Monosaccharide Derivatives Research Articles

Synthesis, characterization and anticancer, antibacterial activities of pentacyclic triterpenoid glycoside derivatives

As a kind of glycoside, pentacyclic triterpenoid saponins have good biological activities, such as anticancer, antibacterial, antiviral and hypoglycemic effects [1]. In this paper, twenty-four pentacyclic triterpenoid derivatives, including twelve monosaccharide derivatives, were designed and synthesized. The anticancer effect and antibacterial activities of all compounds were evaluated. It is noteworthy that compound UA-2b has the strongest inhibitory effect on the growth of A549, Hela and HepG2 cancer cells (IC50 = 5.37 ± 0.22 µM, 5.82 ± 0.25 µM and 5.47 ± 0.06 µM, respectively). Compounds OA-2b, OA-6a, OA-6b, UA-2b and UA-6a have the best activity against Escherichia coli 1924 (MIC = 16 μg/ml).

Molecular Characterization of Gaseous Organic Acids and Nitrogen‐Containing Compounds From Crop Straw and Wood Burning

AbstractBiomass burning serves as important sources of volatile organic compounds (VOCs), yet our understanding of the molecular characteristics of oxygenated volatile organic compounds (OVOCs) from fresh emissions remains limited. In this study, gaseous organic compounds in fresh smokes from burning typical Chinese crop straws and woods are measured using an iodide time‐of‐flight chemical ionization mass spectrometer. Approximately 750 molecular formulas are identified, with CHO compounds containing carbon, hydrogen and oxygen atoms accounting for 77%–95% of the total. C1–C3 organic acids and dicarboxylic acids dominate the total CHO signal intensities by 27%–48%, while well‐known molecular markers of biomass burning, such as monosaccharide, guaiacol and syringol derivatives, contribute 7%–17%. Notably, crop straw and wood burning emit a higher abundance of guaiacol than syringol derivatives by a factor of 5. Additionally, a variety of nitrogen‐containing compounds (mainly in the CHON group) is identified, including isocyanate, amide, amino acids, and pyridine. The mass spectral profiles of organic compounds are largely similar between crop straw and wood burning fuels, although wood burning produces higher contributions of compounds with carbon atoms numbers >10. The saturation concentrations of organic compounds are estimated using molecular formula‐based volatility parameterization, revealing that semi‐volatile and intermediate VOCs (S/intermediate volatility organic compounds (IVOCs)) predominate smoke releases by 35%–60% and 20%–43%, respectively, with only a small fraction of low‐volatility compounds. Given the widespread nature of biomass burning in winter China, our results may have significant implications for interpreting secondary organic aerosol formation through gas‐particle partitioning or aqueous‐phase reactions.

Synthetic approaches of carbohydrate based self-assembling systems.

Carbohydrate-based self-assembling systems are essential for the formation of advanced biocompatible materials via a bottom-up approach. The self-assembling of sugar-based small molecules has applications encompassing many research fields and has been studied extensively. In this focused review, we will discuss the synthetic approaches for carbohydrate-based self-assembling (SA) systems, the mechanisms of the assembly, as well as the main properties and applications. This review will mainly cover recent publications in the last four years from January 2020 to December 2023. We will essentially focus on small molecule self-assembly, excluding polymer-based systems, which include various derivatives of monosaccharides, disaccharides, and oligosaccharides. Glycolipids, glycopeptides, and some glycoconjugate-based systems are discussed. Typically, in each category of systems, the system that can function as low molecular weight gelators (LMWGs) will be discussed first, followed by self-assembling systems that produce micelles and aggregates. The last section of the review discusses stimulus-responsive self-assembling systems, especially those forming gels, including dynamic covalent assemblies, chemical-triggered systems, and photoresponsive systems. The review will be organized based on the sugar structures, and in each category, the synthesis of representative molecular systems will be discussed next, followed by the properties of the resulting molecular assemblies.

Helicity control of a polyaromatic coordination capsule through stereoselective CH-π interactions.

Although square-planar ML4 units are essential building blocks for coordination cages and capsules, the non-covalent control of the chirality and helicity of the resultant nanostructures is quite difficult. Here we report the helicity control of an M2L4 polyaromatic capsule, formed from metal ions with square-planar coordination geometry and bent bispyridine ligands, through stereoselective CH-π interactions with monosaccharide derivatives. Thanks to host-guest CH-π multi-interactions, one molecule of various permethylated monosaccharides is quantitatively bound by the capsule in water (K a up to >108 M-1). In the polyaromatic cavity, among them, the selective binding of a β-glucose derivative (>80 : 20 ratio) is demonstrated from a mixture of the α/β-glucoses, through the equatorial-selective recognition of the anomeric (C1) group. A similar stereoselective binding is accomplished from an α/β-galactose mixture. Interestingly, single equatorial/axial configurations on the bound monosaccharides can regulate the helical conformation of the capsule in water, confirmed by CD, NMR, and theoretical analyses. An intense capsule-based Cotton effect is exclusively observed upon encapsulation of the permethylated α-glucose (>20-fold enhancement as compared to the β-glucose derivative), via the induction of a single-handed host helicity to a large extent. Inverse capsule helicity is induced by the binding of a β-galactose derivative under the same conditions.

Effect of D-Allulose Use as a Sugar Substitute on Some Physicochemical, Textural and Sensory Properties of Cakes

D-allulose is a monosaccharide that belongs to the class of sugars known as rare derivatives of monosaccharides in nature. The aim of this study was to investigate how the sugar substitute D-allulose influenced the physicochemical, textural, and sensory characteristics of cakes. Solvent water retention capacity analysis of flour used in cake production and ash, dry matter, texture, color and reducing sugar analyses of cake dough were carried out in a day while water activity, pH, titratable acidity, antioxidant activity analysis and sensory analyses of cakes were performed in three different days. The average heights of control, AL50 and AL100 cakes were 2.60±0.14, 1.75±0.1 and 1.50±0.0 cm while they had the cake yields of 87.2±1.9, 86.2±4.1 and 87.6±3.2%, respectively. Viscosity analysis results showed that viscosity of dough samples decreased with an increase in spindle speed for all groups. The total dry matter content of control cakes was 76.1±3.0% while AL50 and AL100 cakes had a dry matter content of 76.4±4.6 and 75.0±2.6%, respectively. Total ash contents were 1.2±0.0, 1.3±0.0 and 1.4±0.0% for control, AL50 and AL100 cakes, respectively. The mean radical scavenging activity (RSA) of control cakes on the first day of production was 26.1±5.8, 51.6±1.3 in the AL50 group and 53.9±1.2 in the AL100 group. When evaluating the panelists' overall acceptability scores for the sensory qualities of cakes, the first day yielded the highest AL50 (7.9±1.2), while the 8th day of storage yielded the lowest AL50 (8.5±0.8) for the control group. The 8th day analysis yielded the lowest result (6.7±1.4) for the AL100 group. Results indicated that D-allulose preserved the physicochemical, textural, and sensory characteristics of cakes while increasing their antioxidant capacity, and it could be utilized to create novel products in the food industry because of these qualities.

Lignan constituents with α-amylase and α-glucosidase inhibitory activities from the fruits of Viburnum urceolatum

Eleven previously undescribed lignan constituents, including five 8-O-4′ type neolignans, viburnurcosides A–E (1–5), three benzofuran type neolignans, viburnurcosides F–H (6–8), and three tetrahydrofuran type lignans, viburnurcosides I–K (9–11), were isolated from the fruits of Viburnum urceolatum. The structures of all isolates were elucidated by an extensive analysis of the NMR and HRESIMS data. The absolute configurations of these compounds were determined by quantum-chemical electronic circular dichroism calculation and comparison. The sugar units of viburnurcosides A–K were identified by acid hydrolysis and HPLC analysis of the chiral derivatives of monosaccharides. The in vitro enzyme inhibition assay exhibited that viburnurcoside J (10) had the most potent inhibitory activity against α-amylase and α-glucosidase with the IC50 values of 19.75 and 9.14 μM, respectively, which were stronger than those of the positive control acarbose (37.31 and 26.75 μM, respectively). The potential binding modes of viburnurcoside J (10) with α-amylase and α-glucosidase were also analyzed by molecular modeling.

Glucosamine Improves Non-Alcoholic Fatty Liver Disease Induced by High-Fat and High-Sugar Diet through Regulating Intestinal Barrier Function, Liver Inflammation, and Lipid Metabolism.

Non-alcoholic fatty liver disease (NAFLD) is a liver disease syndrome. The prevalence of NAFLD has continued to increase globally, and NAFLD has become a worldwide public health problem. Glucosamine (GLC) is an amino monosaccharide derivative of glucose. GLC has been proven to not only be effective in anti-inflammation applications, but also to modulate the gut microbiota effectively. Therefore, in this study, the therapeutic effect of GLC in the NAFLD context and the mechanisms underlying these effects were explored. Specifically, an NAFLD model was established by feeding mice a high-fat and high-sugar diet (HFHSD), and the HFHSD-fed NAFLD mice were treated with GLC. First, we investigated the effect of treating NAFLD mice with GLC by analyzing serum- and liver-related indicator levels. We found that GLC attenuated insulin resistance and inflammation, increased antioxidant function, and attenuated serum and liver lipid metabolism in the mice. Then, we investigated the mechanism underlying liver lipid metabolism, inflammation, and intestinal barrier function in these mice. We found that GLC can improve liver lipid metabolism and relieve insulin resistance and oxidative stress levels. In addition, GLC treatment increased intestinal barrier function, reduced LPS translocation, and reduced liver inflammation by inhibiting the activation of the LPS/TLR4/NF-κB pathway, thereby effectively ameliorating liver lesions in NAFLD mice.

Identification and Quantification of Monosaccharides from Fungal Cell Walls and Exopolysaccharides by Gas Chromatography Coupled to Mass Spectrometry.

The fungal cell wall and secreted exopolysaccharides play an important role in the interactions between fungi and their environment. Despite their central role in fungal biology, ecology, and host-pathogen interactions, the composition of these polymers and their synthetic pathways are not well understood. The protocols presented in this article describe an approach to isolate fungal cell wall polysaccharides and to identify and quantify the monosaccharide composition of these polymers by gas chromatography-mass spectrometry (GC-MS). © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: O-methyl trimethylsilyl monosaccharide derivatives composition analysis by GC-MS Support Protocol: Fungal cell wall extraction.

Novel β1,4 N-acetylglucosaminyltransferase in de novo enzymatic synthesis of hyaluronic acid oligosaccharides.

The efficiency of de novo synthesis of hyaluronic acid (HA) using Pasteurella multocida hyaluronate synthase (PmHAS) is limited by its low catalytic activity during the initial reaction steps when monosaccharides are the acceptor substrates. In this study, we identified and characterized a β-1,4-N-acetylglucosaminyl-transferase (EcGnT) derived from the O-antigen gene synthesis cluster of Escherichia coli O8:K48:H9. Recombinant β1,4 EcGnT effectively catalyzed the production of HA disaccharides when the glucuronic acid monosaccharide derivative 4-nitrophenyl-β-D-glucuronide (GlcA-pNP) was used as the acceptor. Compared with PmHAS, β1,4 EcGnT exhibited superior N-acetylglucosamine transfer activity (~ 12-fold) with GlcA-pNP as the acceptor, making it a better option for the initial step of de novo HA oligosaccharide synthesis. We then developed a biocatalytic approach for size-controlled HA oligosaccharide synthesis using the disaccharide produced by β1,4 EcGnT as a starting material, followed by stepwise PmHAS-catalyzed synthesis of longer oligosaccharides. Using this approach, we produced a series of HA chains of up to 10 sugar monomers. Overall, our study identifies a novel bacterial β1,4 N-acetylglucosaminyltransferase and establishes a more efficient process for HA oligosaccharide synthesis that enables size-controlled production of HA oligosaccharides. KEY POINTS: • A novel β-1,4-N-acetylglucosaminyl-transferase (EcGnT) from E. coli O8:K48:H9. • EcGnT is superior to PmHAS for enabling de novo HA oligosaccharide synthesis. • Size-controlled HA oligosaccharide synthesis relay using EcGnT and PmHAS.

Synthesis of the Hexasaccharide Related to the Exopolysaccharide from Lactobacillus mucosae VG1 through Regioselective Glycosylation.

Chemical synthesis of the hexasaccharide repeating unit associated with the exopolysaccharide of Lactobacillus mucosae VG1 is reported. The total synthesis is accomplished through a convergent [2 + 2 + 2] strategy using rationally protected monosaccharide derivatives. Chemoselective activation of the glycosyl donors and regioselective nucleophilicity of the acceptors were successfully employed throughout the chemical synthesis.

Synthesis of sugar enones and their use as powerful synthetic precursors of thiodisaccharides

Monosaccharide derivatives having a double bond conjugated to a carbonyl (sugar enones or enuloses) are relevant synthetic tools. They are also suitable starting materials, or versatile intermediates, for the synthesis of a wide variety of natural or synthetic compounds with a broad spectrum of biological and pharmacological activities. The preparation of enones is mainly focused on the search for more efficient and diastereoselective synthetic methodologies. The usefulness of enuloses relies on the diverse reaction possibilities offered by alkene and carbonyl double bonds, which are prone to undergo varied reactions such as halogenation, nitration, epoxidation, reduction, addition, etc. The addition of thiol groups that led to sulfur glycomimetics, such as thiooligosaccharides, is particularly relevant. Therefore, the synthesis of enuloses and the Michael addition of sulfur nucleophiles to give thiosugars or thiodisaccharides are discussed here. Chemical modifications of the conjugate addition products to afford biologically active compounds are also reported.

Conformational Distributions of Phenyl β-D-Glucopyranoside and Gastrodin in Solution by Vibrational Optical Activity and Theoretical Calculations.

The conformational landscapes of two highly flexible monosaccharide derivatives, namely phenyl β-D-glucopyranoside (ph-β-glu) and 4-(hydroxymethyl)phenyl β-D-glucopyranoside, also commonly known as gastrodin, were explored using a combined experimental and theoretical approach. For the infrared, Raman, and the associated vibrational optical activity (VOA), i.e., vibrational circular dichroism and Raman optical activity, experiments of these two compounds in DMSO and in water were carried out. Extensive and systematic conformational searches were performed using a recently developed conformational searching tool called CREST (conformer-rotamer ensemble sampling tool) in the two solvents. Fourteen and twenty-four low-energy conformers were identified at the DFT level for ph-β-glu and gastrodin, respectively. The spectral simulations of individual conformers were done at the B3LYP-D3BJ/def2-TZVPD level with the polarizable continuum model of the solvents. The VOA spectral features exhibit much higher specificity to conformational differences than their parent infrared and Raman. The excellent agreements achieved between the experimental and simulated VOA spectra allow for the extraction of experimental conformational distributions of these two carbohydrates in solution directly. The experimental percentage abundances based on the hydroxymethyl (at the pyranose ring) conformations G+, G-, and T for ph-β-glu were obtained to be 15%, 75%, and 10% in DMSO and 53%, 40%, and 7% in water, respectively, in comparison to the previously reported gas phase values of 68%, 25%, and 7%, highlighting the important role of solvents in conformational preferences. The corresponding experimental distributions for gastrodin are 56%, 22%, and 22% in DMSO and 70%, 21%, and 9% in water.

Expanding Knowledge of Methylotrophic Capacity: Structure and Properties of the Rough-Type Lipopolysaccharide from Methylobacterium extorquens and Its Role on Membrane Resistance to Methanol.

The ability of Methylobacterium extorquens to grow on methanol as the sole carbon and energy source has been the object of intense research activity. Unquestionably, the bacterial cell envelope serves as a defensive barrier against such an environmental stressor, with a decisive role played by the membrane lipidome, which is crucial for stress resistance. However, the chemistry and the function of the main constituent of the M. extorquens outer membrane, the lipopolysaccharide (LPS), is still undefined. Here, we show that M. extorquens produces a rough-type LPS with an uncommon, non-phosphorylated, and extensively O-methylated core oligosaccharide, densely substituted with negatively charged residues in the inner region, including novel monosaccharide derivatives such as O-methylated Kdo/Ko units. Lipid A is composed of a non-phosphorylated trisaccharide backbone with a distinctive, low acylation pattern; indeed, the sugar skeleton was decorated with three acyl moieties and a secondary very long chain fatty acid, in turn substituted by a 3-O-acetyl-butyrate residue. Spectroscopic, conformational, and biophysical analyses on M. extorquens LPS highlighted how structural and tridimensional features impact the molecular organization of the outer membrane. Furthermore, these chemical features also impacted and improved membrane resistance in the presence of methanol, thus regulating membrane ordering and dynamics.

Bacteria of the Black Sea are Producers of α-L-Rhamnosidase

The search for new producers of α-L-rhamnosidases and the study of their properties are constantly carried out, which makes it possible to identify enzymes with unique properties. Thus, the α-L-rhamnosidases producers of marine species of microorganisms can radically differ in habitat conditions from terrestrial ones. Previously, we have isolated the producers of α-L-rhamnosidases from a number of representatives of the Black Sea microbiota. However, the results of these studies did not allow us to isolate a strain promising for further study of the α-L-rhamnosidase synthesized by it. Therefore, the purpose of this work was to further search for effective producers of α-L-rhamnosidases among the microbiota of the Black Sea obtained from its different depths. Methods. Glycosidase activities were determined by the Romero and Davis methods. Results. The study of α-L-rhamnosidase activity in the dynamics of growth of 10 cultures isolated from the Black Sea showed that the only glycosidase activity, which was found on the third day of cultivation in six (07, 044, 050, 052, 054, 247) of ten cultures studied, was toward α-L-rhamnosidase. However, on the 5th day of cultivation, an increase (and in some strains, the appearance) of activity was noted in all tested cultures (from 0.01 to 0.12 U/mL). On the 7th day of cultivation, α-L-rhamnosidase activity in the supernatant of the culture liquid ranged from 0.02 to 0.2 U/mL. The highest activity (0.2 U/mL) was found in strain 052. On the 10th day of cultivation, the maximum activity (0.55 U/mL) was noted in culture 052 and slightly lower (0.35 U/mL, 0.28 U/mL, and 0.23 U/mL) in cultures 044, 050, and 054 respectively. Cultures 051, 020, and 247, which showed the same activity (0.1 U/mL), as well as 056 (0.09 U/mL) were an order of magnitude less active. The minimum activity was noted in culture 046 (0.03 U/mL). In the supernatant of the culture liquid of strain 07 on the 10th day of cultivation, α-L-rhamnosidase was absent at all. Since the highest α-L-rhamnosidase activity was found in the supernatants of culture liquids of 5 strains (044, 052, 054, 056, and 247), partially purified complex preparations of those α-L-rhamnosidases were obtained for further research. The study of the substrate specificity of complex enzyme preparations of α-L-rhamnosidases of strains 044, 051, 052, 056, and 247 on natural flavonoids, such as naringin, neohesperidin, and rutin, indicated that α-L-rhamnosidase obtained from strain 052 showed the highest activity on three investigated substrates: rutin, naringin (0.55 U/mL), and neohesperidin (0.52 U/mL). In addition to natural substrates, complex preparations of α-L-rhamnosidases of strains 052, 054, 056, and 247 also hydrolyzed synthetic derivatives of monosaccharides, such as p-nitrophenyl-α-L-rhamnopyranoside and p-nitrophenyl-β-D-glucopyranoside. The maximum activity (0.15 U/mL) was noted in strain 052, whereas strain 044 was unable to hydrolyze synthetic substrates. Conclusions. Complex enzyme preparations of α-L-rhamnosidase obtained from strain 052 are promising for further investigations. They showed the highest activity both on three natural substrates, such as rutin, naringin, and neohesperidin, as well as on such synthetic derivatives of monosaccharides as p-nitrophenyl-α-L-rhamnopyranoside and p-nitrophenyl-β-D-glucopyranoside.

Monitoring the hepatobiliary function using image techniques and labeled cholephilic compounds

Evaluation of the hepatobiliary function is critical for the clinicians, not only for the diagnosis of a large variety of liver diseases but also in the follow-up and management of some patients, for instance, those with different degrees of cholestasis suffering from a drug-induced liver injury (DILI) or scheduled for liver resection. Currently, the determination of global liver function mainly relies on laboratory tests, clinical scores, and data from images obtained with ultrasonography, computed tomography (CT), or magnetic resonance. Nuclear medicine scanning, displaying either planar or three-dimensional spatial distribution of liver function, is enhanced when using hepatotropic tracers based on classical radioisotopes such as technetium-99m (99mTc) and with higher resolution using metabolized probes such as those based on monosaccharide derivatives labeled with 18F. Other cholephilic compounds, and hence selectively secreted into bile, have been proposed to visualize the correct function of the liver parenchyma and the associated secretory machinery. This review aims to summarize the state-of-the-art regarding the techniques and chemical probes available to monitor liver and gallbladder function, in some cases based on imaging techniques reflecting the dynamic of labeled cholephilic compounds.

The Light-Controlled Release of 2-fluoro-l-fucose, an Inhibitor of the Root Cell Elongation, from a nitrobenzyl-caged Derivative.

Glycan metabolic engineering is a powerful tool for studying the glycosylation in living plant cells. The use of modified monosaccharides such as deoxy or fluorine-containing glycosides has been reported as a powerful pharmacological approach for studying the carbohydrate metabolism. 1,3,4-tri-O-acetyl-2-fluoro-l-fucose (2F-Fuc) is a potent inhibitor of the plant cell elongation. After feeding plant seedlings with 2F-Fuc, this monosaccharide derivative is deacetylated and converted by the endogenous metabolic machinery into the corresponding nucleotide-sugar, which then efficiently inhibits Golgi-localized fucosyltransferases. Among plant cell wall polymers, defects in the fucosylation of the pectic rhamnogalacturonan-II cause a decrease in RG-II dimerization, which in turn induce the arrest of the cell elongation. In order to perform the inhibition of the cell elongation process in a spatio-temporal manner, we synthesized a caged 3,4-di-O-acetyl-1-hydroxy-2-fluoro-l-fucose (1-OH-2F-Fuc) derivative carrying a photolabile ortho-nitrobenzyl alcohol function at the anomeric position: 3,4-di-O-acetyl-1-ortho-nitrobenzyl-2-fluoro-l-fucose (2F-Fuc-NB). The photorelease of the trapped 1-OH-2F-Fuc was performed under a 365 nm LED illumination. We demonstrated that the in planta elimination by photoexcitation of the photolabile group releases free 2F-Fuc in plant cells, which in turn inhibits in a dose-dependent manner and, reversibly, the root cell elongation.

Chemical synthesis of the pentasaccharide repeating unit of the O-antigen from Escherichia coli strain SDLZB008 in the form of its 2-aminoethyl glycoside

Chemical synthesis of the pentasaccharide repeating unit of the O-antigen from E. coli strain SDLZB008 is accomplished through a linear strategy using rationally protected monosaccharide derivatives ensuring desired stereochemical outcome up on glycosylations. 2-Aminoethyl glycoside is incorporated at the reducing end of the target pentasaccharide. The terminal free amine may be used for further conjugation with suitable aglycon without hampering the reducing end stereochemistry. The rare D-Fucp3NAc moiety is incorporated through the corresponding 3-azido derivative derived from a known 3-azido quinovose derivative.

COMPARATIVE ANALYSIS OF CARBOHYDRATE METABOLITES IN AMARANTH LEAVES OF DIFFERENT AGE

The recent study aimed to investigate the composition of monosaccharides and their derivatives in the leaves of vegetable species Amaranthus tricolor L. cv. ‘Valentina’ of different ages, as well as, their vital role in enhancing the adaptive potential of the plant. Forty-eight monosaccharides and 28 of their derivatives have been identified in the composition of amaranth leaves of different ages. The maximum number of hydrophilic carbohydrate metabolites clustered in the young leaf. However, in older leaves, the number of water soluble metabolites showed similarities to that of the soluble in ethyl alcohol. Along with the general carbohydrate metabolites, the old leaves also contained specific monosaccharides, such as, lixopyranose, glucose, sorbose, mannobiose, cellobiose, and monosaccharide derivatives, i.e., methyl galactoside, glucopyranosiduronic and glucuronic acids, and alcohol erythritol. However, in Amaranthus tricolor L., the young leaf is characterized by arabinofuranose and carbohydrate derivatives, i.e., alpha-ketogluconic, arabinohexane, glucaric, galactaric, xylonic-D, lactone acids, and alcohol pentatriol. The leaves of different ages’ composition showed polyhydric alcohols (glycerin, ribitol, and myo-inositol). It also showed osmoprotective and antioxidant properties.

Dynamic Analysis of Physicochemical Properties and Polysaccharide Composition during the Pile-Fermentation of Post-Fermented Tea.

Ultra-high performance liquid chromatography-quadrupole-time of flight tandem mass spectrometry (UHPLC-Q-TOF-MS/MS) was used to study the diversity of tea polysaccharides and the dynamic changes in the physicochemical indexes of tea samples. FT-IR spectra and the free radical scavenging ability of tea polysaccharides, during pile-fermentation of post-fermented tea, were analyzed. The results showed that 23 saccharide co mponents in tea polysaccharides were identified: these belonged to 11 monosaccharides, 5 oligosaccharides, and 6 derivatives of monosaccharides and oligosaccharides. The abundance of oligosaccharides decreased gradually, while monosaccharides, and derivatives of monosaccharides and oligosaccharides increased gradually with the development of pile-fermentation. According to the differences in polysaccharide composition and their abundance, the tea polysaccharide samples extracted from different pile-fermentation stages could be clearly classed into three groups, W-0, W-1~W-4 and W-5~C-1. The pile-fermentation process affected the yield, the content of each component, FT-IR spectra, and the DPPH free radical scavenging ability of tea polysaccharides. Correlation analysis showed that microorganisms were directly related to the changes in composition and the abundance of polysaccharides extracted from different pile-fermentation stages. The study will further help to reveal the function of tea polysaccharides and promote their practical application as a functional food.

Glycoprofiling of Oligosaccharides of Regular and Lactose-Free Milk by Mass Spectrometry

Oligosaccharides from regular milk and lactose-free milk were analyzed by Electrospray Ionization interface coupled with Ion Trap Mass Spectrometry (IT-MS). The negative mode mass spectrometry of sugar compositions was obtained either by direct infusion and mass spectrometry with Liquid Chromatography (LC). Hexose (Hex) and the other oligomeric sugar components were observed in both regular and lactose-free milk. While lactose derivatives (deprotonated lactose dimer, chloride adducts, chloride dimer) in regular milk have seen to be dominated, monosaccharide derivatives (Hex-H2O, Hex, Hex-Cl) in the lactose-free milk were observed as abundant which was lytic product of lactose. Phosphate/sulfate ester substitution on lactose and sialyllactose in both regular and lactose-free milk samples were observed with similar intensity thus it has been understood that these important milk components are not digested during lactose removing process.