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.     

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.     

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.     

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.     

Structural diversity of d-galacto-d-mannan components isolated from lichens having ascomycetous mycosymbionts

d-Galacto-d-mannan fractions were isolated from six common Canadian lichens having ascomycetous mycosymbionts, namely Parmelia sulcata, Stereocaulon paschale, Peltigera aphthosa, Letharia vulpina, Actinogyra muehlenbergii, and an Usnea sp. Their chemical structures were compared with each other and those of six species previously investigated; only Parmelia sulcata and Cetraria islandica (Iceland moss) contained galactomannans of closely related structures. The structural diversity depends on substituents on the (1→6)-linked α-d-mannopyranosyl main-chains. The side-chains occur as monosubstituents at O-2 or O-4 or as disubstituents at O-2,4. Frequently, the main-chain units are unsubstituted. Thus far, eight types of substitution have been recognized (1–8) in which β-d-Galp is linked (1→4), α-d-Galp and α-d-Manp (1→2), and β-d-Galf (1→4).     

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.     

The structure of the neutral polysaccharide gum secreted by Rhizobium strain cb744

A previous investigation of the structure of the extracellular polysaccharide gum from the nitrogen-fixing Rhizobium strain cb744 (a member of the slow-growing Cowpea group) indicated that there were two β-(1→4)-linked d-glucopyranosyl residues for each α-(1→4)-linked d-mannopyranosyl residue, and that each mannose was substituted at O-6 by a β-d-galactopyranosyl residue having 71% of the galactose present as 4-O-methylgalactose. The present study shows that, although the gum appeared to have a simple tetrasaccharide repeating unit, it is composed of two closely associated components. One is a (1→4)-linked α-d-mannan substituted at each O-6 by a β-d-galactopyranosyl residue (71% 4-O-methylated). The second component is a (1→4)-linked β-d-glucan. The existence of the two polysaccharides was established by separation of the β-d-galactosidase-treated gum on a column of concanavalin A-Sepharose 4B. The d configurations were determined and the anomeric attribution of the linkages confirmed by the use of enzymes. The interaction between the two gum components is discussed.     

Isolation and characterization of β-d-glucan,heteropolysaccharide, and trehalose components of the basidiomycetous lichen Cora pavonia

Cora pavonia, a lichen having a basidiomycetous mycobiont, is rich in protein (36%), of which 10% is tyrosine. α,α-Trehalose is present and was isolated in 4.4% yield. The lichen was found to contain polysaccharides typical of basidiomycetes and different from those of ascomycetes and ascomycetous lichens. Isolated and characterized were a β-d-glucan and a heteropolysaccharide containing l-rhamnose, l-fucose, d-xylose, d-mannose, d-glucose, and d-galactose. The β-d-glucan was highly branched with 21% of nonreducing end-groups, contained 3-O-, 6-O-, and 3,6-di-O-substituted β-d-glucopyranosyl units, and had a main chain consisting of (1→3)- and (1→6)-links. The heteropolysaccharide component contained mainly mannose and xylose, having a mannose-containing nucleus and a main chain with preponderant (1→3)-linked α-d-mannopyranosyl residues. These were unsubstituted (10%), and 4-O- (10%) and 2,4-di-O-substituted (10%) with residues of β-d-xylopyranose. On methylation analysis of the heteropolysaccharide, a capillary column of DB-210 proved to be particularly useful for gas-liquid chromatographic resolution of partially O-methylated alditol acetates.     

Characterization of the extracellular,water-insoluble α-D-glucans of oral streptococci by methylation analysis,and by enzymic synthesis and degradation

Methylation analysis of water-insoluble α-D-glucans synthesized from sucrose by culture filtrates from several strains of Streptococcus spp. has proved that all of the glucans were highly branched and that the chains contained (1→6)- and (1→3)-linked D-glucose residues not involved in branch points. Hydrolysis of the glucans with a specific endo-(1→3)-α-D-glucanase demonstrated that the majority of the (1→3)-linked glucose residues were arranged in sequences. D-Glucose was the major product of the hydrolysis, and a small proportion of nigerose was also released. The use of a specific endo-(1→6)-α-D-glucanase similarly indicated that the glucans also contained sequences of (1→6)-linked α-D-glucose residues, and that those chains were branched. Two D-glucosyltransferases (GTF-S and GTF-I), which reacted with sucrose to synthesize a soluble glucan and a water-insoluble glucan, respectively, were separated from culture filtrates of S. mutans OMZ176. The soluble glucan was characterized as a branched (1→6)-α-D-glucan, whereas the insoluble one was a relatively linear (1→3)-α-D-glucan. The hypothesis is advanced that the glucosyltransferases can transfer glucan sequences by means of acceptor reactions similar to those proposed by Robyt for dextransucrase, leading to the synthesis of a highly branched glucan containing both types of chain. The resulting structure is consistent with the evidence obtained from methylation analysis and enzymic degradations, and explains the synergy displayed when the two D-glucosyltransferases interact with sucrose. Variations in one basic structure can account for the characteristics of water-insoluble glucans from S. sanguis and S. salivarius, and for the strain-dependent diversity of S. mutans glucans.     

Bis(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl)amine obtained by a fusion reaction

A unique, alkali-soluble polysaccharide has been isolated from the cell walls of the basidiomycete Coprinus macrorhizus microsporus. The polysaccharide, which is primarily a glucan, contains a large proportion of α-(1→4)-linked d-glucose residues and a smaller amount of β-(1→3) and (1→6) linkages, as suggested by methylation, partial acid hydrolysis, periodate oxidation, and enzymic studies. Hydrolysis of the methylated polysaccharide gave equimolar amounts of 2,4-di- and 2,3-di-O-methyl-d-glucose; no 2,6-di-O-methyl-d-glucose was identified, indicating the absence of branch points joined through O-1, O-3, and O-4. The isolation and identification of 2-O-α- glucopyranosylerythritol from the periodate-oxidized polysaccharide suggests that segments of the a-(1→4)-linked d-glucose residues are joined by single (1→3)-linkages. An extracellular enzyme-preparation from Sporotrichum dimorphosporum (QM 806) containing both β-(1→3)- and α-(1→4)-d-glucanohydrolase activity released 76% of the reducing groups from the polysaccharide. The polysaccharide also contains minor proportions of xylose, mannose, 2-amino-2-deoxyglucose, and amino acids.     

Some structural features of a heteropolysaccharide from the leaves of the cactus Pereskia aculeata

A homogenous water-soluble mucilaginous heteropolysaccharide containing 3.5 % protein was isolated from the leaves of Pereskia aculeata. It contains arabinose, galactose, rhamnose and galacturonic acid in a molar ratio of 5.1:8.2:1.8:1.0 and, based on conventional polysaccharide analysis techniques, has a (1→4)-linked β-D-galactopyranosyl main chain partially substituted at O-3 by β-L-arabinopyranosyl units, which are, in turn, di-O-substituted at O-2 and O-4 by non-reducing end-groups of α-L-arabinofuranose. Also present are O-substituted units of galactopyranosyluronic acid, which are also present as non-reducing end-groups. They are then linked (1→2) to rhamnopyranosyl units. Aqueous solutions of the heteropolymer had a maximum viscosity at pH 4.5 and viscosity was reduced in the presence of salts over a wide range of pHs. The ¹³C NMR spectrum of the polysaccharide in DMSO indicated a great difference between the elevated segmental motion of the arabinosyl side chains and that of the core, since signals of the former were sharp and those of the latter extremely broad.     

Biosynthesis of salep mannan

A particulate enzyme system, isolated from growing orchid tubers (Orchis morio), was shown to catalyse the transfer of mannose from guanosine-diphosphate-mannose-¹⁴C and its incorporation into alkali-insoluble mannan with the same type of linkage [β(1 → 4)-d-mannopyranosyl] as is contained in the naturally-occurring reserve polysaccharide.     

Rhamnogalactofuranan from the microalga Myrmecia biatorellae,symbiotic partner of Lobaria linita

A structural study of the cell wall polysaccharides of Myrmecia biatorellae, the symbiotic algal partner of the lichenized fungus Lobaria linita was carried out. It produced a cold-water insoluble rhamnogalactofuranan, with a (1 → 3)-linked β-d-galactofuranosyl main-chain, substituted at O-6 by single units of β-d-Galf, or by side-chains of 2-O- and 2,4-di-O-linked α-l-Rhap units. The structure of the polysaccharide was established by chemical and NMR spectroscopic analysis.     

An arabinogalactan from the culture medium of Rubus fruticosus cells in suspension

A water-soluble arabinogalactan, isolated from the extracellular medium of suspension-cultured cells of Rubus fruticosus, contained arabinose, rhamnose, galactose, and also protein (6.5%) and uronic acid (2.5%). Methylation analysis of the arabinogalactan and the arabinose-free product obtained by mild acid hydrolysis showed that the polysaccharide was a typical arabino-3,6-galactan in which rhamnose and glucuronic acid occupied non-reducing terminal positions. Successive Smith-degradations combined with methylation analysis and ¹³C-n.m.r. spectroscopy revealed that the arabinogalactan contained a main chain of (→3)-linked β-d-galactopyranosyl residues with a high degree of branching at positions 6 by (1→6)-linked d-galactopyranosyl side-chains of various lengths, in which several contiguous residues were substituted at positions 3. The polymer is thus an arabinogalactan-protein belonging to the galactans of Type II.     

Chemical properties and antiinflammatory activity of a galactomannoglucan from Arecastrum romanzoffianum

A galactomannoglucan (GMG) with an estimated weight-average molar mass of 1.5 × 10⁵ was obtained from an aqueous extract of the mesocarp of fruits of Arecastrum romanzoffianum (Cham.) Becc. by fractionation by Sephacryl S-300 HR and Sephadex G-25. Chemical and spectroscopic studies indicated that GMG has a chain of (1 → 4)-linked β-d-mannopyranosyl residues, a chain of (1 → 3)-linked β-d-galactopyranosyl residues, a chain of (1 → 4)-linked α-d-glucopyranosyl residues, repeating units of β-d-galactopyranosyl-(1 → 4)-β-d-mannopyranosyl and β-d-mannopyranosyl-(1 → 4)-α-d-glucopyranosyl and terminal residues of d-galactopyranosyl and d-glucopyranosyl which comprised galactose, mannose and glucose in the molar ratio of 10:37:53. The polysaccharide exhibited significant antiinflammatory activity against carrageenan-induced mouse paw oedema.     

Structural study of the extracellular polysaccharide gum from Rhizobium strain CB744

The structure of the extracellular polysaccharide gum from nitrogen-fixing Rhizobium sp. strain CB744 (a member of the slow-growing Cowpea group) has been investigated. Gas-chromatographic analysis of the alditol acetates of the acid hydrolysate showed the gum to be composed of galactose, 4-O-methylgalactose, mannose, and glucose in the molar ratio of 1:2.5:3.5:7.0. The polysaccharide is unusual in that it contains no carbonyl substituent, although such substituents are common amongst polysaccharides produced by the slow-growing group. The native and de-branched polysaccharides were examined by methylation analysis. The anomeric configurations were determined by ¹³C-n.m.r. and oxidation by chromium trioxide. It is concluded that there are two β-(1→4)-linked glycopyranosyl residues for each α-(1→4)-linked mannopyranosyl residue, and that each mannose is substituted at O-6 by a β-galactopyranosyl residue, with 71% of the galactose groups being present as 4-O-methylgalactose.     

Structure and biodegradation of the polysaccharide components of egg masses isolated from snails of an Ampullarius species

A polysaccharide preparation, isolated from egg masses deposited by snails of an Ampullarius species, was purified via precipitation with Cetavlon in the presence of sodium borate, and found to contain d-galactose and a smaller proportion of d-glucose, and to have two components with sedimentation coefficients of 10S and 40S. A polysaccharide, isolated from freshly laid egg masses, was highly branched and was shown to contain nonreducing α-d-glucopyranosyl and β-d-galactopyranosyl end-groups, and 3,6-di-O-substituted β-d-galactopyranosyl residues. One or more of the polysaccharide components was a d-glucopyrano-d-galactopyranan with non-reducing α-d-glucopyranosyl end-groups (1→4)-linked to β-d-galactopyranosyl residues. The polysaccharide preparations, obtained from freshly laid egg masses and from those that were left for 10 and 15 days after being laid, were structurally different from each other. With the passage of time, progressive diminution of the 10S component and the proportion of d-glucose in the polysaccharide took place, suggesting that each constituent was consumed preferentially by the snail embryos as an energy source.     

Crithidia spp.: Structural comparison of polysaccharides for taxonomic significance

The chemical structures of polysaccharide components of cells of several Crithidia species have been partially elucidated. The structures have been used as criteria to evaluate evolutionary lines previously proposed for species of Crithidia and Herpetomonas and for Trypanosoma cruzi. In accord with the suggestion that Crithidia and Herpetomonas are closely interrelated, all species investigated synthesize a linear (1→2)-linked β-d-mannopyranan and a heteropolysaccharide. These differ from T. cruzi polysaccharide, which contains α-d-mannopyranosyl structures and likely indicates a separate evolutionary route for this flagellate. Crithidia fasciculata, Crithidia harmosae, and Crithidia luciliae form a closely knit group since they form arabinogalactans with related structures. The similarity is particularly close between arabinogalactans of C. fasciculata and C. harmosae whose ¹³C nuclear magnetic resonance spectra show a high degree of resemblance. An unnamed Crithidia sp. contains polysaccharides with fucose and xylose units, intermediate between those of Crithidia deanei, which gave glucose and fucose on hydrolysis, and Herpetomnas samuelpessoai, which gave glucuronic acid and xylose.     

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.     

Synthesis of 7-(tetrahydropyran-2-yl)- and 7-(4-acetoxytetrahydropyran-2-yl)-ε-rhodomycinone and 7-(tetrahydropyran-2-yl)-ε-pyrromycinone

The ¹³C.n.m.r spectra of water-soluble and -insoluble glucans synthesized by enzymes isolated from six strains of Streptococcus mutans are interpreted. The glucans are shown to be composed primarily of α(1→3)- and α-(1→6)-linked glucosyl residues, and the relative abundance of each linkage is estimated from peak areas. Treatment of water-insoluble glucans with dextranase is found to result in water-soluble and -insoluble products, the former enriched in α-(1→6)-linkages and the latter in α-(1→3)-linkages. The structural conclusions arrived at by ¹³C-n.m.r. spectroscopy are consistent with data from methylation analysis and ¹H-n.m.r. spectroscopy.