Carbohydrates of the seaweeds,Desmarestia ligulata and D. firma

Crystalline mannitol and some oligosaccharides were separated from ethanolic extracts of Desmarestia ligulata and D. firma. Laminaran, ‘fucans’ and alginic acid were also isolated from both species. The laminaran from D. ligulata comprised both M- and G-chains but no M-chains were found in the laminaran from D. firma. In both species the amount of ‘fucan’ was small, particularly in D. firma. Both ‘fucans’ contained glucuronic acid, galactose, xylose and fucose and that from D. ligulata also contained mannose. After sequential extraction of D. ligulata with water, acid and alkali evidence was obtained for the presence of cellulose, a uronan, and protein in the residual material.     

Carbohydrates of the antarctic brown seaweed Ascoseira mirabilis

Mannitol, sucrose and four monosaccharides were obtained from an ethanolic extract of Ascoseira mirabilis. Sequential extraction with aqueous calcium chloride, dilute acid and dilute alkali gave mixtures of laminaran, ‘fucan’ and alginic acid. Laminarans fractionated from the extracts contained different proportions of uniformly (1 → 3) and (1 → 6) linked chains of β-D-glucose residues. The ‘fucan’ contained varying proportions of fucose, galactose and glucuronic acid, small amounts of xylose, mannose, glucose, half ester sulphate and protein. Extraction of the weed under mild alkaline conditions gave a yield of 13.4% of low molecular weight calcium alginate with a mannuronate to guluronate ratio of 30:70 and only a small proportion of sequences of alternating residues. Selective extraction and fractionation gave alginate fractions rich (> 80%) in mannuronate or guluronate.     

Partial structure of a polysaccharide from leaves of Welwitschia mirabilis

Gum-tears from the leaves of Welwitschia mirabilis contain a polysaccharide composed of arabinose, galactose and glucuronic acid as main constituents with xylose, fucose and rhamnose in smaller quantities. Periodate oxidation and permethylation studies indicated that the gum could consist of a framework of glucuronic acid residues linked 1 → 4 and galactose residues linked 1 → 6 and of short chains of arabinose, xylose, fucose and rhamnose linked 1 → 3 to both residues. All rhamnose and fucose and part of arabinose were found as non-reducing terminal units.     

Some structural features of a new sulphated heteropolysaccharide from Padina pavonia

An acid-extractable, water-soluble, polysaccharide sulphate, isolated from Padina pavonia, comprised variable proportions of glucuronic acid, galactose, glucose, mannose, xylose, and fucose in addition to a protein moiety. Partial acid hydrolysis and autohydrolysis of the free acid polysaccharide yielded several oligosaccharides. Evidence from periodate oxidation studies indicated that the inner polysaccharide portion is composed of (1 → 4)-linked β-D-glucuronic acid, (1 → 4)-linked β-D-mannose and (1 → 4)-linked β-D-glucose residues. The heteropolymeric partially sulphated exterior portion is attached to the inner part and comprises various ratios of (1 → 4)-linked β-D-galactose, β-D-galactose-3-sulphate residues, (1 → 4)-linked β-D-glucose residues, (1 → 2)-linked α-L-fucose 4-sulphate residues and (1 → 3)-linked β-D-xylose residues.     

Structural investigation of a fucoidan containing a fucose-free core from the brown seaweed, Hizikia fusiforme

A fucoidan, obtained from the hot-water extract of the brown seaweed, Hizikia fusiforme, was separated into five fractions by DEAE Sepharose CL-6B and Sepharose CL-6B column chromatography. All five fractions contained predominantly fucose, mannose and galactose and also contained sulfate groups and uronic acid. The fucoidans had MWs from 25 to 950 kDa. The structure of fraction F32 was investigated by desulfation, carboxyl-group reduction, partial hydrolysis, methylation analysis and NMR spectroscopy. The results showed that the sugar composition of F32 was mainly fucose, galactose, mannose, xylose and glucuronic acid; sulfate was 21.8%, and the MW was 92.7 kDa. The core of F32 was mainly composed of alternating units of -->2)-alpha-D-Man(1--> and -->4)-beta-D-GlcA(1-->, with a minor portion of -->4)-beta-D-Gal(1--> units. The branch points were at C-3 of -->2)-Man-(1-->, C-2 of -->4)-Gal-(1--> and C-2 of -->6)-Gal-(1-->. About two-thirds of the fucose units were at the nonreducing ends, and the remainder were (1-->4)-, (1-->3)- and (1-->2)-linked. About two-thirds of xylose units were at the nonreducing ends, and the remainder were (1-->4)-linked. Most of the mannose units were (1-->2)-linked, and two-thirds of them had a branch at C-3. Galactose was mainly (1-->6)-linked. The absolute configurations of the sugar residues were alpha-D-Manp, alpha-L-Fucp, alpha-D-Xylp, beta-D-Galp and beta-D-GlcpA. Sulfate groups in F32 were at C-6 of -->2,3)-Man-(1-->, C-4 and C-6 of -->2)-Man-(1-->, C-3 of -->6)-Gal-(1-->, C-2, C-3 or C-4 of fucose, while some fucose had two sulfate groups. There were no sulfate groups in either the GlcA or xylose residues.     

Analytical and structural features of the gum exudate from Combretum hartmannianum schweinf.

The gum exudate from Combretum hartmannianum is water-soluble, forms very viscous solutions, and contains galactose (22%), arabinose (43%), mannose (10%), xylose (6%), rhamnose (4%), glucuronic acid (6%), 4-O-methylglucuronic acid (2%), and galacturonic acid (7%). The acidic components produced on hydrolysis of the gum were 6-O-(β-D-glucopyranosyluronic acid)-D-galactose, and two saccharides that had the same chromatographic mobility, and contained mannose and galacturonic acid, and galactose and 4-O-methylglucuronic acid, respectively. Methylation and methanolysis of the gum indicated the presence of terminal uronic acid, rhamnose, xylose, galactose, arabinofuranose, and arabinopyranose. Controlled, acid hydrolysis indicated the presence of (1→3)-linked arabinopyranose side-chains and (1→6)-linked galactose residues. C. hartmannianum gum, when subjected to two Smith-degradations, yielded Polysaccharides I and II, both of which contained galactose, arabinose, and mannose. Insufficient crude gum was available for a complete structural study, but the molecule was shown to contain long, sparsely branched chains of (1→6)-linked galactose residues, to which are attached (1→3)-linked arabinose and (1→3)-linked mannose side-chains.     

The polysaccharides of the brown seaweed Turbinaria murrayana

Polysaccharides of the brown seaweed Turbinaria murrayana were isolated. Laminaran (3.2%) was isolated from the hot-water extract of the algae by using ion-exchange chromatography. Fucans (2.1%) were isolated from the hot-water extract, as well (4.7%) as from the extract of the algae with dilute acid. Acid hydrolsysis of the isolated fucans revealed glucose, amnnose, fucose, glucuronic acid, xylose, and galactose. Alginic acid (22.6%) was separated, and reduced to a neutral polysaccharide. The polysaccharides isolated were analyzed by methylation and Smith degradation.     

Sargassan: A sulphated heteropolysaccharide from Sargassum linifolium

A new sulphated heteropolysaccharide containing glucuronic acid, mannose, galactose, xylose, fucose and a protein moiety has been extracted from Sargassum linifolium. The polysaccharide extracted with HCl was richer in its carbohydrate and protein contents and contained lower amounts of ash than that extracted with oxalic acid.     

Characterization and antioxidant activity of Ginkgo biloba exocarp polysaccharides

Ginkgo biloba exocarp polysaccharide (GBEP) was obtained by hot water extraction, the crude polysaccharide was deproteinized by Sevag method and fractionized by a DEAE Sepharose fast flow anion-exchange column. Five fragments were obtained, including neutral polysaccharide (GBEP-N) and four acidic polysaccharides (GBEP-A1, GBEP-A2, GBEP-A3 and GBEP-A4). GBEP-N and GBEP-A3 were further purified by Superdex 200 gel column chromatography. The resulted two fractions GBEP-NN, and GBEP-AA were characterized by FT-IR, and HPGFC (high pressure gel filtration chromatography). Monosaccharide composition was determined by RP-HPLC method of precolumn derivatization with 1-phenyl-3-5-pyrazolone. GBEP-NN was mainly composed of rhamnose, arabinose, mannose, glucose and galactose, while GBEP-AA was mainly made up of mannose, rhamnose, glucuronic acid, galacturonic acid, galactosamine, glucose, galactose, xylose, arabinose, and fucose. The crude GBEP exhibited certain antioxidant activity. At the concentration of 5 mg/mL, the hydroxyl radical scavenging effect of GBEP was 90.52%, greater than 77.37% for the positive control ascorbic acid.     

Chemistry of the polysaccharides of the diatom Coscinodiscus nobilis

The extracellular polysaccharide of Coscinodiscus nobilis, a member of the Coscinodiscaceae, contains a highly branched heteropolysaccharide(s) containing fucose, rhamnose, mannose, d-glucose, xylose, d-glucuronic acid, galactose (trace) and half ester sulphate. The positions of linkages between the monosaccharides have been established and evidence for the linkages between d-glucuronic acid and monosaccharides was obtained. The extracellular polysaccharide contained also a chrysolaminaran, but this may have been derived from dead cells. Fucose and mannose occur also in a separate polymer. The diatom contained polysaccharide material consisting of glucose, mannose, fucose and uronic acid residues.     

Characterization of anti-complementary acidic heteroglycans from the seed of Coix lacryma-jobi var. ma-yuen

The anti-complementary polysaccharides, CA-1 and CA-2, were purified from the seed of Coix lacryma-jobi L. var. ma-yuen. CA-1 consists of rhamnose, arabinose, xylose, galactose, galacturonic acid and glucuronic acid in molar ratios of 1.8:43.8:10.8:33.2:3.2:7.2, and CA-2 consists of rhamnose, arabinose, xylose, mannose, galactose, glucose, galacturonic acid and glucuronic acid in molar ratios of 2.4:37.0:11.8:1.7:35.6:2.9:2.6:6.0. CA-1 and CA-2 contained 8 ∼ 11% protein. Their M_rs were estimated to be 160 000 in CA-1 and 70 000 in CA-2 by gel filtration. CA-2 showed more potent anti-complementary activity than CA-1 in low dose.Methylation analysis of CA-1, its carboxyl-reduced products (reduced CA-1a and CA-1b) and CA-2 were carried out by the use of GC/MS and the results suggested that CA-1 has a very complicated and highly branched structure, and CA-2 is also composed of the same glycosidic linkages as CA-1 in different molar proportions. The results of exo α-L-arabinofuranosidase treatment and partial acid hydrolysis suggested that CA-1 and CA-2 contained arabino 3,6-galactan moiety and most of the arabinose was present as an α-L-furanosyl residues in the non-reducing terminals and (1 → 5)-linked side chains which mostly attached to the O-3 of (1 → 6)-linked galactopyranosyl residues. The results also suggested that CA-1 and CA-2 contained rhamnogalacturonan moiety which has a main chain consisting of (1 → 4)-linked galacturonic acid and (1 → 2)-linked rhamnose, and arabino 3,6- and 4-galactan might be attached to the rhamnosyl residue at the O-4. All glucuronic acid residues were present at the non-reducing terminals.     

Chemical characterisation of the released polysaccharide from the cyanobacterium Aphanothece halophytica GR02

The released polysaccharide from the halophilic cyanobacterium Aphanothece halophytica GR02 was separated into two main fractions byanion-exchange chromatography. The major fraction consisted of glucose,fucose, mannose, arabinose and glucuronic acid. Judging from thechromatography on Sepharose 2B, the major fraction was not furtherfractionated, and its apparent molecular weight was above 2.0 × 10⁶ Da.The minor fraction consisted of rhamnose, mannose, fucose,glucose, galactose and glucuronic acid, with traces of arabinose.Methylation and GC-MS spectrometry analyses of the major fractionrevealed the presence of 1-linked glucose, 1,3-linked glucose, 1,3-linkedfucose, 1,4-linked fucose, 1,3-linked arabinose, 1,2,4-linked mannose,1,3,6-linked mannose, 1-linked glucuronic acid and 1,3-linked glucuronicacid residues. The major fraction was thought to originate from capsularpolysaccharide. The released polysaccharides, obtained from cultures atdifferent age of culture, showed no striking variations in themonosaccharide composition and the relative proportions of themonosaccharides. However, the proportions of galactose and rhamnose inthe released polysaccharides, obtained from cultures under different salinity,were significantly different. The released polysaccharide also exhibitedgelling properties and strong affinity for metal ions.     

Isolation and structural characterization of a polysaccharide FCAP1 from the fruit of Cornus officinalis

A water-soluble polysaccharide, FCAP1, was isolated from an alkaline extract from the fruits of Cornus officinalis. Its molecular weight was 34.5 kDa. Monosaccharide composition analysis revealed that it was composed of fucose, arabinose, xylose, mannose, glucose, and galactose in a molar ratio of 0.29:0.19:1.74:1:3.30:1.10. On the basis of partial acid hydrolysis and methylation analysis, FCAP1 was shown to be a highly branched polysaccharide with a backbone of β-(1→4)-linked-glucose partially substituted at the O-6 position with xylopyranose residues. The branches were composed of (1→3)-linked-Ara, (1→4)-linked-Man, (1→4,6)-linked-Man, (1→4)-linked-Glc, and (1→2)-linked-Gal. Arabinose, fucose, and galactose were located at the terminal of the branches. The structure was further elucidated by a specific enzymatic degradation with an endo-β-(1→4)-glucanase and MALDI-TOF-MS analysis. Oligosaccharides generated from FCAP1 indicated that FCAP1 contained XXXG-type and XXG-type xyloglucan fragments.     

EXTRACELLULAR POLYSACCHARIDES FROM ANKISTRODESMUS DENSUS (CHLOROPHYCEAE)

The dissolved extracellular compounds produced by the Chlorococcalean Ankistrodesmus densus Kors. were investigated for their molecular masses and chemical composition. Gel permeation chromatography showed apparent relative molecular masses of 2 × 10⁶ and 10⁴, respectively, for two distinct fractions, termed A and B. The higher molecular weight fraction (A) contained mainly fucose and 3- O -methylgalactose, whereas galactose, glucose, mannose, and rhamnose were present in smaller amounts. Methylation analyses showed that the main structural features are fucose as a highly branched part of polymer A with substitutions in both position 2 and position 4, the substitutions on one of those positions being primarily terminal 3- O -methylgalactose and the other one involved as the linkage of the main chain of the polymer. Because of the presence of both fucose and 3- O -methylgalactose, this polymer is highly hydrophobic. In fraction B, mannose represented more than 60% of the carbohydrate material present, whereas the remaining part contained rhamnose, fucose, xylose, and glucose in almost equal amounts. 3- O -methylgalactose and galactose were present as minor elements. Fraction B is basically a mannose-containing polymer in which the mannose units are either 1→4 or 1→2 linked. Traces of glucuronic acid and protein were present in both fractions; neither sulfate nor phosphate was detected.     

STRUCTURE OF EXTRACELLULAR POLYSACCHARIDES PRODUCED BY A SOIL CRYPTOMONAS SP. (CRYPTOPHYCEAE)1

The Hindak strain of a Cryptomonas species (Cryptophyceae) produces extracellular polysaccharides. Because there is no information on the structure of these compounds in the Cryptophyceae we conducted structural studies. Gas–liquid chromatographic analyses showed that the polysaccharide is composed of fucose, rhamnose, xylose, mannose, glucose, galactose, galacturonic acid, glucuronic acid, and traces of 3-O-methyl galactose. The polysaccharide was separated into two subtractions by ion-exchange chromatography. Fraction A consisted mainly of 1,3-linked galactose units and 1,4-linked galacturonic acid. Unlike fraction B, fraction A did not have xylose, 3-O-methyl galactose, or glucuronic acid. Also, its degree of branching was low compared to that of fraction B. Only traces of sulfate were present infraction A, but fraction B was 10–15% sulfated. Protein was approximately 1% in both fractions. These polysaccharides appear to be a novel type of polymer in algae.     

ESIMS analysis of fucoidan preparations from Costaria costata, extracted from alga at different life-stages

Four fucoidan fractions from brown alga Costaria costata, collected at different life-stages: vegetative, May (5F2 and 5F3) and generative, July (7F1 and 7F2) collections were characterized. It was found that seaweed synthesizes different set of fucoidans - one with high fucose content and substantial percentage of hexoses and uronic acid and lower sulfate content (7F1, 5F2 and 5F3) and other - highly sulfated galactofucan (7F2). Structural features of fractions 7F2 and 5F3 were predominantly determined by mass spectrometric analysis of low-molecular-weight (LMW) oligosaccharide fragments, obtained by autohydrolysis of 7F2 and mild acid hydrolysis of 5F3 fucoidans. It was found that oligosaccharides from 7F2 fractions were mainly built up of sulfated at C-2 and/or at C-2/C-4 (1→3)-linked α-l-fucopyranose residues. d-Galactose residues, sulfated either at C-2 or C-6, were found as parts of mixed di- and trisaccharides at both termini and, probably, internal. Fucose residues in 5F3 fucoidan fragments were sulfated at C-2 and sometimes at C-4. Galactose residues were sulfated at C-4 and less frequently at C-2. Resistant to hydrolysis fraction was probably a core, built up with fucose, mannose and glucuronic acid. Presumably, oligosaccharide fragments were branches at C-4 of GlcA. They were sulfated at C-2 and sometimes at C-4 (1→3)- and/or (1→4)-linked fucooligosaccharides (sometimes terminated with (1→3)-linked galactose) and sulfated at C-4 or C-2 (1→4)- or, probably, (1→6)-linked galactooligosaccharides, probably, with own branches, formed by (1→2)-linked galactose residues. Unsulfated xylose residues were probably terminal in chains built up of fucose. It was confirmed, that monosaccharide content and structure of fucoidans of vegetative algae changed following its life stage. Generative alga in general produced highly sulfated galactofucan having lower MW along with less sulfated mannoglucuronofucan with higher MW, which was extensively synthesized by vegetative algae.     

Polysaccharides from the brown seaweed Padina tetrastromatica: Characterization of a sulfated fucan

Sulfated fucans, the complex polysaccharides from brown seaweeds, possess various biological activities. To understand the structure activity relationship of sulfated fucans, we have investigated the structural features of one such polymer from Padina tetrastromatica using standard methods of carbohydrate structural analysis. We report a novel structural motif for this polymer. The average structure of this macromolecule that has a molecular mass of 25 kDa differs from the previous models in three respects. First, the core region of this macromolecule is composed primarily of α-(1 → 2)- and α-(1 → 3)-linked fucopyranosyl residues. Sulfate groups, when present are located at position 4 and 2 of fucosyl residues. Secondly, fucose and xylose is attached to this polymer to form branch points, one for every two residues within the chain. Finally, this macromolecule contained smaller amount of sulfate (0.21 mol of sulfate per mol of deoxyhexose).     

Structural elucidation and immuno-stimulating activity of an acidic heteropolysaccharide (TAPA1) from Tremella aurantialba

A novel acidic heteropolysaccharide (TAPA1) was purified from hot water extracts of Tremella aurantialba fruiting bodies by DEAE-Sepharose Fast Flow and Sephacryl S-500 High-Resolution Chromatography. The heteropolysaccharide had a molecular weight of ca. 1.35 × 10⁶ Da, and a carbohydrate content estimated to be ∼98.7% by the phenol-sulfuric acid method. It was composed mainly of d-mannose, d-xylose, and d-glucuronic acid in the ratio of ca. 5:4:1, along with trace amounts of d-galacturonic acid and d-glucose. Monosaccharide compositional analysis and GC-MS of methylated derivatives, combined with ¹H and ¹³C NMR spectroscopies (including COSY, TOCSY, NOESY, HSQC, and HMBC spectra), revealed TAPA1 to consist of an α-(1→3)-linked mannopyranosyl backbone, partially substituted at position 4 with xylose side chains, and at position 2 with side chains composed of either xylose, mannose, and glucuronic acid or of xylose and mannose. Bioactivity testing showed that TAPA1 stimulated the proliferation of mouse spleen lymphocytes in vitro.     

Separation procedure and sugar composition of oligosaccharides in the surface glycoprotein of friend murine leukemia virus

The sugar composition of the surface glycoprotein from Friend murine leukemia virus was determined by gas-liquid chromatography of the alditol acetates and by the thiobarbituric acid method, respectively. N-Acetylglucosamine, mannose, galactose, sialic acid and fucose were found in a molar ratio around 15.2:11.6:7.4:3.3:1.0. Ten ogligosaccharide fractions were obtained from glycoprotein preparations by a suitable sequence of degradation (with pronase, endo-β-N-acetylglucosaminidase H, neuraminidase, and by hydrazinolysis) and separation procedures (concanavalin A-affinity chromatography and gel filtration). The qualitative sugar composition of these fractions was analyzed by in vivo labelling with D-[6-³H]glucosamine, D-[2-³H]mannose, D-[6-³H]galactose, or L-[6-³H]fucose, and their molecular weights were estimated from the gel elution volumina. Four fractions of N-glycosidically linked oligosaccharides of the oligomannosidic (‘high mannose’) type oligomannosidic₇-oligomannosidic₁₀, about seven to ten sugar residues), two of the mixed (M₁₁ and M₁₂), and four of the N-acethyllactosaminic (‘complex’) type (N-acetyllactosaminic₉, probably nine sugar residues; (N-acetyllactosaminic_a-N-acetyllactosaminic_c, size unknown) were thus identified.     

Studies on the Non-starchy Polysaccharides of the Endosperm of Buckwheat

Water soluble polysaccharides from the buckwheat endosperm was fractionated by salting out and a DEAE-cellulose column (phosphate form) chromatography and the main component (polysaccharide A₁) was isolated as an ultracentrifugally and electrophoretically pure preparation.

The content of polysaccharide A₁ in the buckwheat endosperm was 0.1~0.2%.

Its water solution showed high viscosity and [α]_d was +39.4°. The molecular weight was 240,000~260,000.

Polysaccharide A₁ consisted of xylose, mannose, galactose and glucuronic acid. The hydrolysis of methylated polysaccharide A₁ gave 2,3,4-tri-O-methyl-xylose, 2,3,4,6-tetra-O-methyl-galactose, 2,4,6-tri-O-methyl-galactose, di-O-methyl-mannose and 4-O-methyl- and 5-O-methyl-glucuronic acid. These results suggested that the main chain of this polysaccharide consisted of glucuronic acid, mannose and galactose and the former two occupied branching position with xylose and galactose residues as nonreducing end.