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.     

Smith degradation of gum exudates from some prosopis species

The polysaccharide of P. hymantophora has been shown to be composed of (1→4)-linked galactopyranosyl, (1→3)-linked galactopyranosyl, (1→3)-linked galactopyranosyl 2- and 4-sulphate and 2,6-disulphate residues. The (1→3)- and (1→4)-linked units are present in approximately equal amounts. The polysaccharide of P. hieroglyphica has been shown to possess (1→4)-linked galactopyranosyl, (1→3)-linked galactopyranosyl, and (1→3)-linked galactopyranosyl 2- and 4-sulphate residues. The (1→3)- and (1→4)-linked units are present in a 4:1 ratio. Both polysaccharides contain small proportions of non-reducing xylosyl end-groups.     

Purification,structural characterization and antioxidant property of an extracellular polysaccharide from Aspergillus terreus

The marine fungus Aspergillus terreus produces an extracellular polysaccharide, YSS, when grown in potato dextrose-agar medium. YSS was isolated from the fermented liquids using ethanol precipitation, anion-exchange and size-exclusion chromatography. YSS was mainly composed of mannose and galactose in a molar ratio of 7.68:1.00, its average molecular weight was estimated to be about 18.6 kDa. On the basis of chemical and spectroscopic analyses, including one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) spectroscopy, structure of YSS may be represented, at an average, as a backbone of mannan with two types of branches. The mannan backbone is mainly composed of (1→2)-linked α-mannopyranose with small amounts of (1→6)-linked α-mannopyranose residues. The branches consist of terminal β-galactofuranose residues, and disaccharide units of (1→6)-linked α-mannopyranose. The branches are linked to C-6 of (1→2)-linked α-mannopyranose residues of backbone. The antioxidant activity of YSS was evaluated with the scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals in vitro, and the results indicated that YSS had good antioxidant activity, especially scavenging ability on DPPH radicals. The investigation demonstrated that YSS is a novel branched galactomannan with antioxidant activity, and differs from previously described extracellular polysaccharides.     

Structural features of two amyloids from the hemi-cellulosic fraction of field-bean (Dolichos lablab) hulls

Two amyloid-type fractions were isolated from field-bean (Dolichos lablab) hulls by 10% alkali extraction followed by acetylation and solvent fractionation. The major, chloroform-insoluble fraction and a minor, chloroform-soluble fraction were found to be homogeneous in sedimentation analysis and molecular-sieve chromatography. The polysaccharides contained xylose and glucose in various proportions. Methylation analysis, periodate oxidation, Smith degradation, oxidation by chromium trioxide, and oligosaccharide studies indicated a new type of structure for the major fraction (glucose:xylose ratio of 1.9:1) in that it had a backbone of (1→4)-linked β-d-glucose residues interspersed with single or multiple residues of (1→4)-linked β-d-xylose, and to which some single d-xylosyl groups are attached through O-6 of d-glucose. In contrast, the minor fraction (glucose:xylose ratio of 1:3.7) had a backbone of (1→4)-linked β-d-xylose interspersed with (1→4)-β-d-glucose and having a side chain of d-xylose, attached through O-6 of d-glucose. The third fraction was found to be a mixture of linear (1→4)-d-glucan and (1→4)-d-xylan.     

Purification and chemical characterization of polysaccharides obtained from Lampteromyces japonicus by concanavalin A-sepharose affinity chromatography

Two classes of neutral polysaccharide which could not be separated from each other by conventional methods were isolated from the fungus, Lampteromyces japonicus, by affinity chromatography using concanavalin A-Sepharose. The polysaccharide retained on the concanavalin A-Sepharose column was eluted with 0.05 M methyl α-d-mannopyranoside and appeared to be α-mannan, while that which passed through the column was virtually all β-glucan.Both polysaccharides were subjected to Smith-type degradation, methylation, acetolysis and glucosidase treatment. The results indicated that the α-mannan contained predominantly α-(1 → 2)-linked side chains branching from an α-(1 → 6)-linked backbone at the (1 → 2,6)-linked mannopyranosyl residues. Galactose was attached to approximately one-quarter of the non-reducing mannose terminals. The β-glucan seemed to contain mainly (1 → 6)-linked side chains branching from a (1 → 3)-linked backbone at the (1 → 3,6)-linked glucopyranosyl residues.     

The galactomannan-like oligosaccharides from the endosperm of the seed of Gleditsia triacanthos

The endosperm of the seed of Gleditsia triacanthos contains 4.8% of 85% ethanol-soluble, galactomannan-like oligosaccharides having Man:Gal ratios of 1.5–2.6:1 and an average degree of polymerization of 15. They have a narrow distribution of molecular weights and of ratio of components. The oligosaccharides have the gross structure accepted for the galactomannans, namely, a β-(1→4)-linked d-mannopyranosyl backbone having single stubs of α-(1→6)-linked d-galactopyranosyl groups. Some of the lateral chains contain more than one unit, and a minor proportion of the branches are ended by arabinofuranose or fucopyranose residues. Unusual branching points formed by 3,4-linked d-mannosyl, or 3,6-linked d-galactosyl units, or both, were also found. Despite their low molecular weight, the oligosaccharides form aggregates with a structure similar to that of the aggregates of the related galactomannans, but having a lower association energy. This fact, together with the difficulty of combining with more than one partner (due to the short, central chain), results in an increased solubility and in nonviscous solutions. The ¹³C-n.m.r. spectrum differentiated clearly the five structural units of the oligosaccharides, namely, the reducing and nonreducing end-chains of the d-mannosyl backbone; substituted and nonsubstitued, internal β-(1→4)-linked mannopyranosyl units of the backbone; and the galactosyl nonreducing end-chain of the lateral chains. The C-4 signal of the (1→4)-linked d-mannose and the C-6 signal of the same, but substituted, units showed splitting into three lines. The first has been attributed to sequence-related heterogeneity, whereas the latter is tentatively explained by assuming that this resonance is sensitive to whether the mannosyl units linked to that residue are also branched, or not.     

Polysaccharides of basidiomycetes. Alkali-soluble polysaccharides from the mycelium of white rot fungus <Emphasis Type="Italic">Ganoderma lucidum</Emphasis> (Curt.: Fr.) P. Karst

Two polysaccharides were isolated from submergedly cultured mycelium of the basidiomycete Ganoderma lucidum by extraction with alkali followed by fractionation with Fehling reagent. The polysaccharides were shown to be a linear (1→3)-α-D-glucan and a highly branched xylomannan containing a backbone built up of (1→3)-linked α-D-mannopyranose residues, the majority of which are substituted at O-4 by single β-D-xylopyranose residues or by disaccharide fragments β-D-Manp-(1→3)-β-D-Xylp-(1→. Polysaccharide structures were elucidated by NMR spectroscopy in combination with methylation analysis and periodate oxidation. An interesting feature of the xylomannan is the simultaneous presence of α-D-mannopyranose and β-D-mannopyranose residues, the first forming the backbone, and the second being the non-reducing terminal units of disaccharide side chains.     

Structure of l-arabino-d-galactan-containing glycoproteins from radish leaves

Two l-arabino-d-galactan-containing glycoproteins having a potent inhibitory activity against eel anti-H agglutinin were isolated from the hot saline extracts of mature radish leaves and characterized to have a similar monosaccharide composition that consists of l-arabinose, d-galactose, l-fucose, 4-O-methyl-d-glucuronic acid, and d-glucuronic acid residues. The chemical structure features of the carbohydrate components were investigated by carboxyl group reduction, methylation, periodate oxidation, partial acid hydrolysis, and digestion with exo- and endo-glycosidases, which indicated a backbone chain of (1→3)-linked β-d-galactosyl residues, to which side chains consisting of α-(1→6)-linked d-galactosyl residues were attached. The α-l-arabinofuranosyl residues were attached as single nonreducing groups and as O-2- or O-3-linked residues to O-3 of the β-d-galactosyl residues of the side chains. Single α-l-fucopyranosyl end groups were linked to O-2 of the l-arabinofuranosyl residues, and the 4-O-methyl-β-d-glucopyranosyluronic acid end groups were linked to d-galactosyl residues. The O-α-l-fucopyranosyl-(1→2)-α-l-arabinofuranosyl end-groups were shown to be responsible for the serological, H-like activity of the l-arabino-d-galactan glycoproteins. Reductive alkaline degradation of the glycoconjugates showed that a large proportion of the polysaccharide chains is conjugated with the polypeptide backbone through a 3-O-d-galactosylserine linkage.     

Structural studies on the specific capsular polysaccharide from Rhizobium trifolii, TA-1

The repeating unit of the specific capsular polysaccharide from the bacterium Rhizobium trifolii (TA)-1 has been shown to contain (a) terminal 4,6-O-(1-carboxyethylidene)-D-galactose (1 residue), (b) (1 → 3)-linked 4,6-O-(1-carboxyethylidene)-D-glucose (1 residue), (c) (1 → 4)-(1 → 6)-linked D-glucose (1 residue), (d) (1 → 4)-linked D-glucuronic acid (1 residue), and (e) (1 → 4)-linked D-glucose (4 residues). The pyruvylated sugars were shown to be positioned sequentially, and at least one other unit was interposed between them and the branch point.     

Further study of the structure of lentinan,an anti-tumor polysaccharide from Lentinus edodes

The structure of lentinan, an anti-tumor polysaccharide from Lentinus edodes, has been further investigated. Periodate oxidation, Smith degradation, methylation analysis, and bioassay were the principal methods used. These studies showed that a branched molecule having a backbone of (1→3)-β-d-glucan and side chains of both β-d-(1→3)- and β-d-(1→6)-linked d-glucose residues, together with a few internal β-d-(1→6)-linkages, is present.     

Further studies on the composition and structure of a fucoidan preparation from the brown alga Saccharina latissima

The polysaccharide composition of a fucoidan preparation isolated from the brown alga Saccharina latissima (formerly Laminaria saccharina) was reinvestigated. The preparation was fractionated by anion-exchange chromatography, and the fractions obtained were analyzed by chemical methods combined with NMR spectroscopy. Several 2D procedures, including HSQC, HMQC-TOCSY, and HMQC-NOESY, were used to obtain reliable structural information from the complex spectra, and the signal assignments were additionally confirmed by comparison with the literature spectra of the related polysaccharides and synthetic oligosaccharides. In accordance with the previous data, the main polysaccharide component was shown to be a fucan sulfate containing a backbone of 3-linked α-l-fucopyranose residues sulfated at C-4 and/or at C-2 and branched at C-2 by single sulfated α-l-fucopyranose residues. In addition, three other types of sulfated polysaccharide molecules were detected in the total fucoidan preparation: (i) a fucogalactan having a backbone of 6-linked β-d-galactopyranose residues branched mainly at C-4 and containing both terminal galactose and fucose residues; (ii) a fucoglucuronomannan having a backbone of alternating 4-linked β-d-glucopyranosyluronic acid and 2-linked α-d-mannopyranose residues with α-l-fucopyranose residues as single branches at C-3 of α-d-Manp; and (iii) a fucoglucuronan having a backbone of 3-linked β-d-glucopyranosyluronic acid residues with α-l-fucopyranose residues as single branches at C-4. Hence, even a single algal species may contain, at least in minor amounts, several sulfated polysaccharides differing in molecular structure. Partial resolution of these polysaccharides has been accomplished, but unambiguous evidence on their presence as separate entities was not obtained.     

The structure of the polysaccharide of Pachymenia carnosa

The sulphated polysaccharide of Pachymenia carnosa and its desulphated derivative have been studied by methylation analysis. Depolymerization during the desulphation process has been shown to occur mainly through the cleavage of (1→3) linkages. The methylation results indicate that the ratio of (1→4) to (1→3) linkages in the native polysaccharide is 1:2.26. The sulphate groups occur on positions 2, 4, and 2,6 of (1→3)-linked galactose residues. Methylations carried out in methyl sulphoxide with the Purdie reagents lead to extensive desulphation; 2-sulphate units appear to be more susceptible to desulphation than 4- or 6-sulphate units. Desulphation does not occur during methylation by the Hakomori method.     

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.     

4-O-Methylglucuronoxylan Isolated from the Midrib of Nicotiana tabacum

An acidic xylan from the midrib of Nicotiana tabacum was isolated by alkaline extraction and fractionation on a DEAE-cellulose column. Based on the results of methylation analysis, partial acid hydrolysis and Smith degradation, the acidic xylan was concluded to be composed of a linear backbone of β-(1→4)-linked D-xylopyranosyl residues with approximately every ninth residue carrying a terminal 4-O-methyl-α-D-glucopyranosyluronic acid residue linked as a single side chain by (1→2) linkage.     

Structure of an l-arabino-d-xylan from the bark of Cinnamomum zeylanicum

An arabinoxylan isolated from the bark of Cinnamomum zeylanicum was composed of l-arabinose and d-xylose in the molar ratio 1.6:1.0. Partial hydrolysis furnished oligosaccharides which were characterised as α-d-Xylp-(1→3)-d-Ara, β-dXylp-(1→4)-d-Xyl, β-d-Xylp-(1→4)-β-d-Xylp-(1→4)-d-Xyl, β-d-Xylp-(1→4)-β-d-Xylp-(1→4)-β-d-Xylp-Xylp-(1→4)-d-Xyl, xylopentaose, and xylohexaose. Mild acid hydrolysis of the arabinoxylan gave a degraded polysaccharide consisting of l-arabinose (8%) and d-xyolse (92%). Methylation analysis indicated the degraded polysaccharide to be a linear (1→4)-linked d-xlan in which some xylopyranosyl residues were substituted at O-2 or O-3 with l-arabinofuranosyl groups. These data together with the results of methylation analysis and periodate oxidation of the arabinoxylan suggested that it contained a (1→4)-linked β-d-xylan backbone in which each xylopyranosyl residue was substituted both at O-2 and O-3 with l-arabinofuranosyl, 3-O-α-d-xylopyranosyl-l-arabinofuranosyl, and 3-O-l-arabinofuranosyl-l-arabinofuranosyl groups.     

Mammalian-lung galactan

Exopolysaccharides of Agrobacterium tumefaciens and Rhizobium meliloti, containing d-glucose, d-galactose, pyruvic acid, and O-acetyl groups in the approximate proportions 6:1:1:1.5, were analysed by methylation. They were found to contain the following main structural units (all β-glycosidic): chain residues of (1→3)-linked d-glucose (24%), (1→3)-linked d-galactose (15%), (1→4)-linked d-glucose (20%), and (1→6)-linked d-glucose (18%); (1→4,1→6)-linked branching residues of d-glucose (12%), and terminal d-glucose residues substituted at positions 4 and 6 by pyruvate (11%). Uronic acid-containing exopolysaccharides of Rhizobium leguminosarum, R. phaseoli, and R. trifolii contained d-glucose, d-glucuronic acid, d-galactose, pyruvic acid, and O-acetyl groups in the approximate proportions 5:2:1:2:3. Methylation gave identical patterns of methylated sugar components, from which the following structural elements were deduced: chain residues of (1→3)-linked d-glucose substituted at positions 4 and 6 by pyruvate (13%), (1→4)-linked d-glucose (32%), and (1→4)-linked d-glucuronic acid (20%); (1→4,1→6)-linked branching residues of d-galactose and/or d-glucose (13%), and terminal d-glucose and/or d-galactose residues substituted at positions 4 and 6 by pyruvate (13%).     

Structural investigations of the extracellular polysaccharide elaborated by s19, a Xanthomonas-type bacterium

The extracellular, acidic heteropolysaccharide from Xanthomonas S19 consists of D-glucuronic acid, D-glucose, D-galactose, and D-mannose residues in the approximate molar ratios of 1.6:3:1:1, plus acetyl groups liked to C-2 and/or C-3 of a large proportion of the glucose residues. Methylation studies showed that the glucose is present as non-reducing end-group also as 1,2- and 1,4-linked units, the galactose residues are solely 1,3-linked, a major proportion of the mannose residues are 1,2,4-linked and the rest 1,2-linked. A high proportion of the glucuronic acid units are 1,4-linked. Periodate oxidation confirmed the presence of these linkages. The disaccharides D-Glc-(1→4)-D-Glc,D-Glc-(1→2)-D-Man, D-Glc-(1→3)-D-Gal, D-Gal-(1→2)-D-Glc, D-GlcA-(1→4)-D-GlcA, and β-D-GlcA-(1→4)-D-Man were isolated from a partial hydrolysate of the polysaccharide, and characterised. The similarities and differences between this polysaccharide and those from other Xanthomonas species are discussed.     

Chemical and biological properties of a highly branched β-glucan from edible mushroom Pleurotus sajor-caju

Hot aqueous extraction of the basidiocarps of the mushroom Pleurotus sajor-caju provided a cold water-soluble, gel-like glucan, which was characterized chemically, and its effects on RAW 264.7 cell line (mouse leukaemic monocyte macrophage) activation were determined. NMR spectroscopy, HPSEC, methylation analysis, and a controlled Smith degradation showed it to have a branched structure with a (1→3)-linked β-Glcp main-chain, substituted at O-6 by single-unit β-Glcp side-chains, on the average of two to every third residues of the backbone, with a molar mass of 9.75×10(5)gmol(-1). In macrophage cell culture, the β-glucan induced production of NO and the cytokines TNF-α, IL-1β, these effects being very similar as those of Escherichia coli serotype 0111:B4 Sigma-Aldrich lipopolysaccharide (LPS), although not modifying the response of LPS-activated macrophages. The results suggest that the (1→3), (1→6)-linked β-glucan from P. sajor-caju may have potential for immunological activities, although additional experiments are necessary for a better understanding of the mechanisms involved.     

Structure of Hemicellulose Isolated from Rice Endosperm Cell Wall : Mode of Linkages and Sequences in Xyloglucan, β-Glucan and Arabinoxylan

A hemicellulosic polysaccharide, which was homogeneous on sedimentation analysis and also on electrophoresis, was isolated from the rice endosperm cell walls by the combination of alkaline extraction, ion exchange chromatography and iodine complex formation. It is composed of arabinose, xylose and glucose (molar ratio, 1.0: 2.0: 5.7) together with a small amount of galactose and rhamnose. Methylation analysis, Smith degradation and fragmentation with cellulase showed that this polysaccharide is composed of three distinct polysaccharide moieties i.e., xyloglucan, β-glucan and arabinoxylan. The xyloglucan consists of β-(1→4)-linked glucan back bone and short side chains of single xylose units or galactosylxylose both attached to C-6 of the glucose residues. The β-glucan contains both (1 →3)-and (1→4)-linkages similarly to the other cereal β-glucans, but differ from them in containing the blocks of (1→3)-linked glucose residues in the chain. The arabinoxylan has a highly branched structure, in which 78% of (1→4)-linked xylose residues have short side chains of arabinose at C-3 position.

On the basis of these findings, the interconnection of these polysaccharide moieties is discussed.     

An Acidic Polysaccharide Isolated from the Midrib of Leaves of Nicotiana tabacum

An acidic polysaccharide (APS-H) purified from the hemicellulosic fraction of the midrib of Nicotiana tabacum was composed of d-galacturonic acid, l-rhamnose, l-arabinose and d-galactose in a molar ratio of 31.8: 15.4: 9.9: 42.9. Its molecular weight was estimated to be 90,000 by gel filtration chromatography. APS-H had a pectin-like structure in which the rhamnogalacturonan backbone was composed of (1 → 2)-linked l-rhamnopyranosyl and (1 → 4)-linked d-galacturonosyl residues in a ratio of approximately 1: 2.1. It also contained (1 → 4)-linked d-galactan and (1 → 5)-linked l-arabinofuranosyl moieties as the side chains. Branch points occurred mainly at C-4 of (1 → 2)-linked l-rhamnosyl residues in the backbone and at C-6 of (1 → 4)-linked d-galactosyl residues in the side chains.