Structures of pectic polysaccharides isolated from the Siberian apricot (Armeniaca siberica Lam.)

Structural characterization of arabinogalactan-II and pectin from Urtica cannabina

Comparative analysis of extracellular and cell wall glycans from Urtica cannabina leaves was performed using chemical methods, GC, GC-MS, 1D, and 2D NMR spectroscopy. The structures of extracellular AG-II and cell wall AG-II are similar. The units are typical for AG-IIs: β-GlcpA-4-OMe-(1→, Rhap-(1 → 4)-β-GlcpA-(1→, attached to β-Galp at O-6, as well as arabinan chains attached to β-Galp at O-3. A single Araf and a trisaccharide formed by 2,5-Araf and two terminal Araf form short arabinan side chains in AG-II. 1,5-arabinan with a backbone substituted by a single Araf at O-3 was identified only in the side chains of cell wall AG-II. The side chains can be attached to O-3 and O-6 of the same β-Galp to form a bifurcated AG side chain. The backbone of AG-II is formed by 1,6- rather than 1,3-linked Galp, although it does include some 1,3-Galp. The high content of 3,6-Galp shows the highly branched nature of the AG carbohydrate chains. From the cell wall, AGP was extracted together with pectin, the simultaneous elution of which from both DEAE-cellulose and Sepharose may indicate a link between them.

Pectic polysaccharides of the fresh plum Prunus domestica L. isolated with a simulated gastric fluid and their anti-inflammatory and antioxidant activities

A pectic polysaccharide, designated as PD, was extracted from fresh plums (Prunus domestica L.) with a simulated gastric fluid. Galacturonan, which was partially substituted with methyl and O-acetyl ester groups, and rhamnogalacturonan were the main constituents of the linear regions of the sugar chains of PD. The ramified region contained mainly 1,4-linked β-d-galactopyranose residues and, to a lesser extent, 1,5-linked α-l-arabinofuranose residues. The separation of PD, by DEAE-cellulose column chromatography, yielded two pectic fractions: PD-1 and PD-2, eluted with 0.1 and 0.2 M NaCl, respectively. Enzymatic digestion of PD with 1,4-α-d-polygalacturonase yielded the fraction PD-E. The parent pectin PD and the PD-1 fraction were found to diminish the adhesion of peritoneal leukocytes at the concentrations of 0.05-1.0mg/ml. However, the PD-E fraction failed to have an effect on cell adhesion at the concentrations of 0.05-0.1mg/ml. PD, PD-1 and PD-E were found to inhibit the production of superoxide anion radicals by reducing xanthine oxidase activity by 38%, 97% and 47%, respectively. Therefore, the PD-1 fraction appeared to be an active fragment of pectic macromolecule isolated from fresh plum with a simulated gastric fluid.

The Study of the Reaction of Pectin-Ag(0) Nanocomposites Formation

Pectin polysaccharides (PSs) were isolated from a bark of Larix sibirica Ledeb. Structure of PS fragments determined by chemical transformations, chromatography, and spectroscopic analyses was found to be a linear galacturonane comprising 1,4-linked α-D-GalpA residues and a rhamnogalacturonan I (RG-I). The fifth part of galacturonane residues was methyl esterified at at C-2 and/or C-3 and C-6 atoms. Some of RG-I side chains were identified as arabinogalactan subunits with highly branched structure consisting of linear backbone with3,6)-β-D-Galp-(1residues, substituted at C-6 by neutral side chains. This side chains contained2,5)-α-L-Araf-(1and3,5)-α-L-Araf-(1residues and terminal arabinose in the pyranose and furanose form. It was found that “pectin-Ag(0)” nanobiocomposites were formed via the interaction between PS aqueous solutions and silver nitrate, with PS playing both reducing and stabilizing functions. It was shown that the content of Ag(0) particles in “pectin-Ag(0)” depended on the reaction conditions and can range from 0.1 to 72 %, the size of Ag(0) particles being 3–27 nm. Using 13C NMR technique, it was revealed that PS underwent destructive changes and they they were more considerable, more than the lot of Ag(I) that was inputed into the reactionary medium.

Poly[3-(3,4-dihydroxyphenyl)glyceric Acid] from Anchusa italica Roots

Elucidation of the main structural unit of a water-soluble, high-molecular weight preparation from the crude polysaccharides of Anchusa italica Retz. roots has been carried out. According to 13C NMR, 1H NMR and 2D heteronuclear 1H/13C HSQC spectral data, the main structural element of the high-molecular, water-soluble preparation was a regularly substituted polyoxyethylene chain, namely poly[oxy-1-carboxy-2-(3,4-dihydroxyphenyl)ethylene]. Most carboxylic groups of this caffeic acid-derived polymer of A. italica are methylated.

Structural features of pectic polysaccharides from the skin of Opuntia ficus-indica prickly pear fruits

After removal of the mucilage with water at room temperature, pectic polysaccharides were solubilized from Opuntia ficus-indica fruit skin, by sequential extraction with water at 60 degrees C (WSP) and EDTA solution at 60 degrees C (CSP). Polysaccharides with neutral sugar content of 0.48 and 0.36 mol/mol galacturonic acid residue were obtained, respectively, in the WSP and CSP extracts. These pectic polysaccharides were de-esterified and fractionated by anion-exchange chromatography, yielding for each extract five fractions, which were thereafter purified by size-exclusion chromatography. Two of these purified fractions were characterized by sugar analysis combined with methylation and reduction-methylation analysis. The study was then supported by (1)H and (13)C NMR spectroscopy. The results showed that the water-soluble fraction WSP3 and the EDTA soluble fraction CSP3, consisted of a disaccharide repeating unit -->2)-alpha-l-Rhap-(1-->4)-alpha-d-GalpA-(1--> backbone, with side chains attached to O-4 of the rhamnosyl residues. The side chains contained highly branched alpha-(1-->5)-linked arabinan and short linear beta-(1-->4)-linked galactan.

Structural studies of the pectic polysaccharide from duckweed Lemna minor L

The pectic polysaccharide of duckweed Lemna minor L. termed lemnan (LM) was shown to contain the ramified, "hairy" region. Using partial acid hydrolysis and Smith degradation followed by NMR spectroscopy of the fragments obtained, some structural features of the hairy region of LM were elucidated. Partial acid hydrolysis of LM afforded the crude polysaccharide fraction LMH that was separated into two polysaccharide fractions: LMH-1 and LMH-2. In addition, the oligosaccharide fraction LMH-3 contained 97% D-apiose was obtained from the supernatant. A further more rigorous acidic hydrolysis of LMH led to the crude polysaccharide fraction LMHR which was separated in to two fractions: LMHR-1 and LMHR-2. Smith degradation of LMH afforded the polysaccharide fragment LMHS differed in low contents of apiose residues. Unfortunately, NMR-spectroscopy failed to provide significant evidence concerning the structure of LMH-1 due to the complexity of the macromolecule. The structure of the 1H/13C-NMR spectroscopy including the correlation 2D NMR spectroscopy. As a result, alpha-1,4-D-galactopyranosyluronan was confirmed to be the main constituent of the LM backbone. In addition, the ramified, "hairy" region of the macromolecule appeared to contain segments consisting of residues of terminal and beta-1,5-linked apiofuranose, terminal and alpha-1,5-linked arabinofuranose, terminal and beta-1,3- and beta-1,4- linked galactopyranose, the terminal and beta-1,4-linked xylopyranose, and beta-1,4-linked 2-mono-O-methyl xylopyranose. Analytical and NMR-spectral data of LMHS confirmed the presence of considerable amounts of the non-oxidized of 1,4-linked D-galactopyranosyl uronic acid residues. Thus, some side chains of the ramified region of lemnan appeared to attach to D-galactopyranosyl uronic acid residues of the backbone.