The structure of bael (Aegle marmelos) gum

Purified, bael-gum polysaccharide containsd-galactose (71%),l-arabinose (12.5%),l-rhamnose (6.5%), andd-galacturonic acid (7%). Hydrolysis of one mole of the fully methylated polysaccharide gave: (a) from the neutral part, 2,3,4-tri-O-methyl-l-rhamnose (2 moles), 2,3,5-tri-O-methyl-l-arabinose (4 moles), 2,3,4,6-tetra-O-methyl-d-galactose (8 moles), 3,4-di-O-methyl-l-rhamnose (2 moles), 2,5-di-O-methyl-l-arabinose (1 mole), 2,4,6-tri-O-methyl-d-galactose (10 moles), 2,3-di-O-methyl-l-arabinose (1 mole), 2,4-di-O-methyl-d-galactose (14 moles), and 2-O-methyl-d-galactose (2 moles); and (b) from the acidic part, 2,3,4-tri-O-methyl-d-galacturonic acid (1 mole), 2,4,6-tri-O-methyl-3-O-(2,3,4-tri-O-methyl-d-galactopyranosyluronic acid)-d-galactose (2.6 moles), and 2,4,6-tri-O-methyl-3-O-[2,4,6-tri-O-methyl-3-O-(2,3,4-tri-O-methyl-d-galactopyranosyluronic acid)-d-galactopyranosyl]-d-galactose (1 mole). Mild hydrolysis of the whole gum yielded oligosaccharides from which 3-O-β-d-galactopyranosyl-l-arabinose, 5-O-β-d-galactopyranosyl-l-arabinose, 3-O-β-d-galactopyranosyl-d-galactose, and 6-O-β-d-galactopyranosyl-d-galactose could be isolated and characterized. The results of methylation, periodate oxidation, Smith degradation, Barry degradation, and graded hydrolysis studies were employed for the elucidation of the structure of the whole gum.     

A new water-soluble polysaccharide from the seeds of Cassia multijuga

A polysaccharide consisting of D-galactose, D-mannose, and D-xylose in the molecular ratios 5:1:2 has been isolated from the defatted seeds of Cassia multijuga. Methylation analysis yielded 2,3-di-O-methyl-D-galactose (2 mol), 2,3,6-tri-O-methyl-D-galactose (4 mol), 2,3,4,6-tetra-O-methyl-D-galactose (4 mol), 2,3-di-O-methyl-D-mannose (2 mol), 2-O-methyl-D-xylose (1 mol), 2,3-di-O-methyl-D-xylose (2 mol), and 2,3,4-tri-O-methyl-D-xylose (1 mol). Periodate oxidation indicated 32.4% of end-groups and methylation indicated 31.2%. Partial hydrolysis with acid gave 6-O-α-D-galactosyl-D-galactose, 6-O-α-D-galactosyl-D-mannose, 4-O-β-D-galactosyl-D-xylose, and 3-O-β-D-xylosyl-D-xylose, together with monosaccharides. The polysaccharide is highly branched, consisting of galactosyl, mannosyl, and xylosyl residues in the main chain, with (1→4)-β linkages, and galactosyl and xylosyl end-groups.     

Methylation studies of the polysaccharides resulting from sequential Smith-degradations of the galactan from the snail strophocheilus oblongus

When the galactan from the albumen glands of the snail Strophocheilus oblongus was submitted to three Smith-degradations, the degraded polysaccharide, isolated in 6% yield, was much more linear. Methylation analysis showed that the Smith-degraded polysaccharide gave an increased percentage of 2,4,6-tri-, decreased percentages of 2,3,4,6-tetra- and 2,4-di-, and a large variation in the amount of 2,3,4-tri-O-methyl-d-galactose. The sugars in the polysaccharide which result in the formation of 2,3,4,6-tetra- and 2,3,4-tri-O-methyl-d-galactose are destroyed in subsequent degradation procedures. The above observations suggest that the degradation by periodate oxidation proceeds via non-reducing end-groups and through some internal residues that are exposed as the degradation proceeds. As a result of the overall process, new non-reducing end-groups are formed and new (1 → 6)-linked d-galactose residues are then exposed. The isolation of glycosides of low molecular weight supports the suggestion that the molecule, in the main, is sequentially degraded from the external layers.     

The structure of lannea coromandelica gum

Lannea coromandelica trees exude a water-soluble gum polysaccharide containing galactose (70%), arabinose (11%), rhamnose (2%), and uronic acids (17%). Three aldobiouronic acids are present (chromatographic analysis), namely 4-O-(α-d-galactopyranosyluronic acid)-d-galactose, 6-O-(β-d-glucopyranosyluronic acid)-d-galactose, and 6-O-(4-O-methyl-d-glucopyranosyluronic acid)-d-galactose. Linkage analysis of degraded gum A, obtained by controlled, acid hydrolysis, gave (chromatographic analysis) 3-O-β-l-arabinofuranosyl-l-arabinose, 3-O-β-l-arabinopyranosyl-l-arabinose, 3-O-α-d-galactopyranosyl-l-arabinose, 3-O-β-d-galactopyranosyl-d-galactose, and 6-O-β-D-galactopyranosyl-d-galactose. Degraded gum A was examined by methylation analysis, and was subjected to a Smith-degradation, giving degraded gum B, which was studied by linkage and methylation analysis. The O-methyl derivative of the whole gum was prepared by the Haworth and Purdie procedures and examined, after methanolysis, by g.l.c.: 2,3,4-tri-O-methyl-l-rhamnose, 2,3,5- and 2,3,4-tri- and 2,5-di-O-methyl-l-arabinose; 2,3,4,6-tetra-, 2,3,6-, 2,4,6-, and 2,3,4-tri-, and 2,6- and 2,4-di-O-methyl-d-galactose; 2,3,4-tri-O-methyl-d-glucuronic acid and 2,3,4-tri-O-methyl-d-galacturonic acid were identified. The whole gum was subjected to three successive Smith-degradations, giving Polysaccharides I–III which were examined by linkage and methylation analysis. The structural evidence obtained indicates that the gum molecules are very highly branched, based on a galactan framework consisting of short chains of β-(1→3)-linked d-galactose residues, branched and interspersed with β-(1→6) linkages. To positions 3 and 6 of this framework are attached either single d-galactose end-groups or short side-chains of d-galactose or of l-arabinose residues, and three aldobiouronic acids. The structure therefore appears to be very similar to that established recently for Lannea humilis gum.     

A complex polysaccharide from the seeds of anthocephalus indicus a. rich

The seeds of Anthocephalus indicus contain a water-soluble polysaccharide composed of D-xylose, D-mannose, and D-glucose in the molar ratios 1:3:5. Methylation analysis afforded 2,3,4-tri-O-methyl-D-xylose, 2,3,6,-tri-O-methyl-D-mannose, 2,3,6-tri-O-methyl-D-glucose, 2,3-di-O-methyl-D-glucose, and 2,3,4,6-tetra-O-methyl-D-glucose in the molar ratios 7:21:12:15:8. Periodate oxidation and methylation data indicated 22.5% and 21.9% of end groups, respectively. The above findings, together with the results of partial hydrolysis with acid, indicate the polysaccharide to consist of a linear chain of (1→4)-linked β-D-mannosyl and β-D-glucosyl residues to which α-D-xylosyl and β-D-glucosyl groups are attached by (1→6)-linkages.     

Structural studies of capsular polysaccharide of type XII Diplococcus pneumoniae

The capsular polysaccharide of Diplococcus pneumoniae Type XII contains residues of d-glucose and d-galactose in a molar ratio of 2:1. The methylated polysaccharide yielded upon hydrolysis 2,3,4,6-tetra- and 3,4,6-tri-O-methyl-d-glucose and 2,3,4,6-tetra-O-methyl-d-galactose as the only neutral methyl sugars. Periodate oxidation of the polysaccharide resulted in destruction of all neutral sugars and immunochemical activity against rabbit antisera. Periodate oxidation of the methyl O-methylglycosides obtained after hydrolysis of the methylated polysaccharide indicated that at least 30% of the l-fucosamine residues are substituted at C-4 in the polysaccharide. It is concluded that the polysaccharide consists of a hexosamine backbone that is substituted by d-galactosyl and kojibiosyl side-chains. The proposed terminal d-galactosyl residues apparently are sterically hindered from interacting with several d-galactose-binding proteins.     

A gel-forming (1→3)-β-D-glucan isolated from cyttaria harioti fischer

An alkali-soluble glucan, [α]_D + 11° (M potassium hydroxide) having a degree of polymerization of 220, has been isolated from the fruit bodies of the tree fungus Cyttaria harioti Fischer. Periodate oxidation and methylation analysis show that it consists of a highly branched β-D-(1→3)-linked backbone. Hydrolysis of the methylated polysaccharide yielded 2,3,4,6-tetra-O-methyl- (24.5 mol%), 2,4,6-tri-O-methyl-(39.4 mol%), 2,3,4-tri-O-methyl- (8.6 mol%), and 2,4-di-O-methyl-D-glucose (27.5 mol%). Periodate-oxidation results substantiate the methylation studies. The general structural features of the glucan are discussed.     

The preparation of a crystalline guanosine trialcohol and its sodium salt

A polysaccharide has been extracted from Cassia corymbosa seeds with cold, acidulated water, and purified to give a water-soluble product containing d-galactose and d-mannose in 4:7 molar ratio. Acid-catalyzed fragmentation, periodate oxidation, methylation, and enzymic hydrolysis showed that the seed gum has a branched structure consisting of a linear chain of β-d-(1→4)-linked mannopyranosyl units, some of which are substituted at O-6 by two α-d-(1→6) galactopyranosyl units mutually linked glycosidically. Methylation analysis of the galactomannan afforded 2,3,4-tri- and 2,3,4,6-tetra-O-methylgalactose, along with 2,3-di- and 2,3,6-tri-O-methylmannose, in the molar ratios of 2:2:2:5. Both the methylation and the periodate-oxidation studies showed ～36.4% of end groups. The significance of these results, together with the findings of partial hydrolysis with acid, are discussed, in relation to ascertaining the structure of the repeating unit of the polysaccharide.     

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.     

Mucilage from a fresh-water red alga of the genus Batrachospermum

The gelatinous polysaccharides of a Batrachospermum species have been extracted from the alga. The major polysaccharide is acidic and has been separated from neutral polysaccharides by chromatography on DEAE-cellulose. The constituent sugars of the acidic polysaccharide include d- and l-galactose, d-mannose, d-xylose, l-rhamnose, d-glucuronic acid, and two O-methyl sugars, which have been characterized as 3-O-methyl-l-rhamnose (l-acofriose and 3-O-methyl-d-galactose. Partial acid hydrolysis of this polysaccharide has given a complex mixture of neutral and acidic oligosaccharides. The two preponderant acidic oligosaccharides contained galactose and glucuronic acid in 1:1 ratio, suggesting the presence of a repeating sequence of these two residues as a major structural feature of the polysaccharide.     

Les polysaccharides des graines de quelques liliacees et iridacees

The alkali-soluble polysaccharides have been surveyed in the seeds of 7 species of the Liliaceae and 2 species of the Iridaceae. All appear to contain galactoglucomannans and/or glucomannans. The structure of the water-soluble galactoglucomannan from the endosperm of Asparagus officinalis has been studied in detail. It contains residues of glucose, mannose and galactose in the ratio 43:49:7. Hydrolysis of the fully methylated polysaccharide released 2,3,4,6-tetra-O-methyl-d-hexoses (mannose and glucose), 2,3,4,6-tetra-O-methyl-d-galactose, 2,3,6-tri-O-methyl-d-mannose, 2,3,6-tri-O-methyl-d-glucose, 2,3-di-O-methyl-d-mannose and 2,3-di-O-methyl-d-glucose in the molar proportions of 1:4.5:50:41:2:1·5. The following oligosaccharides were identified on partial hydrolysis of the galactoglucomannan: mannobiose, mannotriose, mannotetraose, cellobiose, glucopyranosylmannose, mannopyranosylglucose and a trisaccharide composed of two mannosyl residues and one glucosyl residue. The galactoglucomannan consists of a linear chain of β(1 → 4)-Iinked d-mannosyl and d-glucosyl residues, to which are attached single-unit galactosyl side chains. The galactose residues are linked 1 → 6, probably α. The terminal, non-reducing residues of the main chain may be either glucosyl or mannosyl units but the former predominate.     

The structure of Lannea humilis gum

Lannea humilis trees exude a water-soluble gum polysaccharide containing galactose (75%), arabinose (11%), rhamnose (2%), and uronic acids (12%). Three aldobiouronic acids are present (chromatographic analysis), namely 4-O-(α-D-galactopyranosyluronic acid)-D-galactose, 6-O-(β-D-glucopyranosyluronic acid)-D-galactose, and 6-O-(4-O-methyl-β-D-glucopyranosyluronic acid)-D-galactose. Linkage analysis of degraded gums A and B, obtained by controlled, acid hydrolysis, gave (chromatographic analysis) 3-O-β-L-arabinofuranosyl-L-arabinose, 3-O-β-L-arabinopyranosyl-L-arabinose, 3-O-α-D-galactopyranosyl-L-arabinose, 3-O-β-D-galactopyranosyl-D-galactose, and 6-O-β-D-galactopyranosyl-D-galactose. Degraded gums A and B were examined by methylation analysis, and the former was subjected to a Smith-degradation, giving degraded gum C, which was studied by linkage and methylation analysis. The O-methyl derivative of the whole gum was prepared (a) by the Haworth and Purdie procedures, and (b) by the sodium hydride-methyl iodide-methyl sulphoxide technique. Both products were examined, after methanolysis, by g.l.c.: 2,3,4-tri-O-methyl-L-rhamnose; 2,3,5- and 2,3,4-tri- and 2,5-di-O-methyl-L-arabinose; 2,3,4,6-tetra-, 2,3,6-, 2,4,6- and 2,3,4-tri-, 2,6- and 2,4-di-, and 2-O-methyl-D-galactose; 2,3,4-tri-O-methyl-D-glucuronic acid and 2,3,4-tri-O-methyl-D-galacturonic acid were identified. The whole gum was subjected to four successive Smith-degradations giving Polysaccharides I–IV, which were examined by linkage and methylation analysis. Polysaccharide IV is a branched galactan; the arabinose-containing sidechains in L. humilis gum therefore do not contain more than four residues, and only a few of that length occur. The evidence obtained indicates that the gum molecules are very highly branched. The galactan framework consists of short chains of β-(1→3)-linked D-galactose residues, branched and interspersed with β-(1→6)-linkages. To positions 3 and 6 of this framework are attached either single D-galactose end-groups or short side-chains of D-galactose or of L-arabinose residues, and three aldobiouronic acids. A possible structural fragment that shows these features is proposed.     

Structural investigation of oxalate-soluble rapeseed (Brassica campestris) polysaccharides. 3. An arabinan

An arabinan isolated from rapeseed was shown by sedimentation studies to be essentially homogeneous, and methylation analysis revealed a highly branched structure. Hydrolysis of the methylated polysaccharide yielded 2,3,5-tri-O-methyl-L-arabinose (11 mol.), 2,3-di-O-methyl-L-arabinose (7 mol.), 3-O-methyl-L-arabinose (trace), 2-O-methyl-L-arabinose (7 mol.), and L-arabinose (2 mol.). Periodate-oxidation data substantiate the methylation results. The general, structural features of the arabinan are discussed.     

Facile syntheses of methyl α-D-altropyranoside and its 3,4-and 4,6-O-isopropylidene derivatives

An L-arabino-D-glucurono-D-xylan isolated from the mature stalk of the reed Arundo donax contained the neutral sugars D-xylose, L-arabinose, and D-glucose in molar proportions 8.9:1:traces. 2-O-(4-O-Methyl-α-D-glucopyranosiduronic acid)-D-xylose was also present. The results of methylation analysis showing the presence of 2,3,4-tri-, 2,3-di-, 2-, and 3-O-methyl-D-xylose together with 2,3,5-tri-O-methyl-L-arabinose were determined by the gas-liquid chromatography-mass spectrometry technique and were in good agreement with those of the periodate oxidation. The D-xylan has an average degree of polymerization of about 80 and is essentially linear. The polysaccharide has structural features similar to those of polysaccharides isolated from other Gramineae.     

Structural investigation of a heteropolysaccharide isolated from the green fruits of Capsicum annuum

A water-soluble polysaccharide isolated from the hot water extract of the green fruits of Capsicum annuum was found to consist of 3-O-acyl-l-rhamnose, d-methyl galacturonate, 6-O-methyl-d-galactose in a molar proportion of nearly 1:2:1. Structural investigation of the polysaccharide was carried out using total hydrolysis, methylation analysis, periodate oxidation followed by GLC-MS, and NMR experiments. On the basis of the above-mentioned experiments it is concluded that the following repeating unit is present in the polysaccharide.     

An Escherichia coli antimicrobial effect of arabinoglucomannan from fruit of Bryonia lacinosa

Extraction of the pulp of ripe berries of Bryonia lacinosa with 1% aqueous acetic acid yielded a polysaccharide material, having d-glucose, d-mannose and l-arabinose in the molar ratio of. 5.00:3.01:4.00. Hydrolysis of the fully methylated polysaccharide furnished 2,3,4,6-tetra-O-methyl-d-glucose, 2,3-di-O-methyl-d-glucose, 2,3,6-tri-O-methyl-d-mannose, 2,3-di-O-methyl-d-mannose and 2,3,5,-tri-O-methyl-l-arabinose in 1:4:2:1:4 molar ratio. Partial hydrolysis of the polysaccharide furnished; mannobiose, epicellobiose, 6-O-β-l-arabinofuranosyl-d-glucose, 6-O-α-mannopyranosyl-d-mannose and epimaltose along with the component monosaccharides. On metaperiodate oxidation studies, 100 g of the polysaccharide liberated 0.055 mol of HCOOH consuming 0.7127 mol of periodate, indicating about 8.33% of the end groups. On the basis of the above results, a structure for the repeating unit of the polysaccharide has been proposed. The polysaccharide was tested for the microbial activity and was found to be active against Escherichia coli with a minimum dose of 6.25 mg/mL.     

Methylation analysis of carrageenans from the seaweed Iridaea undulosa

Two carrageenans from Iridaea undulosa, isolated by precipitation of the crude polysaccharide at O.70–1.05 M and 1.55–1.65 M KCl concentrations, were studied by methylation analysis. Acid hydrolysis of the methylated derivative of the less soluble carrageenan (molar ratio galactose: 3,6-anhydrogalactose: sulphate 1.00: 0.50: 1.20) yielded major amounts of 2,6-di-O-methylgalactose (51.3 mol %), 4,6-di-O-methylgalactose (25.6%) and 4-O-methylgalactose (51.3mol%), 4,6-di-O-methylgalactose (25.6%) and 4-O-methylgalactose (13.4%). Minor quantities of 3-O-methylgalactose (4.6%) and 6-O-methylgalactose (3.2%) were found together with traces of 2,3,6- and/or 2,4,6-tri-O-methylgalactose, 2-O-methylgalactose and galactose. Oxidative acid hydrolysis produced 3,6-anhydro-2-O-methylgalactonic acid and 3,6-anhydrogalactonic acid in a molar ratio 3.5-4.0:1.0. The methylated derivative of the more soluble carrageenan (molar ratio galactose:3,6-anhydrogalactose:sulphate 1.00:0.04:1.43) gave on acid hydrolysis, 2,3,4,6-tetra-O-methylgalactose (4.6%), 2,3,6-tri-O-methylgalactose (4.2%), 2,4,6-tri-O-methylgalactose (10.7%), 4,6-di-O-methylgalactose (24.1%), 3,6-di-0-methylgalactose (8.0%), 2,3-di-O- methylgalactose (3.4%), 2,4-di-O-methylgalactose (4.6%), 2,6-di-O-methylgalactose (4.2%), 3-O-methylgalactose (19.5%),4-O-methylgalactose (9.6%),6-O-methylgalactose(3.1%),galactose (3.4%)and traces of 2-O-methylgalactose.     

Structural investigation of the sodium hydroxide-soluble polysaccharides of tobacco (Nicotiana tabacum): An arabinoxyloglucan

An arabinoxyloglucan (amyloid) isolated from bright tobacco (Nicotiana tabacum, L. cv., Delhi 76) consists of l-arabinose, d-xylose, and d-glucose residues in the molar ratios 1:2.2:6.8. Sedimentation data indicate that the polysaccharide is homogeneous. The methylation analysis data show a statistical unit of 20 sugar residues with 5 terminal, non-reducing end-groups (3 d-xylosyl and 2 l-arabinosyl). There are 5 residues of d-glucose involved in branching through positions 4 and 6. The remaining 10 non-terminal residues consist of two (1→2)-linked d-xylosyl residues and eight (1→4)-linked d-glucosyl residues. The proposed statistical unit accords with the periodate-oxidation results.The formation of ∼0.1 mol each of 2,3,4,6-tetra-O-methyl- and 2,3,4-tri-O-methyl-d-glucose suggests that an average unit may contain ∼200 sugar residues.     

Methanolysis as a model reaction for oligosaccharide synthesis of some 6-substituted 2,3,4-tri-O-benzyl-D-galactopyranosyl derivatives

In the methanolysis of some 2,3,4-tri-O-benzyl-D-galactopyranosyl derivatives, the nature of the C-6 substituent appears to have minor influence on the steric outcome of the reaction compared with the effects of solvent and the nature of the leaving group at C-1. Different combinations of experimental parameters have given methyl glycosides mixtures, the compositions of which vary between 0–70% of α-anomer. Attempts to prepare oligosaccharides from 6-O-substituted 2,3,4-tri-O-benzyl-D-galactopyranosyl derivatives have shown methanolysis to be a less satisfactory model reaction than is the case for the D-glucose series, even when the alcohol and glycosyl derivative are in near equivalent quantities.     

Structural investigations on two hemicellulosic polysaccharides from groundnut (Arachis hypogea) seed endosperm

A highly branched xylan and a linear, β-d-(1→4)-linked glucomannan are the two hemicellulosic components isolated from the endosperms of groundnut (Arachis hypogea). Electrophoretic, sedimentation, and sugar analysis indicate the polysaccharides to be fairly homogeneous. The O-methyl derivatives of the polysaccharides were analysed, after reduction and O-acetylation, by gas-liquid chromatography and g.l.c.-mass spectrometry. 2,3,4-Tri-O-methyl-d-xylose (3.6 mol), 2,3-di-O-methyl-d-xylose (21.0 mol), 3-O-methyl-d-xylose (2.8 mol), and d-xylose (4.2 mol) were detected in the xylan, whereas 2,3,4,6-tetra-O-methyl-d-glucose and/or mannose (1.6 mol), 2,3,6-tri-O-methyl-d-mannose (5.6 mol), and 2,3,6-tri O-methyl-d-glucose (21.2 mol) were found in the glucomannan. Periodate and Smith-degradation studies substantiate the results of methylation analysis on the xylan. A glucose: mannose ratio of 3:1 for the glucomannan, however, suggests that this fraction may be an aggregate of true glucomannan and glucan or degraded cellulose.