Structural characteristics and biological effects of exopolysaccharide produced by cyanobacterium Nostoc sp.

Complex structure of cyanobacterium Nostoc sp. exopolysaccharide (EPS), with apparent molecular weight 214 × 10 g/mol, can be deduced from its composition. Chemical and NMR analyses found four dominant sugar monomers, namely (1 → 4)-linked α-l-arabinopyranose, β-d-glucopyranose, β-d-xylopyranose and (1 → 3)-linked β-d-mannopyranose, two different uronic acids and a lactyl group, with (1 → 4,6)-linked β-d-glucopyranose as the only branch point suggest a complex structure of this polymer.

Structural characterisation of polysaccharides from roasted hazelnut skins.

Two polysaccharide fractions sequentially extracted with water 1W and alkali 1A, were isolated from the hazelnut skins. The monosaccharide composition together with the FTIR and NMR analyses, indicated that both fractions are formed from a mixture of polysaccharides. The fraction 1W consists of methyl-esterified pectic polysaccharide with rhamnogalacturonan I blocks, branching with arabinose side chains, and with 1,5-, 1,3,5-arabinan and galactan polysaccharides.

Bioactive hemicelluloses alkali-extracted from Fallopia sachalinensis leaves.

Fallopia sachalinensis, regarded as an invasive plant in Europe and designated for disposal, is traditionally used in Japan and China as herbal medicine. Attempted for valorization of the leaves, this paper reports on two protein-free polysaccharide fractions, a neutral (FS-5A) and an acidic (FS-5B) one, obtained via alkali extraction and consecutive purification. Both fractions were characterized by chemical, molecular, structural and bioactive properties.

Non-cellulosic polysaccharides from the leaves of small balsam (Impatiens parviflora DC.).

The leaves of the annual plant Impatiens parviflora DC., a herbal medicine in Asian countries and invasive in managed forests and natural environments in Central Europe, have the potential as a source of bioactive phenolic compounds and polysaccharides. Extractives accounted for ∼22% of the leaves, whereby, the methanolic extract contains mainly caffeic acid, ferulic acid, kaempferol, and quercetin derivatives, and 1,2,4-trihydroxynaphthalene-1-O-glucoside.

Antioxidant activity of herbal polysaccharides and cough reflex.

The extraction of Fallopia sachalinensis leaves resulted in two fractions (FS-1 and FS-2). Chemical and spectral analyses of samples revealed the prevalence of pectic polysaccharides with high galacturonic acid, arabinose, galactose, and rhamnose content. Arabinogalactan with a higher content of phenolic prevailed in the FS-1, whereas rhamnogalacturonan predominated in the FS-2 fraction.

Structural diversity of pectins isolated from the Styrian oil-pumpkin (Cucurbita pepo var. styriaca) fruit.

To evaluate the seeded fruit biomass of the Styrian oil-pumpkin in view of its pectin component, a series of acidic polysaccharides were isolated by a six-step sequential extraction using hot water, EDTA, dilute HCl (twice) and dilute and stronger NaOH solutions. Chemical, physicochemical and spectroscopy analyses revealed that the first four fractions comprised partially methyl-esterified and acetylated pectins with varying proportions of rhamnogalacturonan regions ramified with galactose- and arabinose-containing side chains and showed considerable polymolecularity. The alkali-extracted polysaccharides contained lower amounts of pectins with homogalacturonan and arabinose-rich rhamnogalacturonan regions next to hemicelluloses prevailing in the last polysaccharide.

Structural features of two heteroxylan polysaccharide fractions from wheat bran with anti-complementary and antioxidant activities.

Wheat bran is a rich source of bioactive substances ascribed to its arabinoxylan component. Two water-soluble arabinoxylans were sequentially extracted from wheat bran. WB1, released during enzymatic digestion of starch and protein, contained medium-branched arabinoxylan (A/X=0.

Suppressive effect of pectic polysaccharides from Cucurbita pepo L. var. Styriaca on citric acid-induced cough reflex in guinea pigs.

Several water-soluble pectic polysaccharides were isolated from the pumpkin fruit biomass and characterized by composition, structural features and molecular properties. The pectic polysaccharides were tested for antitussive activity by studying the effects of citric acid-induced cough reflex in guinea pigs and reactivity of the airway smooth muscle in vivo conditions in comparison to the narcotic drug codeine. Oral administration of all pectic polysaccharides from pumpkin inhibited the number of coughs induced by citric acid in guinea pigs, but to various extents.

The pharmacological activity of wheat bran polysaccharides.

(Glucurono)arabinoxylans were extracted from the wheat bran with acetate buffer in the first step (WBH1) and with dilute alkali in the second step (WBH2). In both samples xylose and arabinose dominated, accompanied with smaller amounts of galactose, glucose, mannose and uronic acids mainly in WBH1. WBH1 was free of protein and with low content of phenolic compounds.

Comparison of conventional and ultrasound-assisted extraction of phenolics-rich heteroxylans from wheat bran.

Various two-step extraction procedures with and without a short application of ultrasound in the first step at various reaction conditions (extracting agent, temperature and time), and constant conditions in the second step (5% NaOH, room temperature, 60 min) were used to isolate the hemicellulose component of industrial wheat bran. The polysaccharides recovered from the extracts were characterised by yield, chemical composition and radical scavenging activity. Similar total yields of polysaccharides were achieved by a short ultrasound-assisted extraction (up to 10 min) in the first step using 0.

Norway spruce galactoglucomannans exhibiting immunomodulating and radical-scavenging activities.

Wood-derived naturally acetylated galactoglucomannans (AcGGM) can be recovered even in ton-scale at mechanical pulp mills using spruce as raw material. These cell wall polysaccharides have a great potential as hydrocolloids and bioactive polymers in food and pharmaceutical applications, or as starting material for production of functional polymers. The immunostimulatory activity of both AcGGM and its deacetylated form (GGM) was now in vitro tested.

Weak self-association in a carbohydrate system.

The physiological importance of weak interactions between biological macromolecules (molar dissociation constants >10 microM) is now well recognized, particularly with regard to cell adhesion and immunological phenomena, and many weak interactions have been measured for proteins. The concomitant importance of carbohydrate-carbohydrate interactions has also been identified, although no weak interaction between pure carbohydrate systems has ever been measured. We now demonstrate for the first time to our knowledge using a powerful probe for weak interactions--sedimentation velocity in the analytical ultracentrifuge--that at least some carbohydrates (from the class of polysaccharides known as heteroxylans and demonstrated here to be biologically active) can show well-defined weak self-interactions of the "monomer-dimer" type frequently found in protein systems.

Effect of salt stress on the production and properties of extracellular polysaccharides produced by Cryptococcus laurentii.

The composition, main structural features and molecular properties of exopolysaccharides (EP) produced by Cryptococcus laurentii var. laurentii CCY 17-3-16 under optimal (EPo) and NaCI-stress conditions (EPs) as well as their subfractions isolated by gel chromatography were studied using chemical, FT-IR and NMR spectroscopy methods. The results showed that under stress conditions the yeast produced EP with a lower content of protein and phosphorus.

Xyloglucan degradation using different radiation sources: a comparative study.

Tamarind seed xyloglucan was subjected to different radiation sources-ultrasound, gamma-radiation, and microwave heating, and the effects of these energies upon its molecular and structural properties were characterised by gel permeation chromatography, viscometry, sugar analysis, FT-IR and NMR spectroscopic techniques. In dependence on the degradation methods and experimental conditions used, the decrease of the relative molecular mass (RMM) was accompanied with alteration of the primary structure. Depolymerisation by ultrasound at a frequency of 20 kHz yielded after 120 min products with RMM of about 131 x 10(3) without significant alteration of the primary structure of the polysaccharide.

Ultrasonic extraction of plant materials--investigation of hemicellulose release from buckwheat hulls.

Various one- and two-step extraction procedures with and without a short application of ultrasound at the beginning of the extraction were used to examine the effect of sonication on the extractibility of the hemicellulose components of buckwheat hulls. The polysaccharides recovered from the extracts were characterised by yield as well as composition determined by chemical methods and spectroscopic techniques. They comprised a complex of glucuronoxylan and co-extracted amylose-rich starch in various proportions contaminated with other cell wall components (protein, pectic polysaccharides).

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.

Effect of ultrasound on the extractibility of corn bran hemicelluloses.

Various two-step extraction procedures with and without a short application of ultrasound in the first step were used to examine the effect of sonication on the extractibility and properties of the non-cellulose components of industrial corn bran (CB). The polysaccharides recovered from the extracts of the first (FI) and second (FII) extraction step were characterised by yield and composition. Using water as extractant in the first step, similar yields of total extracted polysaccharides (FI + FII) were obtained by the short sonication treatment when compared to the classical procedures using H2O2-containing alkaline media in the first step.

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.

Ultrasound-assisted extraction of water-soluble polysaccharides from the roots of valerian (Valeriana officinalis L.).

The insoluble plant residues, obtained after preparation of medicinal tinctures from the roots of valerian (Valeriana officinalis L.) by classical and ultrasound-assisted extraction with aqueous ethanol in a pilot plant, were subsequently treated with hot water to isolate the accessible polysaccharide cell wall components. At almost equal amounts of the hot-water extractable material, the yields of the recovered polysaccharides were lower in the ultrasonical experiment.

Comparison of classical and ultrasound-assisted extraction of polysaccharides from Salvia officinalis L.

After preparation of medicine tinctures from the herbal plant Salvia officinalis by classical and ultrasound-assisted extraction with aqueous ethanol, the insoluble plant residues were subsequently treated with hot water and dilute alkali to isolate polysaccharide cell wall components. The yields of the hot water extract as well as total extracted polysaccharides were higher in the case of the ultrasound-treated plant in both laboratory and pilot plant experiments. The water-extractable polysaccharide fractions, in all cases, contained glucose, galactose and arabinose as main sugar components, whereas the alkali-extractable fractions were rich in xylans.

Effect of ultrasound on the immunogenic corn cob xylan.

Changes in the structural, molecular and functional properties of the immunogenic corn cob xylan evoked by ultrasonication in water, 1% NaOH and 5% NaOH were investigated. The reduction of the high molar mass (MM) fraction was more intense than that of the medium MM fraction, depending on the sonic power, sonication time, and alkali concentration. The chain degradation was more effective in the alkaline media.

The effect of ultrasound on the structure and properties of the water-soluble corn hull heteroxylan.

Ultrasonic irradiation of a water-soluble corn hull xylan fraction in neutral and alkaline aqueous medium has been found to produce significant changes in its molecular properties. Degradation is first manifested by a decrease in the large molar mass component under generation of polymer chains with about the same size as those of the main molar mass component. The latter is slightly shifted to the lower molar mass region only at stronger irradiation conditions.

Structure and mitogenic activities of corn cob heteroxylans.

Various structurally different water-soluble (ws) and water-insoluble (wis) heteroxylans have been tested for mitogenic and co-mitogenic activity and shown to differ in their stimulating potency. The ws arabinoglucuronoxylan (ws-AGX) from corn cobs exhibited the highest potency which was comparable to that of the immunomodulator zymosan, whereas the wis-AGX from corn cobs was inactive. Water-soluble derivatives of wis-AGX as well as hydrolytically modified ws-AGX fractions were prepared and tested for their mitogenic and co-mitogenic activity.

Structural features of a water-soluble L-arabino-D-xylan from rye bran.

A water-soluble L-arabino-D-xylan, obtained from the chlorite holocellulose of de-lipidated, de-starched, and de-pectinated rye bran by ammoniacal extraction, was composed of L-Ara and D-Xyl in the molar ratio 7.8:10 and had Mw 36,500 and Mn 26,950. The backbone of the polysaccharide was shown to comprise (1----4)-linked beta-D-Xylp residues, with approximately 41% unsubstituted, approximately 33% 2- or 3-substituted, and approximately 26% disubstituted.