Improvement of simultaneous determination of neutral monosaccharides and uronic acids by gas chromatography

Integrated transcriptomic and proteomic analyses provide insights into the biosynthesis of Lycii fructus polysaccharides from different cultivation regions

Polysaccharides from L. fructus (LFPs) serve as important active biomacromolecules for the wide spectrum of bioactivities exhibited by Lycii fructus. However, the influence of ecological environments on the biosynthesis and structural characteristics of LFPs remains largely unexplored. The present research conducted a comprehensive strategy combining physicochemical structural elucidation, stoichiometric analysis, transcriptomic profiling, and proteomic analysis in L. fructus samples collected from typical cultivation regions including Ningxia, Xinjiang, and Qinghai. The results revealed distinct structural variations in LFPs from Ningxia compared to those from other regions in terms of Glc, Ara, GalA composition percentages as well as overall content. The omics data identified 5531 and 8084 differentially expressed genes (DEGs), as well as 3728 and 4732 differentially expressed proteins (DEPs) in Xinjiang and Qinghai compared to Ningxia, respectively. The integration of transcriptomic and proteomic analyses revealed enrichment of DEGs and DEPs involved in the biosynthesis pathway of LFPs, including UDPs, AXS, and UGDH. Temperature and precipitation were the significant ecological factors affecting LFPs biosynthesis. These comprehensive analyses provide a novel perspective for explaining the important material basis and environmental response mechanism underlying the quality formation of L. fructus.

Decoding Sugars: Mass Spectrometric Advances in the Analysis of the Sugar Alphabet

Monosaccharides play a central role in metabolic networks and in the biosynthesis of glycomolecules, which perform essential functions across all domains of life. Thus, identifying and quantifying these building blocks is crucial in both research and industry. Routine methods have been established to facilitate the analysis of common monosaccharides. However, despite the presence of common metabolites, most organisms utilize distinct sets of monosaccharides and derivatives. These molecules therefore display a large diversity, potentially numbering in the hundreds or thousands, with many still unknown. This complexity presents significant challenges in the study of glycomolecules, particularly in microbes, including pathogens and those with the potential to serve as novel model organisms. This review discusses mass spectrometric techniques for the isomer-sensitive analysis of monosaccharides, their derivatives, and activated forms. Although mass spectrometry allows for untargeted analysis and sensitive detection in complex matrices, the presence of stereoisomers and extensive modifications necessitates the integration of advanced chromatographic, electrophoretic, ion mobility, or ion spectroscopic methods. Furthermore, stable-isotope incorporation studies are critical in elucidating biosynthetic routes in novel organisms.

Methods for Detection, Extraction, Purification, and Characterization of Exopolysaccharides of Lactic Acid Bacteria-A Systematic Review

Exopolysaccharides (EPSs) are large-molecular-weight, complex carbohydrate molecules and extracellularly secreted bio-polymers released by many microorganisms, including lactic acid bacteria (LAB). LAB are well known for their ability to produce a wide range of EPSs, which has received major attention. LAB-EPSs have the potential to improve health, and their applications are in the food and pharmaceutical industries. Several methods have been developed and optimized in recent years for producing, extracting, purifying, and characterizing LAB-produced EPSs. The simplest method of evaluating the production of EPSs is to observe morphological features, such as ropy and mucoid appearances of colonies. Ethanol precipitation is widely used to extract the EPSs from the cell-free supernatant and is generally purified using dialysis. The most commonly used method to quantify the carbohydrate content is phenol-sulfuric acid. The structural characteristics of EPSs are identified via Fourier transform infrared, nuclear magnetic resonance, and X-ray diffraction spectroscopy. The molecular weight and composition of monosaccharides are determined through size-exclusion chromatography, thin-layer chromatography, gas chromatography, and high-performance liquid chromatography. The surface morphology of EPSs is observed via scanning electron microscopy and atomic force microscopy, whereas thermal characteristics are determined through thermogravimetry analysis, derivative thermogravimetry, and differential scanning calorimetry. In the present review, we discuss the different existing methods used for the detailed study of LAB-produced EPSs, which provide a comprehensive guide on LAB-EPS preparation, critically evaluating methods, addressing knowledge gaps and key challenges, and offering solutions to enhance reproducibility, scalability, and support for both research and industrial applications.

Polysaccharides from Hericium erinaceus and its immunomodulatory effects on RAW 264.7 macrophages

This study aimed to optimize the extraction of Hericium erinaceus polysaccharides (HEP) using ultrasound-assisted enzymatic extraction combined with Plackett-Burman design (PBD) and response surface methodology (RSM). The optimal extraction conditions were identified as: 33 min extraction time, 30:1 liquid to material ratio, 38 °C extraction temperature, 9 g/kg cellulase amount, pH 4, and 20 % ethanol concentration. Under these conditions, the extraction yield of HEP was 5.87 ± 0.16 %, consistent with the predicted results. Additionally, the potential immunomodulatory activity of HEP on RAW 264.7 macrophage was evaluated. The results revealed that HEP improved the immunostimulatory activity of RAW264.7 cells, evident from increased production of IL-6 and TNF-α. These findings suggest that HEP is capable of enhancing the immune activity of RAW 264.7 macrophage.

Natural resourced polysaccharides: Preparation, purification, structural elucidation, structure-activity relationships and regulating intestinal flora, a system review

Natural resourced polysaccharides (NRPs), as metabolites synthesized during activity of organisms, widely present in animal cell membranes or plant and microbial cell walls. NRPs have garnered extensive attention in the fields of medicine, foods, and farming owing to their distinct bioactivities and structural diversity. Despite the burgeoning growth in NRPs research, the available literature focuses primarily on a review of specific polysaccharides, necessitating an urgent need for a comprehensive summary of NRPs to offer readers a whole landscape of current advancements in NRPs research. Based on this, this article comprehensively reviews the latest research progress regarding preparation, purification, structure elucidation, structure-activity relationships and regulation of intestinal flora of NRPs in electronic databases, such as PubMed, Wiley, ScienceDirect and Web of Science from last 5 years. This review analyzes the effects of various extraction techniques on NRPs and also delves into the intrinsic correlation between the biological activity and structure of NRPs, highlighting that chemical modification can enhance their structural diversity and confer novel or improved biological functions. Moreover, this article extensively explores the application of NRP in promoting intestinal microecology balance, underscoring its significant potential as a probiotic initiator. This review lays a solid theoretical foundation for the future research and development of NRPs.

Polysaccharides in fruits: Biological activities, structures, and structure-activity relationships and influencing factors-A review

Fruits are a rich source of polysaccharides, and an increasing number of studies have shown that polysaccharides from fruits have a wide range of biological functions. Here, we thoroughly review recent advances in the study of the bioactivities, structures, and structure-activity relationships of fruit polysaccharides, especially highlighting the structure-activity influencing factors such as extraction methods and chemical modifications. Different extraction methods cause differences in the primary structures of polysaccharides, which in turn lead to different polysaccharide biological activities. Differences in the degree of modification, molecular weight, substitution position, and chain conformation caused by chemical modification can all affect the biological activities of fruit polysaccharides. Furthermore, we summarize the applications of fruit polysaccharides in the fields of pharmacy and medicine, foods, cosmetics, and materials. The challenges and perspectives for fruit polysaccharide research are also discussed.

Monosaccharide composition analysis by 2D quantitative gsHSQCi

The physicochemical properties and biological activities of polysaccharides depend on their structures. Monosaccharide composition analysis is indispensable for the structural characterization of polysaccharides and is helpful in the quality control of polysaccharide preparation. Here, using a model mixture and tamarind seed polysaccharide as examples, we demonstrated that a quantitative 2D NMR method, gsHSQCi (three gradient-selective Heteronuclear Single Quantum Coherence spectra acquired with incremented repetition times, i = 1, 2, 3) can directly quantify a variety of monosaccharides in solution with adequate precision and accuracy, requiring no derivatization, postprocessing steps and column separation. Both anomeric and non-anomeric signals of monosaccharides can be utilized for content determination. More accurate quantification of fructose in a mixture containing nine monosaccharides is obtained, which is difficult to achieve by quantitative 1D 1HNMR and the common PMP-HPLC method (high-performance liquid chromatography through pre-column derivatization with 1-phenyl-3-methyl-5-pyrazolone) due to the peak overlapping and the poor derivatization efficiency, respectively. The results also revealed that Na[Fe(EDTA)] can serve as a proper relaxation-enhancing agent for saccharide samples to save experimental time. We expect that this approach can be applied as an alternative to analyzing the monosaccharide composition and be helpful in interpreting the structure of polysaccharides.

A typical acidic extracellular polysaccharide alludes to algae-bacteria-collaboration in microalgal-bacterial symbiosis

Microalgal-bacterial symbioses are prevalent in aquatic ecosystems and play a pivotal role in carbon sequestration, significantly contributing to global carbon cycling. The understanding of the contribution of exopolysaccharides (EPSs), a crucial carbon-based component, to the structural integrity of microalgal-bacterial symbioses remains insufficiently elucidated. To address this gap, our study aims to enhance our comprehension of the composition and primary structure of EPSs within a specific type of granular microalgal-bacterial symbiosis named microalgal-bacterial granular sludge (MBGS). Our investigation reveals that the acidic EPSs characteristic of this symbiosis have molecular weights ranging from several hundred thousand to over one million Daltons, including components like glucopyranose, galactopyranose, mannose, and rhamnose. Our elucidation of the backbone linkage of a representative exopolysaccharide revealed a →3)-β-D-Galp-(1→4)-β-D-Glcp-(1→ glycosidic linkage. This linear structure closely resembles bacterial xanthan, while the branched chain structure bears similarities to algal EPSs. Our findings highlight the collaborative synthesis of acidic EPSs by both microalgae and bacteria, emphasizing their joint contribution in the production of macromolecules within microalgal-bacterial symbiosis. This collaborative synthesis underscores the intricate molecular interactions contributing to the stability and function of these symbiotic relationships.

Structure and immunostimulatory activity studies on two novel Flammulina velutipes polysaccharides: revealing potential impacts of →6)-α-D-Glcp(1→ on the TLR-4/MyD88/NF-κB pathway

Two novel Flammulina velutipes (F. velutipes) polysaccharides, FVPH1 and FVPH2, were isolated and purified after hot water extraction. The structural characterization revealed that the backbone of FVPH1 consisted mainly of →6)-α-D-Glcp(1→, →3,4)-α-D-Galp(1→, →4)-α-L-Fucp(1→, and →4)-β-D-Manp(1→, while the backbone of FVPH2 consisted of →3)-α-D-Galp(1→, →3,4)-α-D-Manp(1→,→6)-α-D-Glcp(1→. The branches of FVPH1 contained →6)-α-D-Glcp(1→ and α-D-Glcp(1→ and the branches of FVPH2 consisted of →3)-α-D-Galp(1→, →6)-α-D-Glcp(1→, and β-L-Fucp(1→. FVPH2 exhibited significantly better immunostimulatory activity than FVPH1 (P < 0.05), as evidenced by the increased expression of NO, IL-1β, IL-6, and TNF-α and pinocytic activity of RAW264.7 cells. As the most abundant structure in the polysaccharides of F. velutipes, the content of →6)-α-D-Glcp(1→ might play a crucial role in influencing the immunostimulatory activity of F. velutipes polysaccharides. The F. velutipes polysaccharide with a lower content of →6)-α-D-Glcp(1→ and a higher branching degree could significantly enhance the immunostimulatory activity of F. velutipes polysaccharides via activating the TLR-4/MyD88/NF-κB pathway more effectively.

A new perspective on structural characterisation and immunomodulatory activity of arabinogalactan in Larix kaempferi from Qinling Mountains

In this study, crude polysaccharide (LAG-C) and homogeneous arabinogalactan (LAG-W) were isolated from Qinling Larix kaempferi of Shaanxi Province. Bioactivity assays showed that LAG-W and LAG-C enhanced the phagocytic ability, NO secretion, acid phosphatase activity, and cytokine production (IL-6, IL-1β, and TNF-α) of RAW264.7 macrophages. Notably, LAG-W exhibited a significantly stronger immunomodulatory effect than LAG-C. The primary structure of LAG-W was characterised by chemical methods (monosaccharide composition, methylation analysis, and alkali treatment) and spectroscopic techniques (gas chromatography-mass spectrometry, high-performance liquid chromatography-mass spectrometry, and 1D/2D nuclear magnetic resonance). LAG-W was identified as a 22.08 kilodaltons (kDa) neutral polysaccharide composed of arabinose and galactose at a 1:7.5 molar ratio. Its backbone consisted of repeated →3)-β-Galp-(1→ residues. Side chains, connected at the O-6 position, were mainly composed of T-β-Galp-(1→ and T-β-Galp-(1→6)-β-Galp-(1→ residues. And it also contained small amounts of T-β-Arap-(1→, T-α-Araf-(1→6)-β-Galp-(1→6)-β-Galp-(1→, and T-α-Araf-(1→3)-α-Araf-(1→6)-β-Galp-(1→ residues. By structurally and functionally characterising L. kaempferi polysaccharides, this study opens the way for the valorisation of this species.

Development of a joint derivatization protocol for the unequivocal identification of the monosaccharide composition in four dendrobium polysaccharides and free monosaccharide by GC-MS

The determination of monosaccharides is crucial for studying the structure of polysaccharides and the composition of free monosaccharides in living organisms. Based on previous derivatization gas chromatography-mass spectrometry (GC-MS) methods, we aimed to develop a novel analytical protocol for better quantifying monosaccharides. In this study, sugar alcohol acetylation, saccharonitrile acetylation, silylation and a combination of sugar alcohols acetylation and saccharonitrile acetylation were compared. The optimal method was verified with the monosaccharide determination of four polysaccharides and four free monosaccharides from Dendrobium. The results showed that the novel combined derivatization method was superior to the other three methods in terms of content analysis of monosaccharides. Furthermore, it possessed good linearity (all calibration curves showed relative coefficients ≥ 0.999), sensitivity, precision (relative standard deviation < 2%), and accuracy (recovery, 95.7-105%). Finally, the novel method established in this study was successfully employed in determining the monosaccharide composition of four polysaccharides and four free monosaccharide samples from Dendrobium.

Lipid-Lowering Effects of a Novel Polysaccharide Obtained from Fuzhuan Brick Tea In Vitro

Lipid accumulation causes diseases such as obesity and abnormal lipid metabolism, thus impairing human health. Tea polysaccharide is one of the natural, active substances that can lower lipid levels. In this paper, an oleic-acid-induced HepG2 cell model was established. The lipid-lowering effects of a novel group of Fuzhuan brick tea polysaccharides (FTPs)-obtained from Fuzhuan brick tea-were examined in vitro. The monosaccharide composition of FTP3 was Glc, Gal, Ara, Man, Rha, GalAc, GlcAc, and Xyl with a molar ratio of 23.5:13.2:9.0:5.5:5.4:2.7:1.3:1.0, respectively. A molecular weight of 335.68 kDa was identified for FTP3. HepG2 cells treated with FTP3 achieved a prominent lipid-lowering effect compared with cells treated with oleic acid. Images of the Oil Red O staining treatment showed that FTP3-treated groups had significantly fewer red fat droplets. TC and TG levels were lower in FTP3-treated groups. FTP3 alleviated lipid accumulation in HepG2 cells, activated AMPK, and decreased the SREBP-1C and FAS protein expressions associated with fatty acid synthesis. FTP3 holds promising potential for its lipid-lowering effects.

Optimization, fractional characterization, and antioxidant potential of exopolysaccharides from Levilactobacillus brevis NCCP 963 isolated from "kanji"

A novel exopolysaccharide (EPS) was obtained from Levilactobacillus brevis NCCP 963 isolated from a black carrot drink named "kanji". The culture conditions for maximum EPS yield were explored by the Plackett-Burman (PB) design and response surface methodology (RSM) along with the fractional characterization and antioxidant potential of EPSs. The PB design screened out five significant factors, namely, glucose, sucrose, tryptone, CaCl₂, and di-potassium phosphate out of eleven independent factors. The RSM indicated glucose and CaCl₂ as significant factors in EPS production and a maximum EPS production of 968.89 mg L^-1 was obtained at optimized levels of 10.56% glucose, 9.23% sucrose, 0.75% tryptone, 0.446% CaCl₂, and 0.385% K₂HPO₄. A R² value above 93% indicates higher variability, depicting the validity of the model. The obtained EPS has a molecular weight of 5.48 × 10⁴ Da and is a homopolysaccharide in nature with glucose monosaccharides. FT-IR analysis showed significant band stretching of C-H, O-H, C-O and C-C and indicated the β-glucan nature of EPSs. The comprehensive antioxidant investigation showed significant in vitro DPPH, ABTS, hydroxyl, and superoxide scavenging capacity with EC₅₀ values of 1.56, 0.31, 2.1, and 6.7 mg mL^-1 respectively. Curd formation from the resulting strain prevented syneresis.

Regulating effects of phytosterol esters-loaded emulsions stabilized with green tea polysaccharide conjugates and Tween on lipids in KKAy mice

Phytosterol esters (PSE) have been shown to have cholesterol-lowering effects, but their insolubility in water limits their applications. Green tea polysaccharide conjugates (gTPC) have hypoglycemic and emulsifying effects. To address lipid dysregulation in diabetic patients, we developed PSE-loaded emulsions stabilized with gTPC and Tween-20 (gTPC-PSE emulsions) and evaluated their physicochemical properties. We subsequently investigated the lipid-regulating potential of these emulsions to in KKAy mice. The KKAy mice were randomly assigned to eight groups: the model group, the Lipitor (10 mg·kg^-1)-acarbose (30 mg·kg^-1) combination group, two gTPC groups, two PSE groups, and two gTPC-PSE groups with a 1:2 mass ratio of gTPC to PSE. The administered doses were 90 and 270 mg kg^-1, respectively. Administration of a 270 mg·kg^-1 dose of gTPC-PSE emulsions led to the most significant effects including increased levels of liver and serum high-density lipoprotein cholesterol (HDL-CH), reduced serum leptin and insulin, and improved liver superoxide dismutase (SOD) and reduced malondialdehyde (MDA). In general, gTPC and PSE demonstrated a synergistic effect on lipid regulation in mice. Our results indicate that gTPC-PSE emulsions hold potential as a nutritional intervention for diabetes by modulating lipid levels.

Quantitative determination of galacturonic acid in pectin and pectin products by combined pectinase hydrolysis and HPLC determination

Pectin is a complex heteropolysaccharide with a predominantly galacturonic acid (GalA) main chain and various branching sugars, leading to some analytical and quantitative determination challenges. By comparison with various acid hydrolysis methods, an effective and precise hydrolysis method for GalA determination from pectin was investigated using a combination of pectinase hydrolysis (PH) and HPLC determination, which was named the PH-HPLC method. With a pectinase loading of 2250 U/g pectin, 4.0 g/L commercial pectin was almost completely hydrolysed to the intact and detectable GalA at 50 °C after 24 h, for quantitative determination by HPLC. Acid-catalysis methods showed obvious disadvantages in terms of GalA degradation or incomplete hydrolysis of pectin, resulting in imprecise determination results. Moreover, the PH-HPLC method was employed for the quantitative determination of GalA in three common natural pectin feedstocks and indicated 45.5-233.1% higher content of GalA than the acid hydrolysis method. Thus, the PH-HPLC method is demonstrated to be a precise approach for analysing and quantifying the GalA of pectin and respective feedstock.

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.

Optimization and cholesterol-lowering activity of exopolysaccharide from Lactiplantibacillus paraplantarum NCCP 962

Exopolysaccharides (EPSs) are biological polymers with unique structural features have gained particular interest in the fields of food, chemistry and medicine, and food industry. EPS from the food-grade lactic acid bacteria (LAB) can be used as a natural food additives to commercial ones in the processing and development of functional foods and nutraceuticals. The current study was aimed to explore the EPS-producing LAB from the dahi; to optimize the fermentation conditions through Plackett-Burman (PB) and response surface methodology (RSM); and to study its physicochemical, rheological, functional attributes, and cholesterol-lowering activity. Lactiplantibacillus paraplantarum NCCP 962 was isolated among the 08 strains screened at the initial stage. The PB design screened out four independent factors that had a significant positive effect, i.e., lactose, yeast extract, CaCl2, and tryptone, while the remaining seven had a non-significant effect. The RSM exhibited lactose, yeast extract, and CaCl2, significantly contributing to EPS yield. The maximum EPS yield (0.910 g/L) was obtained at 6.57% lactose, 0.047% yeast extract, 0.59% CaCl2, and 1.37% tryptone. The R2 value above 97% explains the higher variability and depicts the model's validity. The resulted EPS was a heteropolysaccharide in nature with mannose, glucose, and galactose monosaccharides. FTIR spectrum reflected the presence of functional groups, i.e., O-H, C-H, C = O, C-O-H, and CH2. SEM revealed a porous and rough morphology of EPS, also found to be thermally stable and negligible weight loss, i.e., 14.0% at 257 °C and 35.4% at 292.9 °C was observed in the 1st and 2nd phases, respectively. Rheological attributes revealed that strain NCCP 962 had high viscosity by increasing the EPS concentration, low pH, and temperature with respectable water holding, oil capacities, foaming abilities, and stability. NCCP 962 EPS possessed up to 46.4% reduction in cholesterol concentration in the supernatant. Conclusively, these results suggested that strain NCCP 962 can be used in food processing applications and other medical fields. KEY POINTS: • The fermentation conditions affect EPS yield from L. paraplantarum and significantly increased yield to 0.910 g/L. • The EPS was heteropolysaccharide in nature and thermally stable with amorphous morphology. • Good cholesterol-lowering potential with the best rheological, emulsifying, and foaming capacities.

Systematic Comparison of Structural Characterization of Polysaccharides from Ziziphus Jujuba cv. Muzao

To investigate the structural information differences of Ziziphus Jujuba cv. Muzao polysaccharides, ten samples were successfully extracted from aqueous and alkaline solutions, prepared via DEAE-Sepharose Fast Flow through different eluents and Sephacryl S-300 columns, and systematically analyzed. Their characteristics were studied and then compared using chemical testing, high-performance gel permeation chromatography (HPGPC), gas chromatography (GC), methylation analysis, and NMR spectroscopy. The data achieved demonstrated that different jujube polysaccharide fractions possessed different structural characteristics, and most of them belonged to pectic polysaccharides. Overall, the structural information difference of jujube polysaccharides was preliminarily illuminated, which could not only promote the potential application of Z. Jujuba cv. Muzao polysaccharides but also provide an effective way to analyze the structures of polysaccharides from other genera jujube fruit.

Structural characterization of a new high molecular weight polysaccharide from jujube fruit

From Ziziphus Jujuba cv. Muzao fruit, a new polysaccharide (PZMP3-1) with high molecular weight was isolated. Constructional characterization revealed that PZMP3-1 comprized 2.56 rhamnose, 7.70 arabinoses, 3.73 galactose, and 6.73 galactose, and it has a 241 kDa average molecular weight. The principal structural components of PZMP3-1 were 1,2,4 and 1,4-linked GalpA, 1,4-linked Galp, 1,3 and 1,5-linked Araf, and 1-linked Rhap based on methylation and nuclear magnetic resonance spectroscopy (NMR) analyses. X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and scanning electron microscopy (SEM) structural analysis of PZMP3-1 revealed a tangled and branching pattern. Overall, these structural results suggested that PZMP3-1 could have unique bioactivities and be widely used in nutritional supplements.

Extraction optimization and characterization of persimmon peel pectin extracted by subcritical water

•

Persimmon peel pectin (PPP) was extracted by subcritical water.

•

PPP had low M_w of 21.79 kDa and its degree of esterification was 40.61 %.

•

PPP attributed to a degradation temperature of 228.05 ℃.

•

The IC₅₀ of PPP to ABTS•+ was 9.8-times that of commercial citrus pectin in vitro.

•

PPP altered microbial intestinal communities in mice.

Persimmon peel pectin (PPP) was extracted by subcritical water via the response surface methodology. The optimal crude PPP extraction yield of 7.62 ± 0.7 % was found at 138 °C, 2.84 min, and liquid–solid ratio of 1:10.02. After treatment of deproteinization and decolorization with papain and hydrogen peroxide, 83.19 % of protein and 78.56 % of the colour in crude PPP were removed, respectively. PPP owned the M_w of 21.79 kDa and its uronic acids content was 64.03 %. PPP was further affirmed by fourier transform infrared, X-ray diffractometer and ¹H NMR analysis. Moreover, the degradation temperature (228.05 ℃) of PPP was verified via differential scanning calorimetry. Then, the IC₅₀ of PPP to ABTS•+ was 9.8 times that of commercial citrus pectin. Moreover, PPP could change microbial communities and selectively enrich Bacteroides, Cetobacterium, Erysipelatoclostridium, Parabacteroides and Phocaeicola sartorii. This study demonstrated that subcritical water was practicable for extraction of persimmon peel pectin.

Analysis of the chemical composition of natural carbohydrates - An overview of methods

Natural carbohydrates are gaining importance over a wide spectrum of human activity due to their versatile functionalities. The properties of carbohydrates are currently used in many branches of industry and new possibilities of their utilization, like in medicine or materials science, are demonstrated systematically. The attractive properties of carbohydrates result from their chemical structure and ability to form macromolecules and derivatives. Each application of carbohydrate requires a knowledge of their chemical composition, which due to the number and differentiation of monosaccharides and their spatial forms is often challenging. This review presents an overview on sample preparation and the methods used for the determination of the fine chemical structure of natural carbohydrates. Most popular and reliable colorimetric, chromatographic and spectroscopic methods are presented with an emphasis on their pros and cons.

Determination of Polysaccharides Composition in Polygonatum sibiricum and Polygonatum odoratum by HPLC-FLD with Pre-column Derivatization

A high-performance liquid chromatography-fluorescence detection (HPLC-FLD) method was established for the determination of seven monosaccharides in Polygonatum sibiricum and Polygonatum odoratum. The polysaccharides were de-esterified, extracted, hydrolyzed and derivatized with p-aminobenzoic acid (PABA) to obtain fluorescently labeled monosaccharide compounds, which were finally detected by HPLC-FLD. Inertsil ODS-3, C18 chromatographic column (250 mm × 4.6 mm, 5 μm) was used for chromatography. The excitation wavelength (E_x) was 313 nm, and the emission wavelength (E_m) was 358 nm. Ethyl acetate extraction reduced the peaks of chromatogram and improved the detection sensitivity than other agents. The established method had high sensitivity, strong specificity, good linear relationship and recovery efficiency. The results showed that the roots and fibrous roots of Polygonatum sibiricum and Polygonatum odoratum contained these seven monosaccharides, and the highest monosaccharide content was mannose. The method of PABA-HPLC-FLD for determination of monosaccharide content in Polygonatum sibiricum and Polygonatum odoratum was sensitive and accurate. The method established in this work provides a feasible analytical tool for the study of polysaccharides, and the findings on polysaccharides from Polygonatum sibiricum and Polygonatum odoratum can provide guidance for the natural medicine industry.

Effects of multi-frequency ultrasonic on the physicochemical properties and bioactivities of polysaccharides from different parts of ginseng

The effect of multi-frequency ultrasonic extraction (MUE) on the yields, physicochemical properties, antioxidant and α-glucosidase inhibitory activities of polysaccharides (GPs) from different parts of ginseng were compared. Results demonstrated that yields of polysaccharides from different parts were found to vary significantly differences, in the order of roots (M-GRPs) > flowers (M-GFPs) > leaves (M-GLPs). Compared with heat reflux extraction, MUE not only increased the yield of GPs by up to 9.14%-210.87%, with higher uronic acid content (UAC: increased by 4.99%-53.48%), total phenolics content (TPC: increased by 7.60% to 42.61%), total flavonoids content (TFC: increased by 2.52%-5.45%), and lower molecular weight (Mw: reduced by 6.51%- 33.08%) and protein content (PC: reduced by 5.15%-8.95%), but also improved their functional properties and bioactivities. All six purified polysaccharides extracted by MUE were acidic pyran polysaccharide with different monosaccharide composition, possessed remarkable antioxidant and α-glucosidase inhibitory activities. Especially, M-GFP-1 exhibited the highest bioactivities, illustrated that the activities were highly correlated with UAC and TPC, Mw, and triple helical structure. These results indicate that MUE was an efficient technique for improving yields, physicochemical and functional properties and enhancing biological activities of polysaccharide.

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.

Comprehensive analysis of natural polysaccharides from TCMs: a generic approach based on UPLC-MS/MS

Here, we report a new application using liquid chromatography-electrospray mass spectrometry (UHPLC-ESI-MS) using aldononitrile acetate derivatives for simultaneous baseline separation and detection of eight neutral saccharides, two uronic acids, one ketose, and eight alditols within 14 min. The separation was performed on a Cortecs C₁₈ column using acetonitrile (A) and water (B) as the mobile phase with gradient elution. The target components were detected in selected ion monitoring (SIM) mode by mass spectrometry with an electrospray ionization (ESI) source operating in positive ionization mode. A comparison with traditional methods was used to determine the validity of the results. The UHPLC-ESI-MS method was used for quantitative analysis of free carbohydrates in water extracts of Crataegus pinnatifida as well as determination of Polygonatum cyrtonema and Glossy ganoderma monosaccharides in polysaccharides. The results demonstrate that this protocol is a comprehensive and effective technique for qualitative and quantitative analysis of plant polysaccharides from TCMs.

Systematic evaluation of a series of pectic polysaccharides extracted from apple pomace by regulation of subcritical water conditions

To investigate the influences of different subcritical water conditions on apple pomace pectic polysaccharides (APP) extraction, 20 samples were successfully prepared and systematically analyzed. At low temperature region (100-120 °C), extraction effect was predominant and extracted APP was high molecular weight, esterification degree and galacturonic acid content as well as light color. At middle temperature region (140 °C), the balance of extraction and degradation effects was reached and led to the highest APP yield (14.89%). At high temperature region (160-180 °C), degradation effect was predominant and led to serious degradation of APP and more extraction of co-extracts, which endowed the APP with low viscosity and good antioxidant activities in vitro. Overall, the relationship between different subcritical water conditions and APP properties are preliminarily illuminated, which not only provides a promising way for directed extraction of specific APP, but also promotes the potential application of subcritical water to commercial pectin.

Quantification of carbohydrates in human serum using gas chromatography–mass spectrometry with the stable isotope-labeled internal standard method

Comparison of two derivatization approaches (silylation and acylation) for carbohydrate separation based on optimizing reaction conditions by artificial neural networks.

A Novel Polysaccharide Isolated From Fresh Longan (Dimocarpus longan Lour.) Activates Macrophage via TLR2/4-Mediated PI3/AKT and MyD88/TRAF6 Pathways

A novel immunomodulatory polysaccharide (LP4) with a molecular weight 6.31 × 10⁴ g/mol was purified from fresh longan pulp. It was composed of mannose, glucose, glucuronic acid, galactose, xylose, arabinose, galacturonic acid, fucose, and rhamnose in a molar percentage of 36:31:10:7:4:4:3:2:2, and mainly linked by (1→6)-β-Man, (1→4)-β-Glc and (1→6)-α-Glc. LP4 can obviously enhance the phagocytosis of macrophages and promote the proliferation of lymphocytes. After treating macrophages with LP4 (12.5–50 μg/ml), the production of IL-1β and TNF-α was significantly increased. These increases of cytokines were suppressed when the TLR2/TLR4 receptors were inhibited by anti-TLR2 and/or anti-TLR4 antibodies. Moreover, the mRNA expression of INOS, AKT, PI3K, TRAF6 and MyD88 was significantly suppressed by TLR2/TLR4 antibodies. These results indicated that LP4 induced macrophage activation mainly via the TLR2 and TLR4-induced PI3K/AKT and MyD88/TRAF6 pathways.

A capillary electrophoresis method for the determination of soluble monosaccharides in Ginkgo biloba leaves

A method for the simultaneous determination of six monosaccharides by pre-column derivatization with 1-phenyl-3-methyl-5-pyrazolone and capillary electrophoresis was developed in this work. The derivatization (i.e., reaction temperature, capillary electrophoresis duration, and extraction number) and separation (i.e., pH and buffer concentration) conditions for capillary electrophoresis were optimized. Results showed that the limits of detection under optimal conditions were in the range of 0.036-0.35 mg/L with a mean correlation coefficient >0.99. The recoveries were in the range of 87.3-108.49%, and the relative standard deviations of intra- and inter-day variations were in the ranges of 2.2-3.8 and 3.2-5.0%, respectively. The method was successfully applied to the analysis of six free monosaccharides in three types of Ginkgo biloba leaves.

Isolation, characterization and HepG-2 inhibition of a novel proteoglycan from Flammulina velutipes

Flammulina velutipes has anti-inflammatory, immunomodulatory, antioxidant and many bioactive properties with high contents of carbohydrate, proteins and fibers. In this study, a novel proteoglycan with polysaccharide complexes and protein chain, named PGD1-1, was isolated from F. velutipes. The structural characteristics of PGD1-1 were then determined, and its anti-proliferation and pro-apoptotic activities against HepG-2 cells were demonstrated in vitro. Results proved that the average molecular weight of PGD1-1 was 32.71 kDa, and the carbohydrate and protein contents were 93.35 and 2.33%, respectively. The protein moiety was bonded to a polysaccharide chain via O-glycosidic linkage. The monosaccharides consisted of d-glucose, D-galactose and D-xylose in a molar ratio of 21.90:2.84:1.00. PGD1-1 significantly inhibited the proliferation of HepG-2 cells by affecting cell lipid peroxidation and nitric oxide production. In addition, PGD1-1 promoted the apoptosis of HepG-2 cells, especially the early apoptosis. These findings proved that PGD1-1 was a novel potent ingredient against the proliferation of HepG-2, which will provide a theoretical basis for the development and utilization of the functional ingredients of the F. velutipes.

Progress in the pretreatment and analysis of carbohydrates in food: An update since 2013

Carbohydrates in foods and other matrices plays vital roles in their diverse biological functions. Carbohydrates serve not only as functional substances but also as structural materials, such as components of membranes, and participate in cellular recognition. The fact that carbohydrates are indispensable has contributed to the need for pretreatment and analytical methods to be developed for their characterization. The aim of this review is to provide a comprehensive overview of carbohydrate pretreatment and determination methods in various matrices. The pretreatment methods include simple and more developed approaches (e.g., solid phase extraction, supercritical fluid extraction, and different microextraction methods, among others). The analytical methods include those by liquid chromatography (including high-performance anion-exchange chromatography), capillary electrophoresis, gas chromatography and supercritical fluid chromatography, and others. Different pretreatment methods and determination approaches are updated, compared, and discussed. Moreover, we discuss and compare the strengths and weaknesses of different methods and suggest their future prospects.

Structure analysis and antioxidant activity of polysaccharide-iron (III) from Cordyceps militaris mycelia

Iron-enriched Cordyceps militaris was obtained by adding FeSO₄ solution to the mycelia for biotransformation. The polysaccharide-iron (III) was extracted by water extraction and alcohol precipitation. High performance liquid chromatography showed that the crude polysaccharide-iron (III) had three components. The second component was purified by Sephadex G-150 and named as CPS-iron-II. The average molecular weight of CPS-iron-II was 44.136 kDa. The content of iron was 2.73%. The monosaccharide composition analysis indicated that the CPS-iron-II was composed of rhamnose, arabinose, galactose, glucose, mannose, galacturonic acid with percentage ratio of 0.94:3.12:27.01:36.62:30.20:2.12. The results of methylation analysis revealed that the CPS-iron-II was made of →2)-β-D-Glcp-(1→, with →2, 4)-α-D-Glcp-(1→ highly branched. Congo-red test showed that CPS-iron-II can cause flocculation of Congo red solution. The anti-oxidative analysis showed that antioxidant activity of CPS-iron-II was almost equal to that of Vc. The manuscript provided a new way for the preparation of polysaccharide-iron(III) from Cordyceps militaris.

A New, Quick, and Simple Protocol to Evaluate Microalgae Polysaccharide Composition

In this work, a new methodological approach, relying on the high specificity of enzymes in a complex mixture, was developed to estimate the composition of bioactive polysaccharides produced by microalgae, directly in algal cultures. The objective was to set up a protocol to target oligomers commonly known to be associated with exopolysaccharides' (EPS) nutraceutical and pharmaceutical activities (i.e., rhamnose, fucose, acidic sugars, etc.) without the constraints classically associated with chromatographic methods, while maintaining a resolution sufficiently high to enable their monitoring in the culture system. Determination of the monosaccharide content required the application of acid hydrolysis (2 M trifluoroacetic acid) followed by NaOH (2 M) neutralization. Quantification was then carried out directly on the fresh hydrolysate using enzyme kits corresponding to the main monosaccharides in a pre-determined composition of the polysaccharides under analysis. Initial results showed that the enzymes were not sensitive to the presence of TFA and NaOH, so the methodology could be carried out on fresh hydrolysate. The limits of quantification of the method were estimated as being in the order of the log of nanograms of monosaccharides per well, thus positioning it among the chromatographic methods in terms of analytical performance. A comparative analysis of the results obtained by the enzymatic method with a reference method (high-performance anion-exchange chromatography) confirmed good recovery rates, thus validating the closeness of the protocol. Finally, analyses of raw culture media were carried out and compared to the results obtained in miliQ water; no differences were observed. The new approach is a quick, functional analysis method allowing routine monitoring of the quality of bioactive polysaccharides in algal cultures grown in photobioreactors.

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.

Glucose-rich polysaccharide from dried 'Shixia' longan activates macrophages through Ca2+ and CR3- mediated MAPKs and PI3K-AKT pathways

A water-soluble glucose-rich polysaccharide from dried 'Shixia' longan pulp (LPsx) has been isolated for the first time, and its structure and immuno-regulatory mechanism were studied. LPsx is a hetero-polysaccharide with the average molecular weight 4102 g/mol. It was mainly consisted of glucose (95.9%), and small proportions of arabinose (2.1%), galactose (1.0%), mannose (0.6%), and xylose (0.4%). As analyzed by NMR, LPsx was mainly composed of (1 → 6)-α-d-glucose and (1 → 6)-β-d-glucose, branched with α-d-glucose-(1→. The immunomodulatory activity study showed that LPsx significantly increased the phagocytosis of macrophages, and strongly promoted the production of NO, IL-1β, IL-6 and TNF-α. Moreover, LPsx could inhibit the inflammatory response induced by lipopolysaccharide. The immuno-regulatory mechanism of LPsx was studied using RNA- sequencing and receptors activity analyses. It was found that LPsx induced macrophage activation via Ca²⁺ and CR3-mediated MAPKs and PI3K-AKT signaling pathways. The results would be helpful for revealing the health promoting mechanism of dried 'Shixia' longan in traditional Chinese medicine.

A sustainable and nondestructive method to high-throughput decolor Lycium barbarum L. polysaccharides by graphene-based nano-decoloration

Lycium barbarum L. polysaccharides (LBPs) with outstanding biological activities are of increasing interest. Traditional purification approaches are time-consuming and often involve toxic solvents that destroy the functionality and structure of polysaccharides. Herein, we report a sustainable and nondestructive strategy for purifying LBPs using graphene-based nano-decoloration. The amination of graphene oxide (GO) enables the resulted aminated reduced GO (NH₂-rGO) with abundant sp²-hybridized carbon domains, displaying high adsorption capacity toward pigments in crude polysaccharides. As such, within 5 min, NH₂-rGO can highly effectively and fast to decolor LBPs, with a high decoloration ratio of 98.72% and a high polysaccharides retention ratio of 95.62%. Importantly, compared with traditional decoloration methods, NH₂-rGO is nondestructive toward LBPs and has good reusability. Moreover, it exhibited widespread-use decoloration performance to decolor several common plant species. Overall, our proposed nano-decoloration approach is a general-purpose, sustainable, and nondestructive method to purify LBPs.

Optimization of Biosynthesis Conditions for the Production of Exopolysaccharides by Lactobacillus plantarum SP8 and the Exopolysaccharides Antioxidant Activity Test

Lactobacillus plantarum SP8, isolated from traditional Chinese pickle juice, was utilized for the production of exopolysaccharides (EPSs), but the EPS yield was low under normal MRS medium. The single factor experiment and response surface methodology were used to optimize the medium components and culture conditions and the optimal conditions for EPS production were successfully obtained. Results showed that the optimum condition was glucose 22 g/L, yeast extract 30 g/L, fermentation temperature 35.6 °C, fermentation time 22 h and the theoretical EPS yield was 282.494 mg/L. The results were similar to the actual yield, 280.105 mg/L. By optimizing the culture conditions, the yield of L. plantarum SP8 EPS was improved by nearly 19 times. In the gas chromatography analysis, it was found that L. plantarum SP8 EPS consisted of d-rhamnose, arabinose, galactose, and d-acetylglucosamine, but glucose was not included, which was quite different from the reported heteropolysaccharide component of Lactobacillus. Furthermore, the antioxidant activity of L. plantarum SP8 EPS was evaluated with the in vitro scavenging abilities on DPPH·, O 2 - and ·OH. The in vitro antioxidant activity study indicated that L. plantarum SP8 EPS possessed certain antioxidant activity. All results demonstrated the potential of L. plantarum SP8 in the food and dairy industry.

Validation of a sensitive high performance liquid chromatography tandem mass spectrometric method for measuring carbohydrates in aerosol samples

Carbohydrates (such as levoglucosan) are a class of important water-soluble organic compounds in atmosphere. In this study, a high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was applied to characterize carbohydrates in aerosol particles. Since carbohydrate was a kind of compound with low response in mass spectrometry, the conventional HPLC-MS/MS method was not sensitive enough to determine it. When acetate acid was added into mobile phase as buffer, the transition of [M+CH₃COO]^-→[M-H]^- could be selected as the quantification ions. In the range from 1.0 μg L^-1 to 20 μg mL^-1, the coefficients of regression (r²) were more than 0.990, and relative standard deviations (RSD) for replicated injections were lower than 2%. The limit of detection (LOD) and quantification (LOQ) were lower than 2.5 ng L^-1 and 10 ng L^-1, respectively. The precision and accuracy were examined by spiked samples at three different concentration levels (10 μg L^-1, 100 μg L^-1, and 500 μg L^-1) in five replicates. Recovery ratios ranged from 85% to 115% with RSD lower than 16%. Matrix effects of different carbohydrates ranged from 62% to 120%. The most sensitive HPLC-MS/MS method was developed and validated to analyze 40 aerosol samples successfully. The carbohydrates including three sugar alcohols (threitol, arabitol and sorbitol), one monosaccharide sugar (inositol), two disaccharides (sucrose, trehalose), one anhydrosugar (levoglucosan) and one 2-methyltetrols (2-Methylbutane-1,2,3,4-tretraol) were successfully quantified.