of other monosaccharides, such as Rha, Gal and GalA. It is the first time to systematically elucidate structural features as well as fractionation, physicochemical properties of non-arabinoxylan polysaccharide from the seeds of Plantago asiatica L.. Non-arabinoxylan polysaccharide named as PLWE-NAX was successfully isolated and separated from the water extract of the seeds at a temperature of 50 °C. PLWE-NAX was purified into five fractions by anion exchange chromatography and gel permeation chromatography. The non-arabinoxylan fractions included arabinogalactan (PLWE-1), xylan (PLWE-2) and pectin (PLWE-3, PLWE-4, PLWE-5). PLWE-2, PLWE-3, PLWE-4 and PLWE-5 were acidic polysaccharide. PLWE-4 was subjected for structural characterization by methylation analysis and 1D/2D NMR. It was mainly consisted of α-1,2-linked Rhap (25.01%), T-linked Araf (12.11%) and β-1,3,4-linked Xylp (20.01%) residues. Uronic acid in PLWE-4 was α-1,4-linked GalAp (31.55%). PLWE-4 had the back bone as following, →1)-α-GalAp-(4 → 1)-α-Rhap-(2 → 1)-α-GalAp-(4 → .

In the current study, we evaluated the antioxidant activities of highly purified monosaccharides, oligosaccharides and complex carbohydrates using six in vitro antioxidant assays, including oxygen radical absorbance capacity (ORAC), ferric reducing antioxidant power (FRAP), β-carotene bleaching assay, 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, hydroxyl radical scavenging and superoxide radicals scavenging methods. The results suggested that monosaccharides and oligosaccharides scarcely exhibited antioxidant activities in vitro. For example in the β-carotene bleaching assay the inhibitory effects of monosaccharides at 1 mg/mL were between 0.24% to 2.25% although galacturonic acid demonstrated some inhibitory effects (8.59%). Significant lower antioxidant activities were observed for complex carbohydrates compared to ascorbic acid and BHT (e.g. ferric reducing antioxidant power by the FRAP assay), >1800 μmol Fe (Ⅱ)/g were observed for ascorbic acid and BHT compared to only 10–60 μmol Fe (Ⅱ)/g for complex carbohydrates, and 1.60 and 6.43 μmol Fe (Ⅱ)/g for mono and oligosaccharides. The observed antioxidant activities for complex carbohydrates are correlated with the presence of phenolic and/or protein components. The findings from the current study indicate that it is necessary to re-evaluate the antioxidant activities claimed for complex carbohydrates in the literature as many of them did not consider the contribution of other minor components such as phenolics and proteins.

Arabinoxylan (BIF-60) was isolated from barley water-insoluble fiber (BIF) by ethanol precipitation at 60 % (v/v). BIF-60 was composed of xylose (48.5 %) and arabinose (30.3 %). Its average molecular weight was 1360 kDa. Methylation and 1D/2D NMR analysis showed that BIF-60 possessed β-(l→4)-xylan as backbone, comprised of un-substituted (1,4-linked β-Xylp, 56.9 %), mono-substituted (1,2,4-linked and 1,3,4-linked β-Xylp, 22.1 %) and di-substituted (1,2,3,4-lin4ked β-Xylp, 18.4 %) xylose units, as well as other residues (T-Araf-(1→, T-Xylp-(1→, →5)-Araf-(1→, →2)-Araf-(1→, →3)-Araf-(1→ and →4)-Glcp-(1→). BIF-60 exhibited shear-thinning behaviour, low gel stability and weak gelling ability at high concentrations. This work provides a theoretical and experimental basis for molecular structure and properties of the alkali-extracted arabinoxylan from barley kernel, which could guide further functional research and application of barley-derived arabinoxylan.

Arabinoxylan (AX), an important dietary fiber from cereal grains, is mainly metabolised in the large intestine by gut bacteria, especially bifidobacteria. This study investigated the uptake and metabolism of wheat AX by a Bifidobacterium longum strain that could grow well with AX as the sole carbon source. The bacterial growth rate showed a significant correlation to the molecular weight (MW) of AX and its acid hydrolysates. Assessment of the key AX degrading enzymes suggested that the uptake and consumption of AX involved extracellular cleavage of xylan backbone and intracellular degradation of both the backbone and the arabinose substitution. The preference for native or partially hydrolysed AX with single substitutions and a sufficiently high MW suggested the structure-dependant uptake by the bacterial cells. Genetic analysis of B. longum showed the lack of β-xylosidase, suggesting the existence of unknown enzymes or dual/multiple-specific enzymes for hydrolysis of the non-reducing end of xylan backbone.