The isolation and analysis of cell wall material from the alcohol-insoluble residue of cabbage (Brassica oleracea var. capitata)

Cell wall material (CWM) was isolated from the wet ball-milled alcohol-insoluble residue of cabbage by treatment with Pronase, phenol-acetic acid-water and 90% aqueous dimethyl sulphoxide to remove precipitated proteins, starch and other intracellular compounds. Some solubilisation (mainly of pectic material) occurred during the purification stages. Methylation analysis of the cold water-soluble polysaccharides showed that the main neutral glycosidic linkages in descending order of concentration, were: non-reducing terminal arabinose groups, 5-linked arabinose and 4-linked galactose. The CWM contained a high level of arabinose-containing pectic polysaccharides. The main linkages present in the non-cellulosic polysaccharides were 4-linked galacturonic acid, non-reducing terminal arabinose groups and 5-linked arabinose; doubly branched arabinose residues were also present. Sequential extraction of the CWM by aqueous inorganic solvents yielded further information on the types of polysaccharides present. The general structural features of the CWM are discussed in the light of these results.     

Pectin isolated from white cabbage--structure and complement-fixing activity

This study was done to investigate whether white cabbage contained polysaccharides with immunostimulatory activity using the complement-fixing test as an indicator. The main polysaccharide isolated was of pectin nature. Methanolysis and (13)C-NMR showed that the polymers consisted of highly esterified alpha-galactopyranoside (alpha-GalpA), significant amounts of alpha-arabinose furanoside (alpha-Araf), beta-Galp and lesser amounts of rhamnose in the pyranose form (Rhap) and xylose in the pyranose form (Xylp). Linkage analyses showed that the alpha-GalpA residues were mainly 1,4-linked with small amounts of 1,3,4-linkages. The alpha-Araf residues were mainly terminally (t)- and 1,5-linked, whereas beta-Galp was t-, 1,3-, 1,6-, and 1,3,6-linked. Positive Yariv reaction indicated polymers with arabinogalactan type 2 like structures. alpha-Rhap was mainly present as 1,2- and 1,2,4-linked residues and Xylp was t- and 1,4-linked. The molecular weight varied greatly and was from 10 to 150 kDa. Cabbage polymers had biological activity and this complement-fixing activity was greatly affected by hydrolytic removal of Araf from pectic side chains.     

Arabinan and arabinan-rich pectic polysaccharides from quinoa (Chenopodium quinoa) seeds: Structure and gastroprotective activity

After removal of starch, cell wall polysaccharides of seeds of quinoa were studied. They were extracted successively with water and with aq. 10% KOH. The extracted polysaccharides were fractionated and purified by freeze–thaw treatment and by sequential ultrafiltration through membranes. The purified fractions (PQW, K2-30EM, K1-10RM and K1-30RM) were analyzed by sugar composition, HPSEC, methylation and ¹³C NMR spectroscopy analysis. The results showed that PQW consisted of a linear arabinan with (1 → 5)-linked α-l-arabinofuranosyl units. Fractions K2-30EM, K1-10RM and K1-30RM were related to rhamnogalacturonan type I with a branched arabinan and galactan side-chains. This arabinan has (1 → 5)-linked α-l-arabinofuranosyl units substituted exclusively in O-3. The main differences between these fractions were their molecular mass and content of Rha and GalA, which probably arise from an increase in their rhamnogalacturonan backbone. A pool of these polysaccharides (arabinan and arabinan-rich pectic polysaccharides) showed gastroprotective activity on ethanol-induced acute gastric lesions in rats.     

Structure of a galactoarabinoglucuronoxylan from tamarillo (Solanum betaceum), a tropical exotic fruit,and its biological activity

Tamarillo (Solanum betaceum) is a tropical exotic fruit whose polysaccharides were extracted from the ripe pulp. After various purification steps, homogeneous fractions (designated PTW, STK-1000R and PF) were analyzed by sugar composition, HPSEC, methylation and NMR spectroscopy analysis. The results showed that the fraction PTW consisted of a linear arabinan with (1 → 5)-linked α-l-arabinofuranosyl units. Fractions designated as STK-1000R and PF contained galactoarabinoglucuronoxylans, with (1 → 4)-linked β-d-Xylp residues in the backbone, carrying branches exclusively at O-2. The polysaccharide in STK-1000R is less branched than that in the PF fraction (∼20.0% and 36.5%, respectively), with side-chains formed by (1 → 5)-linked α-l-Araf residues and (1 → 4)-linked α-d-GlcpA residues and with non-reducing end units formed by α-l-Araf, β-Arap, β-d-Galp, α-d-GlcpA and 4-O-Me-α-d-GlcpA. Intraperitoneal administration of the STK-1000R fraction in mice significantly reduced the number of abdominal constrictions induced by 0.6% acetic acid and the inflammatory phase of nociception induced by 2.5% formalin, indicating that that fraction has an antinociceptive effect on inflammatory pain models.     

Extraction of pectic polysaccharides from sugar‐beet cell walls

Previous methods of extracting pectin from sugar‐beet have used pulp as the starting material. As the temperature and pressure of the pulping process may modify the architecture of the cell wall, we have adapted a relatively non‐disruptive method to characterise cell wall material (CWM) isolated directly from the sugar‐beet. Cell walls from mature sugar‐beets (Beta vulgaris L Aztec) were sequentially extracted four times with imidazole and twice with sodium carbonate to produce six heterogeneous pectic polysaccharide extracts, and with KOH to produce a hemicellulosic extract which was predominantly xylans. Heterogeneity of the extracted pectins was indicated by differences in FTIR spectra, uronic acid content, % methyl esterification, % feruloylation, % acetylation, molecular weight distribution and neutral sugar composition. The highest proportion of feruloyl esters was found in polysaccharides solubilised by the second sodium carbonate extraction. Anion exchange chromatography of these polysaccharides gave three fractions, one of which contained most of the feruloyl ester. These results indicate that feruloyl esters are not randomly distributed among the different pectic polysaccharides in the sugar‐beet cell wall, and that esterification is likely to be dependent on the local sugar sequence or conformation. © 2000 Society of Chemical Industry     

Physical and chemical changes in developing strawberry fruits

Strawberry fruits of thevariety Red Gauntlet were harvested at 7 day intervals after petal fall. Changes in fruit weight, percentages survival on the plant, chlorophyll: carotenoid and anthocyanin, titratable acid, pH of extracts and sugar content were measured. Also changes in soluble and total pectic polysaccharides in alcoholinsoluble residues of harvested fruits were followed during development. Fruit growth was not exponential and in later stages of growth the falling survival rate was correlated to fruit softening. Net synthesis of chlorophyll and carotenoid pigments took place up to 28 days and anthocyanin synthesis commenced 28 to 35 days after petal fall. The sugar content of berries increased with time and titratable acid concentrations increased slightly during development, falling in ripening fruits. The specific viscosity of soluble pectic polysaccharides fell from 28 days after petal fall. There was net synthesis of polyuronide but not neutral polysaccharide during the development of fruits and the amount of insoluble pectic polysaccharide became small and relatively constant compared with the amount of soluble polysaccharide by 21 days after petal fall. Fruits undergoing senescence lost almost all their insoluble pectic polysaccharides. The developmental processes taking place in growing fruits, especially with respect to changes in cell wall structure, and the relevance of results to fruit storage are discussed.     

A study on the composition of garlic skins and the structural features of the isolated pectic acid

An investigation of the composition of garlic skins showed the presence of proteins, lipids, lignin, mannitol, pectin and polysaccharides. Garlic skins are rich in pectin (27%), combined rhamnose (11.42%) and galactose (5.6%). Periodate oxidation studies of pectic acid showed the absence of 1,3-linked residues and branch points and indicated a linear galacturonan of 1,4-linked D-galacturonic acid. Chromatographic analyses were carried out on the hydrolysis products of pectic acid, which had been oxidised by periodate plus bromine, and also on those obtained after reduction of the periodate-oxidised pectic acid.     

Chemical composition and immunomodulatory activity of a pectic polysaccharide from the ground thistle Cirsium esculentum Siev.

The pectic polysaccharide cirsiuman CE was extracted from the stems of the ground thistle Cirsium esculentum Siev. using 0.7% aqueous ammonium oxalate, yielding 10.4% of the air-dried material. The backbone of cirsiuman was proved to consist of 1,4-α-d-galactopyranosyluronan blocks interconnected by 1,2-linked l-rhamnose residues. The side chains were attached to the 4-position of the l-rhamnopyranose residues. The side chains include 1,4-β-galactopyranan, which contains 3,4- and 4,6-substituted d-galactopyranose residues as branched points, and 1,5-α-arabinofuranan bearing 3,5-substituted α-l-arabinofuranose residues as the branching points. Oral administration of cirsiuman was found to prevent induction of oral tolerance to ovalbumin (OVA), increased the levels of serum IgG2a, and downregulated serum IgE responses, therefore it was tested for anti-allergic properties. The score of systemic anaphylactic reaction and the levels of both serum IgE and IL-4 were found to decrease; however, IFN-γ response was upregulated by cirsiuman feeding.     

Chemical Composition of Cell Wall Material from Sweet Potato Starch Residue

Cell wall material was isolated from the residue obtained after the extraction of sweet potato starch by treatment with the α-amylase. The wall material was fractionated by successive extraction with various reagents. The pectic substance was mainly composed of uronic acid (47.1%) residues and contained galactose as the predominant neutral sugar residues. The hemicellulosic fraction was further fractionated by precipitation with iodine in the presence of calcium chloride to give two fractions, a iodine precipitatable-iodine complex (HC-IP) and a supernatant solution (HC-IS). The HC-IS fraction had a higher glucose content (53.4%), whereas the HC-IP fraction had a high content of xylose residues (35.1%). The HC-IP fraction consisted mainly of xylan, as judged by the degradation with purified xylanase.     

龙胆多糖的结构表征及其体外免疫活性

对龙胆多糖的结构和生物活性进行研究,采用甲基化分析多糖的链接方式。结果表明,龙胆多糖中存在(→1)末端和(1→5)-链接的呋喃阿拉伯糖基、(1→4)-链接的吡喃半乳糖基,同时也存在其他含量比较少的糖基和分支。龙胆多糖中糖醛酸是以(1→4)-链接的半乳糖醛酸方式存在,对龙胆多糖的生物活性起着重要的作用。龙胆多糖可以促进RAW264.7细胞增殖并产生NO,而且NO的产生是通过一氧化氮合成酶mRNA上调实现的,同时龙胆多糖可以上调细胞因子COX-2和TNF-α的mRNA表达水平。     

Stabilization of milk proteins in acidic conditions by pectic polysaccharides extracted from soy flour

Pectic polysaccharides were extracted from soy flour at either room temperature (SPRT) or 121°C (SPH), and their abilities to stabilize milk proteins in acidic conditions were evaluated. Both SPRT and SPH were found to contain proteinaceous components that were difficult to dissociate from polysaccharide components using size exclusion chromatography, whereas the molar mass of the former was approximately twice that of the latter. Due to the higher molar mass, SPRT was expected to provide stronger steric effects to prevent aggregation between milk proteins in acidic conditions than SPH. Alkaline treatment of SPRT for breaking O-linkages between AA and monosaccharide residues decreased its molar mass by approximately 160 kDa, indicating that they contained naturally occurring conjugates of pectic and proteinaceous moieties. Particle size distributions in simulated acidified milk drink samples containing 0.2% SPRT or SPH showed monomodal distributions with median diameters of around 1.2 μm at pH 4. The presence of large protein aggregates (～5 μm) was detected at 0.2% SPRT and pH 3.2, 0.6 to 0.8% SPRT and pH 4, or 0.2% SPH and pH 3.4. The presence of excess polysaccharide molecules unbound to proteins was detected at 0.2% SPRT and pH 3.2 to 3.4, 0.4 to 0.8% SPRT and pH 4, 0.2% SPH and pH 3.4 to 3.6, and 0.4 to 0.8% SPH and pH 4. The present results suggest that molecular characteristics of pectic polysaccharides vary depending on extraction conditions and hence their functional behavior.     

An explorative study on the cell wall polysaccharides in the pulp and peel of dragon fruits (Hylocereus spp.)

The pectic and hemicellulosic cell wall polysaccharides from the pulp and the peel of white-flesh and red-flesh dragon fruits (Hylocereus spp.) were isolated and compared in terms of degree of methoxylation (DM), solubility properties (relative content of uronic acids and neutral sugars in different fractions), neutral sugar composition, molar mass distribution, and affinity toward some specific anti-pectin antibodies. Hereto, the alcohol-insoluble residues were extracted and sequentially fractionated using hot water, a chelating agent, sodium carbonate, and potassium hydroxide solutions to obtain different pectin fractions and a hemicellulose fraction. Chemical analyses were used to characterize these polysaccharide fractions. The results show that cell wall polysaccharides of the pulp and especially of the peel from white-flesh and red-flesh dragon fruits contain significant amounts of pectic substances that are lowly methyl-esterified. The cell wall polysaccharides of the peel as well as those of the pulp contain high amounts (38–47 %) of loosely bound (water-soluble) pectic substances. In the water-soluble fraction (WSF) of the peel samples, uronic acids are the predominant monomers. On the contrary, rhamnogalacturonan-I type neutral sugars, and especially arabinose and galactose, contribute equally, as compared to uronic acid, to the WSF of the pulp samples. Despite the low average DM value of pulp and peel pectin, pectic substances in both samples showed affinity for antibodies with different specificities indicating that a wide range of epitopes, including long blocks of unesterified galacturonic acids (GalA) residues as well as (short) blocks of esterified GalA residues, is present. No large differences between the pectic substances among the different dragon fruit varieties were observed.     

紫薯果胶类多糖的成分分析及稳定性研究

以超声波辅助酶法提取及纯化紫薯果胶类多糖,并对其主要成分及稳定性进行分析.结果表明:所得紫薯果胶类多糖的干燥减量、酸不溶灰分、pH值、总半乳糖醛酸、酯化度、总糖、蛋白质含量分别为4.32％、0.32％、4.22、65.24％、31％、65％、1.02％,符合相关标准.测出所得紫薯果胶类多糖的重均分子量为70745 Da...     

Structural characterization and immunostimulatory activity of a novel protein-bound polysaccharide produced by Hirsutella sinensis Liu,Guo, Yu & Zeng

HS002-II, a novel protein-bound polysaccharide with 44 kDa molecular weight, was fractionated from submerged cultures of Hirsutella sinensis Liu, Guo, Yu & Zeng by DEAE-Sepharose and Sephacryl S200 chromatography. Based on the results of infrared spectroscopy, high performance liquid chromatography, methylation, amino acid analysis, NMR spectroscopy and atomic force microscopy, the polysaccharide moieties of HS002-II mainly contained a long backbone of (1 → 3)-linked α-d-ribofuranosyl units (1 → 4)-linked α-d-xylopyranosyl units and (1 → 4)-linked β-d-glucopyranosyl units, which was substituted at C-6. The two branches were β-d-mannopyranosyl residues and β-d-galactopyranosyl residues terminated with α-l-arabinopyranosyl residues, respectively. HS002-II consisted of 57.9% polysaccharide and 42.1% protein with the existence of N-type carbohydrate–protein linkage. In terms of the pro-inflammatory cytokines assay (NO, TNF-α, IL-1β and NF-κB) using murine macrophages cell line (RAW264.7), HS002-II exhibited significant immunomodulatory activity by stimulating the IκB-NF-κB pathway.     

Polysaccharides from Turbinaria conoides: Structural features and antioxidant capacity

Since reactive oxygen species (ROS) are involved in initiating and promoting several diseases such as cancer and cardiovascular events, this study was designed to evaluate the antioxidant activity of sulphated polysaccharides purified from Turbinaria conoides. A fucoidan (AF3), one alginic acid (B) and a neutral glucan (C1F2) were isolated. The glucan is made up of β-(1 → 3)-linked glucopyranosyl residues and has a molecular mass of 5 kDa. The alginic acid contains equimolar proportions of guluronic and mannuronic acid residues. The fucoidan is highly branched and has an average molecular mass of 50 kDa. The in vitro antioxidant capacity of the fractions was studied by ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays. The fucoidan (AF3) showed the highest potential followed by the alginate (B) and laminaran (C1F2). Taken together, these findings demonstrate that these polysaccharides could be used as natural antioxidants by the food industry.     

Yield and composition of cell wall residues isolated from various feedstuffs used for non-ruminant farm animals

The contents of cell wall residue were measured in 14 common feedstuffs used for non-ruminant farm animals by utilising a technique involving pronase and α-amylase treatments. Comparison with the contents of neutral detergent fibre (NDF) revealed that the NDF procedure underestimated cell wall contents in the dicotyledonous plant materials. The losses of cell wall material due to the neutral detergent solution were correlated (r=0.931, P<0.01) with the amount of pectic substances present in the cell wall residues of the dicotyledonous plant materials. Cell wall residues were analysed for starch, crude protein, polysaccharides, condensed tannins, sulphuric acid lignin, acetyl bromide lignin, and ash. Condensed tannins in the cell wall residues of sorghum, rapeseed meal and field bean resulted in a large protein contamination (11.3–26.6%) of these residues and to an overestimation of their lignin content. Compositions of polysaccharides are discussed from chemical and nutritonal viewpoints.     

Improvement in intestinal function of hamsters as influenced by consumption of polysaccharide-rich sage weed extracts

The purpose of this study was to investigate the effect of the water-soluble polysaccharide-rich sage weed (Salvia plebeia) extracts on intestinal function. The results showed that the extract is rich in water-soluble polysaccharides (60.5/100 g extract), which are mainly composed of pectic polysaccharides and hemicellulose. The inclusion of sage weed extract in the control diet at a level of 0.5/100 g diet resulted in significantly (P < 0.05) improved effects on intestinal and faecal parameters of the hamsters, such as shortened gastrointestinal transit time, reduced caecal ammonia, decreased daily faecal ammonia output, increased short-chain fatty acid concentrations in caecal content, and lowered activities of β-d-glucuronidase, β-d-glucosidase, mucinase, and urease. These findings suggest that an adequate intake of sage weed extracts (0.5/100 g diet) may play a role in the maintenance of intestinal health by reducing the exposure of intestinal mucosa to toxic materials and other harmful compounds.     

Structural characterisation of a water-soluble polysaccharide with high branches from the leaves of Taxus chinensis var. mairei

A large number of polysaccharides present in the leaves of Taxus chinensis var. mairei were successively extracted with hot water after preliminary treatments. The ion-exchange and gel-permeation chromatography was used to isolate and purify the major polysaccharides to afford a complex water-soluble polysaccharide, named T1 with a molecular mass of 3.44 × 10⁶ Da determined by HPGPC. T1 consisted of 2,4-di-O-methyl-mannose, rhamnose, arabinose, xylose, galactose, mannose, galacturonic acid and glucuronic acid in a molar ratio of 2:5:24:9:3:46:1:10, and the acetyl content was estimated to be 2.1%. On the basis of methylation analysis, periodate and chromium trioxide oxidations, Smith degradation, graded acid hydrolysis, and NMR and IR spectroscopy, T1 possessed a 1,3,6-linked β-d-Manp main chain, substituted by mannose, arabinose, galactose, xylose, rhamnose, 2,4-di-O-methyl-mannose, galacturonic acid, and glucuronic acid residues. These contained non-reducing end-units of mannose, arabinose, xylose, 2,4-di-O-methyl-mannose, and glucuronic acid. This is the first report on isolation of an acid heteropolysaccharide from Taxus species.     

Cocoa bean carbohydrates: roasting-induced changes and polymer interactions

Roasting induced change to carbohydrates and cell wall polysaccharides was investigated in three varieties of cocoa beans. The concentrations of glucose and fructose decreased after roasting but levels of the non-reducing sugars, sucrose, raffinose, stachyose and verbascose, were not markedly affected. Approximately 10% of the arabinose content of the polysaccharides was degraded but, overall, the pectic and hemicellulosic polymers remained intact after roasting. The degree of esterification and acetylation of the pectic polysaccharides were unaffected by roasting. Roasting did promote an interaction between polysaccharides, proteins, polyphenolics and Maillard products. This led to the formation of insoluble complexes which co-purified with, and augmented, the levels of cell wall material isolated from roasted compared to unroasted beans. The implications of the results are discussed in relation to the role that “Klason lignin” plays in the formation of these chemical amalgams during roasting.     

Cell Wall Composition of Olives

Cell walls of olives (Olea europaea L.), Hojiblanca and Manzanilla, were isolated and fractionated into polysaccharides, and compositions compared. Pectic and hemicellulosic fractions were purified by ion exchange and gel filtration chromatography, and neutral sugar and uronic acid composition determined. Differences occurred between cultivars and seasons: Manzanilla had higher pectic polysaccharides and lower xylans. Hojiblanca showed similar but lesser differences. Arabinans were the main neutral pectic polysaccharides with arabinose > 80%. Homogalacturonans and rhamnogalacturonans were > 50% of the acidic pectic fractions. Degree of esterification and molecular weights were related to extracting solvent. Xyloglucans and galactoglucomannans were neutral hemicelluloses with molecular weights ? 260 kD. Glucuronoarabinoxylans had higher molecular weights (up to 400 kD). Acidic xylans were important in the pulp.