Pradyot K. Ghosal

Structural features of the acidic polysaccharide of Spondias pinnata gum exudate

Abstract The purified, homogeneous, acidic polysaccharide isolated from the gum exudate of Spondias pinnata, and its degraded product prepared by controlled autohydrolysis, were found to contain d -galactose, l -arabinose, and d -galacturonic acid. Complete methylation followed by hydrolysis, both before and after reduction with lithium aluminum hydride, revealed the probability of a (1 →3)-linked, galactan backbone. The linkages of the interior parts were confirmed by methylation studies, and by the results of periodate oxidation and Smith degradation.

Antioxidative Carbohydrate Polymer from Enhydra fluctuans and Its Interaction with Bovine Serum Albumin

Enhydra fluctuans leaves are traditionally sold on Indian markets for various health benefits. However, no phytochemical study on its high molecular weight compound has so far been performed. Chemical, chromatographic, ESI-TOF-MS, and NMR analyses of the water extracted carbohydrate polymer (CP) of E. fluctuans leaves showed the presence of a 24 kDa arabinogalactan having a (1,3)-linked β-d-Galp main chain, substituted at O-6 by (1,6)-linked β-d-Galp side chains. The latter residues were substituted at O-3 by (1,3)-, (1,5)-, and (1,3,5)-linked α-l-Araf chains, and nonreducing end-units of α-l-Araf and β-d-Galp. This polymer contained esterified phenolic acids. Biochemical analysis revealed similarity in antioxidative potential between the identified carbohydrate polymer and known standard antioxidants. The highly branched side chains and the phenolic acid residues of the arabinogalactan might be the functional sites. Fluorimetric and ultraviolet spectrometric analyses showed that the studied carbohydrate polymer can form complex with bovine serum albumin having binding constant K = 2.42 × 10(6)/M and changes its microenvironment. Thus, traditional aqueous extraction method provides a carbohydrate polymer, which stimulates a fair biological response: this could represent an interesting approach in phytotherapeutic treatments.

Isolation, purification and some structural features of the mucilaginous exudate from Musa paradisiaca.

The water-soluble polysaccharides isolated from the vascular gel of Musa paradisiaca, were fractionated via anion exchange chromatography into four fractions. Fractionated polymers contained arabinose, xylose and galacturonic acid as major sugars, together with traces of galactose, rhamnose, mannose and glucose residues. Methylation analysis revealed the presence of a highly branched arabinoxylan with a significant amount of terminal arabinopyranosyl units and an arabinogalactan type I pectin. Periodate oxidation studies supported the results of methylation analysis.

In vitro anti-oxidant activity, fluorescence quenching study and structural features of carbohydrate polymers from Phyllanthus emblica.

The water-extracted carbohydrate polymers (WE) of Phyllanthus emblica are analyzed using chemical, chromatographic, and spectroscopic methods. Anion-exchange-chromatography of WE yielded four fractions (F1-F4) with different chemical compositions and all of them contain phenolics. The major fraction F4 possesses 50% polysaccharide and 26% phenol, and is a glycoconjugate. The antioxidant capacities of WE and F4 are comparable to standard anti-oxidants. Notably, activities of F1-F4 correlate with their phenol content. Evidence for the complexation of F4 with bovine serum albumin is presented by fluorescence quenching measurement. The results also indicate conformational change of protein at high carbohydrate polymer concentration.

Structural studies on a polysaccharide fraction from the fruits of Cordia dichotoma Forst

Abstract 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.

Cell-wall polysaccharides from the fruits of Limonia acidissima: isolation, purification and chemical investigation

Polysaccharides were isolated from the fruits of Limonia acidissima by sequential extraction with water, and 1 M and 4 M KOH. The water extract contained pectic polymers substituted with side chains comprising mainly of 1,5-, 1,3,5-linked arabinose together with 1,4-, 1,6-, 1,3,6-linked galactose, and lesser amounts of 1,2,4- and 1,3-linked galactose residues. Galactosyl and arabinofuranosyl groups terminated most of the branched residues. The alkaline extracts contained both pectic and hemicellulosic polymers. The insoluble material consists mainly of cellulose-rich material.

Structural features of a water soluble gum polysaccharide from Murraya paniculata fruits.

A water soluble gum polysaccharide was isolated from Murraya paniculata fruits. Hydrolytic experiments, methylation analysis, periodate oxidation studies and NMR data revealed that the polysaccharide was extensively branched and it consisted of 1,3-, and 1,3,6-linked beta-D-galactopyranosyl units, terminal beta-D-galactopyranosyl units and terminal alpha-D-glucopyranosyl 1,4-beta-D-galactopyranosyl units. Small amounts of 4-O-methylglucuronic acid residues were also present.

Structural studies of an acidic polysaccharide from the seeds of Acacia auriculaeformis A. Cunn

Abstract An acidic polysaccharide isolated from the defatted seeds of Acacia auriculaeformis contained l -arabinose, d -xylose, d -galactose, d -glucose, and d -glucuronic acid in the molar ratios 1.5:2:2.2:1:3. Autohydrolysis of an aqueous solution of the polysaccharide yielded an electrophoretically homogeneous, degraded polysaccharide consisting of d -xylose, d -galactose, d -glucose, and d -glucuronic acid in the molar ratios 1:3.9:1.9:6.7. Methylation analysis, periodate oxidation, and Smith degradation of the native and degraded polysaccharide and their carboxyl-reduced derivatives indicated that the polysaccharide is branched with 3,6-linked galactosyl and 2,4-linked glucosyl residues at the branch points to which are attached chains comprised of arabinose, xylose, glucose, galactose, and glucuronic acid residues via different linkages. Oxidation of the acetylated polysaccharide with chromium trioxide indicated that most of the glucose and arabinose residues were α, while xylose, galactose, and glucuronic acid were mostly β. A d.p. of ∼89 was established for the polysaccharide by end-group analysis.

Structural studies on the polysaccharide of Swietenia mahogany gum

Abstract The acidic polysaccharide isolated from the gum exudate of Swietenia mahogany, and the degraded polysaccharide obtained by its mild hydrolysis with acid, are composed of residues of d -galactose, l -arabinose, l -rhamnose, and d -galacturonic acid. The products of methylation of these two polysaccharides and their carboxyl-reduced derivatives were characterized. The results of the methylation and periodate-oxidation experiments showed that these polysaccharides are extensively branched, and that their backbone is a (1 → 3)-linked d -galactan chain. The periodate consumption was in accord with the linkage distributions proposed. End-group analysis showed that the polysaccharide has a high value of average degree of polymerization.