Spectroscopic determination of the degree of esterification of pectic substances from kenaf

Pectins were isolated from bark, wood and pith of four kenaf (Hibiscus cannabinus L.) varieties. The degree of esterification of isolated pectins was studied using Fourier transform infrared spectroscopy. It was determined as being between 57 and 90% and there were no notable differences between kenaf varieties. The higher value of the degree of esterification was presented in wood pectins (86-90%), the interim in pith (75-83%) and the lower in bark (57-64%).     

Isolation, chemical composition, and structural features of polysaccharides fromLupinus species

Polysaccharides ofLupinus angustifolius (Bryansk 123 and Krystall varieties) andLupinus luteus (SG-91 variety) are extracted and hydrolyzed. Their chemical composition and structural features are studied. Optimal conditions for extraction, hydrolysis, and purification of the lupine polysaccharides are found. Structural features of the isolated pectins are determined based on¹³C NMR and IR spectroscopy.Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 32–34, January–February, 2000.     

A study of the pectins of wild apples

Pectins have been isolated from five species of wild apples and have been characterized. They contain galacturonic acid, galactose, glucose, and arabinose residues. The titrimetric indices of the substances isolated have been determined. It has been shown by IR spectroscopy the pectins isolated are extracted partially in the form of pectic acids.     

Isolation of Pectins from Flax Pedicels and Fibers and Their Characterization

Isolation of pectins form flax pedicels and fibers was studied. Isolated pectins and flax fibers treated by various chemical procedures were studied by IR spectroscopy. The morphology of fascicles of flax fibers was studied by electron microscopy as influenced by chemical treatment.     

A study of the pectins of wild apples

Pectins have been isolated from five species of wild apples and have been characterized. They contain galacturonic acid, galactose, glucose, and arabinose residues. The titrimetric indices of the substances isolated have been determined. It has been shown by IR spectroscopy the pectins isolated are extracted partially in the form of pectic acids.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbekistan Republic, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 355–357, May–June, 1993.     

Structural characterization of native high-methoxylated pectin using nuclear magnetic resonance spectroscopy and ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Comparative use of 2,5-dihydroxybenzoic acid and nor-harmane as UV-MALDI matrices

The successful analysis by ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (UV-MALDI-TOF MS) of native and hydrolyzed high-methoxylated pectin samples is described. In order to find the optimal conditions for UV-MALDI-TOF MS analysis several experimental variables were studied such as: different UV-MALDI matrices (nor-harmane, 2,5-dihydroxybenzoic acid), sample preparation methods (mixture, sandwich), inorganic salt addition (doping salts, NaCl, KCl, NH(4)Cl), ion mode (positive, negative), linear and reflectron mode, etc. nor-Harmane has never been used as a UV-MALDI matrix for the analysis of pectins but its use avoids pre-treatment of the sample, such as an enzymatic digestion or an acid hydrolysis, and there is no need to add salts, making the analysis easier and faster. This study suggested an alternative way of analyzing native high-methoxylated pectins, with UV-MALDI-TOF MS, by using nor-harmane as the matrix in negative ion mode. The analysis by (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy of the native and hydrolyzed pectin is also briefly described.     

Compositional heterogeneity in pectic polysaccharides: NMR studies and statistical analysis

Pectins are a class of heterogeneous polysaccharides used in the food industry as a result of their ability to form gels. They are primarily composed of a (1ŕ4)-α-D-galactopyranosyluronic acid backbone where the carboxylic acid group is methyl esterified at a level which depends on the source of the pectin and processing conditions used to isolate the material. Of considerable interest is the distribution of the free acid and methyl ester groups along this polymer chain. NMR spectroscopy, coupled with statistical analysis, is a powerful technique for the study of sequence distribution of monomers. Experimental conditions (temperature, pD) are reported which are appropriate for the analysis of pectic polysaccharides. Results are presented from a study of sequence distribution in native, modified, and fractionated pectins using ¹H and ¹³C solution NMR methods. The triad sequence information was examined using Bernoullian and Markovian probability models in conjunction with continuous Gaussian distribution and discrete models. Intermolecular heterogeneity in pectins results in triad frequencies which reflect the distribution of acid and ester monomers for native and base saponified pectins. Fractionation of pectin through physicochemical methods and subsequent spectroscopic analysis provide insight into this heterogeneity. Segregation into discrete polymer populations shows a structural diversity best approximated by a 3-component statistical model.     

Enzymatically Extracted Apple Pectin Possesses Antioxidant and Antitumor Activity

The biological activity of apple pectin extracted conventionally or enzymatically using endo-xylanase and endo-cellulase, was tested in vitro. The analyses were performerd in tetraplicates and the statistical significance of the differences were assessed using ANOVA, Tukey post hoc and LSD (the least significant difference) tests. Multivariate regression analysis was applied to determine the structural components that have a crucial importance for antioxidant and antitumor properties of pectins. The pectins extracted by enzymes contained up to four times more ferulic acid and showed twice as great ability to neutralize free radicals and Fe(III) reduction. The antiradical potential positively correlated with phenols, fucose and rhamnose content. In the assays performed on HT-29 human adenocarcinoma and B16F10 melanoma cell cultures, the “green” pectins, contrary to acid isolated ones, exhibited remarkable anti-neoplastic potential while being nontoxic to nontransformed L929 cell line. The pectins in the dose of 1 mg/mL were capable of inhibiting adhesion (max 23.1%), proliferation (max 40.4%), invasion (max 76.9%) and anchorage-independent growth (max 90%) of HT-29 cells (significance level p < 0.001). These pectin preparations were slightly less active towards B16F10 cells. The enzyme-isolated apple pectins may be useful as a functional food additive and an ingredient of the ointment formulas for post-surgical melanoma treatment.     

The protopectin of the leaves and petioles of Sosnovskii's cowparsnip and heartleaf colewort

Summary 1. The protopectins of the petioles and leaves of Sosnovskii's cowparsnip and heartleaf colewort have been studied. It has been shown that the protopectins of wild-growing herbs are similar to the pectins of fruit and vegetables.2. The heterogeneity of the pectins isolated has been shown by the fractionation method. Two main fractions were obtained — neutral (weakly acidic) and acidic.M. V. Lomonosov Odessa Technological Institute of the Food Industry. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 760–763, November–December, 1977.     

Complete assignments of 1H and 13C NMR spectra of leucanthoside A, a new triterpenoid saponin from Cephalaria leucantha L

Leucanthoside A, a new allose-containing triterpenoid saponin (1), was isolated from the aerial parts of Cephalaria leucantha L. Its structure was determined by electrospray ionization mass spectrometry and NMR spectroscopy. Complete assignments of the 1H and 13C NMR chemical shifts were achieved by two-dimensional NMR experiments: DQF-COSY, NOESY, TOCSY, HSQC, DINE-HSQC, HMBC, 13C-1H 2D-J-resolved spectroscopy, and 1,1-ADEQUATE.     

Characterization of Pectins Isolated from Mongolian Plants

Abstract

Pectic polysaccharides (HP, RP) were extracted from Mongolia hawthorn berries and from rhubarb stalks by hot aqueous oxalic acid treatment. Both polysaccharides contained approximately 78% of galacturonate. HP displayed a low degree of esterification (DE) and arabinose/galactose molar ratio 1.7:1. RP was higher in DE and contained these sugars in a molar ratio 0.5:1. Rhamnose, fucose, xylose, glucose, mannose, 2-O-methylxylose, and 2-O-methylfucose were found in lower amounts. Results from ¹³C NMR spectroscopy and methylation analysis indicated the presence of branched arabinans, (1?>4)-and (1?>3,6)-linked galactans and hemicelluloses of the xylan and glucan types. The pectins differed in theirmolecular properties. HP exhibited a low molecular weight (M _W = 45,000), whereas RP had a broad M _W-distribution with M _W= 360,000. Independently of these differences, the binding capacity of both pectins towards divalent cations was influenced by the DE only and increased in the order: Ca²⁺ < Cd²⁺ < Pb²⁺ < Cu²⁺.     

Metal Complexes of Pharmacophore-Containing Pectin with d -Elements Ions (Cu 2+ , Co 2+ , and Mn 2+ )

Spectral methods have been used to study the complexation of apple pectin modified with organic pharmacophores (nicotinic, salicylic, 5-aminosalicylic, or anthranilic acid) with Cu2+, Co2+, and Mn2+ ions in an aqueous solution. The composition and stability series of the metal complexes, corresponding to the empirical Irving–Williams series, have been established. The standard thermodynamic parameters (ΔH°, ΔG°, and ΔS°) of the complexation process have been calculated. It has been shown by means of 13C NMR and IR spectroscopy that the interaction of pharmacophore-containing pectins with d-metal ions (Cu2+, Co2+, Mn2+) occurs via the carbonyl and hydroxyl groups of the modified polymer matrices. The viscosity and thermal properties of the metal complexes have been determined.     

Effect of electrosurface properties of pectin substances on their sorption capacity for water and heavy metals

Three industrial pectins, viz., citrus, apple, and beet pectins were examined for the chemical composition, sorption, and electroosmotic transfer. The gelation concentrations, charge, and binding of the pectins to water and heavy metals were determined.     

Viscosity of Blends of Pectins of Various Origins with Ethylene-Vinyl Acetate Copolymers

The rheological properties of ethylene-vinyl acetate copolymers of various compositions in blends with pectins of various origins (pectins recovered from apple pulp, watermelon peel, and citrus fruits) were studied. The degrees of swelling of blend films in water were measured.     

Labdane-type diterpenoids from the wood of Cunninghamia konishii

Five new labdane-type diterpenes, 12beta,19-dihydroxymanoyl oxide (1), 8(17),13-labdadien-12,15-olid-19-oic acid (2), 12,15-epoxy-8(17),13-labdadien-18-oic acid (3), 8alpha-hydroxy-11E,13Z-labdadien-15-al (4), and (13R)-13-hydroxy-8(17), 11E,14-labdatrien-18-oic acid (5) were isolated from the wood of Cunninghamia konishii. Their structures were elucidated by two-dimensional NMR spectroscopy.     

Macrophyllosaponin E: a novel compound from the roots of Astragalus. oleifolius

Macrophyllosaponin E, a novel cycloartane-type triterpene, has been isolated from the roots of Astragalus oleifolius. The structure elucidation of the compound was achieved by a combination of one- and two-dimensional NMR techniques [1H-1H-correlation spectroscopy (COSY), 1H-13C-heteronuclear multiple guantum correlation spectroscopy (HMQC), and 1H-13C-heteronuclear multiple-bond correlation spectroscopy (HMBC)l and high resolution electrospray ionization Fourier transformation mass spectrometry (HR-ESI-FT-MS).     

Synthesis of a ball-chain system C_(60) aza-derivative

Nitrenes generated by thermolysis of alkyl azides were found to add to C60 in chloroben-zene solvent. The product was isolated by means of silica gel chromatography and identified by field desorption mass spectroscopy and 13C NMR spectroscopy.     

Biosynthesis of zeaxanthin via mevalonate in Paracoccus species strain PTA-3335. A product-based retrobiosynthetic study

Cultures of the zeaxanthin-producing bacterium Paracoccus species strain PTA-3335 (formerly Flavobacterium) were grown with supplements of (13)C-labeled glucose. Zeaxanthin was isolated and analyzed by (13)C NMR spectroscopy. The data showed that the isoprenoid precursors of zeaxanthin were biosynthesized via the mevalonate pathway. The microorganism was found to utilize glucose mainly via the Entner-Doudoroff pathway.     

Polydispersity of pectins and some physicochemical properties of their solutions

Pectin solutions obtained in the presence of HNO₃, HCl, H₂SO₄, and H₃PO₄ have been studied by viscometry, turbidity spectra, and ultracentrifugation. Cotton pectin extracts with phosphoric acid proved to be the most unstable. The molecular masses of pectins obtained from various materials (apple, lemon, and grape press residues, beet pulp, and cotton boll valves) ranged between 14,000 and 37,000. The polydispersity of the pectins isolated was studied.Tashkent State Technical University, fax (3712) 29 48 36. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 349–353, May–June, 1998.     

New eudesmane derivatives and other sesquiterpenes from the epigeal parts of Dittrichia graveolens

In bioassay-guided searches for novel bioactive natural products from higher plants of the Egyptian flora, two new eudesmane sesquiterpene derivatives, 3alpha-hydroxyilicic acid methyl ester (1) and 2alpha-hydroxy-4-epi-ilicic acid (2), together with 11 known sesquiterpenes were isolated from bioactive fractions of the active epigeal parts extracts of Dittrichia graveolens (L.) GREUTER (Asteraceae) growing in the coastal regions of northwestern Egypt. Four other known sesquiterpene lactones with different carbon skeletons, named 2alpha-hydroxy-2R-xanthalongin (8), 4-epi-isoinuviscolide (9), 8-epi-helenalin (10), and bigelovin (11), were also isolated for the first time from the same source. The stereochemical structures of the isolated compounds were elucidated on the basis of physical and spectroscopic methods including UV, IR, 1H-, 13C-NMR, distortionless enhancement by polarization transfer, 2D NMR, 1H-1H correlation spectroscopy, 1H-13C heteronuclear single-quantum coherence, 1H-13C heteronuclear multiple-bond connectivity, 1H-1H nuclear Overhauser effect spectroscopy experiments, and high-resolution mass spectrometry, as well as some chemical transformations. The antimicrobial, antiinflammatory, and antipyretic activities of D. graveolens extracts and chromatographic fractions were carried out and the various bioactivities of our findings are discussed.