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.     

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.     

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.     

The Structural Characterization of a Novel Water-Soluble Polysaccharide from Edible Mushroom Leucopaxillus giganteus and Its Antitumor Activity on H22 Tumor-Bearing Mice

In the present study, a novel cold water-soluble polysaccharide fraction (LGP) with the average molecular weight of 1.78×10⁶ Da was extracted and purified from Leucopaxillus giganteus and its primary structure as well as in vivo antitumor activity was evaluated. The monosaccharide composition of LGP was determined by ion chromatography to be galactose, xylose, glucose and fucose in a molar ratio of 2.568 : 1.209 : 1 : 0.853. Its backbone was composed of α-D-Glu, α-D-Xyl, α-D-Gal and α-L-Fuc. The results of in vivo antitumor experiment demonstrated that LGP could effectively protect immune organs, has excellent antitumor activity, and inhibit the proliferation of H22 solid tumors in a dose-dependent manner. By analyzing Annexin V-FITC/PI staining, cell cycle and mitochondrial membrane potential detection assay, we concluded that LGP induced apoptosis of H22 cells via S phase arrest and mitochondria-mediated apoptotic pathway. Our results could provide valuable information for the potential application of LGP as an anti-hepatoma agent.     

Structures and Antitumor Activities of the Polysaccharides Isolated from Fruiting Body and the Growing Culture of Mycelium of Ganoderma lucidum

Several β-D-glucans, appertaining to the same molecular species but having different degrees of branching, were isolated from water and alkali extracts of the fruiting body of Ganoderma lucidum (Reishi). The purified glucans that were mostly water-insoluble had a backbone of (1 →3)-linked D-glucose residues, attached mainly with single D-glucosyl units at 0-6 and also with a few short (l→4)-linked glucosyl units at 0-2 positions. However, their degrees of branching appeared to differ in the range of d.b. 1/3 ~ 1/23, depending on the extracted glucan fractions. In addition to the ^-glucans, the fruiting body contained water-soluble heteropolysaccharides, comprising D-glucose, D-galactose, D-mannose, L-(or D)-arabinose, D-xylose, and L-fucose.

A branched (1 →3)-β-D-glucan was also isolated from the culture filtrate of G. lucidum grown in a glucose-yeast extract medium. The extracellular β-D-glucan was less soluble in water after purification, but soluble in dilute alkali. This glucan has essentially the same structure as that of hot-water extracted polysaccharide from the fruiting body. The repeating unit of the glucan contains a backbone chain of (1 →3)-linked D-glucose residues, five out of sixteen D-glucose residues being substituted at 0-6 positions with single D-glucosyl units and one D-glucose residue at 0-2 positions probably with a cellobiose unit.

The hot-water extractable fruiting body glucan and the extracellular glucan of the culture of growing mycelium showed relatively high growth-inhibition activities against Sarcoma 180 solid tumor in mice, when administered by. successive intraperitoneal injections. When the moderately branched glucans were modified to D-glucan-polyols by periodate oxidation and borohydride reduction, they exhibited higher antitumor activities, confirming the previous conclusion that the attachment of polyol groups to the (1 →3)-lmked backbone significantly enhances its host-mediated antitumor effect.     

Water- and alkali-soluble glucans from oak lichen

A water-soluble glucan, [α]²_D +217° (water), and an alkali-soluble glucan,

+152° (sodium hydroxide), have been isolated from the oak lichen Evernia prunastri (L.) Ach. On the basis of methylation analysis, periodate oxidation, and partial acid hydrolysis, the water-soluble polysaccharide has been shown to be a neutral, slightly branched glucan with a main chain composed of (1→3)- and (1→4)- linked glucopyranose residues in the ratio 1?:1. Branching occurs most probably at position 2 of (1→4)-linked glucopyranose residues. On the basis of optical rotation and i.r. spectral data, and enzymic hydrolysis, the α-D configuration has been assigned to the glycosidic linkages. Likewise, the alkali-soluble polysaccharide was shown to be a neutral, branched glucan with a main chain composed of (1→3)- and (1→4)-linked α-D-glucopyranose residues in the ratio 6:1. Each of the (1→4)-linked units was a branch point involving position 6. The presence of some β-D linkages is not excluded since hydrolysis with β-D-glucosidase occurred to a small extent.     

Structure of Succinoglucan: Fragmentation by Partial Acid Hydrolysis

Succinoglucan, a succinylated polysaccharide produced by Alcaligenes faecalis var. myxogenes 10C3, was partially hydrolyzed with acid. Fractionation of the neutral oligosaccharides gave cellobiose, gentiobiose, laminaribiose, laminaritriose, 6-O-β-laminaribiosylglucose, 6-O-β-laminaritriosylglucose, and 3-O-β-cellobiosylgalactose, confirming the previous results that the polysaccharide consists of β-(l→3)-linked, (1→4)-linked and (1 →6)-linked d-glucose residues, and β-(1→3)-linked d-galactose residues.

Possible structural features of succinoglucan were discussed on the basis of the above and previous results obtained by Smith degradation.     

Structure of a new galactomannan from the ascocarps of Cordyceps cicadae shing

A water-soluble galactomannan (C-3), [α]_D²⁰ +30°, isolated from the rod-like ascocarps of Cordyceps cicadae, was determined to be homogeneous, and the molecular weight was estimated by gel filtration to be 27,000. The polysaccharide is composed of d-mannose and d-galactose in the molar ratio of 4:3. The results of methylation analysis, Smith degradation, stepwise hydrolysis with acid, and ¹³C-n.m.r. spectroscopy indicated that the polysaccharide is of highly branched structure, and composed of α-d-(1→2)-linked and α-d-(1→6)-linked mannopyranosyl residues in the core; some of these residues are substituted at O-6 and O-2 with terminal β-d-galactofuranosyl and α-d-mannopyranosyl groups, and with short chains of β-d-(1→2)-linked d-galactofuranosyl units.     

Structural analysis of suisen glucomannan

The main component of the mucilage in the bulbs of Suisen (Narcissus tazetta L., var. chinensis Roem) has been shown to be a glucomannan composed of D-glucose and D-mannose in the ratio of 2:3 and having a relatively low degree of branching. Acetolysis of the polysaccharide led to the isolation of β-(1→4)-β-(1→3)-linked oligosaccharides composed of D-mannose and/or D-glucose residues. The average chain length (c.1.) of the polysaccharide was determined by methylation analysis to be about 22.     

Antitumor Active Polysaccharides from the Chinese Mushroom Songshan Lingzhi,the Fruiting Body of Ganoderma tsugae

A systematic method of extraction, fractionation, and purification of polysaccharides from Songshan Lingzhi (Ganoderma tsugae) with antitumor activity was established.

Seven glycans with strong antitumor activities were obtained from 14 water-soluble, and 15 water-insoluble fractions: FI_o-a, FA-1, FII-1, FIII-2, and FIII-2-a, -b, and -c. FI_o-a and FA-1 were proteincontaining glucogalactans associated with mannose and fucose. FII-l was a (1→3)-β-D-glucan having a lower protein content. The water-insoluble fractions FIII-2-a, -b, and -c were extracted with alkali, and were found to be protein-containing (1→3)-β-D-glucans showing the strongest activity. Chemical properties .and structure of each antitumor polysaccharide were compared with three fungi of the Ganoderma family, Kofukitake (G. applanatum), Mannentake (G. lucidum), and Songshan Lingzhi (G. tsugae).     

Structure of the d-galacto-d-mannan isolated from the seeds of Melilotus indica All

A d-galacto-d-mannan ([α]_D +72.0 and d-galactose-to-d-mannose ratio 1:1.14) was isolated from the seeds of Melilotus indica All., syn. M. parviflora Desf. The ¹H- and ¹³C-n.m.r., and i.r. spectra indicated the presence of α-d-galactopyranosyl and β-d-mannopyranosyl residues. Methylation of the polysaccharide, followed by hydrolysis, afforded, 2,3,4,6-tetra-, 2,3,6-tri-, 2,3-di-, and 3,4-di-O-methyl-d-mannose, and 2,3,4,6-tetra- and 2,3,6-tri-O-methyl-d-galactose in the molar ratios of 1:2:22:6:27:3. Periodate oxidation of the polysaccharide, followed by reduction and hydrolysis, gave erythritol (1 mol) and glycerol (1.24 mol). Partial acid hydrolysis of the polysaccharide afforded O-β-d-mannopyranosyl-(1→2)-d-mannopyranose, O-β-d-mannopyranosyl-(1→4)-d-mannopyranose, O-α-d-galactopyranosyl-(1→6)-d-mannopyranose, O-α-d-galactopyranosyl-(1→4)-d-galactopyranose, and O-α-d-galactopyranosyl-(1→6)-O-β-d-mannopyranosyl-(1→4)-d-mannopyranose. A highly branched structure having a mannan backbone composed of 36% of (1→4)- and 10% of (1→2)-linked β-d-mannopyranosyl units is proposed for the galactomannan.     

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 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.     

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.     

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.     

Re-examination of the acid hydrolysis of 5,6-anhydro-1,2-O-isopropylidene-β-l-idofuranose

The neutral polysaccharide isolated from the fruits of Cordia dichotoma was separated into two fractions, I and II, by gel filtration using Sephadex G-100. The major fraction, II, was found to contain d-glucose and l-arabinose in the molar ratio of 21:4. The results of complete hydrolysis with acid, permethylation studies, periodate oxidation, and Smith degradation suggested it to be an arabinoglucan, and the backbone of the polysaccharide to be composed of (1→6)-linked d-gluco-pyranosyl and (1→2)-linked l-arabinofuranosyl residues. The average degree of polymerization, determined through end-group analysis, was found to be ～144.     

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.     

Isolation and Characterization of a Novel Endo-β-galactofuranosidase from Bacillus sp.

A soil bacterium capable of growing on a polysaccharide containing β(1→6)galactofuranoside residues derived from the acidic polysaccharide of Fusarium sp. as a carbon source has been isolated. From various bacteriological characteristics, the organism was identified as a Bacillus sp. The bacterium produced β- galactofuranosidase inductively in the culture media. The most effective inducer for the β-galactofuranosidase production was a polysaccharide containing β(1→5) or β(1→6)-linked galactofuranoside residues, but gum arabic, gum guar, gum ghati, arabinogalactam, araban, and pectic acid did not induce the enzyme. The enzyme had three different molecular weight forms. The low molecular-weight form was purified by a combination of Toyopearl HW-55 and DEAE-Toyopearl 650S column chromatographies, and preparative polyacrylamide gel electrophoresis. The molecular weight of the enzyme was estimated to be 67,000 by SDS–polyacrylamide gel electrophoresis. The enzyme was most active at pH 6 and 37°C, and was stable between pH 4 to 8 at 5°C. The action of the enzyme was inhibited by the addition of Cd²⁺, Co²⁺, Hg²⁺, Zn²⁺, iodoacetic acid, and EDT A. The purified enzyme cleaved β(1→5) and β(1→6)-linked galactofuranosyl chains. Based upon the mode of liberation of galactofuranosyl residues from pyridylamino β(1→6)-linked galactofuranoside oligomers, the enzyme can be classified as an endo-β-galactofuranosidase that randomly hydrolyzes the linkage.     

The molecular structures of a glucan and a galactan synthesised by Prototheca zopfii

When the unicellular organism Prototheca zopfii was grown on a malt-agar medium, a mixture of polysaccharides was synthesised which could be subsequently extracted from the dried cells with hot water and hot alkali. The major polysaccharide was a galactan which had a branched structure with main chains of (1→6)-linked D-galactopyranose residues, and ≈ 10% of side chains containing terminal D-galacto-furanose residues. A glycogen-type polysaccharide and a (1→4)-linked mannan were also produced.     

An arabinogalactan from the seeds of Pseudium guava

Hemicelluloses of seeds of Pseudium guava containing d-galactose (59.6), d-arabinose (35.9), and a uronic acid (4.5%) were analyzed by methylation analysis and Smith-degradation analysis, and the following structural elements were deduced; chain residues of (1→4)-linked d-galactose, (1→5)-linked d-arabinose, and terminal d-arabinose residues. The following structure was assigned to the polysaccharide. →5)-d-Araf-(1→4)-d-Galf-(1→5)-d-Araf-(1→