Mechanical composites based on biologically active compounds from larch wood

Mechanical composites were prepared by mechanical chemical processing of a mixture of biologically active preparations of arabinogalactan (AG) and dihydroquercetin (DQ) isolated from larch wood. Their properties were studied using HPLC, ¹³C NMR, and IR spectroscopy. It was found that AG and DQ did not react chemically under the studied conditions. According to x-ray phase and thermal analyses, mechanical processing destroyed the DQ crystalline structure and dispersed it into the AG matrix. The resulting mechanical composites had significantly higher (up to 38 times) solubility in water compared with starting DQ and an unprocessed AG/DQ mixture. It was shown that DQ reduces the extent of destruction of polysaccharide macromolecules during mechanical processing.     

Preparation of new cefazolin-containing films based on chitosan and carboxyarabinogalactan

Preparation of a polyelectrolyte complex of chitosan with the oxidized form of Siberian larch arabinogalactan at the component ratio from 0.05: 1 to 1: 1 was studied by spectrometry and laser scattering. Water-insoluble films based on this complex were prepared. These films were used as a matrix for drug immobilization. The possibility of controlling the rate and degree of the drug release from the film by variation of the polysaccharide ratio, modification of the polymer film with a sodium dodecyl sulfate solution, or heat treatment was demonstrated with cefazolin antibiotic as example. The films obtained exhibit high bactericidal activity.     

The impact of cellulose structure on binding interactions with hemicellulose and pectin

Four cellulose substrates including highly crystalline cellulose nanowhiskers (CNWs) from Gluconacetobacter xylinus (cellulose Iα) or cotton (cellulose Iβ) and amorphous cellulose derived from CNWs (phosphoric acid swollen cellulose nanowhiskers, PASCNWs) were used to explore the interaction between cellulose and well-defined xyloglucan, xylan, arabinogalactan and pectin. The binding behavior was characterized by adsorption isotherm and Langmuir models. The maximum adsorption and the binding constant of xyloglucan, xylan and pectin to any CNWs were always higher than to PASCNWs derived from the same source. The binding affinity of xyloglucan, xylan and pectin to G. xylinus cellulose was generally higher than to cotton cellulose, showing that binding interactions depended on the biological origin of cellulose and associated differences in its structure. The surface area, porosity, crystal plane and degree of order of cellulose substrate may all impact the interactions.     

Solid-phase modification of chitosan,pectin, and arabinogalactan with poorly soluble herbicide chlorsulfuron

The chemical modification of chitosan, pectin, and arabinogalactan with poorly soluble herbicide chlorsulfuron under mechanical effect is studied. It is shown that the mechanical stress on polysaccharides and herbicide provokes conformational and configurational transformations and disordering in biopolymer macromolecules as well as an increase in the concentration of defects in the crystalline phase of the polysaccharides and herbicide. The change in the conformational state of the polysaccharides under shock-shear impacts gives rise to intermolecular complexes stabilized by hydrogen bonds.     

Polymeric eye films based on polyvinyl alcohol and arabinogalactan with levofloxacin

Physicochemical methods were used to study the interaction of arabinogalactan from Siberian larch with the antibacterial preparation levofloxacin. Polymeric eye films with controllable output of the medicinal preparation were produced on the basis of an arabinogalactan-polyvinyl alcohol formulation. A high pharmaceutical activity of the new eye films was demonstrated.     

Reaction of arabinoogalactan from the Sibirian larch with kanamycin

By means of the UV, IR, and NMR spectroscopy, densimetry and viscometry reaction of arabinogalactan from Sibirian larch with kanamycin in water solutions was studied. The composition and the stability constant of the complex formed were evaluated, and optimal conditions of its synthesis were established.     

Modification of Arabinogalactan and Its Oxidized Fractions with 5-Aminosalicylic Acid

Modification of arabinogalactan of Siberian larch and of its oxidized oligomers with 5-amino-salicylic acid was studied. The chemical composition, some physicochemical properties of the modification products, and the optimal modification conditions were determined.     

Isolation and structural characterisation of okara polysaccharides

Okara is a byproduct generated during tofu or soymilk production processes. Crude polysaccharide (yield 56.8%) was isolated by removing fat, protein and low molecular weight carbohydrates from initial okara. Crude okara polysaccharide was further divided into four soluble fractions and an insoluble residue fraction by extracting with 0.05 M EDTA + NH(4) oxalate, 0.05 M NaOH, 1 M NaOH and 4 M NaOH, with yields of 7.7%, 3.6%, 20.7%, 16.0% and 27.9%, respectively. Arabinose, galactose, galacturonic acid, xylose and glucose (only for the insoluble fraction) were the major constituent sugars. The primary sugar residues of okara polysaccharides were 1,4-linked β-galactopyranose, 1,5- and 1,3-linked α-arabinofuranose, 1,5-linked α-xylofuranose, 1,2-linked, 1,2,4-linked and terminal α-rhamnopyranose (or fucopyranose), and 1,4-linked β-glucopyranose (only for the insoluble fraction), indicating okara polysaccharides might contain galactan, arabinan, arabinogalactan, xylogalacturonan, rhamnogalacturonan, xylan, xyloglucan and cellulose.     

Complexation of carboxyarabinogalactan of Siberian larch (Larix Sibirica L.) with Kanamycin

Russian Journal of Applied Chemistry - Interaction of oxidized arabinogalactan of Siberian larch (Larix Sibirica L.) with Kanamycin antibiotic in aqueous solutions was studied by physicochemical...     

Total Synthesis of a Partial Structure from Arabinogalactan and Its Application for Allergy Prevention

Arabinogalactan, a microheterogeneous polysaccharide occurring in plants, is known for its allergy-protective activity, which could potentially be used for preventive allergy treatment. New treatment options are highly desirable, especially in a preventive manner, due to the constant rise of atopic diseases worldwide. The structural origin of the allergy-protective activity of arabinogalactan is, however, still unclear and isolation of the polysaccharide is not feasible for pharmaceutical applications due to a variation of the activity of the natural product and contaminations with endotoxins. Therefore, a pentasaccharide partial structure was selected for total synthesis and subsequently coupled to a carrier protein to form a neoglycoconjugate. The allergy-protective activity of arabinogalactan could be reproduced with the partial structure in subsequent in vivo experiments. This is the first example of a successful simplification of arabinogalactan with a single partial structure while retaining its allergy-preventive potential.     

Kinetics of oxidation of an arabinogalactan from larch (Larix sibirica L.) in an aqueous medium in the presence of hydrogen peroxide

The oxidation of an arabinogalactan in an aqueous medium under the action of hydrogen peroxide and dioxygen is accompanied by accumulation of carbonyl and carboxy groups in the oxidized polysaccharide macromolecules and derived oligomers. The addition of iron sulfate accelerates the radical oxidation of the biopolymer, while the addition of phenol inhibits the oxidation. The influence of the temperature and the initial H₂O₂ and arabinogalactan concentrations on the kinetics of the initial oxidation stage of the natural polysaccharide was studied.     

Purification and characterization of anti-complementary polysaccharide from leaves of Thymus vulgaris L.

For the purification of the anti-complementary polysaccharide from Thymus vulgaris L., the hot-water extract of thyme leaves was successively fractionated by ethanol precipitation and ultra-filtration. The retentate with 300-kDa membrane cartridge showed a potent anti-complementary activity. It was further purified by open column chromatographies on DEAE-Toyopearl 650C, Butyl-Toyopearl 650M and Sephadex G-100, obtaining TV3-IIA-I, the purified anti-complementary polysaccharide. The anti-complementary polysaccharide exhibited the anti-complementary activity via both classical and alternative pathways. Based upon the methylation analysis and the reaction with beta-glucosyl Yariv reagent, the anti-complementary polysaccharide from thyme might contain an arabinogalactan moiety, at least in part.     

Reaction of cis-diamminedichloroplatinum(II) with arabinogalactan. The identification and therapeutic effect of the product obtained

A reaction of cis-diamminedichloroplatinum(II) with the natural polysaccharide arabinogalactan gave a product characterized by X-ray powder diffraction, IR spectroscopy, UV spectrophotometry, and thermogravimetry. It was demonstrated that cis-diamminedichloroplatinum(II) is bound to arabinogalactan by a linkage between its -C-O-C- bond and the hydrogen atom of the NH₃ group of the starting complex. The product can suppress tumor growth with no toxic effect on the organism.     

Nanosized Pd(0)-arabinogalactan composites as catalysts in the Sonogashira reaction

Zero-valent palladium nanoparticles stabilized by arabinogalactan polysaccharide matrix were successfully used for the first time as phosphine-free catalyst in the cross-coupling of terminal alkynes with aryl and hetaryl halides.     

Size exclusion chromatography/mass spectrometry applied to the analysis of polysaccharides.

A novel method for analysing polysaccharide materials is described which employs size-exclusion chromatography (SEC) followed by detection by on-line electrospray ionisation mass spectrometry (ESI-MS) and off-line matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS). It is demonstrated through SEC/ESI ion trap mass spectrometry that the formation of multiply charged oligomer ions, which bind up to five sodium cations, allows the rapid analysis of polysaccharide ions with molecular weights in excess of 9 kDa. MALDI spectra generated from fractionation of the effluent collected from the same SEC separation are shown to be in good agreement with the ESI spectra with respect to molecular weight distributions and types of ions generated. ESI and MALDI mass spectra of samples obtained from sequential graded ethanol precipitation and SEC fractionation of acid and enzymatically digested arabinoxylan polysaccharides show important structural differences between polysaccharide fragments. In addition, a comparison is made between the mass spectra of native and permethylated SEC-separated fragments of acid and enzymatically treated arabinogalactan. Linkage information of the permethylated arabinogalactan oligomers can be rapidly established through the use of on-line SEC/ESI-MS( n) experiments.     

Polysaccharide/Surfactant complexes at the air-water interface - effect of the charge density on interfacial and foaming behaviors

The binding of a cationic surfactant (hexadecyltrimethylammonium bromide, CTAB) to a negatively charged natural polysaccharide (pectin) at air-solution interfaces was investigated on single interfaces and in foams, versus the linear charge densities of the polysaccharide. Besides classical methods to investigate polymer/surfactant systems, we applied, for the first time concerning these systems, the analogy between the small angle neutron scattering by foams and the neutron reflectivity of films to measure in situ film thicknesses of foams. CTAB/pectin foam films are much thicker than the pure surfactant foam film but similar for high- and low-charged pectin/CTAB systems despite the difference in structure of complexes at interfaces. The improvement of the foam properties of CTAB bound to pectin is shown to be directly related to the formation of pectin-CTAB complexes at the air-water interface. However, in opposition to surface activity, there is no specific behavior for the highly charged pectin: foam properties depend mainly upon the bulk charge concentration, while the interfacial behavior is mainly governed by the charge density of pectin. For the highly charged pectin, specific cooperative effects between neighboring charged sites along the chain are thought to be involved in the higher surface activity of pectin/CTAB complexes. A more general behavior can be obtained at lower charge density either by using a low-charged pectin or by neutralizing the highly charged pectin in decreasing pH.     

Structural Features of a Polysaccharide from Centella asiatica

Centella asiatica has been used as remedy for sodation, stabilization and against lepra, anabrosis1 in the oriental countries. The low-molecular-weight constituents in Centella asiatica have been investigated1. However, no polysaccharides have been reported. 1BI was the first polysaccharide isolated from C. asiatica, which had immunostimulating activity in vitro. In present study, we report the structural features of 1BI. Experimental Extraction, isolation and purification Dried C.…     

酶解-离子色谱法测定烟草中的果胶

建立了一种测定烟草中果胶含量的酶解-离子色谱法,并对酶解条件进行了优化.即样品经快速溶剂萃取仪用80%乙醇除糖后,在47℃、pH4条件下用果胶酶酶解2 h,用离子色谱测定酶解液中的半乳糖醛酸含量.该法的线性相关系数为0.999 3,回收率98.3%～100.8%,RSD为3.43%.     

Modification of Arabinogalactan Isolated from Larix sibirica Ledeb. into Sulfated Derivatives with the Controlled Molecular Weights

The process of sulfation of arabinogalactan—a natural polysaccharide from Larix sibirica Ledeb.—with sulfamic acid in 1,4-dioxane using different activators has been studied for the first time. The dynamics of the molecular weight of sulfated arabinogalactan upon variation in the temperature and time of sulfation of arabinogalactan with sulfamic acid in 1,4-dioxane has been investigated. It has been found that, as the sulfation time increases from 10 to 90 min, the molecular weights of the reaction products grow due to the introduction of sulfate groups without significant destruction of the initial polymer and sulfation products. Sulfation at 95 °C for 20 min yields the products with a higher molecular weight than in the case of sulfation at 85 °C, which is related to an increase in the sulfation rate; however, during the further process occurring under these conditions, sulfation is accompanied by the destruction and the molecular weight of the sulfated polymer decreases. The numerical optimization of arabinogalactan sulfation process has been performed. It has been shown that the optimal parameters for obtaining a product with a high sulfur content are a sulfamic acid amount of 20 mmol per 1 g of arabinogalactan, a process temperature of 85 °C, and a process time of 2.5 h.     

Modulating surface rheology by electrostatic protein/polysaccharide interactions

There is a large interest in mixed protein/polysaccharide layers at air-water and oil-water interfaces because of their ability to stabilize foams and emulsions. Mixed protein/polysaccharide adsorbed layers at air-water interfaces can be prepared either by adsorption of soluble protein/polysaccharide complexes or by sequential adsorption of complexes or polysaccharides to a previously formed protein layer. Even though the final protein and polysaccharide bulk concentrations are the same, the behavior of the adsorbed layers can be very different, depending on the method of preparation. The surface shear modulus of a sequentially formed beta-lactoglobulin/pectin layer can be up to a factor of 6 higher than that of a layer made by simultaneous adsorption. Furthermore, the surface dilatational modulus and surface shear modulus strongly (up to factors of 2 and 7, respectively) depend on the bulk -lactoglobulin/pectin mixing ratio. On the basis of the surface rheological behavior, a mechanistic understanding of how the structure of the adsorbed layers depends on the protein/polysaccharide interaction in bulk solution, mixing ratio, ionic strength, and order of adsorption to the interface (simultaneous or sequential) is derived. Insight into the effect of protein/polysaccharide interactions on the properties of adsorbed layers provides a solid basis to modulate surface rheological behavior.