Polyuronic Acid Research Articles

Polyuronic acid degradation by polysaccharide lyase family 7

Polyuronic acid degradation by polysaccharide lyase family 7

Relationship between Anti-Wrinkle Property of Cotton Fabrics and Crosslinking Properties of Glycosyl Polyaldehydes and Polyuronic Acids Finishing Agents: A Molecular Simulation Study

In this paper, monosaccharide (glucose and fructose), disaccharide (sucrose and trehalose), trisaccharide (raffinose) and tetrasaccharide (stachyose) were selected as the research objects and the glycosyl polyaldehydes and glycosyl polyuronic acid anti-wrinkle finishing agents were prepared via selective oxidation. The anti-wrinkle properties of their finished fabrics were analyzed, the molecular radius, the number of reactive groups, the number of reaction sites and the number of rotatable bonds of the finishing agent were calculated to evaluate its diffusion rate and crosslinking characteristics inside the cellulose. Through molecular simulation, the number of possible conformations of the anti-wrinkle finishing agent with the single cross-linked state was calculated, and the distance between different cross-linking points was measured, and the relationship between the effective cross-linking radius and the anti-wrinkle performance was studied. The results showed that trehalose polyaldehydes, raffinose polyaldehydes, trehalose polyuronic acid, and raffinose polyuronic acid finished fabrics had an excellent anti-wrinkle property, the strength retention rates of the fabrics were all above 68%, and the whiteness index was above 70. The smaller the molecular radius was, the easier the finishing agent was to diffuse into the cellulose. The most suitable crosslinking radius of glycosyl finishing agent was 3.5–6.0 Å.

Chemical synthesis of C6-tetrazole ᴅ-mannose building blocks and access to a bioisostere of mannuronic acid 1-phosphate.

Alginate is a biocompatible and industrially relevant polysaccharide that derives many of its important properties from the charged carboxylate groups within its polyuronic acid backbone. The design and inclusion of isosteric replacements for these carboxylates would underpin provision of new oligo-/polysaccharide materials with alternate physicochemical properties. Presented herein is our synthesis of mannuronic acid building blocks, appropriately modified at the carboxylate C6 position with a bioisosteric tetrazole. Thioglycosides containing a protected C6-tetrazole are accessed from a C6-nitrile, through dipolar cycloaddition using NaN3 with n-Bu2SnO. We also demonstrate access to orthogonally C4-protected donors, suitable for iterative oligosaccharide synthesis. The development of these building blocks is showcased to access anomeric 3-aminopropyl- and 1-phosphate free sugars containing this non-native motif.

Harnessing Fe(III)–Carboxylate Photochemistry for Radical-Initiated Polymerization in Hydrogels

Coordination of Fe(III) to carboxylates in polyuronic acid hydrogels was used to impart photochemical reactivity to polysaccharide-based hydrogels. This photochemical reaction was then used for light-initiated polymerization to create hydrogels with advanced mechanical and conductive properties by capturing the photogenerated radical with a monomer, either acrylamide, methyl methacrylate, or aniline. The photopolymerization of acrylamide using the Fe(III)-polyuronic acid was quantified in solution and the polymerization efficiency was determined under different conditions. Poly(methyl methacrylate) (PMMA)-modified hydrogels were analyzed by the contact angle, optical microscopy, and rheology. This confirmed formation of a stiff, hydrophobic, PMMA layer on polysaccharide hydrogels after light irradiation in methyl methacrylate. Polyaniline-modified hydrogels were characterized by current-voltage sweeps, which showed the formation of conductive polyaniline integrated into the hydrogel after light irradiation in the aniline monomer. This strategy provided a facile approach to create either layered hydrogels with different stiffness and hydrophobicity or hybrid conductive hydrogels using the simple photochemical reaction of blue light irradiation of Fe(III) coordinated to polyuronic acids.

Alginic acid inhibits non-small cell lung cancer-induced angiogenesis via activating miR-506 expression.

Angiogenesis is a key event in non-small cell lung cancer progression. Alginic acid (AA), a kind of naturally occurring polyuronic acid, is generally enriched in edible brown algae. Recent studies have uncovered its anti-anaphylactic and anti-inflammatory properties. However, the effects of AA on human malignancies remain unknown. Herein, efficient inhibition of AA on NSCLC-induced angiogenesis was observed with tube formation and xenograft models. Subsequent results indicated that AA downregulated the expression of VEGF-A, a key angiogenesis-inducing cytokine. In addition, AA downregulated STAT3, a transcriptional inducer of VEGF-A and increased non-coding RNA miR-506 expression, respectively. Furthermore, miR-506 directly modulated STAT3 relying on base pairing the 3'-UTR in STAT3 mRNA. We also found that abrogation of miR-506 abolished the inhibitory effect of AA on VEGF-A expression and NSCLC-induced angiogenesis. Finally, xenografts experiments also showed that oral administration of AA could significantly attenuate NSCLC angiogenesis, indicated by decreased micro-vessel density (MVD) and the MVD marker CD31 expression in xenografts tissues. Correspondingly, AA treatment also downregulated VEGF-A, STAT3 and increased miR-506 expression in xenografts samples, respectively. Taken together, these results suggested that AA could suppress NSCLC-induced angiogenesis via miR-506/STAT3/VEGF-A axis. .

How alginate properties influence in situ internal gelation in crosslinked alginate microcapsules (CLAMs) formed by spray drying.

Alginates gel rapidly under ambient conditions and have widely documented potential to form protective matrices for sensitive bioactive cargo. Most commonly, alginate gelation occurs via calcium mediated electrostatic crosslinks between the linear polyuronic acid polymers. A recent breakthrough to form crosslinked alginate microcapsules (CLAMs) by in situ gelation during spray drying ("CLAMs process") has demonstrated applications in protection and controlled delivery of bioactives in food, cosmetics, and agriculture. The extent of crosslinking of alginates in CLAMs impacts the effectiveness of its barrier properties. For example, higher crosslinking extents can improve oxidative stability and limit diffusion of the encapsulated cargo. Crosslinking in CLAMs can be controlled by varying the calcium to alginate ratio; however, the choice of alginates used in the process also influences the ultimate extent of crosslinking. To understand how to select alginates to target crosslinking in CLAMs, we examined the roles of alginate molecular properties. A surprise finding was the formation of alginic acid gelling in the CLAMs that is a consequence of simultaneous and rapid pH reduction and moisture removal that occurs during spray drying. Thus, spray dried CLAMs gelation is due to calcium crosslinking and alginic acid formation, and unlike external gelation methods, is insensitive to the molecular composition of the alginates. The 'extent of gelation' of spray dried CLAMs is influenced by the molecular weights of the alginates at saturating calcium concentrations. Alginate viscosity correlates with molecular weight; thus, viscosity is a convenient criterion for selecting commercial alginates to target gelation extent in CLAMs.

Fe(III)-polyuronic acid photochemistry: radical chemistry in natural polysaccharide.

The photochemistry of Fe(III) coordinated to natural uronate-containing polysaccharides has been investigated quantitatively in aqueous solution. It is demonstrated that the photoreduction of the coordinated Fe(III) to Fe(II) and oxidative decarboxylation occurs in a variety of uronate-containing polysaccharides. The photochemistry of the Fe(III)-polyuronic acid system generated a radical species during the reaction which was studied using the spin trapping technique. The identity of the radical species from this reaction was confirmed as CO2•- indicating that both bond cleavage of the carboxylate and oxidative decarboxylation after ligand to metal charge transfer radical reactions may be taking place upon irradiation. Degradation of the polyuronic acid chain was investigated with dynamic light scattering, showing a decrease in the hydrodynamic radius of the polymer assemblies in solution after light irradiation that correlates with the Fe(II) generation. A decrease in viscosity of Fe(IIII)-alginate after light irradiation was also observed. Additionally, the photochemical reaction was investigated in plant root tissue (parsnip) demonstrating that Fe(III) coordination in these natural materials leads to photoreactivity that degrades the pectin component. These results highlight that this Fe(III)-polyuronic acid can occur in many natural systems and may play a role in biogeochemical cycling of iron and ferrous iron generation in plants with significant polyuronic acid content.

Preparation of Polyuronic Acid by Acetobacter xylinum

Water-soluble polyuronic acid was prepared via Acetobacter xylinum in this study. The structural features of the two polyuronic acid samples were characterized by gel permeation chromatography, Fourier transform infrared (FTIR) spectroscopy, and proton nuclear magnetic resonance (1H-NMR) spectroscopy. It was found that when using glucuronic or galacturonic acid as a substrate, with samples incubated at 20 °C to 30 °C in the fermentation medium for 3 weeks to 6 weeks, water-soluble polyuronic acid products could be collected from the colloids that formed on the surface of the medium. The yield of polyuronic acid was approximately 25 wt.%. The weight-average molecular weight of the product was 150,000 to 390,000, and the polydispersity was approximately 1.01 to 1.35. These results indicated that polyuronic acid can be easily prepared by a polymerization method using Acetobacter xylinum. The product polymers possessed high water solubility. The FTIR and 1H-NMR spectra indicated glycosidic linkages were successfully formed.

Stability of (1 → 3)-β-polyglucuronic acid under various pH and temperature conditions

Regioselective oxidation of C6 primary hydroxyls to carboxyls was applied to curdlan, to prepare a water-soluble (1→3)-β-polyglucuronic acid Na salt [(1,3)-β-PGluA], using a 4-acetamido-TEMPO/NaClO/NaClO2 oxidation system at pH 4.7. Changes in the chemical structure and degree of polymerization of (1,3)-β-PGluA treated in water at various temperatures and pHs were studied to evaluate the stability of (1,3)-β-PGluA to these treatments. This polyuronic acid was found to be stable, without any depolymerization, to treatment in water at pHs 1–9 and room temperature for up to 128h; slight depolymerization was observed at pHs 11 and 13. When heated in water at pH 1 and high temperatures (1,3)-β-PGluA molecules were randomly depolymerized by hydrolysis, primarily forming glucuronic acid. In contrast, dicarboxylic-acid-type monomers containing ethylene carbons were formed from the C1-carboxyl or C1 reducing ends of (1,3)-β-PGluA molecules by treatment under alkaline conditions; this was initiated by β-alkoxy elimination, similar to the peeling-off reaction of cellulose.

Polysaccharides derived from tragacanth as biocompatible polymers and Gels

AbstractTragacanth gum (TG) is a natural gum whose biomedical applications are limited because of the low water solubility and the possibility to form only weak water‐insoluble gels. An innovative method to produce water‐soluble tragacanth (WST) is assessed in this work. WST structural characterization indicates a high‐molecular weight polyuronic acid, which can undergo gelling by ionotropic complexation. Biological characterization shows no cytotoxicity on Hela, HepG2, and L929 cell lines. Furthermore, TG‐based and WST‐based gel beads prepared by ionic crosslinking with ferric and zinc ions are studied. Ferric WST gels exerted better cell adhesion with L929 cells than ferric alginate gels. These characteristics make WST a promising candidate for tissue engineering and drug delivery applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A transcriptomic approach to predict the impact of β-(1,3)-polyglucuronic acid sodium salt and derivatives in the main biological processes

β-(1,3)-Polyglucuronic acid sodium salt was produced by the regioselective oxidation of curdlan using 2,2,6,6,-tetramethylpiperidine-1-oxyl radical (TEMPO)/NaBr/NaClO systems. This β-(1,3)-polyuronic acid sodium salt was depolymerized, O-sulphated and O-acetylated. All these molecules have been biologically screened for transcriptomic analysis using DNA array. The transcriptomical responses were studied after statistical gene ontology in order to evaluate biological responses disturbed by the individual treatments of human fibroblast by all these β-(1,3)-polyglucuronic acid sodium salt derivatives.

Application of alginate gels to the study of Mammalian development.

Alginic acid is a linear polysaccharide of approx 240 kDa present in the cell walls of the fronds of various seaweeds, including the giant brown kelp (Macrocystis pyrifera), horsetail kelp (Laminaria digitalis), and sugar kelp (L. saccharina). It is a hydrophilic colloidal polyuronic acid consisting of β-(1 →4)-d-mannuronic acid and α-(1→4)-l-guluronic acid residues with composition varying according to both the age and species of alga. It is capable of absorbing 200–300 times its weight of water in which it has only very limited solubility. The sodium salt of alginic acid, referred to as sodium alginate, is a cream-colored powder that dissolves in aqueous media to form a viscous colloidal solution. Upon addition of calcium, the saccharide chains of sodium alginate crosslink to form a stable gel through the displacement of two monovalent sodium ions by this divalent cation. Aside from its many industrial applications, including giving ice cream a creamy texture and preventing crystalization, it has also been employed widely both clinically in the dressing and repair of wounds, and in basic biomedical research. Encapsulation of cells or tissue for transplantation and achieving controlled release of drugs, growth factors, and other molecules are prominent among the ways it has been exploited in these latter contexts.

Determinant factors for the formation of the calcium oxalate minerals, weddellite and whewellite, on the surface of foliose lichens

The factors influencing the predominance of one of the two mineral forms of calcium oxalate (CO), the monohydrated whewellite (COM) and the di-hydrated weddellite (COD), forming the pruina of the upper cortex of lichens, have been investigated through a simple, sensitive histochemical assay: toluidine blue O (TBO), a metachromatic staining test. The differential reactivity of 43 thalli of 17 pruinose foliose species, supplemented by X-ray diffraction analysis and observations with polarizing and scanning electron microscopy, suggests that the histochemical reactivity of hyphal walls and cementing substances of the upper cortex are related to the density of anionic charges. These factors are probably due to the occurrence of polyuronic acid substances that strongly affects the mineralization of CO. Di-hydrated wedellite is always associated with TBO metachromatic reactivity, and COM with orthochromatic reactivity. When the material has an ambiguous ortho/metachromatic reactivity, COD and COM may occur together. This study presents the first experimental evidence that in lichens CO biomineralization is at least partially biologically controlled.

Measurement of the Activity of Polyuronic Acid C-5 Epimerases

A relatively simple assay procedure for measuring the reactions catalyzed by polyuronic acid C-5 epimerases has been developed. Action of C-5 epimerases inverts the C-6 carboxyl group of polyuronic acids converting β-linked residues into α-linked residues or vice versa. The assay takes advantage of the greater susceptibility of the acid hydrolysis of α-glycosidic linkages than β-glycosidic linkages. The method involves the partial acid hydrolysis of the polyuronic acid before and after reaction with the C-5 epimerase. The greater or lesser amounts of uronic acid released (solubilized) before and after reaction of the C-5 epimerase are a measure of the amount of α- or β-glycosidic linkages that are formed and a measure of the amount of catalysis by the enzyme.

Preparation of Polyuronic Acid from Cellulose by TEMPO-mediated Oxidation

Various cellulose samples were oxidized by 2,2,6,6,-tetramethylpipelidine-1-oxyl radical (TEMPO)-NaBr-NaClO systems, and the effects of oxidation conditions on chemical structures and degrees of polymerization of the products obtained were studied. In the case of regenerated and mercerized celluloses, almost all C6 primary alcohol groups were selectively oxidized to carboxyl groups, and water-soluble polyglucuronic acid (cellouronic acid) sodium salts were obtained almost quantitatively; the degrees of polymerization were influenced greatly by the amount of TEMPO added, and the oxidation time and temperatures. Cellouronic acids prepared from mercerized linter and kraft pulps had size exclusion chromatograms with two separate peaks due to higher and lower molecular weight fractions. On the other hand, only small amounts of carboxyl groups were introduced into native cellulose samples. Since polyglucuronic acids prepared from cellulose by the TEMPO–NaBr– NaClO systems regularly consist of the glucuronic acid repeating unit, differing from the conventional water-soluble cellulose derivatives, they may open new fields of cellulose utilization.

Cytokine production in an ex vivo whole blood model following induction by group B streptococcal polysaccharides and lipoteichoic acid.

An excessive release of pro-inflammatory cytokines, such as TNF-α and IL-1, during bacterial invasive infections can mediate several pathophysiologic phenomena2, 9, 11. Group B streptococci (GBS) are important causes of neonatal sepsis and invasive infections in adults, which are often rapidly fatal despite appropriate therapy. High TNF-α and IL-6 plasma levels were found in children with GBS sepsis2. Infection with GBS can induce the production of TNF-α, IL-1, IL-6 and interferon γ in neonatal rats10. Moreover, in these animals, by the use of heat-killed isogenic GBS mutant strains devoid of the capsular type-specific polysaccharide it was shown that this polysaccharide would not be the only factor which elicits the release of TNF-α6. Many of the host responses to gram-negative bacteria could be attributed to lipopolysaccharide (LPS), which triggers monocytes to release inflammatory cytokines5. Recent studies indicated that, aside from LPS, peptidoglycan and various polysaccharides, including uronic acid, polyuronic acid, rhamnose-glucose polymers, trigger monocytes to release cytokines1, 7, 8. This led us to investigate whether TNF-α, IL-1β, IL-6 and IL-8 could be induced in human whole blood by the addition of purified surface components of GBS, namely group (CHO-B), type Ia (CHO-Ia) and III (CHO-III) specific polysaccharides or lipoteichoic acid (LTA).

Physicochemical properties of ‘Exogel’ exocellular β(1–4)- d-glucuronan from Rhizobium meliloti strain M5N1 C.S. (NCIMB 40472)

The Rhizobium meliloti mutant strain M5N1 C.S. (NCIMB 40472) produces a polyuronic acid as β(1 → 4)- d-glucuronan with molecular weight between 1·5 × 10 5 and 3 × 10 5. With a p K o of about 3 and L p ⋍ 110 A ̊ , this polyelectrolyte is comparable with alginates and pectins. In solution, acetyl content and high external salt concentrations favour aggregation. At high concentrations the polysaccharide forms thermoreversible or thermally stable gels according to the nature of the counterion, the polymer concentration and the ionic strength.

Changes in Cell Wall Polysaccharides During the Growth ofPhaseolus vulgarisLeaves

The changes in pectic and hemicellulosic polysaccharides, and a-cellulose during the expansion growth of the primary leaves of Phaseolus vulgaris L. var. Pinta have been studied. a-Cellulose increased continuously with age, while pectic and water-soluble hemicellulose extracted with 4% KOH fractions slightly decreased. The water-soluble hemicelluloses extracted with 24% KOH showed the most conspicuous changes, increasing until the 8th day, when the absolute growth rate was maximal, and thereafter decreasing. Furthermore, the study of the molecular mass distribution of pectin, and water-soluble polysaccharides extracted with 4% and 24% KOH, showed an increase in the degree of polymerization of polyuronic acid and xylan, and an important depolymerization of galactan and xyloglucan. Accordingly, the mechanism of cell wall loosening in the leaf cell walls is similar to that described for plant axes.

Affinodetection of the sites of formation and of the further distribution of polygalacturonans and native cellulose in growing plant cells

Summary— The object of the present paper is to complement the cytochemical detection of the polysacharides of the plant cell wall and of its precursors, taking benefit of two kinds of affinity methods: the enzyme‐gold technique and immunocytochemistry. Cellobiohydrolase (CBH 1, EC 3.2.1.91) was used to target native crystalline cellulose and two monoclonal antibodies, JIM 5 and JIM 7, were used to target homogalacturonan sequences with various degrees of esterification. Observations were performed at the light microscope level (UV epifluorescence, enzyme‐gold silver staining) and at the electron microscope level. Two types of biological specimens, both in steady state of growth, were chosen: in vitro cultures of melon cells (thin, unidirectional primary walls, loosely associated cells), and elongating zone of mung bean hypocotyl (thick walled and tightly associated cells). The following points were examined successively: the labelling at the histological level, the detection of cellulose and of polygalacturonan components in muro, the visualization of the emerging sites of the polymers along the endomembrane flow and their post‐synthetic modifications (crystallization and methylation respectively). JIM antibodies showed the early labelling of homogalacturonans on the bulging margins of the dictyosomes. The labelled vesicles appeared as sites of polymerization, cytoplasmic transport and beginning of molecular maturation with likely an early action of methyl transferases. The first labelling of cellulose occurred only on the outer face of the plasma‐membrane. Later on, CBH 1‐gold complexes remained distributed throughout the width of the growing wall, despite the surface expansion and the dispersion of the ordered framework. No significant change of the cellulose crystallinity was noticed. A co‐localization of polygalacturonan and cellulose markers was seen from the assembly to the deassembly of the cell wall. In complement, subtractive cytochemistry was performed using PATAg in association with an endopolygalacuronase to split the pectic chains or chelators (EDTA, EGTA, oxalate) to solubilize the calcium‐connected polyuronic acid chains. All the attacks exposed the individual microfibrils of the cellulose framework revealing uniformly the helicoidal organization and confirming that cellulose and polygalacturonans remain closely associated spatially during growth.

Growth-Plate Chondrocyte Cultures for Reimplantation Into Growth-Plate Defects in Sheep

Damage to epiphyseal growth plates due to fracture, trauma, or infection can lead to invasion of bone across the cartilage and localized arrest of long-bone growth. The implantation of a viable de novo cartilage plug into such defects may provide the appropriate cartilage presence necessary to inhibit the initial formation of bony bridges across the epiphysis and so maintain the growth potential. De novo cartilage plugs were prepared from ovine growth plates by culturing isolated epiphyseal chondrocytes from fetal lambs. After 14 days of culture, these de novo cartilage discs were composed of chondroitin sulfate, a small amount (5%) of dermatan sulfate, and cartilage-specific collagen. The cellular morphology and the histochemistry resembled resting zones of normal growth-plate cartilage. Those de novo cartilage discs, which had been embedded in gelled Type I collagen, retained their morphology and could be easily manipulated. On the other hand, Type II collagen and a polyuronic acid gauze (Surgicel) were not satisfactory substrates to facilitate subsequent transplantation into growth-plate defects. The use of 5-carboxyfluorescein diacetate succinimidyl ester (CSFE) throughout the cultures of epiphyseal chondrocytes or prolonged incorporation of [3H]-thymidine appeared to label the cells with useful markers for following their fate subsequent to implantation in vivo.