Revisiting monosaccharide analysis - quantitation of a comprehensive set of monosaccharides using dynamic multiple reaction monitoring

Seaweed-derived fucoidans and rhamnan sulfates serve as potent anti-SARS-CoV-2 agents with potential for prophylaxis

Seaweeds represent a rich source of sulfated polysaccharides with similarity to heparan sulfate, a facilitator of myriad virus host cell attachment. For this reason, attention has been drawn to their antiviral activity, including the potential for anti-SARS-CoV-2 activity. We have identified and structurally characterized several fucoidan extracts, including those from different species of brown macroalga, and a rhamnan sulfate from a green macroalga species. A high molecular weight fucoidan extracted from Saccharina japonica (FSjRPI-27), and a rhamnan sulfate extracted from Monostroma nitidum (RSMn), showed potent competitive inhibition of spike glycoprotein receptor binding to a heparin-coated SPR chip. This inhibition was also observed in cell-based assays using hACE2 HEK-293 T cells infected by pseudotyped SARS-CoV-2 virus with IC50 values <1 μg/mL. Effectiveness was demonstrated in vivo using hACE2-transgenic mice. Intranasal administration of FSjRPI-27 showed protection when dosed 6 h prior to and at infection, and then every 2 days post-infection, with 100 % survival and no toxicity at 104 plaque-forming units per mouse vs. buffer control. At 5-fold higher virus dose, FSjRPI-27 reduced mortality and yielded reduced viral titers in bronchioalveolar fluid and lung homogenates vs. buffer control. These findings suggest the potential application of seaweed-based sulfated polysaccharides as promising anti-SARS-CoV-2 prophylactics.

Polysaccharide structure evaluation of Ganoderma lucidum from different regions in China based on an innovative extraction strategy

The polysaccharides and triterpenes are important functional components of Ganoderma lucidum, but traditional preparation process of G. lucidum functional components can only realize the preparation of single functional component, which has poor targeting and low efficiency. In this study, the existence state of the functional components of G. lucidum was revealed. Then, the single step extraction process for functional components was established, and the precise structure evaluation of polysaccharide and triterpenes was conducted based on the process. The results showed that preparation time required for this strategy is only one-sixth of the traditional one, and 50 % of raw materials can be saved. Structural analysis of the functional components revealed that triterpenes were mainly Ganoderic acid and Lucidenic acid, and the polysaccharide structure was mainly 1,3-glucan and 1,3,6-glucan. The establishment of single step extraction strategy and the evaluation of the fine structure of functional components improved the efficiency of preparation and result determination, and provided an important basis for the development and utilization of green and low-carbon G. lucidum and even edible fungi resources and human nutritional dietary improvement strategies.

Physiochemical changes, metabolite discrepancies of brown seaweed-derived sulphated polysaccharides in the upper gastrointestinal tract and their effects on bioactive expression

Brown seaweed-derived polysaccharides, notably fucoidan and laminarin, are known for their extensive array of bioactivities and physicochemical properties. However, the effects of upper digestive tract modification on the bioactive performance of fucoidan and laminarin fractions (FLFs) sourced from Australian native species are largely unknown. Here, the digestibility and bioaccessibility of FLFs were evaluated by tracking the dynamic changes in reducing sugar content (CR), profiling the free monosaccharide composition using LC-MS, and comparing high-performance gel permeation chromatography profile variation via LC-SEC-RI. The effects of digestive progression on bioactive performance were assessed by comparing the antioxidant and antidiabetic potential of FLFs and FLF digesta. We observed that molecular weight (Mw) decreased during gastric digestion indicating that FLF aggregates were disrupted in the stomach. During intestinal digestion, Mw gradually decreased and CR increased indicating cleavage of glycosidic bonds releasing free sugars. Although the antioxidant and antidiabetic capacities were not eliminated by the digestion progression, the bioactive performance of FLFs under a digestive environment was reduced contrasting with the same concentration level of the undigested FLFs. These data provide comprehensive information on the digestibility and bioaccessibility of FLFs, and shed light on the effects of digestive progression on bioactive expression.

Sensitive, precise fingerprint profiling for monosaccharide analysis of Bacillus Calmette-Guérin polysaccharide and nucleic acid isolates

A sensitive and precise HPLC-DAD method with pre-column PMP derivatization was established and validated, for analyzing the polysaccharides in Bacillus Calmette-Guérin polysaccharide and nucleic acid (BCG-PSN) isolates, after acid hydrolysis. And the HPLC fingerprint profiling was used to analyze its monosaccharide composition. The monosaccharide concentration-peak area calibration curve was of good linearity (R2 > 0.99), over the range of 0.016-0.08 mg/mL for mannose or 0.24-1.20 mg/mL for glucose, with high recovery of 93-105 % for quality control samples. The intra-day RSD values of mannose and glucose concentration were less than 2.5 % and 2.1 %, respectively, and their inter-day RSD values were less than 4.3 % and 2.2 %, respectively, and remained stable for up to 14 days. This method also remained durable against changes in chromatographic parameters, but it's susceptible to the flow rate of mobile phase. Additionally, the method was applied to analyze the content of mannose and glucose in 22 batches BCG-PSN powder and 17 batches BCG-PSN injection. The results showed that the HPLC-DAD fingerprint spectra of all the BCG-PSN powder and BCG-PSN injection samples had a high degree of similarity, with the similar indexes up to 0.999 and 0.998, respectively. The HPLC-DAD method with pre-column PMP derivatization is highly rapid, effective, visual, and accurate for determination of monosaccharide contents. The validated method was successfully applied to the analysis of polysaccharide in both BCG-PSN powder and injection.

Extensive Analysis of Mulberry (Morus rubra L.) Polysaccharides with Different Maturities by Using Two-Step Extraction and LC/QqQ-MS

A primary challenge of polysaccharide analysis is the need for comprehensive extraction and characterization methods. In this study, mulberry polysaccharides at different maturities were fully extracted through a two-step process involving ethylenediaminetetraacetic acid (EDTA) and sodium hydroxide (NaOH), and their structures were determined by a combination analysis of monosaccharides and glycosidic linkages based on liquid chromatography triple quadrupole mass spectrometry (LC/QqQ-MS). The results indicate mulberry polysaccharides mainly contain highly branched pectic polysaccharides, (1,3,6)-linked glucan, xylan, and xyloglucan, but the content of different portions varies at different maturity stages. HG decreases from 19.12 and 19.14% (green mulberry) to 9.80 and 6.08% (red mulberry) but increases to 17.83 and 11.83% as mulberry transitioned from red to black. In contrast, the contents of glucan showed opposite trends. When mulberry turns red to black, the RG-I arabinan chains decrease from 47.75 and 28.86% to 13.16 and 12.72%, while the galactan side chains increase from 1.18 and 1.91 to 8.3 and 6.49%, xylan and xyloglucan show an increase in content. Overall, the two-step extraction combined with LC/QqQ-MS provides a new strategy for extensive analysis of complex plant polysaccharides.

Quantifying Gut Microbial Short-Chain Fatty Acids and Their Isotopomers in Mechanistic Studies Using a Rapid, Readily Expandable LC-MS Platform

Short-chain fatty acids (SCFAs) comprise the largest group of gut microbial fermentation products. While absorption of most nutrients occurs in the small intestine, indigestible dietary components, such as fiber, reach the colon and are processed by the gut microbiome to produce a wide array of metabolites that influence host physiology. Numerous studies have implicated SCFAs as key modulators of host health, such as in regulating irritable bowel syndrome (IBS). However, robust methods are still required for their detection and quantitation to meet the demands of biological studies probing the complex interplay of the gut-host-health paradigm. In this study, a sensitive, rapid-throughput, and readily expandible UHPLC-QqQ-MS platform using 2-PA derivatization was developed for the quantitation of gut-microbially derived SCFAs, related metabolites, and isotopically labeled homologues. The utility of this platform was then demonstrated by investigating the production of SCFAs in cecal contents from mice feeding studies, human fecal bioreactors, and fecal/bacterial fermentations of isotopically labeled dietary carbohydrates. Overall, the workflow proposed in this study serves as an invaluable tool for the rapidly expanding gut-microbiome and precision nutrition research field.

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.

Eat your beets: Conversion of polysaccharides into oligosaccharides for enhanced bioactivity

Bioactive oligosaccharides with the potential to improve human health, especially in modulating gut microbiota via prebiotic activity, are available from few natural sources. This work uses polysaccharide oxidative cleavage to generate oligosaccharides from beet pulp, an agroindustry by-product. A scalable membrane filtration approach was applied to purify the oligosaccharides for subsequent in vitro functional testing. The combined use of nano-LC/Chip Q-TOF MS and UHPLC/QqQ MS allowed the evaluation of the oligosaccharide profile and their monosaccharide complexity. A final product containing roughly 40 g of oligosaccharide was obtained from 475 g of carbohydrates. Microbiological bioactivity assays indicated that the product obtained herein stimulated desirable commensal gut bacteria. This rapid, reproducible, and scalable method represents a breakthrough in the food industry for generating potential prebiotic ingredients from common plant by-products at scale. INDUSTRIAL RELEVANCE: This work proposes an innovative technology based on polysaccharide oxidative cleavage and multi-stage membrane purification to produce potential prebiotic oligosaccharides from renewable sources. It also provides critical information to evidence the prebiotic potential of the newly generated oligosaccharides on the growth promotion ability of representative probiotic strains of bifidobacteria and lactobacilli.

Campylobacter jejuni uses energy taxis and a dehydrogenase enzyme for l-fucose chemotaxis

IMPORTANCE

In this study, we identify a separate role for the Campylobacter jejuni l-fucose dehydrogenase in l-fucose chemotaxis and demonstrate that this mechanism is not only limited to C. jejuni but is also present in Burkholderia multivorans. We now hypothesize that l-fucose energy taxis may contribute to the reduction of l-fucose-metabolizing strains of C. jejuni from the gastrointestinal tract of breastfed infants, selecting for isolates with increased colonization potential.

Precolumn derivatization LC-MS/MS method to simultaneous quantitation of 10 monosaccharides in rat plasma

Monosaccharides are essential for maintaining the normal physiological functions of living organisms. Under disease states, metabolic disorders in vivo will inevitably affect the levels of monosaccharides, which brings the possibility of monosaccharides as a biomarker of some diseases. In this study, a method was developed and validated for simultaneously determining 10 monosaccharides (glucose, galactose, mannose, rhamnose, fucose, xylose, iduronic acid, glucuronic acid, N-acetylgalactosamine and N-acetylglucosamine) in SD rat plasma using liquid chromatography-tandem mass spectrometry. The method employed 1-phenyl-3-methyl-5-pyrazolone (PMP) as a derivatization reagent, considerably improved the chromatographic retention and ionization efficiency of monosaccharides. After protein precipitation of plasma samples, monosaccharides and isotope internal standards were derivatized and liquid-liquid extraction was performed to remove excess PMP. To achieve the baseline separation of several isomers, the resulting derivatives were chromatographed on a Bridged ethyl hybrid (BEH) Phenyl column using gradient elution with a total run time of 8 min. The method was linear within the range of 0.0100-5.00 μg/mL for rhamnose, 0.0500-25.0 μg/mL for fucose, xylose, iduronic acid, glucuronic acid, N-acetylgalactosamine and N-acetylglucosamine, 1.00-500 μg/mL for galactose, 10.0-5000 μg/mL for mannose, and 50.0-25,000 μg/mL for glucose. And the accuracy and precision verification of surrogate matrix samples and plasma samples met the required criteria. The method has been used successfully to study the effect of hepatic insufficiency on monosaccharide levels in rats. It was found that the concentration of glucuronic acid in SD rat plasma was abnormally increased in rats with liver injury.

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.

An Acidic Heteropolysaccharide Isolated from Pueraria lobata and Its Bioactivities

A novel water-soluble acidic heteropolysaccharide, called PPL-1, was purified from Pueraria lobata. PPL-1 had an average molecular weight of 35 Kad, and it was composed of glucose, arabinose, galactose and galacturonic acid (6.3:0.8:0.8:2.1). In accordance with methylation and nuclear magnetic resonance analyses, PPL-1 primarily consisted of (1→2)-linked α-Araf, (1→4)-linked α-Glcp, (1→)-linked β-Glcp, (1→6)-linked α-Glcp, (1→3,6)-linked α-Galp, (1→)-linked β-GalpA and (1→4)-linked α-GalpA. In terms of bioactivities, PPL-1 exhibited remarkable scavenging ability towards DPPH (1,1-Diphenyl-2-picrylhydrazyl) radicals and moderate activity by enhancing the proliferation rate of RAW 264.7 cells by approximately 30% along with the secretion of NO. This work demonstrates that PPL-1 can be a potential source of immunoenhancers and antioxidants.

[Advances in heparin structural analysis by chromatography technologies]

Heparin （Hp） is the most widely used anticoagulant drug in the clinics， with an annual global output of over 10 billion dollars. Hp， a member of the glycosaminoglycans （GAGs）， is prepared from porcine intestinal mucosa via extraction， separation， and purification. Hp is a linear polysaccharide with repeating disaccharide units. Low-molecular-weight heparins （LMWHs） are depolymerized from Hp via chemical or enzymatic degradation. Compared with Hp， LMWHs exhibit less bleeding side effect， milder immunogenicity， and higher bioavailability when injected subcutaneously. In general， Hps， including LMWHs， are high complex drugs with large molecular weights （MWs）， inhomogeneous MW distributions， and structural heterogeneity， including different degrees and locations of sulfonation， and unique residues generated from different production processes. Thus， developing efficient analytical methods to elucidate the structures of Hps and characterize or quantitate their properties is extremely challenging. Unfortunately， this problem limits their quality control， production optimization， clinical safety monitoring， and new applications. Research has constantly sought to elucidate the complicated structures of Hp drugs. Among the structural analysis and quality control methods of Hp currently available， chromatographic methods are the most widely studied and used. However， no literature thoroughly summarizes the specific applications of chromatographic methods in the structural analysis， manufacturing process， and quality control of Hp drugs. This paper systematically organizes and describes recent research progresses of the chromatographic methods used to analyze Hp drugs， including the identification and composition of monosaccharides， disaccharides， oligosaccharides， and polysaccharides. The applications， innovations， and limitations of these chromatographic methods are also summarized in this review. The insights obtained in this study will help production and quality control personnel， as well as drug researchers， obtain a deeper understanding of the complex structures of Hp drugs. This paper also provides a comprehensive reference for the structural analysis and quality control of Hps， proposes ideas for the development of new quality control methods， and lays a strong foundation for the in-depth structural elucidation of Hp drugs.

Extraction, Characterization, and Antioxidant Activity of Polysaccharides from Ajwa Seed and Flesh

The date palm has been cultivated in dry and hot areas of the planet for much of human history. In the Kingdom of Saudi Arabia, dates are the main crop used as a source of food. Among several species of date fruits, the Ajwa AL-Madinah date is unique, growing only in Al-Madinah geographical region. The Ajwa date is used in traditional medicine due to its abundant active components and therapeutic properties. This study investigates the structural properties and the antioxidant effects of water-soluble polysaccharides extracted from Ajwa flesh and seed. The polysaccharides were isolated by two techniques including hot water and ultrasonic extraction. After isolation and partial purification, the physicochemical properties of four samples of polysaccharides extracted from flesh and seed were studied by several techniques including FTIR, solid-state NMR, elemental analysis, and mass spectrometry. Several radical scavenging experiments were combined to study the antioxidant activity of the polysaccharide compounds. FTIR and NMR results showed a structure typical of heterogeneous polysaccharides. Mass spectrometry revealed that the polysaccharide samples were composed mainly of mannose, glucose, galactose, xylose, arabinose, galacturonic acid, and fucose. In addition, the physicochemical properties and composition of polysaccharides extracted from flesh and seed were compared. The extracted polysaccharides showed antioxidant activity, with 2, 2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, Fe chelating ability, hydroxyl free radical scavenging ability, and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging. These results highlight their potential to be a useful nutritional element or supplemental medication.

Bacterial chemotaxis in human diseases

To infect and cause disease, bacterial pathogens must localize to specific regions of the host where they possess the metabolic and defensive acumen for survival. Motile flagellated pathogens exercise control over their localization through chemotaxis to direct motility based on the landscape of exogenous nutrients, toxins, and molecular cues sensed within the host. Here, we review advances in understanding the roles chemotaxis plays in human diseases. Chemotaxis drives pathogen colonization to sites of inflammation and injury and mediates fitness advantages through accessing host-derived nutrients from damaged tissue. Injury tropism may worsen clinical outcomes through instigating chronic inflammation and subsequent cancer development. Inhibiting bacterial chemotactic systems could act synergistically with antibacterial medicines for more effective and specific eradication.

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.

The determination of monosaccharide in different years Qingzhuan Dark Tea polysaccharide by liquid chromatography-mass spectrometry

AIM

To establish a fast, sensitive and accurate high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for determining the monosaccharide content of Qingzhuan Dark Tea polysaccharides in different years (2 years, 5 years and 11 years).

METHODS

The optimised chromatographic conditions were achieved on a C18 column (5.0 μm, 250 mm × 4.6 mm inner diameter). The mobile phase flow rate was 0.9 mL/min and the column temperature was set to 27°C. The aqueous phase A (5 mM aqueous ammonium acetate) and organic phase B (acetonitrile) were used to elute the target analyses isocratically (0-60 min: 18% B). The mass spectrometer detector was equipped with an electron spray ionisation (ESI)source, and multiple reaction monitoring (MRM) mode was used for the determination of 1-phenyl-3-methyl-5-pyrazolone (PMP) derived monosaccharides.

RESULTS

We carried out a comprehensive methodological validation of PMP derived monosaccharides, including linearity, precision, stability and repeatability. Nine monosaccharides (rhamnose, mannose, ribose, glucose, galacturonic acid, xylose, galactose, fucose and arabinose) of Qingzhuan Dark Tea polysaccharides were identified, in which ribose and fucose were reported for the first time. The results showed the contents of these nine monosaccharides differed significantly among different years.

CONCLUSIONS

The validated method is reliable, accurate, repeatable and can be applied to quality assessment of these monosaccharides.

Microbiota drive insoluble polysaccharides utilization via microbiome-metabolome interplay during Pu-erh tea fermentation

Polysaccharides are abundant components in Pu-erh tea, yet the utilization of insoluble polysaccharides under the actions of microbiota has rarely been studied. The aim of this work was to study how insoluble polysaccharides were utilized during fermentation through the investigation of the variations and correlation of microbiota with polysaccharides degradation products. Genomics study revealed the significant changes of microbiota. Metabolomics analysis showed monosaccharides (types 1 and 3) were consumed during early and middle fermentation stages, while carboxylic acids and other monosaccharides (type 2) were accumulated at middle and late pile-fermentation stages. Correlation revealed that type 1 and 3 monosaccharides, which act as energy providers, were positively associated with Aspergillus, while type 2 monosaccharides possessing multiple bioactivities and carboxylic acids influencing tea taste were positively related to Rasamsonia, Thermomyces, Bacillaceae, and Lactobacillaceae. This study would be beneficial to improve production efficiency and provide basis for quality control of Pu-erh tea fermentation.

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.

A High Throughput Lipidomics Method Using Scheduled Multiple Reaction Monitoring

Lipid compositions of cells, tissues, and bio-fluids are complex, with varying concentrations and structural diversity making their identification challenging. Newer methods for comprehensive analysis of lipids are thus necessary. Herein, we propose a targeted-mass spectrometry based lipidomics screening method using a combination of variable retention time window and relative dwell time weightage. Using this method, we identified more than 1000 lipid species within 24-min. The limit of detection varied from the femtomolar to the nanomolar range. About 883 lipid species were detected with a coefficient of variance <30%. We used this method to identify plasma lipids altered due to vitamin B12 deficiency and found a total of 18 lipid species to be altered. Some of the lipid species with ω-6 fatty acid chains were found to be significantly increased while ω-3 decreased in vitamin B12 deficient samples. This method enables rapid screening of a large number of lipid species in a single experiment and would substantially advance our understanding of the role of lipids in biological processes.

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.

Comparative study for analysis of carbohydrates in biological samples

This work presents a comparative study for the analysis of carbohydrates for four common chromatographic methods, each coupled to mass spectrometry. Supercritical fluid chromatography (SFC), hydrophilic interaction liquid chromatography (HILIC), reversed-phase liquid chromatography (RP-LC) and gas chromatography (GC) with detection by triple quadrupole mass spectrometer (QqQ-MS) are compared. It is shown that gas chromatography and reversed-phase liquid chromatography, each after derivatisation, are superior to the other two methods in terms of separation performance. Furthermore, comparing the different working modes of the mass spectrometer, it can be determined that a targeted analysis, i.e. moving from full scan to single ion monitoring (SIM) and multiple reaction monitoring (MRM), results in an improvement in the sensitivity as well as the repeatability of the method, which has deficiencies especially in the analysis using HILIC. Overall, RP-LC-MS in MRM after derivatisation with 1-phenyl-3-methyl-5-pyrazolone (PMP) proved to be the most suitable method in terms of separation performance, sensitivity and repeatability for the analysis of monosaccharides. Detection limits in the nanomolar range were achieved, which corresponds to a mass concentration in the low µg/L range. The applicability of this method to different biological samples was investigated with various herbal liquors, pectins and a human glycoprotein.

Paired Derivatization Approach with H/D-Labeled Hydroxylamine Reagents for Sensitive and Accurate Analysis of Monosaccharides by Liquid Chromatography Tandem Mass Spectrometry

Monosaccharides play important roles in biological processes. Sensitive and accurate analyses of monosaccharides remain challenging because of their high hydrophilicities and poor ionization efficiencies. Here, we developed a paired derivatization approach with H/D-labeled hydroxylamines for simultaneous quantification of 12 monosaccharides by liquid chromatography tandem mass spectrometry (LC-MS/MS). O-(4-Methoxybenzyl)hydroxylamine hydrochloride (4-MOBHA·HCl) showed higher derivatization efficiency for monosaccharides compared to six other hydroxylamine analogues. The derivatization of monosaccharides was readily achieved in an aqueous solution. Furthermore, the deuterium-labeled isotope reagent, d₃-4-MOBHA·HCl, was newly synthesized to stably label monosaccharides to improve its accuracy and precision in complex matrix analysis. As a result, 12 monosaccharides were rapidly detected by LC-MS/MS within 16 min with significant improvements in chromatographic separation and retention time. The detection sensitivity increased by 83 to 1600-fold with limits of quantitation ranging from 0.25 to 3.00 fmol. With the paired derivatization strategy, the monosaccharides could be accurately quantified with good linearity (R² > 0.99) and satisfactory accuracy (recoveries: 85-110%). Using this method, we achieved sensitive and accurate quantification of the monosaccharide composition of herbal polysaccharides and the change in monosaccharide levels in human cell lines under physiopathological conditions. More importantly, the developed method was able to differentiate between the levels of the monosaccharides in fecal samples of human ulcerative colitis (UC) patients and UC mice compared to their respective controls. The differential monosaccharides determined in human feces provided a good diagnostic performance in distinguishing the UC patients from healthy individuals, showing potential for clinical application.

Glycosaminoglycan Quality Control by Monosaccharide Analysis

Glycosaminoglycans (GAGs) are heterogeneous biomacromolecules made by all animal cells with overlapping molecular weight and high negative charge densities, which make thorough separation of different types of GAGs and elimination of all GAG-binding proteins difficult. Even with the constant challenge of quality control, chondroitin sulfate, dermatan sulfate, heparan sulfate, and heparin glycosaminoglycans (GAGs) have been used as nutraceuticals and modern drugs for many years worldwide. Testing galactosamine in heparin has been added to the USP monograph after contaminated heparin event, but the general monosaccharide composition analysis has not been developed for GAG quality control purposes. Using a PCR-facilitated hydrolysis assay, the hydrolyzed GAG saccharides were labeled with 1-phenyl-3-methyl-5-pyrazolone (PMP) and quantified by high performance liquid chromatography (HPLC) coupled with mass spectrometry (MS). Glucosamine was found in both chondroitin sulfate and dermatan sulfate whereas galactosamine was observed in both heparan sulfate and heparin, indicating the cross contamination among different types of GAGs. Moreover, fucose was detected in chondroitin sulfate, dermatan sulfate, and heparan sulfate, and both fucose and mannose were detected in chondroitin sulfate, suggesting the co-presence of other types of glycans or novel fucosylated GAG structures. Furthermore, both the amount and structure of acid-resistant disaccharides provide distinguishable features for each type of GAGs at the same hydrolysis condition. Thus, monosaccharide analysis provides a practical and quantitative way for GAG quality control.

A novel LC-MS/MS method for complete composition analysis of polysaccharides by aldononitrile acetate and multiple reaction monitoring

Carbohydrate analysis has always been a challenging task due to the occurrence of high polarity and multiple isomers. Aldoses are commonly analyzed by gas liquid chromatography (GLC) following aldononitrile acetate derivatization (AND). However, the GLC technique cannot be applied for the simultaneous determination of aldoses, ketoses, and uronic acids. In this study, a new method based on the combination of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and AND is developed for the complete characterization of monosaccharide composition (i.e., aldoses, ketoses, alditols, amino sugars, and uronic acids) in plant-derived polysaccharides. In addition to discussing the possible byproducts, the study optimizes the multiple reaction monitoring (MRM) parameters and LC conditions. The final separation of 17 carbohydrates is performed on a BEH Shield RP18 column (150 mm × 2.1 mm, 1.7 μm) within 25 min, without using any buffer salt. Notably, the complex polysaccharides extracted from Ligusticum chuanxiong, Platycodon grandiflorum, Cyathula officinalis Kuan, Juglans mandshurica Maxim, and Aralia elata (Miq.). Seem bud can be successfully characterized using the developed method. Overall, the results demonstrated that the newly established LC-MS/MS MRM method is more effective and powerful than the GLC-based methods reported previously, and it is more suitable for the analysis of highly complex natural polysaccharides, including complex pectins, fructosans, and glycoproteins.

Progress and Challenges in Quantifying Carbonyl-Metabolomic Phenomes with LC-MS/MS

Carbonyl-containing metabolites widely exist in biological samples and have important physiological functions. Thus, accurate and sensitive quantitative analysis of carbonyl-containing metabolites is crucial to provide insight into metabolic pathways as well as disease mechanisms. Although reversed phase liquid chromatography electrospray ionization mass spectrometry (RPLC-ESI-MS) is widely used due to the powerful separation capability of RPLC and high specificity and sensitivity of MS, but it is often challenging to directly analyze carbonyl-containing metabolites using RPLC-ESI-MS due to the poor ionization efficiency of neutral carbonyl groups in ESI. Modification of carbonyl-containing metabolites by a chemical derivatization strategy can overcome the obstacle of sensitivity; however, it is insufficient to achieve accurate quantification due to instrument drift and matrix effects. The emergence of stable isotope-coded derivatization (ICD) provides a good solution to the problems encountered above. Thus, LC-MS methods that utilize ICD have been applied in metabolomics including quantitative targeted analysis and untargeted profiling analysis. In addition, ICD makes multiplex or multichannel submetabolome analysis possible, which not only reduces instrument running time but also avoids the variation of MS response. In this review, representative derivatization reagents and typical applications in absolute quantification and submetabolome profiling are discussed to highlight the superiority of the ICD strategy for detection of carbonyl-containing metabolites.

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.

DiLeuPMP: A Multiplexed Isobaric Labeling Method for Quantitative Analysis of O-Glycans

As one of the most important post-translational modifications, glycosylation plays a pivotal role in many essential physiological functions, including cell recognition, signaling, and immune response. Thus, various qualitative and quantitative analytical strategies for glycomic profiling have been developed in recent decades. However, while extensive efforts have been devoted to the analysis of N-glycans, high-throughput quantitative analysis of O-glycans is often overlooked and underexplored. This is partially due to the lack of a universal enzyme for the release of O-glycans from the protein backbone. Furthermore, the traditional chemical releasing method suffers from severe side reactions and involves tedious sample preparation procedures. Here, a multiplexed isobaric labeling method enabled by N,N-dimethyl leucine containing pyrazolone analogue (DiLeuPMP) is introduced. This method combines the release and labeling of O-glycans in a one-pot reaction and achieves accurate MS²-based relative quantification with the ability to process four samples at a time. The method has been applied to core-1 O-glycan standard and three glycoproteins first, and the results demonstrated its validity. Following this proof-of-principle demonstration, we analyzed more complex biological specimen using human serum samples. Overall, this method provides an effective and reliable approach for the profiling and high-throughput quantitative analysis of O-glycans in complex samples.

In-depth characterization of non-human sialic acid (Neu5Gc) in human serum using label-free ZIC-HILIC/MRM-MS

Sialic acid Neu5Gc, a non-human glycan, is recognized as a new harmful substance that can cause vascular disease and cancer. Humans are unable to synthesize Neu5Gc due to a genetic defect that converts Neu5Ac to Neu5Gc, but Neu5Gc is often observed in human biological samples. Therefore, the demand for accurately measuring the amount of Neu5Gc present in human blood or tissues is rapidly increasing, but there is still no method to reliably quantify trace amounts of a non-human sugar. In particular, selective isolation and detection of Neu5Gc from human serum is analytically challenging due to the presence of excess sialic acid Neu5Ac, which has physicochemical properties very similar to Neu5Gc. Herein, we developed the label-free approach based on ZIC-HILIC/MRM-MS that can enrich sialic acids released from human serum and simultaneously monitor Neu5Ac and Neu5Gc. The combination of complete separation of Neu5Gc from abundant Neu5Ac by hydrophilic and electrostatic interactions with selective monitoring of structure-specific cross-ring cleavage ions generated by negative CID-MS/MS was remarkably effective for quantification of Neu5Ac and Neu5Gc at the femtomole level. Indeed, we were able to successfully determine the absolute quantitation of Neu5Gc from 30 healthy donors in the range of 3.336 ± 1.252 pg/μL (mean ± SD), 10,000 times lower than Neu5Ac. In particular, analysis of sialic acids in protein-free serum revealed that both Neu5Ac and Neu5G are mostly bound to proteins and/or lipids, but not in free form. In addition, the correlation between expression level of Neu5Gc and biological factors such as BMI, age, and sex was investigated. This method can be widely used in studies requiring sialic acid-related measurements such as disease diagnosis or prediction of immunogenicity in biopharmaceuticals as it is both fast and highly sensitive.

Evaluating microbiome-directed fibre snacks in gnotobiotic mice and humans

Changing food preferences brought about by westernization that have deleterious health effects1,2-combined with myriad forces that are contributing to increased food insecurity-are catalysing efforts to identify more nutritious and affordable foods3. Consumption of dietary fibre can help to prevent cardiovascular disease, type 2 diabetes and obesity4-6. A substantial number of reports have explored the effects of dietary fibre on the gut microbial community7-9. However, the microbiome is complex, dynamic and exhibits considerable intra- and interpersonal variation in its composition and functions. The large number of potential interactions between the components of the microbiome makes it challenging to define the mechanisms by which food ingredients affect community properties. Here we address the question of how foods containing different fibre preparations can be designed to alter functions associated with specific components of the microbiome. Because a marked increase in snack consumption is associated with westernization, we formulated snack prototypes using plant fibres from different sustainable sources that targeted distinct features of the gut microbiomes of individuals with obesity when transplanted into gnotobiotic mice. We used these snacks to supplement controlled diets that were consumed by adult individuals with obesity or who were overweight. Fibre-specific changes in their microbiomes were linked to changes in their plasma proteomes indicative of an altered physiological state.

Anti-Osteoporotic Effects of Commiphora Myrrha and Its Poly-Saccharide via Osteoclastogenesis Inhibition

In traditional oriental medicines, Commiphora myrrha and its resinous exudate (i.e., myrrh) are used as herbal remedies to treat various inflammatory and metabolic disorders. Until now, C. myrrha-derived herbal products are considered useful source for bioactive compounds to manage numerous human diseases. This study investigated the effects of water extract of C. myrrha resin (WCM) and its polysaccharide (WCM-PE) on modulatory effects of osteoclast differentiation and/or ovariectomized-induced bone loss. Oral administration of WCM (200 and 500 mg/kg/day for four weeks) notably decreased trabecular bone loss and lipid accumulation in the bone marrow cavity. WCM and WCM-PE dose-dependently inhibited receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis and suppressed RANKL-mediated overexpression of c-Fos and nuclear factor of activated T cells, cytoplasmic 1, thereby downregulating osteoclast-specific gene (Atp6v0d2, DC-STAMP and cathepsin K) expression. Thus, our results suggest that WCM and WCM-PE are promising nutraceutical candidates for the management of osteoporosis in postmenopausal women.

LC-MS/MS-based non-isotopically paired labeling (NIPL) strategy for the qualification and quantification of monosaccharides

Investigation into monosaccharides is critical for studies of oligosaccharides structure and function in biological processes. However, monosaccharides quantification is still challenge due to their isomeric structure and high hydrophilic properties. Besides, it was difficult to obtain isotopic internal standards (IS) of each monosaccharide in complex matrixes. Herein, we developed a novel strategy for the qualification and quantification of monosaccharides in urine using two structure analogs 1-(4-methylphenyl)-3-methyl-5-pyrazolone (MPMP) and1-phenyl-3-methyl-5-pyrazolone (PMP) as non-isotopically paired labeling (NIPL) reagents by liquid chromatograph-tandem mass spectrometry (LC-MS/MS). The derivatized monosaccharides by NIPL method not only had sufficient retention time differences on reversed-phase column, but also exhibited predominant product ion pairs (m/z 189 & m/z 175) in the multiple reaction monitoring (MRM) mode. In this method, PMP labeled standards were adopted as one-to-one internal standards (ISs). 12 urinary monosaccharides were successfully determined and the linear ranges expanded five orders of magnitude with limit of quantification (LOQ) varied from 0.09 ng mL^-1 to 0.36 ng mL^-1 as well as the accuracy higher than 98.15% and the relative standard derivation (RSD) lower than 7.92%. With assistance of multivariate analysis, the targeted monosaccharide biomarkers were firstly obtained for the diagnosis of bladder cancer. By the inexpensive NIPL reagents-MPMP/PMP, the developed strategy possessed the specific advantages of low cost, simple operation, high sensitivity and high accuracy for the qualification and quantitation of monosaccharides. As expected, this method will provide an alternative application potential for targeted metabolomics analysis.

Recent Advances in Analytical Approaches for Glycan and Glycopeptide Quantitation

Growing implications of glycosylation in physiological occurrences and human disease have prompted intensive focus on revealing glycomic perturbations through absolute and relative quantification. Empowered by seminal methodologies and increasing capacity for detection, identification, and characterization, the past decade has provided a significant increase in the number of suitable strategies for glycan and glycopeptide quantification. Mass-spectrometry-based strategies for glycomic quantitation have grown to include metabolic incorporation of stable isotopes, deposition of mass difference and mass defect isotopic labels, and isobaric chemical labeling, providing researchers with ample tools for accurate and robust quantitation. Beyond this, workflows have been designed to harness instrument capability for label-free quantification, and numerous software packages have been developed to facilitate reliable spectrum scoring. In this review, we present and highlight the most recent advances in chemical labeling and associated techniques for glycan and glycopeptide quantification.

Analysis of monosaccharide composition of water-soluble polysaccharides from Codium fragile by ultra-performance liquid chromatography-tandem mass spectrometry

Codium fragile is a green alga belonging to Codiales family. The sulfated polysaccharides of this alga have anti-coagulation, antiviral, anti-angiogenesis, antioxidant, and immunoregulatory properties. In this study, we developed a reliable and rapid method for the analysis of 10 monosaccharides using ultra-performance liquid chromatography-tandem mass spectrometry in the negative electrospray ionization and multiple reaction monitoring mode. Monosaccharides, including two pentoses (xylose, arabinose); two deoxyhexoses (rhamnose, fucose); three hexoses (mannose, glucose, galactose); two hexuronic acids (glucuronic acid, galacturonic acid), and an N-acetyl-hexosamine (glucosamine), were derivatized using 1-phenyl-3-methyl-5-pyrazolone and simultaneously analyzed within 9 min. Optimization of the derivatization process, especially by using various 1-phenyl-3-methyl-5-pyrazolone concentrations, was studied. The calibration curves showed good linearity with a squared correlation coefficient > 0.995. The spiked recovery was determined to be 91.1-105.7% with the relative intra-day and inter-day standard deviations ranging from 2.58-6.71% and 3.15-7.67%, respectively. The limit of detection and limit of quantification for all 10 monosaccharides ranged from 0.02 to 0.10 μg/mL and 0.05 to 0.25 μg/mL, respectively. Using this method, the monosaccharides comprising the polysaccharides of Codium fragile were determined to be arabinose, galactose, and glucose.

A seven-membered cell wall related transglycosylase gene family in Aspergillus niger is relevant for cell wall integrity in cell wall mutants with reduced α-glucan or galactomannan

Chitin is an important fungal cell wall component that is cross-linked to β-glucan for structural integrity. Acquisition of chitin to glucan cross-links has previously been shown to be performed by transglycosylation enzymes in Saccharomyces cerevisiae, called Congo Red hypersensitive (Crh) enzymes. Here, we characterized the impact of deleting all seven members of the crh gene family (crhA-G) in Aspergillus niger on cell wall integrity, cell wall composition and genome-wide gene expression. In this study, we show that the seven-fold crh knockout strain shows slightly compact growth on plates, but no increased sensitivity to cell wall perturbing compounds. Additionally, we found that the cell wall composition of this knockout strain was virtually identical to that of the wild type. In congruence with these data, genome-wide expression analysis revealed very limited changes in gene expression and no signs of activation of the cell wall integrity response pathway. However, deleting the entire crh gene family in cell wall mutants that are deficient in either galactofuranose or α-glucan, mainly α-1,3-glucan, resulted in a synthetic growth defect and an increased sensitivity towards Congo Red compared to the parental strains, respectively. Altogether, these results indicate that loss of the crh gene family in A. niger does not trigger the cell wall integrity response, but does play an important role in ensuring cell wall integrity in mutant strains with reduced galactofuranose or α-glucan.

Mass spectrometry in clinical glycomics: The path from biomarker identification to clinical implementation

Over the past decades, the genome and proteome have been widely explored for biomarker discovery and personalized medicine. However, there is still a large need for improved diagnostics and stratification strategies for a wide range of diseases. Post-translational modification of proteins by glycosylation affects protein structure and function, and glycosylation has been implicated in many prevalent human diseases. Numerous proteins for which the plasma levels are nowadays evaluated in clinical practice are glycoproteins. While the glycosylation of these proteins often changes with disease, their glycosylation status is largely ignored in the clinical setting. Hence, the implementation of glycomic markers in the clinic is still in its infancy. This is for a large part caused by the high complexity of protein glycosylation itself and of the analytical techniques required for their robust quantification. Mass spectrometry-based workflows are particularly suitable for the quantification of glycans and glycoproteins, but still require advances for their transformation from a biomedical research setting to a clinical laboratory. In this review, we describe why and how glycomics is expected to find its role in clinical tests and the status of current mass spectrometry-based methods for clinical glycomics.

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

Polysaccharides are the most abundant biomolecules in nature, but are the least understood in terms of their chemical structures and biological functions. Polysaccharides cannot be simply sequenced because they are often highly branched and lack a uniform structure. Furthermore, large polymeric structures cannot be directly analyzed by mass spectrometry techniques, a problem that has been solved for polynucleotides and proteins. While restriction enzymes have advanced genomic analysis, and trypsin has advanced proteomic analysis, there has been no equivalent enzyme for universal polysaccharide digestion. We describe the development and application of a chemical method for producing oligosaccharides from polysaccharides. The released oligosaccharides are characterized by advanced liquid chromatography-mass spectrometry (LC-MS) methods with high sensitivity, accuracy and throughput. The technique is first used to identify polysaccharides by oligosaccharide fingerprinting. Next, the polysaccharide compositions of food and feces are determined, further illustrating the utility of technique in food and clinical studies.

Sensory and monosaccharide analysis of drip brew coffee fractions versus brewing time

BACKGROUND

The composition of drip brew coffee versus brewing time has been chemically characterized in previous studies, and it is known that the total dissolved solids (TDS) systematically decreases with each fraction during the brew. Little information exists regarding the corresponding sensory attributes versus time, however, and it is unclear how TDS correlates with flavor profile.

RESULTS

Standard drip brews were fractionated into distinct samples by switching in an empty carafe every 30 s during the brew. Using a trained sensory descriptive panel, we found that most taste and flavor attributes decreased with brew time; for example, the earlier fractions were systematically more bitter and more sour than later fractions. Surprisingly, however, several flavor and taste attributes increased in time; for example, later fractions were systematically sweeter and more floral than earlier fractions. Since later fractions had lower TDS, these results indicate that perceived sweetness in drip brew coffee is negatively correlated with TDS. Mass spectrometry measurements of the monosaccharide content in the brews showed that none of the fractions had perceptible concentrations of any monosaccharide.

CONCLUSION

The results of the sensory analysis and the monosaccharide analysis suggest that perceptible sweetness in coffee is a consequence of masking effects and/or the presence of sweet-associated aromas and flavors. The results further suggest that unique flavor profiles could be obtained from the same coffee grounds by judicious combinations of specific fractions. © 2020 Society of Chemical Industry.

Examination of Carbohydrate Products in Feces Reveals Potential Biomarkers Distinguishing Exclusive and Nonexclusive Breastfeeding Practices in Infants

BACKGROUND

The stable isotope deuterium dose-to-mother (DTM) technique to estimate nonbreast milk water intake demonstrates that maternal self-report methods of infant feeding overestimate the true prevalence of exclusively breastfeeding practices.

OBJECTIVE

We aimed to determine potential monosaccharide and oligosaccharide markers that distinguish between exclusively breastfed (EBF) versus nonexclusively breastfed (non-EBF) infants utilizing LC-MS-based methods.

METHODS

Data for the analysis were collected as part of a larger, longitudinal study of 192 breastfed Indonesian infants aged 2 mo and followed up at 5 mo. Feces samples were collected from infants aged 2 mo (n = 188) and 5 mo (n = 184). EBF and non-EBF strata at each time point were determined via the DTM technique. Feces samples were analyzed to determine monosaccharide content using ultra-high-performance LC-triple quadrupole MS (UHPLC-QqQ MS). Relative abundances of fecal oligosaccharides were determined using nano-LC-Chip-quadrupole time-of-flight MS (nano-LC-Chip-Q-ToF MS).

RESULTS

At age 2 mo, monosaccharide analysis showed the abundance of fructose and mannose were significantly higher (+377% and +388%, respectively) in non-EBF compared with EBF infants (P <0.0001). Fructose and mannose also showed good discrimination with areas under the curve (AUC) of 0.86 and 0.82, respectively. Oligosaccharide analysis showed that a 6-hexose (Hex6) isomer had good discrimination (AUC = 0.80) between EBF and non-EBF groups at 5 mo.

CONCLUSION

Carbohydrate products, particularly fecal mono- and oligosaccharides, differed between EBF and non-EBF infants aged under 6 mo and can be used as potential biomarkers to distinguish EBF versus non-EBF feeding practices.

Rapid Analysis of Monosaccharides in Sub-milligram Plant Samples Using Liquid Chromatography-Mass Spectrometry Assisted by Post-column Derivatization

Monosaccharides play important roles in plant growth and development, and their biofunctions are closely related to their endogenous contents. Therefore, the determination of monosaccharides is beneficial for the further study of monosaccharide biofunction. In this work, we developed a liquid chromatography-mass spectrometry analytical method assisted by a post-column derivatization technique (LC-PCD-MS) for the fast and automatic determination of 16 monosaccharides in samples. Post-column chemical derivatization of monosaccharides was performed by a reaction of monosaccharides with 4-benzylaminobenzeneboronic acid (4-PAMBA) through boronate ester formation in a three-way connector. 4-PAMBA worked as a derivatization reagent to improve the selectivity and sensitivity of monosaccharide detection by MS. The developed LC-PCD-MS method integrates LC separation, chemical derivatization, and MS detection in one run, thus greatly reducing the analysis time for each sample. The limits of detection and limits of quantification for 16 monosaccharides were in the range of 0.002-0.1 and 0.007-0.5 ng/mL, respectively. Good linearity was obtained from the linear regression, with a determination coefficient (R²) ranging from 0.9928 to 1.0000. The relative recoveries were in the range of 80.7-117.8%, with the intra- and interday relative standard deviations less than 19.7 and 16.5%, respectively, indicating good accuracy and acceptable reproducibility of the method. Finally, the method was successfully applied to investigate the spatial and temporal distribution of 16 monosaccharides in the developing flower and germinating seed of Arabidopsis thaliana.

Campylobacter Abundance in Breastfed Infants and Identification of a New Species in the Global Enterics Multicenter Study

Campylobacter jejuni is a leading cause of bacterial diarrhea worldwide and is associated with high rates of mortality and growth stunting in children inhabiting low- to middle-resource countries. To better understand the impact of breastfeeding on Campylobacter infection in infants in sub-Saharan Africa and South Asia, we examined fecal microbial compositions, bacterial isolates, and their carbohydrate metabolic pathways in Campylobacter-positive infants <1 year of age from the Global Enterics Multicenter Study. Exclusively breastfed infants with diarrhea exhibited high Campylobacter abundances, and this negatively correlated with bacterial carbohydrate metabolism. Although C. jejuni and Campylobacter coli are prevalent among these infants, the second most abundant Campylobacter species was a new species, which we named "Candidatus Campylobacter infans." Asymptomatic Campylobacter carriers also possess significantly different proportions of specific gut microbes compared to diarrheal cases. These findings provide insight into Campylobacter infections in infants in sub-Saharan Africa and South Asia and help inform strategies aimed at eliminating campylobacteriosis in these areas.IMPORTANCECampylobacter is the primary cause of bacterial diarrhea in the United States and can lead to the development of the postinfectious autoimmune neuropathy known as Guillain-Barré syndrome. Also, drug-resistant campylobacters are becoming a serious concern both locally and abroad. In low- and middle-income countries (LMICs), infection with Campylobacter is linked to high rates of morbidity, growth stunting, and mortality in children, and breastfeeding is important for infant nutrition, development, and protection against infectious diseases. In this study, we examined the relationship between breastfeeding and Campylobacter infection and demonstrate the increased selection for C. jejuni and C. coli strains unable to metabolize fucose. We also identify a new Campylobacter species coinfecting these infants with a high prevalence in five of the seven countries in sub-Saharan Africa and South Asia examined. These findings indicate that more detailed studies are needed in LMICs to understand the Campylobacter infection process in order to devise a strategy for eliminating this pathogenic microbe.

Structural characterization and anticomplement activity of an acidic polysaccharide from Hedyotis diffusa

An acidic homogeneous polysaccharide (HD-PS-1) was purified from Hedyotis diffusa (Willd.) Roxb. HD-PS-1 possessed a backbone chain of →[4)-β-Glcp-3-OAc-(1]₆→[6)-β-Manp-(1]₂→6)-α-Galp-(1→[4)-α-Galp-(1]₂→, with three branches of β-Manp-(1→3)-β-GlcpA, α-Rhap-(1→3)-α-Rhap and α-Galp attached to the backbone chain at O-4 position of 1,4,6-linked β-Manp, O-3 position of 1,3,6-linked α-Galp and O-3 position of 1,3,4-linked α-Galp, respectively. HD-PS-1 exhibited significant anticomplement activity (CH₅₀: 0.084 ± 0.009 mg/mL, AP₅₀: 0.176 ± 0.013 mg/mL). It was found that the presence of uronic acids is important to anticomplement activity of HD-PS-1, given that the reduced HD-PS-1 showed weaker activity (CH₅₀: 0.456 ± 0.008 mg/mL, AP₅₀: 0.572 ± 0.010 mg/mL). Preliminary mechanism study indicated that HD-PS-1 interacted with C3 and C4 in the complement activation cascade. In addition, a neutral homogeneous polysaccharide (HD-PS-2) was also purified and characterized. HD-PS-2 displayed antioxidant activity by scavenging DPPH· radicals without anticomplement activity.

Development of an Extensive Linkage Library for Characterization of Carbohydrates

The extensive characterization of glycosidic linkages in carbohydrates remains a challenge because of the lack of known standards and limitations in current analytical techniques. This study encompasses the construction of an extensive glycosidic linkage library built from synthesized standards. It includes an improved liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantitation of glycosidic linkages derived from disaccharides, oligosaccharides, and polysaccharides present in complicated matrices. We present a method capable of the simultaneous identification of over 90 unique glycosidic linkages using ultrahigh-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC/QqQ MS) operated in dynamic multiple reaction monitoring (dMRM) mode. To build the library, known monosaccharides commonly found in plants were subjected to partial methylation to yield partially derivatized species representing trisecting, bisecting, linear, and terminal structures. The library includes glycosidic linkage information for three hexoses (glucose, galactose, and mannose), three pentoses (xylose, arabinose, and ribose), two deoxyhexoses (fucose and rhamnose), and two hexuronic acids (glucuronic acid and galacturonic acid). The resulting partially methylated monosaccharides were then labeled with 1-phenyl-3-methyl-5-pyrazolone (PMP) followed by separation and analysis by UHPLC/dMRM MS. Validation of the synthesized standards was performed using disaccharide, oligosaccharide, and polysaccharide standards. Accuracy, reproducibility, and robustness of the method was demonstrated by analysis of xyloglucan (tamarind) and whole carrot root. The synthesized standards represent the most comprehensive group of carbohydrate linkages to date.