A nonenzymatic method for cleaving polysaccharides to yield oligosaccharides for structural analysis

The structures of two polysaccharides from Lepidium meyenii and their immunomodulatory effects via activating NF-κB signaling pathway

Lepidium meyenii Walp., also known as the "Peruvian national treasure", is a popular functional food in the daily lives of Peruvian people due to its bioactive with main polysaccharides. However, studies on polysaccharides isolated from Lepidium meyenii were few. Two new highly heterogeneous polysaccharides, MCP-1a and MCP-2b, were isolated and purified from the tuber of Lepidium meyenii. The structure characterization revealed that MCP-1a primarily consisted of D-Glc and had a molecular weight of 6.6 kDa. Its backbone was composed of 1,4,6-α-D-Glc, while branches feature T-α-L-Ara, 1,5-α-L-Ara, and T-α-D-Glc attached to the O-6 positions. MCP-2b was a rare arabinogalactan with a molecular weight of 49.4 kDa. Interestingly, the backbone of MCP-2b was composed of 1,6-β-D-Gal, 1,3,6-β-D-Gal with a few 1,3-β-D-GlcpA-4-OMe units inserted. Side chains of MCP-2b were mainly composed of 1,3-β-D-Gal, T-β-D-Gal, T-α-L-Ara, 1,5-α-L-Ara, with trace amounts of 1,4-β-D-Glc and T-β-D-Glc. The bioactivity assay results revealed that MCP-1a and MCP-2b increased the release of NO, IL-1β, TNF-α, and IL-6 from RAW 264.7 cells at concentrations ranging from 50 μg/mL to 400 μg/mL. Furthermore, MCP-1a and MCP-2b could promote the expression of key transcription factors (IκB-α, p-IκB-α, p65, and p-p65) in the NF-κB pathway, indicating that MCP-1a and MCP-2b had potential immunomodulatory activities.

Permethylation as a strategy for high-molecular-weight polysaccharide structure analysis by nuclear magnetic resonance-Case study of Xylella fastidiosa extracellular polysaccharide

Current practices for structural analysis of extremely large-molecular-weight polysaccharides via solution-state nuclear magnetic resonance (NMR) spectroscopy incorporate partial depolymerization protocols that enable polysaccharide solubilization in suitable solvents. Non-specific depolymerization techniques utilized for glycosidic bond cleavage, such as chemical degradation or ultrasonication, potentially generate structural fragments that can complicate complete and accurate characterization of polysaccharide structures. Utilization of appropriate enzymes for polysaccharide degradation, on the other hand, requires prior structural knowledge and optimal enzyme activity conditions that are not available to an analyst working with novel or unknown compounds. Herein, we describe an application of a permethylation strategy that allows the complete dissolution of intact polysaccharides for NMR structural characterization. This approach is utilized for NMR analysis of Xylella fastidiosa extracellular polysaccharide (EPS), which is essential for the virulence of the plant pathogen that affects multiple commercial crops and is responsible for multibillion dollar losses each year.

Research of saccharides and related biocomplexes: A review with recent techniques and applications

Saccharides and biocompounds as saccharide (sugar) complexes have various roles and biological functions in living organisms due to modifications via nucleophilic substitution, polymerization, and complex formation reactions. Mostly, mono-, di-, oligo-, and polysaccharides are stabilized to inactive glycosides, which are formed in metabolic pathways. Natural saccharides are important in food and environmental monitoring. Glycosides with various functionalities are significant in clinical and medical research. Saccharides are often studied with the chromatographic methods of hydrophilic interaction liquid chromatography and anion exchange chromatograpy, but also with capillary electrophoresis and mass spectrometry with their on-line coupling systems. Sample preparation is important in the identification of saccharide compounds. The cases discussed here focus on bioscience, clinical, and food applications.

Correlation between monosaccharide, oligosaccharide, and microbial community profile changes in traditional soybean brick (meju) fermentation

Meju is essential for making diverse traditional fermented soybean foods in Korea. To understand the changes in carbohydrates during fermentation, we aimed to identify autochthonous microorganisms from spontaneously fermented meju and compare the alterations in monosaccharides and oligosaccharides throughout the fermentation process. Microbial diversity was determined using a metabarcoding approach, and monosaccharide and oligosaccharide profiles were obtained by HPLC-Q-TOF MS and HPLC-MS/MS analyses, respectively. The dominant bacterial genera were Weissella, Lactobacillus, and Leuconostoc, while Mucor was highly abundant in the fungal community. The total monosaccharide content increased from Day 0 to Day 50, with the highest amount being 4.37 mg/g. Oligosaccharide profiling revealed the degradation of soybean dietary fiber during fermentation, and novel oligosaccharide structures were also discovered. Correlation analysis revealed that the fungus Mucor was positively related to pentose-containing oligosaccharides, galactose, and galacturonic acid, indicating that Mucor may degrade soybean dietary fibers such as xylogalacturonan, arabinogalactan, and rhamnogalacturonan. The negative relationships between the abundances of Weissella and oligo- and monosaccharides suggested that the bacteria may utilize saccharides for fermentation. These findings provide insights into the mechanisms underlying carbohydrate degradation and utilization; the key components involved in saccharide transformation that contribute to the characteristics of traditional meju were subsequently identified.

Comparison of extraction processes, characterization and intestinal protection activity of Bletilla striata polysaccharides

We optimized the extraction process of Bletilla striata polysaccharides using orthogonal design, Box-Behnken design (BBD), and genetic algorithm-back propagation (GA-BP), then compared and evaluated them to confirm that the combination of BBD and GA-BP neural networks was capable of increasing polysaccharide yields and antioxidant activity. The optimal extraction parameters were as follows: liquid-to-solid ratio of 15 mL/g, extraction power of 450 W, and extraction time of 34 min. Under these conditions, the polysaccharide yield and antioxidant activity were 8.29 ± 0.50 % and 26.20 ± 0.28 (mM FE/mg). Subsequently, the polysaccharide was purified to obtain purified Bletilla striata polysaccharides 1 (pBSP1) with a Mw of 255.172 kDa. Scanning electron microscope (SEM), ultraviolet-visible detector (UV), fourier transform infrared spectrometer (FTIR), high performance liquid chromatography (HPLC), X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and periodate oxidation were used to analyze the structure of pBSP1. The results showed pBSP1 had a smooth surface and a rough interior, with a composition of α-D conformation glucose (18.23 %) and β-D conformation mannose (53.77 %), and an amorphous crystal structure. According to the results of thermogravimetric and rheological tests, pBSP1 exhibits good thermal stability and viscoelastic behavior. Furthermore, pBSP1 protected lipopolysaccharide (LPS)-induced GES - 1 and Caco2 cells, the results showed pBSP1(400 μg/mL) lowered TEER synthesis in Caco2 cells as well as apoptosis and reactive oxygen species (ROS) production in both cells, indicating that pBSP1 may have an intestine protective effect.

A homologous series of α-glucans from Hemicentrotus pulcherrimus and their immunomodulatory activity

Seven macromolecular polysaccharides (HPP-2S-HPP-8S) were purified from the gonads of sea urchin Hemicentrotus pulcherrimus. They were characterized as α-glucan homologues, sharing the same α-1,4-glucan backbone substituted at C-6 positions by glucose with HPP-1S that occurs as the major polysaccharide in H. pulcherrimus, while with higher degrees of branching, and additionally possessing minor amounts of mannose and ribose. The branching degree and amounts of non-glucose branches showed a generally increasing tendency across HPP-2S - HPP-8S. These polysaccharides exhibited significant macrophage-activating effects by augmenting the secretion of NO, TNF-α and IL-6, which probably involves the activation of NF-κB and MAPKs signaling pathways. Notably, the polysaccharides with a higher degree of branching exhibited markedly enhanced immunomodulatory capacity with a lowest effective concentration of 1.95 μg/mL. This work provides new cases of bioactive α-glucans and reveals their potential application as immunomodulating agents.

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

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

Bioactive glycans in a microbiome-directed food for children with malnutrition

Evidence is accumulating that perturbed postnatal development of the gut microbiome contributes to childhood malnutrition1-4. Here we analyse biospecimens from a randomized, controlled trial of a microbiome-directed complementary food (MDCF-2) that produced superior rates of weight gain compared with a calorically more dense conventional ready-to-use supplementary food in 12-18-month-old Bangladeshi children with moderate acute malnutrition4. We reconstructed 1,000 bacterial genomes (metagenome-assembled genomes (MAGs)) from the faecal microbiomes of trial participants, identified 75 MAGs of which the abundances were positively associated with ponderal growth (change in weight-for-length Z score (WLZ)), characterized changes in MAG gene expression as a function of treatment type and WLZ response, and quantified carbohydrate structures in MDCF-2 and faeces. The results reveal that two Prevotella copri MAGs that are positively associated with WLZ are the principal contributors to MDCF-2-induced expression of metabolic pathways involved in utilizing the component glycans of MDCF-2. The predicted specificities of carbohydrate-active enzymes expressed by their polysaccharide-utilization loci are correlated with (1) the in vitro growth of Bangladeshi P. copri strains, possessing varying degrees of polysaccharide-utilization loci and genomic conservation with these MAGs, in defined medium containing different purified glycans representative of those in MDCF-2, and (2) the levels of faecal carbohydrate structures in the trial participants. These associations suggest that identifying bioactive glycan structures in MDCFs metabolized by growth-associated bacterial taxa will help to guide recommendations about their use in children with acute malnutrition and enable the development of additional formulations.

Structural Characterization and Anticoagulant Activities of a Keratan Sulfate-like Polysaccharide from the Sea Cucumber Holothuria fuscopunctata

A sulfated polysaccharide (AG) was extracted and isolated from the sea cucumber H. fuscopunctata, consisting of GlcNAc, GalNAc, Gal, Fuc and lacking any uronic acid residues. Importantly, several chemical depolymerization methods were used to elucidate the structure of the AG through a bottom-up strategy. A highly sulfated galactose (oAG-1) and two disaccharides labeled with 2,5-anhydro-D-mannose (oAG-2, oAG-3) were obtained from the deaminative depolymerized product along with the structures of the disaccharide derivatives (oAG-4~oAG-6) identified from the free radical depolymerized product, suggesting that the repeating building blocks in a natural AG should comprise the disaccharide β-D-GalS-1,4-D-GlcNAc6S. The possible disaccharide side chains (bAG-1) were obtained with mild acid hydrolysis. Thus, a natural AG may consist of a keratan sulfate-like (KS-like) glycosaminoglycan with diverse modifications, including the sulfation types of the Gal residue and the possible disaccharide branches α-D-GalNAc4S6S-1,2-α/β-L-Fuc3S linked to the KS-like chain. Additionally, the anticoagulant activities of the AG and its depolymerized products (dAG1-9) were evaluated in vitro using normal human plasma. The AG could prolong activated partial thromboplastin time (APTT) in a dose-dependent manner, and the activity potency was positively related to the chain length. The AG and dAG1-dAG3 could prolong thrombin time (TT), while they had little effect on prothrombin time (PT). The results indicate that the AG could inhibit the intrinsic and common coagulation pathways.

Evaluation of the "Relative Ordered Structure of Hericium erinaceus Polysaccharide" from Different Origins: Based on Similarity and Dissimilarity

Polysaccharides are organic compounds widely distributed in nature, but structural order and disorder remain a formidable problem. In this study, based on the theoretical framework of the "relative ordered structure of polysaccharide" proposed in our previous work, the structural order of Hericium erinaceus polysaccharides from different regions was evaluated by FT-IR, methylation analysis, and 1H NMR spectroscopy combined with chemometric methods. The results of principal component analysis and heatmap cluster analysis revealed that 18-subfractions exhibit four different structural types with representative glycoside linkage types: fucogalactoglucan, glucofucogalactan, fucoglucan, and glucan. The main chain of heteroglucans often consists of β-(1 → 6)-Glcp, β-(1 → 4)-Glcp, and β-(1 → 3)-Glcp residues, which are predominantly substituted at the O-3 and O-6 positions. The main chain structure of heterogalactans is α-(1 → 6)-Galp residues, which may be replaced by Fucp and Galp residues at O-2. Overall, our findings demonstrate the validity of the "relative ordered structure of polysaccharide" in Hericium erectus polysaccharides and simplify the complexity of polysaccharide structures.

Acetylation in Ionic Liquids Dramatically Increases Yield in the Glycosyl Composition and Linkage Analysis of Insoluble and Acidic Polysaccharides

Glycosyl composition and linkage analyses are important first steps toward understanding the structural diversity and biological importance of polysaccharides. Failure to fully solubilize samples prior to analysis results in the generation of incomplete and poor-quality composition and linkage data by gas chromatography-mass spectrometry (GC-MS). Acidic polysaccharides also do not give accurate linkage results, because they are poorly soluble in DMSO and tend to undergo β-elimination during permethylation. Ionic liquids can solubilize polysaccharides, improving their derivatization and extraction for analysis. We show that water-insoluble polysaccharides become much more amenable to chemical analysis by first acetylating them in an ionic liquid. Once acetylated, these polysaccharides, having been deprived of their intermolecular hydrogen bonds, are hydrolyzed more readily for glycosyl composition analysis or methylated more efficiently for glycosyl linkage analysis. Acetylation in an ionic liquid greatly improves composition analysis of insoluble polysaccharides when compared to analysis without acetylation, enabling complete composition determination of normally recalcitrant polysaccharides. We also present a protocol for uronic acid linkage analysis that incorporates this preacetylation step. This protocol produces partially methylated alditol acetate derivatives in high yield with minimal β-elimination and gives sensitive linkage results for acidic polysaccharides that more accurately reflect the structures being analyzed. We use important plant polysaccharides to show that the preacetylation step leads to superior results compared to traditional methodologies.

Analysis of Cell Glycogen with Quantitation and Determination of Branching Using Liquid Chromatography-Mass Spectrometry

Glycogen is a highly branched biomacromolecule that functions as a glucose buffer. It is involved in multiple diseases such as glycogen storage disorders, diabetes, and even liver cancer, where the imbalance between biosynthetic and catabolic enzymes results in structural alterations and abnormal accumulation of glycogen that can be toxic to cells. Accurate and sensitive glycogen quantification and structural determination are prerequisites for understanding the phenotypes and biological functions of glycogen under these conditions. In this research, we furthered cell glycogen characterization by presenting a highly sensitive method to measure the glycogen content and degree of branching. The method employed a novel fructose density gradient as an alternative to the traditional sucrose gradient to fractionate glycogen from cell mixtures using ultracentrifugation. Fructose was used to avoid the large glucose background, allowing the method to be highly quantitative. The glycogen content was determined by quantifying 1-phenyl-3-methyl-5-pyrazolone (PMP)-derivatized glucose residues obtained from acid-hydrolyzed glycogen using ultra-high-performance liquid chromatography/triple quadrupole mass spectrometry (UHPLC/QqQ-MS). The degree of branching was determined through linkage analysis where the glycogen underwent permethylation, hydrolysis, PMP derivatization, and UHPLC/QqQ-MS analysis. The new approach was used to study the effect of insulin on the glycogen phenotypes of human hepatocellular carcinoma (Hep G2) cells. We observed that cells produced greater amounts of glycogen with less branching under increasing insulin levels before reaching the cell's insulin-resistant state, where the trend reversed and the cells produced less but higher-branched glycogen. The advantage of this method lies in its high sensitivity in characterizing both the glycogen level and the structure of biological samples.

Bioactive glycans in a microbiome-directed food for malnourished children

Evidence is accumulating that perturbed postnatal development of the gut microbiome contributes to childhood malnutrition1-4. Designing effective microbiome-directed therapeutic foods to repair these perturbations requires knowledge about how food components interact with the microbiome to alter its expressed functions. Here we use biospecimens from a randomized, controlled trial of a microbiome-directed complementary food prototype (MDCF-2) that produced superior rates of weight gain compared to a conventional ready-to-use supplementary food (RUSF) in 12-18-month-old Bangladeshi children with moderate acute malnutrition (MAM)4. We reconstructed 1000 bacterial genomes (metagenome-assembled genomes, MAGs) present in their fecal microbiomes, identified 75 whose abundances were positively associated with weight gain (change in weight-for-length Z score, WLZ), characterized gene expression changes in these MAGs as a function of treatment type and WLZ response, and used mass spectrometry to quantify carbohydrate structures in MDCF-2 and feces. The results reveal treatment-induced changes in expression of carbohydrate metabolic pathways in WLZ-associated MAGs. Comparing participants consuming MDCF-2 versus RUSF, and MDCF-2-treated children in the upper versus lower quartiles of WLZ responses revealed that two Prevotella copri MAGs positively associated with WLZ were principal contributors to MDCF-2-induced expression of metabolic pathways involved in utilization of its component glycans. Moreover, the predicted specificities of carbohydrate active enzymes expressed by polysaccharide utilization loci (PULs) in these two MAGs correlate with the (i) in vitro growth of Bangladeshi P. copri strains, possessing differing degrees of PUL and overall genomic content similarity to these MAGs, cultured in defined medium containing different purified glycans representative of those in MDCF-2, and (ii) levels of carbohydrate structures identified in feces from clinical trial participants. In the accompanying paper5, we use a gnotobiotic mouse model colonized with age- and WLZ-associated bacterial taxa cultured from this study population, and fed diets resembling those consumed by study participants, to directly test the relationship between P. copri, MDCF-2 glycan metabolism, host ponderal growth responses, and intestinal gene expression and metabolism. The ability to identify bioactive glycan structures in MDCFs that are metabolized by growth-associated bacterial taxa will help guide recommendations about use of this MDCF for children with acute malnutrition representing different geographic locales and ages, as well as enable development of bioequivalent, or more efficacious, formulations composed of culturally acceptable and affordable ingredients.

Permethylation as a Strategy for High Molecular Weight Polysaccharide Structure Analysis by NMR - Case Study of Xylella fastidiosa EPS

Current practices for structure analysis of extremely large molecular weight polysaccharides via solution-state NMR spectroscopy incorporate partial depolymerization protocols that enable polysaccharide solubilization in suitable solvents. Non-specific depolymerization techniques utilized for glycosidic bond cleavage, such as chemical degradation or ultrasonication, potentially generate structure fragments that can complicate the complete characterization of polysaccharide structures. Utilization of appropriate enzymes for polysaccharide degradation, on the other hand, requires prior structure information and optimal enzyme activity conditions that are not available to the analyst working with novel or unknown compounds. Herein, we describe the application of a permethylation strategy that allows the complete dissolution of the intact polysaccharides for NMR structure characterization. This approach is utilized for NMR analysis of Xylella fastidiosa EPS, which is essential for the virulence the plant pathogen that affects multiple commercial crops and is responsible for multibillion dollar losses each year.

Microwave assisted free radical degradation of Schisandra polysaccharides: Optimization, identification and application

In order to establish structural-fingerprinting of polysaccharides for improvement of quality assessment, a sample preparation method based on microwave assisted free radical degradation (MFRD) of plant polysaccharides was proposed to produce oligosaccharides and small M_w polysaccharides. As a case study of Schisandra chinensis and S. sphenanthera fruit polysaccharides (SCP and SSP), the MFRD condition (i.e., 100 °C, 30 s and 80 W) was confirmed to be optimal. The potential structures of the MFRD products of SCP and SSP were further discussed by combinations of HILIC-ESI^--QTOF-MS^E and HILIC-ESI^--Q-OT-IT-MS/MS. As followed, multivariable statistical analysis shows a clear separation of SCP and the SSP in PCA and OPLS-DA plots based HILIC-ESI^--QTOF-MS^E data. The VIP plot unveils several key Q-markers (e.g., peaks 3, 8, 9, 10, 15, 25, 26, 28, 29 and 30) with significant differences and stable emergences. Furthermore, a low-polymerization compositional fingerprinting was successfully constructed for SCP and SSP using a high-performance anion-exchange chromatography with pulsed amperometric detection. Compared to the conventional sample preparation methods, the MFRD took only a few thousandth of the time to accomplish degradations of plant polysaccharides. It significantly improves sample preparations and is generally applicable to various polysaccharide samples.

A novel Stauntonia leucantha fruits arabinogalactan: and structural characterization

Polysaccharides were the key ingredients of many herbal medicines, and were responsible for multiple pharmacological activities. In this study, a novel polysaccharide fraction, named SLP-2, was isolated from Stauntonia leucantha fruits, and purified by DEAE-52 and Sephadex G-100 column chromatography. Furthermore, SLP-2 was identified by congo red, methylation, partial acid hydrolysis and NMR. The results indicated that the backbone of SLP-2 was composed of →4)-β-D-Galp-(1 → 4)-β-D-Galp-(1→ substituted at C-6 with 1,5-linked arabinan. SLP-2 had good anti-oxidation ability in vitro. Surprisingly, we found that reduction of carboxyl groups and methylation of hydroxyl groups enhanced the ability to scavenge 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radicals and inhibit lipid peroxidation, and weakened the activity to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and reduce ferric iron.

Novel constituents of Salvia hispanica L. (chia) nutlet mucilage and the improved in vitro fermentation of nutlets when ground

Upon wetting, chia (Salvia hispanica L.) nutlets produce a gel-like capsule of polysaccharides called mucilage that comprises a significant part of their dietary fibre content. Seed/nutlet mucilage is often used as a texture modifying hydrocolloid and bulking dietary fibre due to its water-binding ability, though the utility of mucilage from different sources is highly structure-function dependent. The composition and structure of chia nutlet mucilage is poorly defined, and a better understanding will aid in exploiting its dietary fibre functionality, particularly if, and how, it is utilised by gut microbiota. In this study, microscopy, chromatography, mass spectrometry and glycome profiling techniques showed that chia nutlet mucilage is highly complex, layered, and contains several polymer types. The mucilage comprises a novel xyloamylose containing both β-linked-xylose and α-linked-glucose, a near-linear xylan that may be sparsely substituted, a modified cellulose domain, and abundant alcohol-soluble oligosaccharides. To assess the dietary fibre functionality of chia nutlet mucilage, an in vitro cumulative gas production technique was used to determine the fermentability of different chia nutlet preparations. The complex nature of chia nutlet mucilage led to poor fermentation where the oligosaccharides appeared to be the only fermentable substrate present in the mucilage. Of note, ground chia nutlets were better fermented than intact whole nutlets, as judged by short chain fatty acid production. Therefore, it is suggested that the benefits of eating chia as a "superfood", could be notably enhanced if the nutlets are ground rather than being consumed whole, improving the bioaccessibility of key nutrients including dietary fibre.

Quantitative estimation of enzymatic released specific oligosaccharides from Hericium erinaceus polysaccharides using CE-LIF

Polysaccharides exhibit multiple pharmacological activities which are closely related to their structural features. Therefore, quantitatively quality control of polysaccharides based on their chemical characteristics is important for their application in biomedical and functional food sciences. However, polysaccharides are mixed macromolecular compounds that are difficult to isolate and lack standards, making them challenging to quantify directly. In this study, we proposed an improved saccharide mapping method based on the release of specific oligosaccharides for the assessment of Hericium erinaceus polysaccharides from laboratory cultured and different regions of China. Briefly, a polysaccharide from H. erinaceus was digested by β-(1-3)-glucanase, and the released specific oligosaccharides were labeled with 8-aminopyrene-1,3,6-trisulfonic-acid (APTS) and separated by using micellar electrokinetic chromatography (MEKC) coupled with laser induced fluorescence (LIF), and quantitatively estimated. MEKC presented higher resolution compared to polysaccharide analysis using carbohydrate gel electrophoresis (PACE), and provided great peak capacity between oligosaccharides with polymerization degree of 2 (DP2) and polymerization degree of 6 (DP6) in a dextran ladder separation. The results of high performance size exclusion chromatography coupled with multi-angle laser light scattering and refractive index detector (HPSEC-MALLS-RI) showed that 12 h was sufficient for complete digestion of polysaccharides from H. erinaceus. Laminaritriose (DP3) was used as an internal standard for quantification of all the oligosaccharides. The calibration curve for DP3 showed a good linear regression (R ² > 0.9988). The limit of detection (LOD) and limit of quantification (LOQ) values were 0.05 μg/mL and 0.2 μg/mL, respectively. The recovery for DP3 was 87.32 (±0.03)% in the three independent injections. To sum up, this proposed method is helpful for improving the quality control of polysaccharides from H. erinaceus as well as other materials.

Quantitative Bottom-Up Glycomic Analysis of Polysaccharides in Food Matrices Using Liquid Chromatography-Tandem Mass Spectrometry

Carbohydrates are the most abundant biomolecules in nature, and specifically, polysaccharides are present in almost all plants and fungi. Due to their compositional diversity, polysaccharide analysis remains challenging. Compared to other biomolecules, high-throughput analysis for carbohydrates has yet to be developed. To address this gap in analytical science, we have developed a multiplexed, high-throughput, and quantitative approach for polysaccharide analysis in foods. Specifically, polysaccharides were depolymerized using a nonenzymatic chemical digestion process followed by oligosaccharide fingerprinting using high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS). Both label-free relative quantitation and absolute quantitation were done based on the abundances of oligosaccharides produced. Method validation included evaluating recovery for a range of polysaccharide standards and a breakfast cereal standard reference material. Nine polysaccharides (starch, cellulose, β-glucan, mannan, galactan, arabinan, xylan, xyloglucan, chitin) were successfully quantitated with sufficient accuracy (5-25% bias) and high reproducibility (2-15% CV). Additionally, the method was used to identify and quantitate polysaccharides from a diverse sample set of food samples. Absolute concentrations of nine polysaccharides from apples and onions were obtained using an external calibration curve, where varietal differences were observed in some of the samples. The methodology developed in this study will provide complementary polysaccharide-level information to deepen our understanding of the interactions of dietary polysaccharides, gut microbial community, and human health.

Structural elucidation of a novel arabinogalactan LFP-80-W1 from Lycii fructus with potential immunostimulatory activity

Polysaccharides are the most important effective components of Lycii fructus, which has a variety of biological activities and broad application prospects in the fields of medicine and food. In this study, we reported a novel arabinogalactan LFP-80-W1 with potential immunostimulatory activity. LFP-80-W1 was a continuous symmetrical single-peak with an average molecular weight of 4.58 × 10⁴ Da and was mainly composed of arabinose and galactose. Oligosaccharide sequencing analyses and NMR data showed that the LFP-80-W1 domain consists of a repeated 1,6-linked β-Galp main chain with branches arabinoglycan and arabinogalactan at position C-3. Importantly, we found that LFP-80-W1 could activate the MAPK pathway and promote the release of NO, IL-6, and TNF-α cytokines in vitro. Therefore, our findings suggest that the homogeneous arabinogalactan from Lycii fructus, can be used as a natural immunomodulator.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2019-2020

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2020. Also included are papers that describe methods appropriate to analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. The review is basically divided into three sections: (1) general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, quantification and the use of arrays. (2) Applications to various structural types such as oligo- and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals, and (3) other areas such as medicine, industrial processes and glycan synthesis where MALDI is extensively used. Much of the material relating to applications is presented in tabular form. The reported work shows increasing use of incorporation of new techniques such as ion mobility and the enormous impact that MALDI imaging is having. MALDI, although invented nearly 40 years ago is still an ideal technique for carbohydrate analysis and advancements in the technique and range of applications show little sign of diminishing.

Structures and functions of algal glycans shape their capacity to sequester carbon in the ocean

Algae synthesise structurally complex glycans to build a protective barrier, the extracellular matrix. One function of matrix glycans is to slow down microorganisms that try to enzymatically enter living algae and degrade and convert their organic carbon back to carbon dioxide. We propose that matrix glycans lock up carbon in the ocean by controlling degradation of organic carbon by bacteria and other microbes not only while algae are alive, but also after death. Data revised in this review shows accumulation of algal glycans in the ocean underscoring the challenge bacteria and other microbes face to breach the glycan barrier with carbohydrate active enzymes. Briefly we also update on methods required to certify the uncertain magnitude and unknown molecular causes of glycan-controlled carbon sequestration in a changing ocean.

Recent advances in qualitative and quantitative analysis of polysaccharides in natural medicines: A critical review

Polysaccharides from natural medicines, being safe and effective natural mixtures, show great potential to be developed into botanical drugs. However, there is yet one polysaccharide-based case that has fulfilled the Botanical Guidance definition of a botanical drug product. One of the reasons is the analytical methods commonly used for qualitative and quantitative analysis of polysaccharides fall far behind the quality control criteria of botanical drugs. Here we systemically reviewed the recent advances in analytical methods. A critical evaluation of the strength and weaknesses of these methods was provided, together with possible solutions to the difficulties. Mass spectrometry with or without robust chromatographic separation was increasingly employed. And scientists have made significant progress in simplifying polysaccharide quantification by depolymerizing it into oligosaccharides. This oligosaccharides-based strategy is promising for qualitative and quantitative analysis of polysaccharides. And continuous efforts are still needed to develop a standardized quality control method that is specific, accurate, repeatable, and applicable for analyzing individual components in natural medicine formulas.

Determining Methyl-Esterification Patterns in Plant-Derived Homogalacturonan Pectins

Homogalacturonan (HG)-type pectins are nutrient components in plants and are widely used in the food industry. The methyl-esterification pattern is a crucial structural parameter used to assess HG pectins in terms of their nutraceutical activity. To better understand the methyl-esterification pattern of natural HG pectins from different plants, we purified twenty HG pectin-rich fractions from twelve plants and classified them by their monosaccharide composition, Fourier transform-infrared spectroscopy (FT-IR) signatures, and NMR analysis. FT-IR shows that these HG pectins are all minimally esterified, with the degree of methyl-esterification (DM) being 5 to 40%. To examine their methyl-esterification pattern by enzymatic fingerprinting, we hydrolyzed the HG pectins using endo-polygalacturonase. Hydrolyzed oligomers were derivatized with 2-aminobenzamide and subjected to liquid chromatography-fluorescence-tandem mass spectrometry (HILIC-FLR-MSn). Twenty-one types of mono-/oligo-galacturonides having DP values of 1–10 were found to contain nonesterified monomers, dimers, and trimers, as well as oligomers with 1 to 6 methyl-ester groups. In these oligo-galacturonides, MSn analysis demonstrated that the number of methyl-ester groups in the continuous sequence was 2 to 5. Mono- and di-esterified oligomers had higher percentages in total methyl-esterified groups, suggesting that these are a random methyl-esterification pattern in these HG pectins. Our study analyzes the characteristics of the methyl-esterification pattern in naturally occurring plant-derived HG pectins and findings that will be useful for further studying HG structure-function relationships.

Milk: A Scientific Model for Diet and Health Research in the 21st Century

The origin of lactation and the composition, structures and functions of milk's biopolymers highlight the Darwinian pressure on lactation as a complete, nourishing and protective diet. Lactation, under the driving pressure to be a sustainable bioreactor, was under selection pressure of its biopolymers with diverse functions acting from the mammary gland through the digestive system of the infant. For example, milk is extensively glycosylated and the glycan structures and their functions are now emerging. Milk contains free oligosaccharides; complex polymers of sugars whose stereospecific linkages are not matched by glycosidic enzymes within the mammalian infant gut. These glycan polymers reach the lower intestine undigested. In this microbe-rich environment, bacteria compete to release and ferment the sugars via different hydrolytic strategies. One specific type of bacteria, Bifidobacterium longum subsp. infantis, (B. infantis) is uniquely equipped with a repertoire of genes encoding enzymes capable of taking up, hydrolyzing and metabolizing the complex glycans of human milk. This combination of a distinct food supply and unique genetic capability shapes the composition and metabolic products of the entire microbial community within the lower intestine of breast fed infants. The intestinal microbiome dominated by B. infantis, shields the infant from the growth of gram negative enteropathogens and their endotoxins as a clear health benefit. The world is facing unprecedented challenges to produce a food supply that is both nourishing, safe and sustainable. Scientists need to guide the future of agriculture and food in response to these 21st century challenges. Lactation provides an inspiring model of what that future research strategy could be.

Biocatalytic quantification of α‐glucan in marine particulate organic matter

Marine algae drive the marine carbon cycle, converting carbon dioxide into organic material. A major component of this produced biomass is a variety of glycans. Marine α‐glucans include a range of storage glycans from red and green algae, bacteria, fungi, and animals. Although these compounds are likely to account for a high amount of the carbon stored in the oceans they have not been quantified in marine samples so far. Here we present a method to extract and quantify α‐glucans (and compare it with the β‐glucan laminarin) in particulate organic matter from algal cultures and environmental samples using sequential physicochemical extraction and enzymes as α‐glucan‐specific probes. This enzymatic assay is more specific and less susceptible to side reactions than chemical hydrolysis. Using HPAEC‐PAD to detect the hydrolysis products allows for a glycan quantification in particulate marine samples down to a concentration of ≈2 µg/L. We measured glucans in three cultured microalgae as well as in marine particulate organic matter from the North Sea and western North Atlantic Ocean. While the β‐glucan laminarin from diatoms and brown algae is an essential component of marine carbon turnover, our results further indicate the significant contribution of starch‐like α‐glucans to marine particulate organic matter. Henceforth, the combination of glycan‐linkage‐specific enzymes and chromatographic hydrolysis product detection can provide a powerful tool in the exploration of marine glycans and their role in the global carbon cycle.

Structural Elucidation, Modification, and Structure-Activity Relationship of Polysaccharides in Chinese Herbs: A Review

Chinese herbal polysaccharides (CHPs) are natural polymers composed of monosaccharides, which are widely found in Chinese herbs and work as one of the important active ingredients. Its biological activity is attributed to its complex chemical structure with diverse spatial conformations. However, the structural elucidation is the foundation but a bottleneck problem because the majority of CHPs are heteropolysaccharides with more complex structures. Similarly, the studies on the relationship between structure and function of CHPs are even more scarce. Therefore, this review summarizes the structure-activity relationship of CHPs. Meanwhile, we reviewed the structural elucidation strategies and some new progress especially in the advanced structural analysis methods. The characteristics and applicable scopes of various methods are compared to provide reference for selecting the most efficient method and developing new hyphenated techniques. Additionally, the principle structural modification methods of CHPs and their effects on activity are summarized. The shortcomings, potential breakthroughs, and developing directions of the study of CHPs are discussed. We hope to provide a reference for further research and promote the application of CHPs.

Using Molecular Tools to Understand Microbial Carbonates

Here we review the application of molecular biological approaches to mineral precipitation in modern marine microbialites. The review focuses on the nearly two decades of nucleotide sequencing studies of the microbialites of Shark Bay, Australia; and The Bahamas. Molecular methods have successfully characterized the overall community composition of mats, pinpointed microbes involved in key metabolisms, and revealed patterns in the distributions of microbial groups and functional genes. Molecular tools have become widely accessible, and we can now aim to establish firmer links between microbes and mineralization. Two promising future directions include “zooming in” to assess the roles of specific organisms, microbial groups, and surfaces in carbonate biomineralization and “zooming out” to consider broader spans of space and time. A middle ground between the two can include model systems that contain representatives of important microbial groups, processes, and metabolisms in mats and simplify hypothesis testing. These directions will benefit from expanding reference datasets of marine microbes and enzymes and enrichments of representative microbes from mats. Such applications of molecular tools should improve our ability to interpret ancient and modern microbialites and increase the utility of these rocks as long-term recorders of microbial processes and environmental chemistry.

The Development of the Davis Food Glycopedia-A Glycan Encyclopedia of Food

The molecular complexity of the carbohydrates consumed by humans has been deceptively oversimplified due to a lack of analytical methods that possess the throughput, sensitivity, and resolution required to provide quantitative structural information. However, such information is becoming an integral part of understanding how specific glycan structures impact health through their interaction with the gut microbiome and host physiology. This work presents a detailed catalogue of the glycans present in complementary foods commonly consumed by toddlers during weaning and foods commonly consumed by American adults. The monosaccharide compositions of over 800 foods from diverse food groups including Fruits, Vegetables, Grain Products, Beans, Peas, Other Legumes, Nuts, Seeds; Sugars, Sweets and Beverages; Animal Products, and more were obtained and used to construct the “Davis Food Glycopedia” (DFG), an open-access database that provides quantitative structural information on the carbohydrates in food. While many foods within the same group possessed similar compositions, hierarchical clustering analysis revealed similarities between different groups as well. Such a Glycopedia can be used to formulate diets rich in specific monosaccharide residues to provide a more targeted modulation of the gut microbiome, thereby opening the door for a new class of prophylactic or therapeutic diets.

Food glycomics: Dealing with unexpected degradation of oligosaccharides during sample preparation and analysis

This study reveals that unexpected degradation of food oligosaccharides can occur during conventional glycomics workflows, including sample preparation and analysis by liquid chromatography-mass spectrometry (LC-MS). With the present investigation, we aim to alert the scientific community of the susceptibility of specific glycosidic linkages to degradation induced by heat and acid. Key standard oligosaccharides representing the major types found in foods (3'-sialyllactose and 6'-sialyl-N-acetyllactosamine for milk, raffinose and stachyose for legumes) were selected as model systems and underwent each of the following treatments independently: (1) labeled with the derivatizing agent 1-aminopyrene-3,6,8-trisulfonic (APTS) (followed by analysis with a capillary electrophoresis system coupled with a fluorescence detector), (2) dried from an acetonitrile-water mixture containing 0.1% trifluoroacetic acid, and (3) injected into an LC-MS system. We demonstrated that both raffinose and stachyose degraded during APTS-labeling by the acid in the labeling reagents. We also discovered that during centrifugal evaporation at 37 °C, all of the four nonderivatized oligosaccharides tested were partially degraded. Additionally, when the LC-MS eluent contained 0.1% formic acid, 3'-sialyllactose, raffinose, and stachyose underwent extensive in-source fragmentation during analysis. Lastly, we identified a simple strategy that can reduce the probability of incorrect oligosaccharide identification resulting from extensive in-source fragmentation.

Oligosaccharide mapping analysis by HILIC-ESI-HCD-MS/MS for structural elucidation of fucoidan from sea cucumber Holothuria floridana

The elucidation of precise structure of fucoidan is essential for understanding their structure-function relationship and promoting the development of marine drugs. In this work, we firstly reported the oligosaccharide mapping of fucoidan from Holothuria floridana using a combination of hydrothermal depolymerization, hydrophilic interaction liquid chromatography (HILIC) coupled with electrospray mass spectrometry (ESI-FTMS) and high energy collision-induced dissociation (HCD-MS/MS) and 2D NMR analysis. With careful selection of fully deprotonated molecular ions of fucoidan oligosaccharides and their NaBD₄ reduced alditols, HILIC-ESI-HCD-MS/MS provided structurally relevant glycosidic product ions with no sulfate loss for definitive assignment of sequence and sulfation pattern of all the oligosaccharides and their isomers from dp2 to dp7 from hydrothermal depolymerization. The oligosaccharide mapping clarified the structure of fucoidan with various oligosaccharide domains with 2,4-di-O-sulfated and 2-O sulfated fucose residues.

A host guest interaction enhanced polymerization amplification for electrochemical detection of cocaine

Cocaine (Coc) is one of the illegal drugs and is harmful to digestive, immune, cardiovascular and urogenital systems. To achieve drug abuse control and legal action, it is essential to develop an effective method for cocaine analysis. In this work, an aptasensor has been developed using atom transfer radical polymerization (ATRP) based on host-guest chemistry for electrochemical analysis of cocaine. The NH₂-DNA (Apt1) was immobilized on the indium tin oxide (ITO) electrode via addition reaction, and Fc-DNA (Apt2) was introduced to ITO relying on the specific recognition of cocaine. The Apt2 can initiate host-guest chemistry between Apt2 and ATRP initiators (β-CD-Br₁₅), then the β-CD-Br₁₅ further triggers ATRP. Moreover, ATRP avoids the sluggish kinetics and poor coupling capability sustained. The result shows a sensitive and selective analysis of cocaine within a linear range from 0.1 ng/mL to 10 μg/mL (R² = 0.9985), with the detection limit down to 0.0335 ng/mL. Thus, this strategy provides a universal method for the analysis of illegal drugs.

A Multidimensional Mass Spectrometry-Based Workflow for De Novo Structural Elucidation of Oligosaccharides from Polysaccharides

Carbohydrates play essential roles in a variety of biological processes that are dictated by their structures. However, characterization of carbohydrate structures remains extremely difficult and generally unsolved. In this work, a de novo mass spectrometry-based workflow was developed to isolate and structurally elucidate oligosaccharides to provide sequence, monosaccharide compositions, and glycosidic linkage positions. The approach employs liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based methods in a 3-dimensional concept: one high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-QTOF MS) analysis for oligosaccharide sequencing and two ultra high performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-QqQ MS) analyses on fractionated oligosaccharides to determine their monosaccharides and linkages compositions. The workflow was validated by applying the procedure to maltooligosaccharide standards. The approach was then used to determine the structures of oligosaccharides derived from polysaccharide standards and whole food products. The integrated LC-MS workflow will reveal the in-depth structures of oligosaccharides.

Chemical Constituents and their Anti-Tumor Mechanism of Plants from Artemisia

BACKGROUND

At present, chemotherapy is still the main treatment method for cancer, but its side effects and multidrug resistance limit the therapeutic effect seriously. Now the screening of anti-tumor drugs with higher efficiency and lower toxicity from natural products is one of the important research directions for oncotherapy. Artemisia has a variety of anti-tumor constituents, which can exert its anti-tumor effect by inducing tumor cell apoptosis, inhibiting tumor angiogenesis, arresting cell cycle, accelerating iron ion-mediated oxidative damage, etc. Objective: This paper will provide a focused, up-to-date and comprehensive overview of the anti-tumor active constituents and their mechanisms of plants in Artemisia.

METHOD

The relevant information about Artemisia and its bioactive components comes from scientific databases (such as PubMed, Web of Science, Science Direct).

RESULTS

Here we have discussed the present situation and mechanism of bioactive components of Artemisia in anti-tumor. The application prospect of active components of Artemisia in cancer prevention and treatment was investigated.

CONCLUSION

The information summarized in this review may provide new ideas for the follow-up treatment of cancer and contribute to the development of new, effective, multi-side effects and fewer side effects of antineoplastic drugs.

A specific and bioactive polysaccharide marker for Cordyceps

Cordyceps is one of the most expensive and widely used functional foods. But the authenticity is still a concern due to the lack of appropriate markers. By targeting polysaccharides, this study aimed to develop a specific, and bioactive marker for Cordyceps. Firstly, the results of screening tests of 250 samples by examining both genetic markers and polysaccharide profile showed that a unique polysaccharide fraction (named CCP) was particular to the caterpillar parts. Its potential as a marker was further demonstrated by its ability to induce NO and cytokine production in RAW 264.7 cells. CCP was characterized to be an α-1,4-glucan with a branch at C-6 by the conventional structure analyzing and de novo oligosaccharides sequencing. The content of CCP was closely correlated to the traditional classification criteria. Generally, CCP was a marker that simultaneously enables qualitative and quantitative analysis of Cordyceps.

Polysaccharide identification through oligosaccharide fingerprinting

The identification of polysaccharide structures in complex samples remains a unique challenge complicated by the lack of specific tools for polymeric mixtures. In this work, we present a method that depolymerizes polysaccharides to generate diagnostic oligosaccharide markers that are then analyzed by high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-QTOF MS). Rapid identification of food polysaccharides was performed by aligning the identified oligosaccharides with a library of oligosaccharide markers generated from standard polysaccharides. Measurements of standard and food polysaccharides were performed to obtain the contributions of the identified polysaccharides using percent peak coverage and angle cosine methods. The method was validated using a synthetic mixture of standard polysaccharides while the reproducibility was confirmed with experimental triplicates of butternut squash samples, where standard deviation was less than 3% for the relative abundance of oligosaccharides. The method was further employed to examine diverse set of food samples.