Alžbeta Kardošová

Immunomodulatory activity of acidic xylans in relation to their structural and molecular properties

The structure/function relationship of two acidic heteroxylan types, the arabino-(glucurono)xylan from corn cobs (AGX) and 4-O-methylglucuronoxylans (GXs) from beechwood and three medicinal herbs (Rudbeckia, Altheae, and Mahonia), has been studied. The effect of the molecular mass of AGX, as well as the content and distribution of the 4-O-methylglucuronic acid side chains in GXs on the immunological activity of these xylans was characterized by their biological response in the mitogenic and comitogenic thymocyte in vitro tests. Depolymerization of AGX by ultrasonication resulted in unequivocal decrease of the immunomodulatory activity, whereas already a short treatment by endo-beta-1,4-xylanase brought about a significant increase in its activity when applied in the highest dose. In the case of the GX samples, neither the uronic acid content nor the distribution pattern of the uronic acid side chains was found to be determinant for the expression of their immunomodulatory activity.

Polysaccharides from the roots of the marsh mallow (Althaea officinalis L.): Structure of an arabinan

Abstract A water-soluble l -arabinan isolated from the mucous material of the roots of the marsh mallow ( Althaea officinalis L.) has a highly branched structure of ∼90 α- l -arabinofuranosyl residues variously linked by (1→5), (1→3), and (1→2) bonds. Some of the l -arabinosyl groups are involved in branches through O-2, O-3, and O-5. There was good agreement between the results obtained by chemical and 13 C-n.m.r.-spectroscopic methods. The polymer has essentially the same structural features as those found for l -arabinans isolated from other plant sources.

(4-O-Methyl-α-d-glucurono)-d-xylan from Rudbeckia fulgida, var. sullivantii (Boynton et Beadle)

From the medicinal plant Rudbeckia fulgida, var. sillivantii (Boynton et Beadle) a low-molecular-mass (4-O-methyl-alpha-D-glucurono)-D-xylan was isolated by alkaline extraction, followed by ethanol precipitation, ion-exchange chromatography and gel filtration. The results of compositional and linkage analyses, supported by those of 1H and 13C NMR measurements of oligomers generated on partial acid hydrolysis, showed the (1-->4)-linked beta-D-xylopyranosyl backbone with about 18% of 4-O-methyl-D-glucuronic acid attached to O-2 of the xylose residues. From the mean distance of adjacent carboxyl groups, obtained from experimentally determined single-ion activity coefficients of calcium counterions, it followed that the uronic acid units are separated and distributed regularly along the xylan chain, i.e. approximately each sixth D-xylose unit bears a 4-O-methyl-D-glucuronic acid residue.

A biologically active fructan from the roots of Arctium lappa L., var. Herkules

From the roots of Arctium lappa L., var. Herkules a low-molecular-weight fructofuranan of the inulin-type has been isolated by water extraction and ethanol precipitation, followed by ion-exchange chromatography and gel filtration of the crude precipitate. The methods employed in structural determination were methylation analysis and 1H and 13C NMR spectral measurements. In tests for antitussive activity in cats the fructan was found to be equally active as some non-narcotic, synthetic preparations used in clinical practice to treat coughing, and in mitogenic and comitogenic tests its biological response was comparable to that of the commercial Zymosan immunomodulator.

Structural characterization and antitussive activity of a glucuronoxylan from Mahonia aquifolium (Pursh) Nutt.

Abstract From the stems of Mahonia aquifolium (Pursh) Nutt. a water-soluble (4-O-methyl-α- d -glucurono)- d -xylan was isolated by alkaline extraction and fractionation of the crude hemicellulose, employing ion-exchange chromatography and gel filtration. The results of compositional and linkage analysis, supported by NMR spectral data of the polysaccharide, showed the (1→4)-linked β- d -xylopyranosyl backbone with about 15% of 4-O-methyl- d -glucuronic acid attached to O-2 of the xylose residues. The distribution pattern of uronic acid units along the xylan chain was determined by the method based on interpretation of the activity coefficient of the calcium counter-ions, estimated in a molecular-disperse solution of calcium salt of the polysaccharide. The results evidenced that the branching of the xylan molecule is not regular. When tested for antitussive activity on mechanically induced coughing in cats, the glucuronoxylan exhibited a much greater effect in comparison to the drugs used in clinical practice to treat coughing.

Mitogenic and comitogenic activities of polysaccharides from some European herbaceous plants

From the leaves of Plantago lanceolata, the green parts of Rudbeckia fulgida, the aerial parts of Salvia officinalis and the roots of Valeriana officinalis, crude polysaccharides have been isolated by extraction with water and further purified and fractionated by various techniques. The water-soluble polysaccharides obtained were examined for their immunomodulatory activities using the in vitro mitogenic and comitogenic rat thymocyte tests. The results indicate that in spite of the considerable differences in chemical composition and structural properties, the tested polysaccharides exhibited similar significant immunomodulatory properties with a particularly high adjuvans activity in the case of the Rudbeckia and Salvia polysaccharides. The pectic polysaccharide-rich complex from Valeriana was shown to also stimulate the immune function of bone marrow cells.

Antitussive activity of a rhamnogalacturonan isolated from the roots of Althaea officinalis L., var. robusta

Abstract Rhamnogalacturonan, one of the constituents of the mucilage isolated from the roots of marsh mallow, has been rested for antitussive activity on nonaesthetized cats of both sexes. The cough reflex was induced mechanically. It was found that rhamnogalacturonan reduced significantly the number of cough efforts and the intensity of attacks from the irritated laryngopharyngeal and tracheobronchial mucose membranes of the airways and promoted expectoration. The exhibited activity was found to be lower than that of the narcotic codeine, but higher than those of the comparative nonnarcotic drugs.

Enzyme preparations fromAspergillus flavus for structural studies of the peach gum polysaccharide

Extra- and intracellular glycanohydrolases were isolated fromAspergillus flavus and partially characterized. Both preparations exhibited β-galactosidase activity. Gel chromatography of the extracellular enzyme preparation on Sephadex revealed one protein fraction containing β-galactosidase activity and a second one exhibiting mainly β-xylosidase activity. Electrophoresis in starch gel and disc electrophoresis in polyacrylamide gel showed that the preparation obtained from the cultivation broth contained five protein fractions, whereas two protein fractions could be detected in the intracellular preparation. Hydrolysis of a partially degraded polysaccharide of peach gum by the above preparations yieldedd-galactose as the main product and traces ofd-mannose,l-arabinose,d-xylose and a number of oligosaccharides.

An Acidic Heteropolysaccharide from the Flowers of Malva Mauritiana L.

Abstract An acidic heteropolysaccharide composed of L-rhamnose, D-galactose, L-arabinose, D-xylose, and uronic acids in 1.0:0.5:0.1:0.1:1.8 mole proportion was isolated from the flowers of M. mauritiana L. Structural studies of the polysaccharide involved compositional and methylation analyses of the intact and carboxyl-reduced polymers, graded acid hydrolysis as well as 1H and 13C NMR spectroscopy. The results of chemical and spectroscopic analyses indicated a branched structure with the backbone made up of alternating sequences of 2- and 4-linked rhamnogalacturonan-type units with linear segments (DP = 2, 4, 12), segments bearing on O-3 of D-GalA monomeric D-GlcA randomly distributed along the chain (DP = 7, 10, 19, 31), and segments having each D-GalA substituted (DP = 15). Moreover, the results of methylation analysis indicated that about 28% of L-rhamnose residues were branched through O-4.

Utilization of degraded peach gum polysaccharide by Aspergillus flavus

Abstract d -Galactose, d -mannose, d -xylose, l -arabinose, and d -glucuronic acid and its γ-lactone were examined as carbon sources for the culture of Aspergillus flavus . d -Mannose was taken up the most rapidly and d -glucuronic acid and its γ-lactone the least rapidly. A partially degraded polysaccharide from peach tree gum ( Prunus persica [ L. ] Batsch containing the above sugars together with d -glucuronic acid and its 4- O -methyl ether was used as substrate for another A. flavus culture. It was found that d -galactose was the major sugar passing into the culture medium with lower proportions of d -xylose, l -arabinose, 2- O -β- d -glucopyranuronosyl- d -mannose, and 6- O -β- d -glucopyranuronosyl- d -galactose. This indicates that the fungus produces extracellular exo- and endo-glycanohydrolases which may be useful in structural studies on polysaccharides.