Chromatographic separation of 1-phenyl-3-methyl-5-pyrazolone-derivatized neutral, acidic and basic aldoses

The α-linkage in funoran and agarose could be hydrolyzed by a GH96 family enzyme: Discovery of the α-funoranase

Agarans represent a group of galactans extracted from red algae. Funoran and agarose are the two major types and commercially applied polysaccharides of agaran. Although the glycoside hydrolases targeting β-glycosidic bonds of agaran have been widely investigated, those capable of degrading α-glycosidic bonds of agarose were limited, and the enzyme degrading α-linkages of funoran has not been reported till now. In this study, a GH96 family enzyme BiAF96A_Aq from a marine bacterium Aquimarina sp. AD1 was heterologously expressed in Escherichia coli. BiAF96A_Aq exhibited dual activities towards the characteristic structure of funoran and agarose, underscoring the multifunctionality of GH96 family members. Glycomics and NMR analysis revealed that BiAF96A_Aq hydrolyzed the α-1,3 glycosidic bonds between 3,6-anhydro-α-l-galactopyranose (LA) and β-d-galactopyranose-6-sulfate (G6S) of funoran, as well as LA and β-d-galactopyranose (G) of agarose, through an endo-acting manner. The end products of BiAF96A_Aq were majorly composed of disaccharides and tetrasaccharides. The identification of the activity of BiAF96A_Aq on funoran indicated the first discovery of the funoran hydrolase for α-1,3 linkage. Considering the novel catalytic reaction, we proposed to name this activity as "α-funoranase" and recommended the assignment of a dedicated EC number for its classification.

Structural investigation of Fun168A unraveling the recognition mechanism of endo-1,3-fucanase towards sulfated fucan

BACKGROUND

Sulfated fucan has gained interest due to its various physiological activities. Endo-1,3-fucanases are valuable tools for investigating the structure and establishing structure-activity relationships of sulfated fucan. However, the substrate recognition mechanism of endo-1,3-fucanases towards sulfated fucan remains unclear, limiting the application of endo-1,3-fucanases in sulfated fucan research.

SCOPE AND APPROACH

This study presented the first crystal structure of endo-1,3-fucanase (Fun168A) and its complex with the tetrasaccharide product, utilizing X-ray diffraction techniques. The novel subsite specificity of Fun168A was identified through glycomics and nuclear magnetic resonance (NMR).

KEY FINDINGS AND CONCLUSIONS

The structure of Fun168A was determined at 1.92 Å. Residues D206 and E264 acted as the nucleophile and general acid/base, respectively. Notably, Fun168A strategically positioned a series of polar residues at the subsites ranging from -2 to +3, enabling interactions with the sulfate groups of sulfated fucan through salt bridges or hydrogen bonds. Based on the structure of Fun168A and its substrate recognition mechanisms, the novel subsite specificities at the -2 and +2 subsites of Fun168A were identified. Overall, this study provided insight into the structure and substrate recognition mechanism of endo-1,3-fucanase for the first time and offered a valuable tool for further research and development of sulfated fucan.

Quantitative determination of chondroitin sulfate with various molecular weights in raw materials by pre-column derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate

A simple and reliable HPLC method was developed for quantification of chondroitin sulfate (CS). The procedure is based on precolumn hydrolysis of CS to liberate galactosamine and subsequent derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate. Hydrolysis and derivatization conditions were optimized. A linear correlation coefficient of 0.9999 was calculated within the range of 10-1500 μg/mL from the standard curve. The method produces good precision and good accuracy (100.75 % recovery). An advantage over other common methods is its ability to quantify CS of all molecular weights and structures, as evidenced by the determination of CS fractions with narrow molecular weight distributions obtained through depolymerization by different methods, while enzymatic HPLC was proven to be infeasible. Extraction recoveries of CS from monosaccharide mixed samples were > 93 %. The reliability was also validated by a small difference (-1.95 % to 4.12 %) relative to enzymatic HPLC results in analysing representative CS samples of different animal origins and suppliers.

An enzyme-pHBH method for specific quantification of porphyran

Porphyran, the major polysaccharide extracted from Porphyra, exhibits tremendous potential for development as functional food or pharmaceutical due to its multiple biological activities. The quantitative analysis of porphyran is important for the quality control in product development. However, the specific quantitative method of porphyran has not been established, and the lack of reference substance makes the quantification more challenging. Here, a common component of porphyran, with high purity, similar molecular weight distribution, sourced from different Porphyra producing areas in China was first prepared by a series of isolation and purification steps, and utilized as the reference substance for porphyran quantification. Subsequently, the porphyran was fully degraded into oligosaccharides by using a β-porphyranase, followed by employing para-hydroxybenzoic acid hydrazide (pHBH) method to detect the content of the generated reducing sugar. The enzyme-pHBH method for porphyran specific quantification was established. Results showed that this method was validated with good linearity, high accuracy and precision, and reliability. Addtionally, NaCl with a concentration below 0.5 %, alcohol under 8 % and other polysaccharide including chitosan, agarose, chondrotin sulfate, alginate, hyaluronic acid and κ-carrageenan did not interfere with this method. This approach is promising for quality control of the porphyran products and offers a feasible strategy for the specific quantification of other polysaccharides.

Characterization of a novel endo-1,3-fucanase from marine bacterium Wenyingzhuangia fucanilytica reveals the presence of diversity within glycoside hydrolase family 168

Sulfated fucans attract increasing research interests in recent decades for their various physiological activities. Fucanases are indispensable tools for the investigation of sulfated fucans. Herein, a novel GH168 family endo-1,3-fucanase was cloned from the genome of marine bacterium Wenyingzhuangia fucanilytica. The expressed protein Fun168D was a processive endo-acting enzyme. Ultra performance liquid chromatography-high resolution mass spectrum and NMR analyses revealed that the enzyme cleaved the α-1 → 3 bonds between α-l-Fucp(2OSO₃^-) and α-l-Fucp(2OSO₃^-) in sulfated fucan from Isostichopus badionotus, and α-1 → 3 bonds between α-l-Fucp(2OSO₃^-) and α-l-Fucp(2,4OSO₃^-) in sulfated fucan from Holothuria tubulosa. Fun168D would prefer to accept α-l-Fucp(2,4OSO₃^-) than α-l-Fucp(2OSO₃^-) at subsite +1, and could tolerate the absence of fucose residue at subsite +2. The novel cleavage specificity and hydrolysis pattern revealed the presence of diversity within the GH168 family, which would facilitate the development of diverse biotechnological tools for the molecule tailoring of sulfated fucan.

Near-infrared hyperspectral imaging for online measurement of the viability detection of naturally aged watermelon seeds

The viability status of seeds before sowing is important to farmers as it allows them to make yield predictions. Monitoring the seed quality in a rapid and nondestructive manner may create a perfect solution, especially for industrial sorting applications. However, current offline laboratory-based strategies employed for the monitoring of seed viability are time-consuming and thus cannot satisfy industrial needs where there is a substantial number of seeds to be analyzed. In this study, we describe a prototype online near-infrared (NIR) hyperspectral imaging system that can be used for the rapid detection of seed viability. A wavelength range of 900-1700 nm was employed to obtain spectral images of three different varieties of naturally aged watermelon seed samples. The partial least square discriminant analysis (PLS-DA) model was employed for real-time viability prediction for seed samples moving through a conveyor unit at a speed of 49 mm/sec. A suction unit was further incorporated to develop the online system and it was programmatically controlled to separate the detected viable seeds from nonviable ones. For an external validation sample set showed classification accuracy levels of 91.8%, 80.7%, and 77.8% in relation to viability for the three varieties of watermelon seed with healthy seedling growth. The regression coefficients of the classification model distinguished some chemical differences in viable and nonviable seed which was verified by the chromatographic analysis after the detection of the proposed online system. The results demonstrated that the developed online system with the viability prediction model has the potential to be used in the seed industry for the quality monitoring of seeds.

Structural characterization and anti-osteoporosis activity of two polysaccharides extracted from the rhizome of Curculigo orchioides

Curculigo orchioides is widely used to treat osteoporosis in China. In this study, we identified the active substances in the crude polysaccharide (CO50) from C. orchioides that had anti-osteoporosis activity in vivo. Two polysaccharides, COP50-1 and COP50-4, were purified from CO50. Based on structural analysis, COP50-1 was composed of α-D-Glcp-(1→, β-D-Galp-(1→, →4)-α-D-Glcp-(1→, →3,4)-α-D-Glcp-(1→, →4,6)-α-D-Glcp-(1→, →4,6)-β-D-Manp-(1→, whereas COP50-4 was composed of α-L-Araf-(1→, →2)-α-L-Rhap-(1→, β-D-Manp-(1→, α-D-Galp-(1→, →2,4)-α-L-Rhap-(1→, →2)-β-D-Manp-(1→, →4)-α-D-GlcAp-(1→, →3)-α-D-GalAp-(1→, →4,6)-α-D-Galp-(1→, →2,3,6)-β-D-Manp-(1→, →2,3,5)-α-L-Araf-(1→, →2,5)-α-L-Araf-(1→, →4)-α-D-Glcp-(1→ and →3)-α-D-Galp-(1→. Pharmacological assessment revealed that COP50-1 had no obvious osteogenic activity. However, COP50-4 (0.5 μM) significantly enhanced the differentiation and mineralization of osteoblasts in vitro. Moreover, the effect of COP50-4 was greater than that of 17β-estradiol. Therefore, COP50-4 may be an effective component of CO50 that has great potential for development as an alternative drug for the treatment of osteoporosis.

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.

Utilizing heterologously overexpressed endo-1,3-fucanase to investigate the structure of sulfated fucan from sea cucumber (Holothuria hilla)

Sea cucumber sulfated fucan (SC-FUC) attracted increasing interests in the recent decades. Endo-1,3-fucanase has been employed in the structural clarification and structure-function relationship investigations of SC-FUC. Nevertheless, the preparation of wild-type endo-1,3-fucanase is costly and time-consuming, which hinders its further utilization. In this study, a heterologously overexpressed endo-1,3-fucanase (FunA) was introduced into structural identification of SC-FUC. FunA was efficiently prepared within one day and utilized in the investigation of sulfated fucan from sea cucumber Holothuria hilla (Hh-FUC). By using enzymatic degradation, glycomics and NMR analysis, the major structure of Hh-FUC was identified to be composed of a tetrasaccharide repeating unit →3-α-l-Fucp-1 → 3-α-l-Fucp2,4(OSO₃^-)-1 → 3-α-l-Fucp2(OSO₃^-)-1 → 3-α-l-Fucp2(OSO₃^-)-1→. Due to the efficient acquisition of enzyme and the superior oligosaccharide recovery, 0.6 mL of E. coli broth and 10 mg of Hh-FUC were sufficient for the structural identification. The results demonstrated the superiority of heterologously overexpressed fucanase over its wild-type enzyme in structural investigation of sulfated fucan.

Comparison of Different Labeling Techniques for the LC-MS Profiling of Human Milk Oligosaccharides

Human milk oligosaccharides (HMOs) exhibit various biological activities for infants, such as serving as prebiotics, blocking pathogens, and aiding in brain development. HMOs are a complex mixture of hetero-oligosaccharides that are generally highly branched, containing multiple structural isomers and no intrinsic chromophores, presenting a challenge to both their resolution and quantitative detection. While liquid chromatography-mass spectrometry (LC-MS) has become the primary strategy for analysis of various compounds, the very polar and chromophore-free properties of native glycans hinder their separation in LC and ionization in MS. Various labeling approaches have been developed to achieve separation of glycans with higher resolution and greater sensitivity of detection. Here, we compared five commonly used labeling techniques [by 2-aminobenzamide, 2-aminopyridine, 2-aminobenzoic acid (2-AA), 2,6-diaminopyridine, and 1-phenyl-3-methyl-5-pyrazolone] for analyzing HMOs specifically under hydrophilic-interaction chromatography-mass spectrometry (HILIC-MS) conditions. The 2-AA labeling showed the most consistent deprotonated molecular ions, the enhanced sensitivity with the least structural selectivity, and the sequencing-informative tandem MS fragmentation spectra for the widest range of HMOs; therefore, this labeling technique was selected for further optimization under the porous graphitized carbon chromatography-mass spectrometry (PGC-MS) conditions. The combination strategy of 2-AA labeling and PGC-MS techniques provided online decontamination (removal of excess 2-AA, salts, and lactose) and resolute detection of many HMOs, enabling us to characterize the profiles of complicated HMO mixtures comprehensively in a simple protocol.

Composition-Activity Relationships of Polysaccharides from Saccharina japonica in Regulating Gut Microbiota in Short-Term High-Fat Diet-Fed Mice

Saccharina japonica polysaccharide could modulate gut microbiota composition; however, the composition-activity relationship remains unclear, thus restricting its application. In the current study, we investigated the impact of eight different S. japonica polysaccharide fractions on the gut microbiota after day 2 and day 14 treatments on high-fat diet (HFD) feeding mice. The results showed that a 2 day HFD dramatically altered gut microbiota composition, and the additional 12 day HFD further strengthened the gut microbiota dysbiosis in the HFD group. LjA-1 and LjA-3 could partially alleviate the dysbiosis of gut microbiota composition and significantly alter gut microbiota function. Multiple linear regression analysis revealed that the sulfate content and the molecular weight distributions were the main factors affecting the dominant gut bacterial genera. Our findings reveal that gut microbiota homeostasis could be disordered by HFD at day 2 and provide insights into the quantitative composition-activity relationships of polysaccharides in regulating gut microbiota.

Kinetic, Thermodynamic, Physicochemical, and Economical Characterization of Pectin from Mangifera indica L. cv. Haden Residues

The effect of temperature (60, 70, 80, and 90 °C) and time (30, 45, 60, 75, and 90 min) on citric acid extraction of Haden mango (Mangifera indica L. cv. Haden) peel pectin was evaluated in the present study. In order to obtain a better understanding of both the extraction process and the characteristics of the pectin (obtained from an agro-industrial waste) for a future scaling process, the following characterizations were performed: (1) Kinetic, with the maximum extraction times and yields at all evaluated temperatures; (2) thermodynamic, obtaining activation energies, enthalpies, entropies, and Gibbs free energies for each stage of the process; (3) physicochemical (chemical analysis, monosaccharide composition, degree of esterification, galacturonic acid content, free acidity, Fourier-transform infrared spectroscopy, thermogravimetric and derivative thermogravimetric analyses); and (4) economical, of the pectin with the highest yield. The Haden mango peel pectin was found to be characterized by a high-esterified degree (81.81 ± 0.00%), regular galacturonic acid content (71.57 ± 1.26%), low protein (0.83 ± 0.05%) and high ash (3.53 ± 0.02%) content, low mean viscometric molecular weight (55.91 kDa), and high equivalent weight (3657.55 ± 8.41), which makes it potentially useful for food applications.

Isolation, Purification, Characterization, and Immunomodulatory Activity Analysis of α-Glucans from Spirulina platensis

Crude polysaccharides from Spirulina platensis (SP) were isolated by maceration with a hot alkali solution and further fractionated by DEAE-52 cellulose and Sephadex G-100 chromatography into two purified fractions PSP-1 and PSP-2. The monosaccharide composition analysis indicated that SP was mainly composed of rhamnose and glucose, while PSP-1 and PSP-2 were composed only of glucose. The composition analysis of PSP-1 and PSP-2 by HPLC, FT-IR, and NMR showed that PSP-1 and PSP-2 were branching dextran, and their structures were (1 → 4)-linked-α-D-Glcp as the main chain, and C-6 replaced the single α-D-Glcp as the linear structure of the branch chain. The glucans (SP/PSP-1/PSP-2) can significantly improve the phagocytic ability of macrophages, enhance iNOS activity, promote NO production, and increase IL-6 mRNA expression, so they may possess certain immunomodulatory activity.

Genomic basis of environmental adaptation in the leathery sea squirt (Styela clava)

Tunicates occupy the evolutionary position at the boundary of invertebrates and vertebrates. It exhibits adaptation to broad environmental conditions and is distributed globally. Despite hundreds of years of embryogenesis studies, the genetic basis of the invasive habits of ascidians remains largely unknown. The leathery sea squirt, Styela clava, is an important invasive species. We used the chromosomal-level genome and transcriptome of S. clava to explore its genomic- and molecular-network-based mechanisms of adaptation to environments. Compared with Ciona intestinalis type A (C. robusta), the size of the S. clava genome was expanded by 2-fold, although the gene number was comparable. An increase in transposon number and variation in dominant types were identified as potential expansion mechanisms. In the S. clava genome, the number of genes encoding the heat-shock protein 70 family and members of the complement system was expanded significantly, and cold-shock protein genes were transferred horizontally into the S. clava genome from bacteria. The expanded gene families potentially play roles in the adaptation of S. clava to its environments. The loss of key genes in the galactan synthesis pathway might explain the distinct tunic structure and hardness compared with the ascidian Ciona species. We demonstrated further that the integrated thyroid hormone pathway participated in the regulation of larval metamorphosis that provides S. clava with two opportunities for adapting to their environment. Thus, our report of the chromosomal-level leathery sea squirt genome provides a comprehensive genomic basis for the understanding of environmental adaptation in tunicates.

Structural Characterization and α-Glucosidase Inhibitory and Antioxidant Activities of Fucoidans Extracted from Saccharina japonica

Two sulfated fucoidan fractions (Lj3 and Lj5) were extracted from Saccharina japonica and then subjected to acid hydrolysis to obtain Lj3h and Lj5h. Lj3h and Lj5h were characterized using IR, methylation analysis, and mass spectrometry. It was found that Lj3h and Lj5h were homogeneous low molecular weight fucoidans. Specifically, Lj3h was composed of the main chain of 1,3-linked α-L-fucopyranose residues with sulfate at C-2 and/or C-4 and three different monosaccharides (galactose, glucose, mannose) branched at C-2 and/or C-4 of fucose residue. Lj5h contained backbones of alternating galactopyranose residues and fucopyranose residues attached via a 1→3 linkage (galactofucan) and 1→6 linked galactan. The sulfation pattern was mainly located at C2/C4 fucose or galactose residues and more branches occupied at C-4 of fucose residue and C-2, C-3 or/and C-6 of galactose residue. In vitro assay indicated that, among the four fucoidans tested, only Lj5 showed potent α-glucosidase inhibitory activity with IC50 of 153.27±22.89 μg/mL, and the two parent fucoidans, Lj3 and Lj5, showed better antioxidant activity than their derivatives. These findings highlight the structure and bioactivity diversity of Saccharina japonica-derived fucoidans.

Structural analysis and potential anti-tumor activity of Sporisorium reilianum (Fries) polysaccharide

A neutral polysaccharide WM-NP-60 was successfully isolated and purified from a phytopathogenic fungus Sporisorium reilianum (Fries). The characteristics and potential antitumor activities of WM-NP-60 were studied. WM-NP-60 was a water-soluble polysaccharide. The molecular weight of WM-NP-60 was 15.6 kDa. The main chain of WM-NP-60 was composed of β-1,6-D-Glcp and its side chains were β-1,3-D-Glcp. The side chains bound to the main chain with glycosyl groups at the C-3 positions. Gal might be attached to the backbone as a side chain or bound to the linear β-1,3-D-Glcp side chain. WM-NP-60 could inhibit the proliferation of HepG2 and SGC7901 cells in a dose-dependently manner. In addition, it was found that WM-NP-60 triggered the HepG2 and SGC7901 cell cycle arrest at the G₁ phase and induced apoptosis of HepG2 and SGC7901 cells. Taken together, these results suggested that WM-NP-60 possessed a tumor-suppressive activity and might be regarded as a potential natural anti-tumor drug.

Depolymerized RG-I-enriched pectin from citrus segment membranes modulates gut microbiota, increases SCFA production, and promotes the growth of Bifidobacterium spp., Lactobacillus spp. and Faecalibaculum spp

Rhamnogalacturonan-I (RG-I)-enriched pectin (WRP) was recovered from citrus processing water by sequential acid and alkaline treatments in a previous study. RG-I-enriched pectin was proposed as a potential supplement for functional food and pharmaceutical development. However, previous studies illustrated that favorable modulations of gut microbiota by RG-I-enriched pectin were based on in vitro changes in the overall microbial structure and the question of whether there is a structure-dependent modulation of gut microbiota remains largely enigmatic. In the present study, modulations of gut microbiota by commercial pectin (CP), WRP and its depolymerized fraction (DWRP) with different RG-I contents and Mw were compared in vivo. It was revealed by 16s rRNA high-throughput sequencing that WRP and DWRP mainly composed of RG-I modulated the gut microbiota in a positive way. DWRP significantly increased the abundance of prebiotic such as Bifidobacterium spp., Lactobacillus spp., while WRP increased SCFAs producers including species in Ruminococcaceae family. By maintaining a more balanced gut microbiota composition and enriching some SCFA producers, dietary WRP and DWRP also elevated the SCFA content in the colon. Collectively, our findings offer new insights into the structure-activity correlation of citrus pectin and provide impetus towards the development of RG-I-enriched pectin with small molecular weight for specific use in health-promoting prebiotic ingredients and therapeutic products.

Extraction Methods Affect the Structure of Goji (Lycium barbarum) Polysaccharides

Polysaccharides are considered to be the most important active substances in Goji. However, the structure of polysaccharides varies according to the extraction methods applied, and the solution used to prepare Goji polysaccharides (LBPs) were limited. Thus, it is important to clarify the connection between extraction methods and structure of Goji polysaccharide. In view of the complex composition of cell wall polysaccharides and the various forms of interaction, different extraction methods will release different parts of the cell wall. The present study compared the effects of different extraction methods, which have been used to prepare different types of plant cell wall polysaccharides based on various sources, on the structure of cell-wall polysaccharides from Goji, by the single separate use of hot water, hydrochloric acid (0.4%) and sodium hydroxide (0.6%), at both high and low temperatures. Meanwhile, in order to explore the limitations of single extraction, sequential extraction methods were applied. Structural analysis including monosaccharide analysis, GPC-MALLS, AFM and ¹H-NMR suggested the persistence of more extensively branched rhamnogalacturonan I (RG-I) domains in the procedures involving low-temperature-alkali, while procedures prepared by high-temperature-acid contains more homogalacturonan (HG) regions and results in the removal of a substantial part of the side chain, specifically the arabinan. A kind of acidic heteropolysaccharide was obtained by hot water extraction. SEC-MALLS and AFM confirmed large-size polymers with branched morphologies in alkali-extracted polysaccharides. Our results provide new insight into the extraction of Goji polysaccharides, which differ from the hot water extraction used by traditional Chinese medicine.

Structural characterization and osteogenic bioactivities of a novel Humulus lupulus polysaccharide

Humulus lupulus is a perennial climbing plant of the subfamily Cannabioideae native to the Northern Hemisphere. The primary use of H. lupulus is in the brewing industry, where it is an essential ingredient for imparting a unique flavor (bitterness and aroma) to beer. The female flowers of H. lupulus are also used in traditional Chinese medicine, but the biologically active ingredients underlying its benefits remain unclear. China is the largest producer and consumer of H. lupulus in Asia. Using the waste from the beer-brewing process of H. lupulus as raw materials, the biologically active polysaccharides can be screened. This is useful for the full utilization of H. lupulus, potentially leading to disease prevention and treatment. In this study, we isolated a homogeneous polysaccharide (HLP50-1) with a molecular weight of 49.13 kDa from female flowers of H. lupulus via a DEAE-Cellulose 52 anion exchange column and a Sephadex G-75 gel filtration column. Methylation, GC-MS, and NMR analyses revealed that the HLP50-1 comprised →4)-α-d-Glcp-(1→, →6)-α-d-Manp-(1→, →3)-α-l-Rhap-(1→, β-d-Glcp-(1→, α-l-Araf-(1→, →4,6)-2-OAc-β-d-Galp-(1→, β-d-Galp-(1→, →3,6)-β-d-Glcp-(1→, →2,3,4)-α-d-Xylp-(1→, →6)-α-d-Glcp-(1→, →3)-α-d-Galp-(1→, →4)-α-d-Galp-(1→. Advanced structural analysis showed that the HLP50-1 contained irregular fragments of different sizes and shapes with a smooth surface. The aggregates appeared be composed of accumulated crystals. Furthermore, the osteogenic activities of the HLP50-1 were evaluated via MC3T3-E1 cells in vitro. The results showed that 0.13 μM HLP50-1 led to outstanding proliferation, differentiation, and mineralization of the MC3T3-E1 cells. Therefore, HLP50-1 has osteogenic effects, and it may be a candidate for the treatment of osteoporosis. It has broad application prospects in functional foods, health-care products, and pharmaceuticals.

Structural Features and Digestive Behavior of Fucosylated Chondroitin Sulfate from Sea Cucumbers Stichopus japonicus

Fucosylated chondroitin sulfate from sea cucumber Stichopus japonicus (FCS_SJ) has been demonstrated with various biological activities; however, its precise structure is still controversial, and digestive behavior remains poorly understood. FCS_SJ was purified, and its detailed structure was elucidated mainly based on the NMR spectroscopic methods. Its main chain was characterized as →4)-β-d-GlcA-(1 → 3)-β-d-GalNAc-(1→ with GalNAc4S6S:GalNAc4S in a ratio of 1.5:1, and three types of sulfated fucosyl branches attaching C-3 of GlcA, namely, Fucp2S4S, Fucp3S4S, and Fucp4S, were found in a ratio of 2:1.5:1. The digestibility of FCS_SJ was investigated in vitro, and the unchanged molecular weight and reducing sugar content indicated that FCS_SJ was not broken down under salivary and gastrointestinal digestion. Furthermore, FCS_SJ showed a significant inhibitory impact on pancreatic lipase dose-dependently but not on α-amylase, indicating that the inhibition of pancreatic lipase by FCS_SJ might be a pathway for its hypolipidemic effect. These findings propose a fucosylated chondroitin sulfate and provide insight into the mechanism of its physiological effects in the digestion system.

Quantitative Analysis of Polysaccharide Composition in Polyporus umbellatus by HPLC-ESI-TOF-MS

Polyporus umbellatus is a well-known and important medicinal fungus in Asia. Its polysaccharides possess interesting bioactivities such as antitumor, antioxidant, hepatoprotective and immunomodulatory effects. A qualitative and quantitative method has been established for the analysis of 12 monosaccharides comprising polysaccharides of Polyporus umbellatus based on high-performance liquid chromatography coupled with electrospray ionization–ion trap–time of flight–mass spectrometry. The hydrolysis conditions of the polysaccharides were optimized by orthogonal design. The results of optimized hydrolysis were as follows: neutral sugars and uronic acids 4 mol/L trifluoroacetic acid (TFA), 6 h, 120 °C; and amino sugars 3 mol/L TFA, 3 h, 100 °C. The resulting monosaccharides derivatized with 1-phenyl-3-methyl-5-pyrazolone have been well separated and analyzed by the established method. Identification of the monosaccharides was carried out by analyzing the mass spectral behaviors and chromatography characteristics of 1-phenyl-3-methyl-5-pyrazolone labeled monosaccharides. The results showed that polysaccharides in Polyporus umbellatus were composed of mannose, glucosamine, rhamnose, ribose, lyxose, erythrose, glucuronic acid, galacturonic acid, glucose, galactose, xylose, and fucose. Quantitative recoveries of these monosaccharides in the samples were in the range of 96.10–103.70%. This method is simple, accurate, and sensitive for the identification and quantification of monosaccharides, and can be applied to the quality control of Polyporusumbellatus as a natural medicine.

Composition and Rheological Properties of Polysaccharide Extracted from Tamarind (Tamarindus indica L.) Seed

A polysaccharide was extracted in high yield from tamarind (Tamarindus indica L.) seed (TSP) by acidic hot water extraction and ethanol precipitation. It was composed of 86.2% neutral polysaccharide, 5.4% uronic acid and 1.3% protein. The molecular weight of TSP was estimated to be about 1735 kDa, with glucose, xylose, and galactose in a molar ratio of 2.9:1.8:1.0 as the major monosaccharides. The steady shear and viscoelastic properties of TSP aqueous solutions were investigated by dynamic rheometry. Results revealed that TSP aqueous solution at a concentration above 0.5% (w/v) exhibited non-Newtonian shear-thinning behavior. Dynamic oscillatory analysis revealed that 10% (w/v) TSP showed as a “weak gel” structure. Apparent viscosities and viscoelastic parameters of TSP solutions decreased drastically in an alkaline solution of pH > 10, but slightly influenced by acidic solution, high temperature and the presence of salt ions and sucrose. These results indicated that TSP possessed excellent pH-resistance and thermo-stability, which might be suitable for applications in acidic beverages and high-temperature processed foodstuffs.

A rapid, accurate and sensitive method for determination of monosaccharides in different varieties of Osmanthus fragrans Lour by pre-column derivatization with HPLC-MS/MS

A specific HPLC-MS/MS (High-Performance Liquid Chromatography with tandem Mass Spectrometry) method was developed and validated for simultaneous determination of several monosaccharides in three kinds Osmanthus fragrans Lour. After extraction, separation, protein removal, pigment removal and hydrolysis, monosaccharides was finally obtained from Osmanthus fragrans Lour. Positive ion mode detection and Multiple Reaction Monitoring (MRM) mode were used for quantitative analysis by PMP pre-column derivatization and Electrospray Ionization (ESI). Analysis and content determination of 6 monosaccharide components in 3 kinds of Osmanthus fragrans Lour. The HPLC separation was achieved on a Shim-pack VP-ODS6022748 (150 L × 2.0) with gradient elution at a flow rate of 0.2 ml/min in a run time of 40 min, and the mobile phase was acetonitrile-5 mmol/L ammonium acetate. PMP derivatization in HPLC-MS/MS can accurately measure Osmanthus fragrans Lour. mannose (Man), ribose (Rib), rhamnose (Rha), galacturonic acid (Gal UA), glucose (Glu), galactose (Gal), xylose (Xyl), fucose (Fuc). The results showed that HPLC-MS/MS pre-column derivatization method was simple and rapid, with small measurement error, but high sensitivity and good repeatability. The analysis of monosaccharide components in polysaccharide components has important practical significance.

Structural characterization and rheological properties of β-D-glucan from hull-less barley (Hordeum vulgare L. var. nudum Hook. f.)

A high purity of β-D-glucan (80.8%) from hull-less barley (Hordeum vulgare L. var. nudum Hook. f.) (HBBG) was isolated by alkali extraction and multi-precipitation with ethanol. The molecular weight (Mw) of HBBG was determined as 571.4 kDa with a broad distribution (Mw/Mn = 1.6) by using HPSEC. According to methylation and GC-MS analysis, HBBG was identified to be composed of (1 → 4)- and (1 → 3)-glucopyranosyl (Glcp) residues with a ratio of (3.19 ± 0.01). The MALDI-TOF MS and NMR spectroscopy were further conducted to analyze the enzyme hydrolysate released by lichenase digestion on HBBG. The results suggested that HBBG possessed a typical chemical structure of cereal β-D-glucans, namely linear homopolysaccharides formed by β-D-Glcp units via (1 → 4)-linkages and occasionally single (1 → 3)-linkage. The trisaccharide and tetrasaccharide of HBBG accounted for 66.6% of total cellulosyl units, accompanying with a ratio of cellotriosyl to cellotetraosyl units = 1.0, which were significant different from those reported for the other cereal β-glucans. Rheological property analysis revealed that HBBG showed a shear-thinning behavior and thermal resilience during heating-cooling process.

Liquid Chromatography-Tandem Mass Spectrometry Approach for Determining Glycosidic Linkages

The structural analysis of carbohydrates remains challenging mainly due to the lack of rapid analytical methods able to determine and quantitate glycosidic linkages between the diverse monosaccharides found in natural oligosaccharides and polysaccharides. In this research, we present the first liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method for the rapid and simultaneous relative quantitation of glycosidic linkages for oligosaccharide and polysaccharide characterization. The method developed employs ultrahigh-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC/QqQ-MS) analysis performed in multiple reaction monitoring (MRM) mode. A library of 22 glycosidic linkages was built using commercial oligosaccharide standards. Permethylation and hydrolysis conditions along with LC-MS/MS parameters were optimized resulting in a workflow requiring only 50 μg of substrate for the analysis. Samples were homogenized, permethylated, hydrolyzed, and then derivatized with 1-phenyl-3-methyl-5-pyrazolone (PMP) prior to analysis by UHPLC/MRM-MS. Separation by C18 reversed-phase UHPLC along with the simultaneous monitoring of derivatized terminal, linear, bisecting, and trisecting monosaccharide linkages by mass spectrometry is achieved within a 15 min run time. Reproducibility, efficacy, and robustness of the method was demonstrated with galactan ( Lupin) and polysaccharides within food such as whole carrots. The speed and specificity of the method enables its application toward the rapid glycosidic linkage analysis of oligosaccharides and polysaccharides.

Fucosylated chondroitin sulfate is covalently associated with collagen fibrils in sea cucumber Apostichopus japonicus body wall

Fucosylated chondroitin sulfate (fCS) is the major carbohydrate constituent of sea cucumber. However, the distribution of fCS in the sea cucumber body wall has not been fully described. We addressed this in the present study employing Apostichopus japonicus as the material, a sea cucumber species with significant commercial importance. It was found that fCS was covalently attached to collagen fibrils via O-glycosidic linkages. Transmission electron microscopy analysis revealed that fCS precipitate was present in gap regions of collagen fibrils as roughly globular or ellipsoidal dots. The fCS dots arranged circumferentially around the fibrils with an axial repeat period that matched the periodicity of the fibrils. Physicochemical analysis indicated that the presence of fCS significantly increased the negative charge of the fibrils. These findings provide novel insight into fCS distribution in the sea cucumber body wall and its supramolecular organization with other macromolecules.

Production and flocculating properties of a compound biopolymer flocculant from corn ethanol wastewater

A compound biopolymer flocculant (CBF) produced using corn ethanol wastewater as substrate was investigated. After optimization of culture conditions, 3.08 g/L of purified CBF was extracted from the culture broth following 48 h of cultivation. The CBF macromolecule is mainly composed of protein (15.9%) and polysaccharide (81.8%). The polysaccharide component includes neutral sugars (28.92%), amino sugars (4.04%) and uronic acid (11.69%), with the neutral sugars being glucose, mannose, and lactose at a molar ratio of 4.1:1.5:1.9. CBF is pH tolerant from 3.0 to 12.0 and thermal tolerant from 20 to 100 °C, allowing for its application over a wide range of conditions. Furthermore, the Langmuir model better describes CBF adsorption on kaolin clay, as compared to the Freundlich model. Charge neutralization and bridging mechanisms are the primary flocculation mechanisms. In addition, CBF shows a high methylene blue removal efficiency. These results indicate that this compound biopolymer flocculant has great potential in dye wastewater treatment.

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

A rapid method for the quantitation of sixteen neutral and acidic monosaccharides, from both animal and plant sources was developed using ultra-high performance liquid chromatography triple quadrupole mass spectrometry (UHPLC/QqQ-MS) in dynamic multiple reaction monitoring (dMRM) mode. Monosaccharides including three pentoses (ribose, xylose, arabinose), two deoxyhexoses (rhamnose, fucose), five hexoses (fructose, mannose, allose, glucose, galactose), two hexuronic acids (glucuronic acid, galacturonic acid), and two N-acetyl-hexosamines (GlcNAc, GalNAc), were derivatized with 1-phenyl-3-methyl-5-pyrazolone (PMP), while underivatized sialic acids, Neu5Ac and Neu5Gc, were simultaneously analyzed with a 10-minute run. With the optimized UHPLC conditions, baseline separations of the isomers were achieved. The sensitivity and calibration ranges of this method were determined. The limits of detection were between femtomoles and attomoles with linear ranges spanning four to six orders of magnitude and coefficients of variation (CVs) ≤7.2%. Spiking experiments performed on a pooled fecal sample demonstrated the high accuracy of this method even when applied to samples with complicated matrices. The validated method was applied to fecal samples from an infant transitioning from breast milk to weaning foods. Major milk monosaccharides including galactose, fucose, glucose, GlcNAc, and Neu5Ac were found to be the most abundant components in the feces of milk-fed infants. PMP-derivatives of nine other monosaccharides including apiose, lyxose, altrose, talose, gulose, glucosamine, galactosamine, mannosamine, and N-acetylmannosamine (ManNAc) were also tested and could be added to the quantitation method depending on the need. The speed and sensitivity of the method makes it readily adaptable to rapid throughput analysis of monosaccharides in biological samples.

The structure property and endothelial protective activity of fucoidan from Laminaria japonica

Four antithrombotic fucoidan fractions F1, F2, LF1, and LF2 with different monosaccharide composition, molecular weight, and degree of sulfation and sulfate position were prepared from Laminaria japonica by hot water extraction and radical degradation. Their endothelial protective activity and possible action mechanism were studied using both cell- and rat-based models systematically. By comparison, the low molecular weight (LMW) fucoidan LF1 and LF2 were more potent than the medium molecular weight (MMW) fucoidan F1 and F2 in endothelial protection, down-regulation of von Willebrand Factor, CD31 and CD51 expressing endothelial microparticles in adrenalin-induced arterial endothelial injury rats and human umbilical vein endothelial cell system. However, the highly sulfated fucoidan fractions F2 and LF2 were better at inducing FGFR1c-expressing BaF3 cell proliferation in the presence of FGF-1, -2, -7, -8, -9 or -10. These results indicated that the chemical property of fucoidan was correlated to its specific biological activity tested. Therefore, defying fucoidan's monosaccharide composition, molecular weight, and degree of sulfation might be important in developing it into a medicine.