A STUDY OF THE PECTIN PRESENT IN THE BARK OF AMABILIS FIR (ABIES AMABILIS)

1965 ◽  
Vol 43 (4) ◽  
pp. 758-765 ◽  
Author(s):  
S. S. Bhattacharjee ◽  
T. E. Timell
Keyword(s):  
Galacturonic Acid ◽  
Structural Formula ◽  
Partial Hydrolysis ◽  
Side Chains ◽  
Pectic Acid ◽  
Abies Amabilis ◽  
Conventional Fractionation ◽  
Glycosidic Bonds ◽  
First Time ◽  
Pectic Material

A pectic material has been isolated from the bark of Abies amabilis (Dougl.) Forbes in a yield of 2%. On hydrolysis it yielded D-galacturonic acid, D-galactose, and L-arabinose in a ratio of 85:4:11, and also traces of rhamnose. The product, when submitted to several conventional fractionation methods, appeared homogeneous. Further resolution could be effected by acidification of an aqueous solution of the pectin, followed by ultracentrifugation. The insoluble portion (50%) was an electrophoretically homogeneous galacturonan with [α]D + 246°. The material remaining in solution (30%), here referred to as a pectic acid, had [α]D + 225° and on hydrolysis gave D-galacturonic acid, D-galactose, and L-arbabinose in a ratio of 74:7:19, as well as traces of rhamnose.The structure of the galacturonan was established by partial hydrolysis and methylation. It consisted of α-D-galacturonic acid residues linked together by (1 → 4)-glycosidic bonds to a linear macromolecule. The same techniques were applied to the pectic acid. While a unique structural formula could not be assigned in this case, one probable alternative involved a framework of (1 → 4)-linked α-D-galacturonic acid residues together with a few residues of 1,2,4-linked L-rhamnose. Some of the galacturonic acid units carried at C-2 and C-3 side chains which were terminated by D-galactopyranose and L-arabinofuranose residues. A few of the latter also occurred as inner units, probably in the side chains. This appears to be the first time a pectic material has been resolved into a galacturonan and a pectic acid containing the four sugar residues usually found in pectins. It is probable that the pectin occurring to a limited extent in wood has a similar composition.

scholarly journals Nouvelles acquisitions structurales sur les substances pectiques de la pulpe de raisin

OENO One ◽  
1988 ◽  
Vol 22 (2) ◽  
pp. 135
Author(s):  
Luc Saulnier ◽  
Jean-Marc Brillouet ◽  
Michel Moutounet
Keyword(s):  
Galacturonic Acid ◽  
Structural Data ◽  
Exchange Chromatography ◽  
Insoluble Residue ◽  
Side Chains ◽  
Neutral Sugar ◽  
Pectic Polysaccharides ◽  
Grape Berries ◽  
Neutral Sugars ◽  
Pectic Material

<p style="text-align: justify;">Après une mise au point rapide sur les connaissances actuelles des polyosides pectiquesdans les végétaux, les résultats acquis sur la structure des substances pectiques de la pulpe deraisin sont exposés, avec un rappel de la méthodologie utilisée.</p><p style="text-align: justify;">Un matériel insoluble à l'alcool (MIA) a été préparé à partir de pulpe de raisin. Quatre fractionspectiques en ont été isolées après traitements successifs par l'eau (25°C; PSE), l'oxalate(25°C; PSOX, l'acide (HCI 0.05M, 80°C; PSH) et la soude (O,05M, 4°C; PSOH).</p><p style="text-align: justify;">Les PSE (35 p.100) et PSH (55 p. 100) représentent l'essentiel du matériel pectique extrait.Les PSE sont séparées par chromatographie d'échange d'ions en fractions neutre (PSEn~ 13 p. 100) et acide (PSEa ~ 87 p. 100). Les PSEa et les PSH sont constituées principalementd'acide galacturonique (PSEa 63 p. 100, PSH 53 p. 100), fortement estérifié par du méthanol(degré d'estérification : PSEa 77 p. 100, PSH 68 p. 100), tandis que des quantités faibles d'acideglucuronique sont détectées dans les PSEn (2 p. 100). Les oses neutres (PSEn 65 p. 100, PSEa28 p. 100, PSH 19 p. 100) sont principalement de l'arabinose et du galactose suivis dans unordre décroissant du rhamnose, glucose, xylose, mannose et fucose. Des protéines sont égaIementdétectées en association avec les polyosides.</p><p style="text-align: justify;">L'action d'une endopolygalacturonase et d'une endopectine-Iyase sur PSEa et PSH met enévidence des zones «lisses» homogalacturoniques dégradées par les enzymes et des zones«hérissées» rhamnogalacturoniques riches en chaînes latérales d'oses neutres, insensibles àl'attaque enzymatique. Le traitement du MIA par une endopectine-Iyase solubilise un matérielpectique (ZH-MIA) riche en oses neutres (56 p. 100) particulièrement en arabinose, et contenantde l'acide galacturonique (23 p. 100) et des protéines (11 p. 100).</p><p style="text-align: justify;">La perméthylation associée à l'hydrolyse spécifique de l'arabinose par une α-L-arabinofuranosidaseet à la RMN du <sup>13</sup>C a permis d'établir la structure des chaînes latérales. Des (1 → 3) / (1 → 6) arabinogalactanes, où l'arabinose est essentiellement sous forme terminale non réductrice, dominent dans les ZH-PSE, tout comme dans les PSEn confirmant leur caractère d'arabinogalactane-protéine. En revanche ces structures ainsi que les (1 → 4) arabinogalactanes sont minoritaires dans les ZH-PSH et ZH-MIA où les structures de type (1 → 5) arabinanes et rhamnogalacturonanes sont prédominants.</p><p style="text-align: justify;">+++</p><p style="text-align: justify;">After a brief review of available knowledges on plant pectic polysaccharides, structural data on pectic substances from the pulp or grape berries and related analytical techniques are reported.</p><p style="text-align: justify;">An alcohol insoluble residue (MIA) was prepared from pulp of grape berries, which was sequentially extracted with water (25°C), oxalate (25°C), acid (0,05N HCI, 80°C) and sodium  hydroxide (0,05N 4°C) yielding four pectic fractions, respectively, PSE, PSOX, PSH and PSOH. PSE (35 p. 100) and PSH (55 p. 100) represented the main part of extracted pectic material.</p><p style="text-align: justify;">PSE were fractionated by ion-exchange chromatography into neutral (PSEn ~ 13 p. 100) and acidic (PSEa ~ 87 p. 100) fractions. PSEa and PSH were constituted mainly of galacturonic acid (PSEa 63 p. 100, PSH 53 p. 100) highly methylesterified (esterification degree : PSEa 77 p. 100; PSH 68 p. 100), whereas PSEn contained minute amounts of glucuronic acid (2 p. 100). Neutral sugars (PSEn 65 p. 100, PSEa 28 p. 100, PSH 19 p. 100) were mainly arabinose and galactose followed by decreasing amounts of rhamnose, xylose, glucose, mannose and fucose. Proteins were also detected along with the polysaccharides.</p><p style="text-align: justify;">Degradation of PSEa and PSH by endopolygalacturonase and endopectin-lyase evidenced «smooth» homogalacturonic areas sensitive to enzymatic degradation and «hairy» rhamnogalacturonic zones highly substituted by neutral sugar side-chains and resistant to enzyme action. Treatment of MIA With endopectinlyase released pectic material (ZH-MIA) rich in neutral sugars (56 p. 100), especially arabinose, and containing galacturonic acid (23 p. 100) and proteins (11 P. 100).</p><p style="text-align: justify;">Structure of neutral sugar side-chains was investigated using methylation analysis associated with specific hydrolysis of arabinose residues with an α-L-arabinofuranosidase, and <sup>13</sup>C NMR spectroscopy. ZH-PSE exhibited a structure of 3,6 -linked arabinogalactan substitued by monomeric terminal arabinose. Similar structures were detected in PSEn which relates them to arabino-3,6-galactan-proteins. Conversely PSH or ZH-MIA showed mainly arabinan-like and rhamnogalacturonan structures associated with minor proportions of 3,6- and 4-linked arabino-galactans.</p>

Extracellular polysaccharides from suspension-cultured sycamore cells

1969 ◽  
Vol 47 (11) ◽  
pp. 1063-1070 ◽  
Author(s):  
G. O. Aspinall ◽  
J. A. Molloy ◽  
J. W. T. Craig
Keyword(s):  
Galacturonic Acid ◽  
Culture Medium ◽  
Extracellular Polysaccharides ◽  
Partial Hydrolysis ◽  
Side Chains ◽  
Acer Pseudoplatanus ◽  
Enzymic Hydrolysis ◽  
Glucan Chain ◽  
Coniferous Woods

Three polysaccharides have been isolated from the culture medium of suspension-cultured sycamore cells (Acer pseudoplatanus L.). A pectinic acid which contains 67% of galacturonic acid residues has been shown to have features in common with other pectins, with arabinose, galactose, and rhamnose as constituent sugars. Methylation and partial hydrolysis have indicated that the arabinogalactan is similar to those from coniferous woods in containing a highly branched framework of D-galactopyranose residues mutually joined by (1 → 3) and (1 → 6) linkages with the majority of side chains terminated by L-arabinofuranose residues. A fucoxyloglucan has been shown by methylation and enzymic hydrolysis to possess a structure similar to those of the so-called seed 'amyloids' with a cellulose-like (1 → 4)-linked β-D-glucan chain with side chains terminated by L-fucopyranose and D-xylopyranose residues.

Polysaccharides of tropical pasture herbage. IV. A pectic acid from Townsville lucerne (Stylosanthes humilis)

1971 ◽  
Vol 24 (5) ◽  
pp. 1049 ◽  
Author(s):  
M Alam ◽  
GN Richards
Keyword(s):  
Phosphate Buffer ◽  
Galacturonic Acid ◽  
Sodium Acetate ◽  
Structural Characteristics ◽  
Small Extent ◽  
Partial Hydrolysis ◽  
Tropical Pasture ◽  
Pectic Acid ◽  
Stylosanthes Humilis

Pectic acid, extracted from the stems of Townsville lucerne in 4% yield, has been fractionated by precipitation with sodium acetate. The product contains two components as revealed by electrophoresis in phosphate buffer, but the major structural characteristics have been determined by partial hydrolysis. The pectic acid is esterified to a very small extent (1% OCH3) and consists predominantly of 1,4-a-linked D-galacturonic acid units with L-arabofuranose units as the major neutral constituent.

The Total Synthesis of Rhabdastrellic Acid A

2018 ◽  
Author(s):  
Yaroslav Boyko ◽  
Christopher Huck ◽  
David Sarlah
Keyword(s):  
Total Synthesis ◽  
Late Stage ◽  
Cross Coupling ◽  
Side Chains ◽  
General Strategy ◽  
Modular Approach ◽  
Linear Sequence ◽  
Generating Sequence ◽  
First Time

<div>The first total synthesis of rhabdastrellic acid A, a highly cytotoxic isomalabaricane triterpenoid, has been accomplished in a linear sequence of 14 steps from commercial geranylacetone. The prominently strained <i>trans-syn-trans</i>-perhydrobenz[<i>e</i>]indene core characteristic of the isomalabaricanes is efficiently accessed in a selective manner for the first time through a rapid, complexity-generating sequence incorporating a reductive radical polyene cyclization, an unprecedented oxidative Rautenstrauch cycloisomerization, and umpolung 𝛼-substitution of a <i>p</i>-toluenesulfonylhydrazone with in situ reductive transposition. A late-stage cross-coupling in concert with a modular approach to polyunsaturated side chains renders this a general strategy for the synthesis of numerous family members of these synthetically challenging and hitherto inaccessible marine triterpenoids.</div>

Glucan isolated from leaves of Althaea officinalis L.

1983 ◽  
Vol 48 (7) ◽  
pp. 2082-2087 ◽  
Author(s):  
Alžbeta Kardošová ◽  
Jozef Rosík ◽  
Rudolf Toman ◽  
Peter Capek
Keyword(s):  
Medicinal Plant ◽  
Periodate Oxidation ◽  
Linear Structure ◽  
Water Soluble ◽  
Partial Hydrolysis ◽  
Methylation Analysis ◽  
Glycosidic Bonds ◽  
Nmr Data ◽  
Althaea Officinalis ◽  
C Nmr

A water-soluble low-molecular D-glucan was isolated from leaves of the medicinal plant marsh-mallow (Althaea officinalis L.). The results of methylation analysis, partial hydrolysis, periodate oxidation, and 13C NMR data indicated a virtually linear structure with α-(1→6) glycosidic bonds.

Halides and oxide halides of molybdenum and tungsten. III. Oxo-bridged species of tungsten(IV) and molybdenum(V)

1968 ◽  
Vol 21 (4) ◽  
pp. 883 ◽  
Author(s):  
R Colton ◽  
GG Rose
Keyword(s):  
Partial Hydrolysis ◽  
First Time ◽  
Hydrolysis Of ◽  
And Tungsten

The compound formulated in the literature as K2W(OH)Cl5 has been shown to be the oxo-bridged dimer K4[WT2Ocl10], and the diamagnetic dimer formed by the partial hydrolysis of the MOOCl2- ion has been isolated for the first time and shown to be the oxo-bridged [Mo2O3Cl8]4- ion.

STRUCTURE OF A GALACTURONAN FROM SUNFLOWER PECTIC ACID

1966 ◽  
Vol 44 (11) ◽  
pp. 1275-1282 ◽  
Author(s):  
V. Zitko ◽  
C. T. Bishop
Keyword(s):  
Galacturonic Acid ◽  
Periodate Oxidation ◽  
Degree Of Polymerization ◽  
Critical Assessment ◽  
Molar Ratio ◽  
Aqueous Methanol ◽  
Pectic Acid ◽  
Potassium Borohydride ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Fractions of sunflower pectic acid containing 89.8%, 94.2%, and 91.4% of D-galacturonic acid were carboxyl reduced as their methyl or ethylene glycol esters by potassium borohydride. Critical assessment of the effects of three different solvents (water, 80% aqueous dimethyl sulfoxide, and 80% aqueous methanol) on the efficiency of reduction showed that the latter solvent was best. The reductions caused a decrease in the degree of polymerization from 270 to 21. Measurement of the rates of hydrolysis of partially reduced pectic acids containing 90%, 41.6%, 19.9%, 11.0%, and 0.65% of D-galacturonic acid showed that the rate of hydrolysis was directly related to the proportion of galacturonosidic linkages present. Methylation and hydrolysis of the carboxyl-reduced pectic acid fractions yielded 2,3,4,6-tetra-O-methyl-D-galactose and 2,3,6-tri-O-methyl-D-galactose in an approximate molar ratio of 1:20. Results of the periodate oxidation of the carboxyl-reduced pectic acid supported the conclusion inferred from the methylation results that the pectic acid was a linear polymer of 1 → 4 linked α-D-galacturonic acid units.

Incorporation of alkylthio side chains on benzothiadiazole-based non-fullerene acceptors enables high-performance organic solar cells with over 16% efficiency

2020 ◽  
Vol 8 (44) ◽  
pp. 23239-23247
Author(s):  
Andy Man Hong Cheung ◽  
Han Yu ◽  
Siwei Luo ◽  
Zhen Wang ◽  
Zhenyu Qi ◽  
...  
Keyword(s):  
Solar Cells ◽  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Organic Solar Cells ◽  
High Performance ◽  
Power Conversion ◽  
Side Chains ◽  
First Time

This is the first time alkylthio chains are employed on Y6-like NFAs to achieve organic solar cells of power conversion efficiency higher than 16%.

ISOLATION AND PROPERTIES OF A GLUCOMANNAN FROM THE WOOD OF RED MAPLE (ACER RUBRUM L.)

1960 ◽  
Vol 38 (9) ◽  
pp. 1511-1517 ◽  
Author(s):  
A. Jabbar Mian ◽  
T. E. Timell
Keyword(s):  
Acer Rubrum ◽  
Partial Hydrolysis ◽  
Red Maple ◽  
Glycosidic Bonds ◽  
Linear Molecules ◽  
Hydrolysis Of

A glucomannan has been isolated from the wood of red maple (Acer rubrum L.) in a yield corresponding to 92% of the mannose residues in this wood and with a ratio of mannose to glucose of 2:1. Partial hydrolysis of the polysaccharide yielded 4-O-β-D-mannopyranosyl-D-mannose, 4-O-β-D-mannopyranosyl-D-glucose, 4-O-β-D-glucopyranosyl-D-mannose, 4-O-β-D-glucopyranosyl-D-glucose, and O-β-D-mannopyranosyl-(l → 4)-O-β-D-mannopyranosyl-(1 → 4)-D-mannose. The methylated glucomannan on hydrolysis gave a mixture of di-O-methylhexoses, 2,3,6-tri-O-methyl-D-mannose, 2,3,6-tri-O-methyl-D-glucose, and 2,3,4,6-tetra-O-methyl-D-glucose in a mole ratio of 7:29:13:1. The methylated polysaccharide contained 55 hexose residues per average molecule, while the corresponding value for the nitrate derivative was 67. It is concluded that the glucomannan is composed of a minimum of 70 glucose and mannose residues linked together by (1 → 4)-β-glycosidic bonds to linear molecules. The glucose residues are probably interposed between two or three contiguous mannose residues.

Purification, characterization and mode of effect of another endo-D-galacturonanase from Aspergillus niger

1981 ◽  
Vol 46 (12) ◽  
pp. 3145-3156 ◽  
Author(s):  
Kvetoslava Heinrichová ◽  
Mária Dzúrová
Keyword(s):  
Molecular Weight ◽  
Aspergillus Niger ◽  
Degradation Products ◽  
Maximal Activity ◽  
Kinetic Constants ◽  
Pectic Acid ◽  
Commercial Preparation ◽  
Glycosidic Bonds ◽  
Pectolytic Enzymes ◽  
Approximate Molecular Weight

A mixture of pectolytic enzymes was isolated from a commercial preparation of Pectinex Ultra. endo-D-Galacturonanase (EC 3.2.1.15) was obtained from this mixture of enzymes, produced by Aspergillus niger cultures, by affinity chromatography using cross-linked pectic acid as a support and by subsequent chromatography on a Sephadex G-100 column. One form of endo-D-galacturonanase only of approximate molecular weight of 35 000 was detected in the purified product by electrophoresis in polyacrylamide gel. The enzyme showed maximal activity and stability at pH 4.9 and 40°. The mode of degradation of a high molecular weight substrate and the per cent of the glycosidic bonds cleaved (6%) at a viscosity decrease by 50% indicate an endo type action pattern. endo-D-Galacturonanase was characterized by the mode of cleavage and the kinetic constants Km and V for oligogalacturonic acids and polygalacturonic acid. On the basis of the knowledge of the kinetic constants and the degradation products the mode of action of the enzyme and the extent of its active site are discussed.

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