Galactopyranose Residues Research Articles

Angelica gigas polysaccharide induces CR3-mediated macrophage activation and the cytotoxicity of natural killer cells against HCT-116 cells via NF-κB and MAPK signaling pathways

Angelica gigas (A. gigas) is traditional medicinal herb that mainly exists in Korea and northeastern China. There have been relatively few studies conducted thus far on its polysaccharides and their bioactivities. We purified and described a novel water-soluble polysaccharide derived from A. gigas and investigated its immunoenhancing properties. The basic components of crude and purified polysaccharides (F1 and F2) were total sugar (41.07% - 70.55%), protein (1.12–10.33%), sulfate (2.9–5.5%), and uronic acids (0.5–31.05%) in total content. Our results demonstrated that the crude and fractions' molecular weights (Mw) varied from 42.2 to 285.2 × 103 g/mol. As the most effective polysaccharide, F2 significantly stimulated RAW264.7 cells to release nitric oxide (NO) and express several cytokines. Furthermore, F2 increased the expression of tumor necrosis factor-α (TNF-α), interferon-gamma (IFN-ɣ), natural killer cytotoxicity receptors (NKp44), and granzyme-B in NK-92 cells and enhanced the cytotoxicity against HCT-116 cells. In our experiments, we found that F2 stimulated RAW264.7 cells and NK-92 cells via MAPK and NF-κB pathways. The monosaccharide and methylation analysis of the high immunostimulant F2 polysaccharide findings revealed that the polysaccharide was primarily composed of 1 → 4, 1 → 6, 1 → 3, 6, 1 → 3 and 1 → 3, 4, 6 galactopyranose residues, 1 → 3 arabinofuranose residues, 1 → 4 glucopyranose residues. These results demonstrated that the F2 polysaccharide of A. gigas which possesses potential immunostimulatory attributes, could be used to create a novel functional food.

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.

Fourier transform infrared (FT-IR) spectroscopic investigations of four agarophytes from northern Arabian sea

The fresh specimens of Champia compressa Harvey, Gelidium usmanghanii Afaq-Husain and M. Shameel, Gracilaria foliifera (Forsskål) Børgesen and Hypnea musciformis (Wulfen) J. V. Lamouroux, were collected from the coastal areas of Karachi (Pakistan) and their yield of agar was observed. With preextraction technique the percentage of algal yield was found to range from 13 to 28%. High quality gel strength was determined by modulus of elasticity i.e. (550 – 612g/cm2) and 1090 kPa and extraction time was 2 hrs. The structure of agar and agar contents were investigated by FT-IR spectroscopy for the first time from Pakistan. The results revealed some interesting characters (non sulphated β-D galacto pyranose residues, 3,6 anhydro galactose vibration), which were not reported earlier.

Preliminary Structural Characteristic of Polysaccharides Extracted From the Callus Tissue of Sosnowskyi’s Hogweed (Heracleum Sosnowskyi Manden) Stem by Aqueous Ammonium Oxalate

Pectic polysaccharides have been isolated from callus tissue of the stem of Sosnowskyi’s hogweed (Heracleum sosnowskyi Manden) by extraction with a 0.7% aqueous solution of ammonium oxalate and characterized. It was shown that they differ from pectic polysaccharides of a native plant by a lower content of D‑galacturonic acid residues and a higher content of arabinose and galactose residues. The results obtained by a combination of ion exchange chromatography, enzymatic hydrolysis, periodate oxidation, methylation and NMR spectroscopy indicated the presence of low-methyl esterified 1,4-α-D-galacturonan, rhamogalacturonan-I, arabinan and galactan or arabinogalactan. The terminal 1,2- and 1,5-linked arabinofuranose residues, terminal, 1,3-, 1,6-linked and 3,6-substituted galactopyranose residues and 1,4-linked hexopyranose (galactopyranose or glucopyranose) residues were identified in the composition of neutral carbohydrate chains. The presence in the NMR spectra of trans-glycosyl correlation peaks of the methyl groups of 2,4-di-O-substituted rhamnose residues indirectly confirm the attachment arabinan, galactan or arabinogalactan carbohydrate chains to rhamnopyranose residues of the backbone at C-4 position.

Structure Analysis and Anti-Tumor and Anti-Angiogenic Activities of Sulfated Galactofucan Extracted from Sargassum thunbergii.

Sulfated galactofucan (ST-2) was obtained from Sargassum thunbergii. It was then desulfated to obtain ST-2-DS, and autohydrolyzed and precipitated by ethanol to obtain the supernatant (ST-2-S) and precipitate (ST-2-C). ST-2-C was further fractionated by gel chromatography into two fractions, ST-2-H (high molecular weight) and ST-2-L (low molecular weight). Mass spectrometry (MS) of ST-2-DS was performed to elucidate the backbone of ST-2. It was shown that ST-2-DS contained a backbone of alternating galactopyranose residues (Gal)n (n ≤ 3) and fucopyranose residues (Fuc)n. In addition, ST-2-S was also determined by MS to elucidate the branches of ST-2. It was suggested that sulfated fuco-oligomers might be the branches of ST-2. Compared to the NMR spectra of ST-2-H, the spectra of ST-2-L was more recognizable. It was shown that ST-2-L contain a backbone of (Gal)n and (Fuc)n, sulfated mainly at C4 of Fuc, and interspersed with galactose (the linkages were likely to be 1→2 and 1→6). Therefore, ST-2 might contain a backbone of (Gal)n (n ≤ 3) and (Fuc)n. The sulfation pattern was mainly at C4 of fucopyranose and partially at C4 of galactopyranose, and the branches were mainly sulfated fuco-oligomers. Finally, the anti-tumor and anti-angiogenic activities of ST-2 and its derivates were determined. It was shown that the low molecular-weight sulfated galactofucan, with higher fucose content, had better anti-angiogenic and anti-tumor activities.

Characterization of rheological and structural properties of a gum from Balangu seeds

With the growing interest in all-natural foods, there has been increased study of sustainable natural sources of polysaccharides with suitable functional properties. Lallemantia royleana seed polysaccharide is one such material. Water-soluble polysaccharides were isolated from L. royleana seed to evaluate their chemical structure and rheological properties. The polysaccharide was consisted of neutral (62.9% w/w) and acidic (16.7% w/w) sugars. The backbone of the isolated rhamnoarabinogalactan was composed of (1 → 4)-linked galactopyranose residues. The weight average molecular weight (Mw) of the polysaccharide was 0.777 × 106 g/mol. Rheological behavior of extracted gum was studied at different concentrations (0.1–2.0%; w/v) and temperatures of 5–50 °C. The extracted gum showed typical non-Newtonian and shear thinning behavior at all concentrations and temperatures. However, higher apparent viscosity was observed with increasing gum concentration or decreasing temperature. The quantification of flow activation energy using Arrhenius model showed a decrease from 29,931 to 8339 kJ/mol−1. The mechanical spectra indicated viscoelastic behavior of the gum in all samples. Dynamic moduli increased with increased frequency and G′ was always greater than G″, indicating a weak gel system. The results of this study will help to increase potential applications of L. royleana polysaccharide in various food formulations.

Synthesis and Biological Activities of 5-Thio-α-GalCers

NKT cells, a unique subset of T cells that recognizes glycolipid antigens presented by CD1d molecules, are believed to produce key cytokines of both Th1 and Th2 T cells and are thus involved in the control of several types of immune response. As an active glycolipid antigen having α-galactosyl ceramide core structure, KRN7000 showed promising immunostimulation activity and was selected as an anticancer drug candidate for further clinical application. In this report, three new KRN7000 structural analogues were designed and synthesized, in which the ring oxygen of the galactopyranose residue is replaced by a sulfur atom along with the variation on the lipid chain. Their abilities for stimulating mouse NKT cells to produce IFN-γ and IL-4 were evaluated both in vivo and in vitro.

Structural analysis of galactoarabinan from duckweed.

A highly branched galactoarabinan named DAG1 (Mw∼4.0×10(4) Da) was purified from Lemna aequinoctialis 6000 via 70% (v/v) ethanol extraction, followed by size-exclusion chromatography on Bio-Gel P2 and Superdex 75. Methylation analysis showed that DAG1 consisted of t-Araf, (1→5)-Araf, (1→2,5)-Araf, (1→3)-Galp, and (1→3,6)-Galp in a relative proportion of approximately 6:4:3:3:3, suggesting an arabinogalactan/galactoarabinan polysacchairde. With the aid of arabinan degrading enzymes, the structure of DAG1 repeating unit was further characterized by ELISA with specific monoclonal antibodies and Yariv reagent assay. Analyses indicated that the proposed repeating unit of DAG1 had a backbone composed of seven α-(1→5)-L-arabinofuranose residues where branching occurred at O-2 with either terminal arabinoses or arabinogalactan side chain. The arabinogalactan side chain was composed of six β-(1→3)-D-galactopyranose residues, half of which were ramified at O-6 with terminal arabinoses and the last galactose was terminated with arabinose.

Structural characterization and antioxidant activity of a heteropolysaccharide isolated from Hedysarum polybotrys

A water-soluble polysaccharide (HPS3aS) with a molecular mass of 1.22 × 104 Da was isolated from Hedysarum polybotrys using anion-exchange and gel-permeation chromatography. HPS3aS exhibits a globular-shaped conformation in 0.1 M NaNO3 by size exclusion chromatography with multi-angle laser light scattering (SEC-MALLS). The investigation of the structural features of this heteropolysaccharide through a combination of chemical and instrumental analyses revealed that the backbone of HPS3aS is composed of α-d-(1 → 4)-linked glucopyranose residues, which occasionally branched at O-6. The branches are composed of (1 → 4)-linked galactopyranose residues and terminated with glucopyranose residues. HPS3aS possesses good in vitro antioxidant activity, as evaluated by scavenging assays with 1,1-diphenyl-2-picrylhydrazyl, hydroxyl, and superoxide radicals, which suggests that HPS3aS could be a potential antioxidant.

Developing highly active small molecule ice recrystallization inhibitors based upon C-linked antifreeze glycoprotein analogues

Ice recrystallization during cryopreservation results in a significant amount of cellular damage making compounds that exhibit ice recrystallization inhibition (IRI) activity desirable as a novel class of cryoprotectants. Herein, we report a systematic structure–function study on a previously identified IRI active C-linked antifreeze glycoprotein (C-AFGP) analogue (1). These studies indicate that while C-AFGPs containing three tripeptide repeats exhibit weak IRI activity 5.5 μM, a minimum number of four tripeptide repeats is required for potent IRI activity at this concentration. In addition, the galactosyl–ornithine building block 5 exhibited only moderate activity at 22 mM, but IRI activity was significantly increased upon addition of two glycine units to the C-terminal end of the amino acid bearing the C-linked galactopyranose residue. Finally, we report that conjugation of long alkyl chains (octyl, nonyl and decyl) to the C-linked galactosyl moiety of 1 can furnish IRI active small molecules. The “ideal” hydrocarbon chain length was 10 carbons for potent activity in this series of compounds. Longer hydrocarbon chain lengths dramatically decreased solubilities. The results of this study emphasize the importance of hydrophobic moieties for IRI activity and while consistent with previously reported small molecule carbohydrate-based and lysine-based ice recrystallization inhibitors, is the first example where a large IRI active glycoconjugate has been successfully truncated to small molecule IRI active components.

Pectin polysaccharides of rowan Sorbus aucuparia L.

Water-soluble polysaccharide fractions were extracted from the fruit of rowan Sorbus aucuparia L. by water and 0.7% ammonium oxalate water solution. The total yield was 4.2%. It is demonstrated that these fractions are pectin polysaccharides, and their carbon chains are primarily composed of galactunoric acid residue (up to 68%), arabinose and galactose. Sephacryl S-500 gelfiltration of rowan fruit pectin polysaccharides proved their relative homogeneity pertaining to their molecular weights, whereas endo-polygalacturonase enzymatic hydrolysis gives evidence of the presence of extended galacturonan (rhamnogalacturonan) ranges in their carbohydrate chains. Methylation of rowan pectin polysaccharides shows that their carbohydrate pendants are formed by 1,5-linked arabinofuranose residue, 1,4-linked glucopyranose residue, 1,6-linked galactopyranose residue, 1,3,6-linked mannopyranose residue and 1,3,6-linked galactopyranose residue. Glucopyranose residue is identified at non reducible ends of these pendants. It was demonstrated that antioxidant activity of water solutions of pectin polysaccharides extracted from rowan S. aucuparia L. (0.5 mg/mL) is 37–53% of trolox activity, which is 100%.

Structural and chemical characterization of abienan, a pectin from the greenery of Siberian fir (Abies sibirica L.)

A pectic polysaccharide, earlier called abienan, has been extracted from the fresh greenery of Siberian fir (Abies sibirica Ledeb.) and described. Like many pectic polysaccharides, the abienan macromolecule consists of linear and branched regions. Results of the ion-exchange chromatography and partial acidolysis demonstrate that linear regions of the abienan macromolecule consist of 1,4-α-D-galacturonan. The side carbohydrate chains of branched regions consist mainly of arabinofuranose and galactopyranose residues.

Structural features of pectic polysaccharide from Angelica sinensis (Oliv.) Diels

The structure of the pectic polysaccharide (ASP3) isolated from roots of Angelica sinensis (Oliv.) Diels was investigated using partial acid hydrolysis, enzymic digestion combined with methylation analysis, and further supported by 1 H and 13 C NMR spectroscopy techniques. The results indicated that ASP3 contained a backbone of linear homogalacturonan fragments as “smooth regions” and rhamnogalacturonan fragments as “hairy regions” with repeating unit of [→ 4)-α- d -Gal p A-(1 → 2)-α- l -Rha p -(1 →]. A total of 58.8% rhamnopyranose residues in the backbone were substituted at O -4 position by the side chains. The side chains contained mainly β-1,6- and β-1,4-galactopyranan bearing 3,6- and 4,6-substituted β- d -galactopyranose residues as branched points and short α-1,5-arabinofuranan possessing 3,5-substituted α- l -arabinofuranose residues as branching points. In addition, β-1,6-galactopyranan side chains were highly branched with α-1,5-arabinofuranan carrying 3- O -substituents (1,3,6-Gal) and terminated by the α-arabinofuranose residues which form arabinogalactan.

Conformational behaviour determines the low-relaxivity state of a conditional MRI contrast agent

The conformational behaviour in aqueous solution of the EgadMe complex, a conditional gadolinium-based contrast agent sensitive to beta-galactosidase enzymatic activity, is investigated by means of ab initio calculations and classical molecular dynamics simulations. Furthermore, force field parameterization of gadolinium-ligand interactions is performed, and its reliability is tested on the bench mark [Gd(DOTA)](-) system by MD simulations. Both computational methods highlight the presence in EgadMe of two main conformational isomers. The lowest energy conformation is a "close" form, corresponding to a state of low-relaxivity (MRI "inactive"), in which the ninth coordination site of the gadolinium ion is occupied by one oxygen atom of the galactopyranose residue. The second isomer, which is 2.9 (at ab initio level) and 4.2 (at MD level) kcal mol(-1) above the global minimum, presents an "open" form, corresponding to a state of high-relaxivity (MRI "active") in which one water molecule coordinates the ion. These results are consistent with experimental findings reported for EgadMe, and show that competition at the ninth coordination site of gadolinium ion, between the intra (the galactopyranose residue) and inter (water molecules) molecular interactions, affects the relaxivity of this system.

Structural features of semi-synthetic galactomannan sulfates

The positions of sulfate groups in two specimens of sulfated galactomannan from Cyamopsis tetragonoloba seeds were established by analysis of 1H and 13C NMR spectra. For the degree of substitution of 0.6, the signals of galactopyranose residues sulfated at position O(6) or simultaneously at positions O(2) and O(3) were the most intense. Minor signals were due to O(2)- or O(3)-monosubstituted and 2,3,4-tri-O-substituted galactose residues. The substitution of mannopyranose residues involved positions O(6) > O(2,3) > O(2) > O(3). At higher degree of substitution (1.0), the pattern of distribution of sulfate groups over various positions in the residues did not change, the molar content of 2,3-di-O-substituted galactopyranose residues being higher than the content of 6-O-monosubstituted residues.

Galactan sulfate of Grateloupia indica: Isolation, structural features and antiviral activity

Natural compounds offer interesting pharmacological perspectives for antiviral drug development with regard to broad-spectrum antiviral properties and novel modes of action. In this study, we have analyzed polysaccharide fractions isolated from Grateloupia indica. The crude water extract (GiWE) as well as one fraction (F3) obtained by anion exchange chromatography had potent anti-HSV activity. Their inhibitory concentration 50% (IC 50) values (0.12–1.06 μg/ml) were much lower than cytotoxic concentration 50% values (>850 μg/ml). These fractions, which were effective antiviral inhibitors if added only during the adsorption period, had very low anticoagulant activity. Furthermore, they had no direct inactivating effect on virions in a virucidal assay. Chemical, chromatographic and spectroscopic methods showed that the active polysaccharide, which has an apparent molecular mass of 60 kDa and negative specific rotation [ α ] D 32 −16° ( c 0.2, H 2O), contains α-(1 → 4)- and α-(1 → 3)-linked galactopyranose residues. Sulfate groups, if present, are located mostly at C-2/6 of (1 → 4)- and C-4/6 of (1 → 3)-linked galactopyranosyl units, and are essential for the anti herpetic activity of this polymer.

Structures and immunological activities of two pectic polysaccharides from the fruits of Ziziphus jujuba Mill. cv. jinsixiaozao Hort.

Abstract Two pectic polysaccharides were isolated from Ziziphus jujuba Mill. cv. jinsixiaozao Hort. and their structures were characterized by acid hydrolysis, methylation, partial acid hydrolysis and NMR spectroscopy. The purified fraction Ju-B-3 had a molecular mass of over 2000 kDa and showed [ α ] D 20 + 151 (c = 1.00, H2O). Chemical and spectroscopic analyses indicated that Ju-B-3 was a polygalacturonan with 7.49% methoxylation. The purified fraction Ju-B-2 had a molecular weight of over 2000 kDa and showed [ α ] D 20 + 125 (c = 1.00, H2O). Ju-B-2 was proposed as a polygalacturonan interspersed with rhamnogalacturonan in the main chain. 10.47% d -galacturonic acid existed as methoxylation and O-acetyl groups were amounted to 2.5%. The branched side chains were mainly composed of 1,5-linked arabinofuranosyl residues and 1,6-linked galactopyranose residues attached to O-4 of rhamnose residues. Ju-B-2 induced a rat spleen cells proliferation in a dose-dependent manner while Ju-B-3 could not show any proliferation activity compared with control.

Structural Studies on Pectin from Marsh Cinquefoil Comarum palustre L.

Pectin with [alpha]D(20) +192 degrees (c 0.1; water), named comaruman, was isolated from marsh cinquefoil Comarum palustre L., which is widespread in the European North. The sugar chain of comaruman contains residues of D-galacturonic acid (64%), D-galactose (13%), L-rhamnose (12%), L-arabinose (6%), and trace amounts of xylose and glucose. Partial acid hydrolysis and digestion with pectinase demonstrated that comaruman composed of the backbone comprised regions of linear alpha-1,4-D-galactopyranosyl uronan interconnected by numerous residues of alpha-1,2-L-rhamnopyranose. In addition to the backbone (core of the macromolecule), ramified regions are involved in comaruman and comprise alpha-2,4-L-rhamno-alpha-4-D-galacturonan with side chains consisting mainly of beta-1,4-linked residues of D-galactopyranose. The ramified region contains additionally residues of 5-O-substituted arabinofuranose and 3- and 6-O-substituted galactopyranose. The present 3,4- and 4,6-di-O-substituted residues of galactopyranose appear to be branching points of the side chains. Some galactopyranose residues were found to occupy the terminal positions of the side chains or appeared to be single sugar residues attached to the side chains. Methylation analysis data indicated that comaruman contains residues of terminal, 3- and 3,4-di-O-substituted galactopyranosyl uronic acid, which appeared to be constituents of the side chains, and the latter represented additionally branching points of the backbone.

Some structural features of pectic polysaccharide from tansy, Tanacetum vulgare L.

The structure of polysaccharide isolated from tansy, Tanacetum vulgare L. referred to as tanacetan was elucidated by a combination of partial acid hydrolysis, Smith degradation, digestion by a commercial pectinase preparation and NMR spectral analysis of the fragments obtained. They consist of pectin built on a linear backbone of rhamnogalacturonan and the ramified ‘hairy’ regions. The backbone proved to consist of α-1,4- d-galactopyranosyluronan blocks interconnected by 1,2-linked rhamnose residues involved in the linear sugar chain. The hairy regions were shown to contain the following fragments of the backbone: →4)-α-Gal pA-(1→2)-α-Rha p-(1→4)-α-Gal pA-(1→ and the side chains attached to the residues of rhamnopyranose of these fragments. The single and β-1,4-linked residues of galactopyranose were found to substitute 4-position of α-1,2-linked rhamnose residues of the backbone. In addition, the chains composed of β-1,4-, and 1,6-linked galactopyranose residues as well as the terminal residues of β-galactopyranose, α-arabinofuranose, and 2-mono- O-methyl-β-galactopyranose were detected. Some residues of α-arabinofuranose were shown to be substituted in 2-, 5-, 2,5-, and 3,5-positions, and residues of β-galactopyranose were found to be substituted in 4,6-positions. Some α-1,2-linked rhamnose residues appeared to occupy at the reducing end of the backbone. Smith degradation of the parent tanacetan TVF and of the product of its pectinase digestion led to polysaccharide fragments differed in high contents of the arabinose residues (42.5 and 48.6%, respectively) thus indicating to an occurrence of some ramified regions consisted of the arabinose residues.

The isolation, preliminary structural studies, and physiological activity of water-soluble polysaccharides from the squeezed berries of the snowball treeViburnum opulus

Water-soluble polysaccharide fractions VO1–VO4 were isolated from the squeezed berries of the snowball tree (Viburnum opulus) by successive extraction with water at various temperatures and pH and with aqueous solutions of ammonium oxalate. These fractions were purified by ion-exchange chromatography on DEAE cellulose, and the homogeneity of the purified polysaccharides was determined by gel filtration on Sephacryl S-500. Acidic polysaccharides close to pectins in their sugar composition were found in all the extracts (fractions VO1-1, VO2-1, VO3-2, and VO4-2). Residues of galacturonic acid, galactose, arabinose, and (to a lesser extent) rhamnose are their main constituents. Neutral polysaccharides composed mainly of galactose and mannose residues were additionally found in fractions extracted with acidified water (pH 4.0) and with aqueous ammonium oxalate solutions. Partial acidic hydrolysis and digestion with pectinase of acidic polysaccharides indicated that their carbohydrate backbone consists of α-1,4-linked residues ofD-galacturonic acid. NMR spectra of acidic polysaccharides (fractions VO3-2 and VO3-3) confirmed this and demonstrated that their side oligosaccharide chains are composed of β-1,4-linked galactopyranose residues and of terminal and 2,5- and 3,5-substituted residues of α-arabinofuranose at a Gal : Ara ratio of 3 : 1. Some polysaccharides fromV. opulus were found to possess an immunostimulating activity: they enhance phagocytosis, in particular, the phagocytic index and the secretion of lysosomal enzymes with peritoneal macrophages. Calcium ions were found to be necessary for the appearance of the stimulating effect of acidic polysaccharides fromV. opulus.