Elena N. Makarova

Structural studies of the pectic polysaccharide from Siberian fir (Abies sibirica Ledeb.).

The pectic polysaccharide named abienan AS-A was isolated from the wood greenery of Abies sibirica using dilute hydrochloric acid (pH 4.0) at 70°C. The structure of abienan AS-A was elucidated using sugar composition analysis, ion-exchange chromatography and partial acid hydrolysis followed by NMR spectroscopy. The linear region of abienan AS-A was shown to contain linear 1,4-α-D-galactopyranosyluronan partially substituted with methyl esters or 3-O-acetyl groups and rhamnogalacturonan blocks consisting of 1,4-α-D-galacturonan partially substituted with methyl ester groups and connected by 2-O-substituted α-rhamnopyranose residues. The branched region of abienan AS-A was found to be made of RG-I. The side chains of RG-I were shown to contain 1,4-β-galactan and branched arabinan. Some 4-O-substituted β-galactopyranose residues were shown to be attached to the 4-position of the 2-O-substituted α-rhamnopyranose residues of the RG-I backbone. The arabinan groups were made up of a 1,5-linked α-L-arabinofuranan backbone that was 3-O-, 2-O-, and 2,3-di-O-substituted with the terminal and 1,3-linked α-L-arabinofuranose residues.

Structural studies of arabinan-rich pectic polysaccharides from Abies sibirica L. Biological activity of pectins of A. sibirica

Highly branched arabinan-rich pectic polysaccharides, containing 84% of arabinose, was extracted from wood greenery of Abies sibirica L. The structure of arabinan was studied by the 1D and 2D NMR spectroscopy. The macromolecule backbone was represented mainly by RG-I (molar ratio GalA:Rha ∼ 1.3:1) patterns with high degree of rhamnose branching. Side chains were comprised of 1,5-linked α-L-Araf residues (the major part of polymer mass), 1,3,5-di-O- and 1,2,3,5-tri-O-linked α-L-Araf residues, confirming the presence of highly branched 1,5-α-L-arabinan. Although most L-Araf were in α-anomeric form, minor terminal β-L-Araf-(1 →... was detected. 1,4-β-D-linked Galp residues found in the side chains account for minor AG-I or 1,4-galactan, as compared to arabinan. A tentative structure was proposed. Polysaccharides obtained from Siberian fir greenery were screened for biological activity. Galacturonan had a strongest stimulating effect on germination and growth rate of seeds, germs and roots of Triticum aestivum, Avena sativa, and Secale cereale.

Structural characteristics of water-soluble polysaccharides from Heracleum sosnowskyi Manden

Fractions containing arabinogalactan proteins (AGPs) and pectic polysaccharides were isolated from above-ground parts of Heracleum sosnowskyi. Major units of their structure were elucidated using ion-exchange chromatography, gel chromatography, and NMR spectroscopy. The carbohydrate backbone of the polysaccharides consisted of 1,3-β-D-galactopyranosyl residues, whereas side chains of the branched region consisted of the residues of 1,6-β-galactopyranose, 1,5-α-L-arabinofuranose, 1,4-β-D-glucuronic acid, and 1,6-β-D-glucopyranose. The branching points were identified as 1,3,6-β-D-galactopyranose residues. Side chains were terminated with β-D-galactopyranose, α-L-arabinofuranose and α-L-rhamnopyranose. A significant part of the side-chain β-1,6-galactan was substituted at C6 by 4-OMe-β-D-glucuronic acid. A minor part of glucuronic acid was included in the α-Rhap-(1 → 4)-β-GlcA-(→ fragment. All the studied fractions contained 1,4-β-D-galacturonic acid as well.

Extraction and structural characteristics of pectic polysaccharides from Abies sibirica L

Structurally different pectins were isolated from the wood greenery of Abies sibirica L. by the sequential extraction with water (ASW), HCl solution (pH∼4) (ASA), and NH3 solution (pH∼8.5) (ASN). The GalA/Rha molar ratios for the ASW (15), ASA (8.9), and ASN (3.9) polysaccharides diminish in the order ASW>ASA>ASN, indicating a decrease in homogalacturonans and increase in rhamnogalacturonan I in this series. The ASWH, ASAH, and ASNH homogalacturonans derived by acid hydrolysis of ASW, ASA, and ASN have similar Mw 23.8, 21.1, and 18.9kDa, respectively, corresponding to a mean polymerization degree of 97-122 for the GalA residue. The macromolecule backbone of ASN was represented mainly by moieties of partially methylesterified homogalacturonan and partially 2-O- and/or 3-O-acetylated rhamnogalacturonan I. The carbohydrate side chains of the branched region are primarily made up of terminal, 1,5-O-, 1,3,5-di-O- and 1,2,3,5-tri-O-substituted α-L-Araf residues and terminal, 1,3-O- and 1,3,6-di-O-substituted β-D-Galp residues. The currently known pectin models were refined.

Structural characteristics of pectic polysaccharides and arabinogalactan proteins from Heracleum sosnowskyi Manden

Polymers with different structures were isolated from the aboveground part of Heracleum sosnowskyi Manden. The sequential treatment of Heracleum with water, HCl solution, and (NH4)2C2O4 solution was observed to decrease the arabinogalactan proteins (AGP) content and increase the pectins content in the extracted polysaccharides. The linear region of the HSO-I polysaccharide having the highest yield was found to be composed mainly of partially methylesterified homogalacturonan fragments, whereas the branched region was made up of fragments of rhamnogalacturonan I whose core represents 1,2-α-L-rhamno-1,4-α-D-galacturonan. The carbohydrate side chains of the branched region are linked to the α-L-Rhap core residues via the 1,4-glycosidic bond and consist chiefly of T-β-D-Galp, 1,4-β-D-Galp and 1,6-β-D-Galp residues indicating the presence of the 1,4-β-D-galactan. NMR spectroscopy revealed the carbohydrate moiety of the AGP molecule to consist mainly of 1,3- and 1,3,6-β-D-Galp residues. The side chains comprised 1,6-β-D-Galp, terminal 4-O-Me-β-D-GlcpA, and β-D-Galp.

Deprivation of food during pregnancy and reproduction in the water vole (Arvicola terrestris)

The effect of food deprivation (for 16 h on day 15 and day 18 of gestation) on reproduction in water voles ( Arvicola terrestris ) and their offspring was examined. In food-deprived mothers, fecundity was diminished and sex ratio of young was skewed toward males. Maternal food deprivation in late pregnancy had no effect on the reproductive performance of young males, but it increased reproductive potency of young females. A prolonged positive effect of food restriction on reproduction of female offspring may be important in restoring the size of the population in the next generation.

Regulation of Food Consumption during Pregnancy and Lactation in Mice

The aim of the present work was to assess the expression of agouti-like protein and neuropeptide Y in pregnant and lactating mice and to compare this with the leptin level and food consumption. Food consumption, blood leptin levels, and agouti-like protein and neuropeptide Y mRNA levels in the hypothalamus of C57Bl/6J mice were assessed on days 7, 13, and 18 of pregnancy and on days 10 and 21 of lactation, and in virgin females of the same ages. During pregnancy, food consumption and leptin levels decreased on day 7 and increased in day 18 of pregnancy, while neuropeptide Y mRNA levels increased on day 13 and then remained unaltered, and the agouti-like protein level increased on day 18. After parturition, food consumption continued to increase, while leptin levels and neuropeptide Y mRNA levels decreased to normal. Thus, hyperphagia in pregnancy was due to sequential activation of the expression of neuropeptide Y and agouti-like protein, while in lactation hyperphagia resulted from mechanisms not associated with changes in the expression of these neuropeptides.

Pregnancy and lactation have anti-obesity and anti-diabetic effects in Ay/a mice

Aim:  Dominant ‘yellow’ mutation at the mouse agouti locus (Ay) results in obesity. Pregnancy and lactation are characterized by large energy demand. The aim of this study was to investigate whether obesity would develop in pregnant and suckling Ay mice.

Structural characteristics of oxalate-soluble polysaccharides of Sosnowsky's hogweed (Heracleum sosnowskyi Manden)

Arabinogalactan proteins (AGP) and pectic polysaccharides were isolated from above-ground parts of Heracleum sosnowskyi. The structural study has shown that a linear region of the pectic macromolecules consists of 1,4-α-d-galactopyranosyluronan blocks partially methyl esterified and acetylated. The branched region consists of 3-O- and partially 2-O-acetylated rhamnogalacturonan I. Side chains of the RG-I backbone include the regions of arabinogalactan I and branched 1,5-α-l-arabinan. The carbohydrate part of AGP consists of arabinogalactan II with a 1,3-β-d-Galp main chain. The side chains of the branched area of AG-II are composed of 1,6-β-d-Galp, 1,5-, 1,3,5-α-l-Araf, 4-O-Me-β-d-GlcA and 1,4-β-d-GlcpA, and non-reducing ends residues of β-d-Galp, α-l-Araf, α-l-Rhap and α-l-Fucp. The branch points of the main and side chains are formed by 3,6-di-O-substituted β-d-Galp. It was found that at least a portion of pectin is probably covalently linked to AGP, wherein AGP is linked to RG-I, but not with galacturonan.

Structural and chemical charactertistics of pectins, arabinogalactans, and arabinogalactan proteins from conifers

In this review, we summarized the research data on the contents and chemical structures of pectic polysaccharides, arabinogalactans, and arabinogalactan proteins from coniferous species. The presently known structures of these polymers are given. Special attention is given to the description of chemical structural features of pectic polysaccharides from the Abies sibirica and Picea abies tree verdures (branches and needles). Three models presently suggested for the description of pectin macromolecular structures are discussed.