Properties of cell wall polysaccharides of raw nectarine fruits after treatment under conditions that modulate gastric digestion.

The results of the study of the physicochemical properties of the high-molecular-weight soluble and insoluble components of nectarine cell walls obtained by fruit treatment under conditions that modulate of gastric digestion are presented. Homogenized nectarine fruits were sequentially treated by natural saliva and simulated gastric fluid (SGF) at pH 1.8 and 3.0. The isolated polysaccharides were compared with polysaccharides obtained by sequential extraction of nectarine fruit with cold, hot, and acidified water, solutions of ammonium oxalate and sodium carbonate. As a result, high-molecular-weight water-soluble pectic polysaccharides, weakly bound in the cell wall, were dissolved in the simulated gastric fluid, regardless of pH. Homogalacturonan (HG) and rhamnogalacturonan-I (RG-I) were identified in all pectins. It was shown that their quantity and ability to form highly viscous solutions determine high values of the rheological characteristics of the nectarine mixture formed under simulated gastric conditions. The modifications occurring with the insoluble components under the influence of acidity of SGF were importance. They determined difference in the physicochemical properties of both the insoluble fibres and the nectarine mixtures.

Xylogalacturonan-enriched pectin from the fruit pulp of Adansonia digitata: Structural characterization and antidepressant-like effect.

The low methyl-esterified and acetylated xylogalacturonan (DM 20 %, DA 2 %, Mw ∼ 58 kDa) was isolated by water extraction for 4 h × 2 at 50 °C (yield 23 %) from the pulp of baobab fruit (Adansonia digitata L.). Subsequent tightening of the conditions for water extraction by mean increasing the temperature to 70 °C and time to 12 h led to the co-extraction of small amounts of starch components and RG I with xylogalacturonan. Structural analysis (DEAE-cellulose ion-exchange chromatography, HPSEC, monosaccharide analysis, NMR spectroscopy) revealed that about 12 mol. % of 1,4-linked α-GalpA residues were substituted by single ß-Xylp residues at the O-3 position. The xylogalacturonan was found to possess an antidepressant-like effect in mice. The study offers using the baobab fruit as a rich source of soluble dietary fiber - water-soluble pectin with beneficial physiological effect.

Structural, rheological and antioxidant properties of pectins from Equisetum arvense L. and Equisetum sylvaticum L.

The pectins were isolated from sterile stems of E. arvense (EA, yield 5.9%) and E. sylvaticum (ES, yield 4.8%) (Equisetaceae) using ammonium oxalate extraction after preliminary treatment with dilute HCl (рH 4.0). The pectins possessed high molecular weight (Mw, 340-360 kDa), high GalA content (ca. 85%), low degrees of methyl-esterification (14-16%) and acetylation (3-8%). NMR analysis indicated extensive regions of partially methyl-etherified and 3-O-acetylated HG and minor regions of low branched RG in the fragment isolated after hydrolysis of pectin EA by pectinase. Pectin EA produced a higher viscosity solution, formed a stronger and more rigid ionotropic hydrogel than pectin ES. The pectins scavenged DPPH and hydroxyl radicals, but not the superoxide radical and hydrogen peroxide. Phenolic compounds (0.11 and 0.23%) associated with polysaccharide moieties were apparently responsible for the differences in the anti-DPPH scavenging activity of pectins EA and ES (63 and 49%). The findings suggested that pectin from E. arvense should be more perspective than pectin from E. sylvaticum on their use as components of wound healing remedies.

[Comparative Analysis of Spectrophotometric Methods of the Protein Measurement in the Pectic Polysaccharide Samples].

For the assay to reliability of determination of the protein content in the pectic polysaccharide samples by absorbance in the ultraviolet and visible regions of the spectrum a comparison of the eleven techniques called Flores, Lovry, Bradford, Sedmak, Rueman (ninhydrin reaction) methods, the method of ultraviolet spectrophotometry, the method Benedict's reagent, the method Nessler's reagent, the method with amide black, the bicinchoninic reagent and the biuret method was carried out. The data obtained show that insufficient sensitivity of the seven methods from the listed techniques doesn't allow their usage for determination of protein content in pectic polysaccharide samples. But the Lowry, Bradford, Sedmak methods, and the method Nessler's reagent may be used for determination of protein content in pectic polysaccharide samples, and the Bradford method is advisable for protein contaminants content determination in pectic polysaccharide samples in case protein content is less than 15%, and the Lowry method--for samples is more than 15%.

Synthesis of sulfated pectins and their anticoagulant activity.

The following pectins were sulfated: bergenan BC (the pectin of Bergenia crassifolia L), lemnan LM (the pectin of Lemna minor L), and galacturonan as a backbone of pectins. Pyridine monomethyl sulfate, pyridine sulfotrioxide, and chlorosulfonic acid were used as reagents for sulfation. Chlorosulfonic acid proved to be the optimal reagent for sulfation of galacturonan and other pectins. Galacturonan and pectin derivatives with different degrees of sulfation were synthesized and their anticoagulant activities were shown to depend on the quantity of sulfate groups in the pectin macromolecules.

Chemical characterization and anti-inflammatory effect of rauvolfian, a pectic polysaccharide of Rauvolfia callus.

The pectic polysaccharide named rauvolfian RS was obtained from the dried callus of Rauvolfia serpentina L. by extraction with 0.7% aqueous ammonium oxalate. Crude rauvolfian RS was purified using membrane ultrafiltration to yield the purified rauvolfian RSP in addition to glucan as admixture from the callus, with molecular weights 300 and 100-300 kD, respectively. A peroral pretreatment of mice with the crude and purified samples of rauvolfian (RS and RSP) was found to decrease colonic macroscopic scores, the total area of damage, and tissue myeloperoxidase activity in colons as compared with a colitis group. RS and RSP were shown to stimulate production of mucus by colons of the colitis mice. RSP appeared to be an active constituent of the parent RS. The glucan failed to possess anti-inflammatory activity.