Articles de revues : « Polysaccharide oxidation »

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Cumpstey, Ian. « Chemical Modification of Polysaccharides ». ISRN Organic Chemistry 2013 (10 septembre 2013) : 1–27. http://dx.doi.org/10.1155/2013/417672.

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This review covers methods for modifying the structures of polysaccharides. The introduction of hydrophobic, acidic, basic, or other functionality into polysaccharide structures can alter the properties of materials based on these substances. The development of chemical methods to achieve this aim is an ongoing area of research that is expected to become more important as the emphasis on using renewable starting materials and sustainable processes increases in the future. The methods covered in this review include ester and ether formation using saccharide oxygen nucleophiles, including enzymatic reactions and aspects of regioselectivity; the introduction of heteroatomic nucleophiles into polysaccharide chains; the oxidation of polysaccharides, including oxidative glycol cleavage, chemical oxidation of primary alcohols to carboxylic acids, and enzymatic oxidation of primary alcohols to aldehydes; reactions of uronic-acid-based polysaccharides; nucleophilic reactions of the amines of chitosan; and the formation of unsaturated polysaccharide derivatives.

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Hangasky, John A., Anthony T. Iavarone et Michael A. Marletta. « Reactivity of O2 versus H2O2 with polysaccharide monooxygenases ». Proceedings of the National Academy of Sciences 115, n^o 19 (23 avril 2018) : 4915–20. http://dx.doi.org/10.1073/pnas.1801153115.

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Enzymatic conversion of polysaccharides into lower-molecular-weight, soluble oligosaccharides is dependent on the action of hydrolytic and oxidative enzymes. Polysaccharide monooxygenases (PMOs) use an oxidative mechanism to break the glycosidic bond of polymeric carbohydrates, thereby disrupting the crystalline packing and creating new chain ends for hydrolases to depolymerize and degrade recalcitrant polysaccharides. PMOs contain a mononuclear Cu(II) center that is directly involved in C–H bond hydroxylation. Molecular oxygen was the accepted cosubstrate utilized by this family of enzymes until a recent report indicated reactivity was dependent on H2O2. Reported here is a detailed analysis of PMO reactivity with H2O2 and O2, in conjunction with high-resolution MS measurements. The cosubstrate utilized by the enzyme is dependent on the assay conditions. PMOs will directly reduce O2 in the coupled hydroxylation of substrate (monooxygenase activity) and will also utilize H2O2 (peroxygenase activity) produced from the uncoupled reduction of O2. Both cosubstrates require Cu reduction to Cu(I), but the reaction with H2O2 leads to nonspecific oxidation of the polysaccharide that is consistent with the generation of a hydroxyl radical-based mechanism in Fenton-like chemistry, while the O2 reaction leads to regioselective substrate oxidation using an enzyme-bound Cu/O2 reactive intermediate. Moreover, H2O2 does not influence the ability of secretome from Neurospora crassa to degrade Avicel, providing evidence that molecular oxygen is a physiologically relevant cosubstrate for PMOs.

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Pandeirada, Carolina O., Max Achterweust, Hans-Gerd Janssen, Yvonne Westphal et Henk A. Schols. « Periodate oxidation of plant polysaccharides provides polysaccharide-specific oligosaccharides ». Carbohydrate Polymers 291 (septembre 2022) : 119540. http://dx.doi.org/10.1016/j.carbpol.2022.119540.

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Anugrah, Daru Seto Bagus, Hugo Alexander, Rianita Pramitasari, Dwi Hudiyanti et Christyowati Primi Sagita. « A Review of Polysaccharide-Zinc Oxide Nanocomposites as Safe Coating for Fruits Preservation ». Coatings 10, n^o 10 (16 octobre 2020) : 988. http://dx.doi.org/10.3390/coatings10100988.

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Safe coating formulated from biopolymer can be an alternative for better packaging for fruits. Among biopolymers used for safe coating, polysaccharides attracted more attention due to its biocompatibility and edibility. However, polysaccharide-based materials have weaknesses such as low water barrier and mechanical properties which result in lower capability on preserving the coated fruits. Hence, the incorporation of nanoparticles (NPs) such as zinc oxide (ZnO) is expected to increase the ability of polysaccharide-based coating for the enhancement of fruit shelf life. In this review paper, the basic information and the latest updates on the incorporation of ZnO NPs into the polysaccharide-based safe coating for fruit are presented. Various research has investigated polysaccharide-ZnO nanocomposite safe coating to prolong the shelf life of fruits. The polysaccharides used include chitosan, alginate, carrageenan, cellulose, and pectin. Overall, polysaccharide-ZnO nanocomposites can improve the shelf life of fruits by reducing weight loss, maintaining firmness, reducing the ripening process, reducing respiration, reducing the oxidation process, and inhibiting microbial growth. Finally, the challenges and potential of ZnO NPs as an active agent in the safe coating application are also discussed.

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Richards, James C., Malcolm B. Perry et Peter J. Kniskern. « The structure of the specific capsular polysaccharide of Streptococcus pneumoniae type 11F (American type 11) ». Canadian Journal of Biochemistry and Cell Biology 63, n^o 9 (1 septembre 1985) : 953–68. http://dx.doi.org/10.1139/o85-118.

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The specific polysaccharide of Streptococcus pneumoniae type 11F (American type 11) is composed of 2-acetamido-2-deoxy-D-glucose (one part), D-glucose (one part), D-galactose (two parts), ribitol (one part), phosphate (one part), and O-acetyl (two parts). Hydrolysis, dephosphorylation, periodate oxidation, methylation, optical rotation, and 1H and 13C nuclear magnetic resonance studies showed that the polysaccharide is an unbranched linear polymer of a ribitol-phosphate substituted repeating tetrasaccharide unit having the structure:[Formula: see text]The specific capsular polysaccharides of S. pneumoniae type 11B and 11C (American types 76 and 53) were found to have the same tetrasaccharide repeating unit as the 11F polysaccharide, but differed from it in their mode of O-acetylation and the replacement of the ribitol phosphate by glycerol phosphate in the 11C specific polysaccharide.

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Shigemasa, Yoshihiro, Hitoshi Sashiwa, Koji Nakamura, Yasuo Takeuchi et Hiroyuki Saimoto. « Ruthenium Catalyzed Oxidation of Polysaccharide ». Polymer Journal 23, n^o 10 (octobre 1991) : 1279–81. http://dx.doi.org/10.1295/polymj.23.1279.

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Ní Cheallaigh, Aisling, et Stefan Oscarson. « Synthesis of building blocks for an iterative approach towards oligomers of the Streptococcus pneumoniae type 1 zwitterionic capsular polysaccharide repeating unit ». Canadian Journal of Chemistry 94, n^o 11 (novembre 2016) : 940–60. http://dx.doi.org/10.1139/cjc-2016-0006.

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Zwitterionic capsular polysaccharide extracts, ∼8 kDa in mass, from Streptococcus pneumoniae type 1 (Spt1) have shown unique T-cell activating properties. Oligomers of the trisaccharide repeating unit of the Spt1 capsular polysaccharide [→3)-4-NH2-α-d-QuipNAc-(1→4)-α-d-GalpA-(1→3)-α-d-GalpA-(1-]n of defined length are needed to further investigate this response. An approach towards iteratively extendable trisaccharide building blocks of the zwitterionic capsular polysaccharides of Spt1 is described. Key elements include the comparison of pre-glycosylation oxidation and post-glycosylation oxidation approaches using thioglycoside donors to the target trisaccharide, the optimisation of the post-glycosylation oxidation approach, and the conversion of the trisaccharide to building blocks tailored for iterative glycosylation. The construction and evaluation of stereotunable 2-N-3-O-oxazolidinone donors for the common bacterial 2-acetamido-4-amino-2,4,6-trideoxy-α-d-galactopyranoside motif is also described, as is a key intermediate for their efficient synthesis.

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Gaspar, Armindo, Dmitry V. Evtuguin et Carlos Pascoal Neto. « Lignin reactions in oxygen delignification catalysed by Mn(II)-substituted molybdovanadophosphate polyanion ». Holzforschung 58, n^o 6 (1 octobre 2004) : 640–49. http://dx.doi.org/10.1515/hf.2004.118.

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Abstract The lignin oxidation in the oxygen delignification/bleaching process catalysed by Mn(II) substituted heptamolybdopentavanadophosphate polyanion (HPA-5-MnII) was studied using monomeric lignin model compounds and Eucalyptus globulus dioxane lignin adsorbed on the bleached sulphite pulp. The analysis of reaction products after lignin models oxidation in the presence HPA-5-MnII and the parent heptamolybdopentavanadophosphate polyanion (HPA-5) showed similar qualitative and quantitative patterns, indicating the identical lignin oxidative delignification mechanisms with both catalysts. The higher delignification selectivity of the pulp in the reaction system HPA-5-MnII/O2 than with HPA-5/O2 was explained by the protective effect of MnII in the heteropolyanion towards oxidative degradation of polysaccharides. The study of lignin adsorbed on bleached sulphite pulp, in the HPA-5-MnII/O2 delignification system, showed the cleavage of β-O-4 linkages as the major contribution to the lignin depolymerisation. The formation of Cα-O-polysaccharide linkages in β-O-4 structures of lignin during the delignification was observed.

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Fabio, José L. Di, Jean-Robert Brisson et Malcolm B. Perry. « Structural analysis of the three lipopolysaccharides produced by Salmonella madelia (1,6,14,25) ». Biochemistry and Cell Biology 67, n^o 2-3 (1 février 1989) : 78–85. http://dx.doi.org/10.1139/o89-012.

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Salmonella madelia reported to express the O-antigenic factors 1, 6, 14, and 25, defined in the Kauffmann–White classification system, was found to produce three different homogeneous lipopolysaccharides, which differed in having three structurally distinct O-polysaccharide components. The O-polysaccharide fraction obtained by mild acetic acid hydrolysis of the S. madelia lipopolysaccharide was analyzed by chemical composition, nitrous acid deamination, periodate oxidation, methylation, and 1H and 13C nuclear magnetic resonance methods and was demonstrated to be composed of three polysaccharides, PS(I), PS(II), and PS(III), which had the structures of repeating oligosaccharide units:[Formula: see text]Key words: Salmonella madelia, lipopolysaccharide, structure, analysis, nuclear magnetic resonance.

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Rekulapally, Rohit, K. Udayachandrika, Sirisha Hamlipur, Anuja Sasidharan Nair, Biswajit Pal et Shashi Singh. « Tissue engineering of collagen scaffolds crosslinked with plant based polysaccharides ». Progress in Biomaterials 10, n^o 1 (18 février 2021) : 29–41. http://dx.doi.org/10.1007/s40204-021-00149-4.

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AbstractIdeally, a bioscaffold should mimic the characteristics of an extracellular matrix of a living organ of interest. The present study deals with the formation of composite scaffolds of collagen with gum arabic. Collagen was cross-linked with oxidized gum arabic having aldehyde groups to form a porous block. By changing the oxidation level of gum arabic, incorporation of the polysaccharides into the scaffold could be varied resulting in scaffolds with variable polysaccharide to protein content. A series of scaffolds were made by altering collagen concentration and oxidation level of gum arabic. The scaffolds were tested for their physical properties, stability, biocompatibility and ability to support the cell growth. Results implied that variable polysaccharide incorporation into the scaffolds was possible depending on the oxidation level of gum arabic which could influence the swelling behavior. The scaffolds showed non-toxic behavior towards the mesenchymal stem cells and nucleus pulposa cells using viability assay in culture conditions up to 30 days; the growth of cells was seen at all combinations of gels. Nucleus pulposa cells were able to maintain their phenotype in the GACO gels. The studies show that these scaffolds are potential candidates in applications, such as tissue engineering, and can be designed to match the requirement of different cell/tissues as per their ECM.

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Kracher, Daniel, Zarah Forsberg, Bastien Bissaro, Sonja Gangl, Marita Preims, Christoph Sygmund, Vincent G. H. Eijsink et Roland Ludwig. « Polysaccharide oxidation by lytic polysaccharide monooxygenase is enhanced by engineered cellobiose dehydrogenase ». FEBS Journal 287, n^o 5 (octobre 2019) : 897–908. http://dx.doi.org/10.1111/febs.15067.

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Chen, Zhixia (Grace), Karen Suzanne Bishop, Hartono Tanambell, Peter Buchanan et Siew Young Quek. « Assessment of In Vitro Bioactivities of Polysaccharides Isolated from Hericium Novae-Zealandiae ». Antioxidants 8, n^o 7 (8 juillet 2019) : 211. http://dx.doi.org/10.3390/antiox8070211.

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The objective of this study was to investigate the potential effect of the polysaccharides isolated from Hericium novae-zealandiae, a native New Zealand fungus, on the in vitro proliferation of prostate cancer cell lines, gene expression, acetylcholinesterase (AChE) activity, and oxidation. One water-soluble and two alkali-soluble polysaccharide fractions were isolated from H. novae-zealandiae. The proliferation of the prostate cancer cell lines DU145, LNCaP, and PC3 was evaluated following treatment with these polysaccharide fractions. It was found that the polysaccharides possess anti-proliferative activity on LNCaP and PC3 cells, with a 50% growth inhibition (IC50) value as low as 0.61 mg/mL in LNCaP. Subsequently, it was determined through via RT-qPCR assay that apoptosis was one of the possible mechanisms responsible for the anti-proliferative activity in LNCaP. This was supported by the up-regulation of CASP3, CASP8, and CASP9. An alternative, discovered in PC3, was revealed to be anti-inflammation, which was hinted at by the down-regulation of IL6 and up-regulation of IL24. The polysaccharides also exhibited antioxidant and weak AChE inhibitory activities. This is the first report on the potential health benefits of polysaccharides prepared from the New Zealand fungus, H. novae-zealandiae.

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Chiemchaisri, W., J. S. Wu et C. Visvanathan. « Methanotrophic production of extracellular polysaccharide in landfill cover soils ». Water Science and Technology 43, n^o 6 (1 mars 2001) : 151–59. http://dx.doi.org/10.2166/wst.2001.0363.

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A bench-scale soil reactor was used to study methane oxidation and EPS production under tropical conditions. The study of pertinent environmental factors affecting EPS production was carried out by batch cultivation of methanotrophs. These factors included variations in temperature (20°C to 45°C), soil water content (5% to 33%), and the supply ratios of methane/oxygen. The bench-scale study revealed that excessive EPS was accumulating in an active methane oxidation zone located 5-45 cm below the soil surface of the reactor. The observed peak rates of oxidation could not be sustained over an extended period of time due to EPS accumulation. Results from the batch cultivation experiments confirmed the production of EPS in soils subject to methane oxidation. EPS production was found to correlate with methane oxidation rates which, in turn, were regulated by the variance of temperature and soil water content. A larger amount of EPS production was obtained at 30°C and 17% soil water content. Oxygen is required for methane oxidation; however, at high oxygen tension it may accelerate the production of EPS by methanotrophs causing limited oxygen diffusion and declining rates of methane oxidation.

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Ciriminna, Rosaria, Antonino Scurria et Mario Pagliaro. « Enhanced polysaccharide nanofibers via oxidation over SiliaCat TEMPO ». Chemical Communications 57, n^o 64 (2021) : 7863–68. http://dx.doi.org/10.1039/d1cc02684d.

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Drawing on independent work carried out by academic and industrial researchers using the immobilized TEMPO catalyst SiliaCat TEMPO, in this study, we show how shifting the carboxylation process mediated by TEMPO in solution to a process mediated by the above-mentioned hybrid sol–gel catalyst allows the synthesis of insoluble polysaccharide nanofibers of superior quality, eliminating waste.

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Matsumura, Kazuaki, et Robin Rajan. « Oxidized Polysaccharides as Green and Sustainable Biomaterials ». Current Organic Chemistry 25, n^o 13 (2 septembre 2021) : 1483–96. http://dx.doi.org/10.2174/1385272825666210428140052.

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Polysaccharide-based materials have been widely used as the first-choice candidates for various applications, especially in the field of biomaterials. The primary reasons for this are the sustainable nature of these materials and their high bioavailability. Their ability to be easily chemically modified enables them to be utilized in various avenues, with oxidation of the backbone being one of the most common chemical modifications. Additionally, these materials degrade via different pathways (enzymatically and chemically) and are hence ideal candidates for biomedical applications. This review summarizes the recent progress made with different oxidized polysaccharides and their potential applications to the field of biomaterials.

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Li, Ping, Zong Gang Mou, Geng Xiu Zheng et Run Yu Ma. « Characterization and Antioxidant Activities of Polysaccharides from Fructus corni ». Advanced Materials Research 560-561 (août 2012) : 231–36. http://dx.doi.org/10.4028/www.scientific.net/amr.560-561.231.

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The composition and antioxidant activities of two polysaccharides PFCAⅢ and PFCCⅠ, isolated from Fructus corni, have been investigated. The monosaccharide components of PFCAⅢ were found to be rhamnose, arabinose and glucose in a molar ratio of 13.74: 50.54: 35.72, whilst PFCCⅠ was found to consist of xylose and glucose in a molar ratio of 18.8: 81.2. The weight-average molecular weights of PFCAⅢ and PFCCⅠwere 1.74×104 and 7.57×104 respectively. The polysaccharides showed potential antioxidant activity by scavenging superoxide anion (O2−∙) and hydroxyl free radicals (OH∙) and this was confirmed by their ability to inhibit oxidation of axunge and gingili. The concentrations required to scavenge 50% of hydroxyl free radicals (EC50) of PFCAⅢ and PFCCⅠ were 430μg/ml and 80μg/ml respectively, and the extents of scavenging O2−∙ by 500μg PFCAⅢ and PFCCⅠwere 15.9% and 68.0% respectively. The polysaccharide PFCCⅠ shows much more significant antioxidant activity than PFCAⅢ. PFCCⅠ was mainly linked with β(1→4)-D-glucosyl with side chains including 1-linked β-D-Glc, 1,6-linked β-D-Glc and 1,4-linked β-D-Xyl with branching points at C-6 of 1,4-linked Glc in main chain. It had the potential to be exploited by the food and pharmaceutical industries in the future with further research on this polysaccharide.

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Rana, Vikrant Singh, et Nisha Sharma. « Oxidation Assisted Fabrication of Sterculia Gum/Protein Hybrid Hydrogel Networks through Schiff Base Formation : Characterization and Swelling Kinetic Studies ». Asian Journal of Chemistry 33, n^o 5 (2021) : 1063–76. http://dx.doi.org/10.14233//ajchem.2021.23132.

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Polysaccharide/protein hybrid conjugate system becomes an emerging system with integrated characteristics of protein as well as polysaccharide to be exploited for recent advancements in biomedical sectors. Present study is an attempt to fabricate a sterculia gum/gelatin hybrid hydrophilic network system via Schiff base formation using oxidative route at ambient conditions. This route transforms hydrogel synthesis through green mode without employing any crosslinking systems so as to minimize the toxicity issues associated. Fabricated Schiff base based gel systems have been characterized by FT-IR, powdered XRD, FESEM and EDX to confirm the inclusion of new characteristics, morphological changes and functionalization. Oxidation of natural gum drastically alter the physico-chemical behaviour of the gum as confirmed by powdered XRD by incorporating crystalline nature of oxidized sterculia gum as compared to the native sterculia gum and the Schiff base formed. The changes observed are due to the chemical modification of sterculia gum during Schiff base formation. Further the swelling capacity of oxidized sterculia gum and crosslinked network formed is also modulated and was less as compared to native sterculia gum and gelatin. This article also elaborates the mechanistic changes which take place during oxidative route of hydrogel formation in various segments of sterculia gum during oxidation and Schiff base formation.

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Sfar, Manel, Ghada Souid, Fahad M. Alminderej, Zeineb Mzoughi, Yassine El-Ghoul, Christophe Rihouey, Didier Le Cerf et Hatem Majdoub. « Structural Characterization of Polysaccharides from Coriandrum sativum Seeds : Hepatoprotective Effect against Cadmium Toxicity In Vivo ». Antioxidants 12, n^o 2 (10 février 2023) : 455. http://dx.doi.org/10.3390/antiox12020455.

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Coriandrum sativum is one of the most widespread curative plants in the world, being vastly cultivated in arid and semi-arid regions as one of the oldest spice plants. The present study explored the extraction of polysaccharides from Coriandrum sativum seeds and the evaluation of their antioxidant potential and hepatoprotective effects in vivo. The polysaccharide from coriander seeds was extracted, and the structural characterization was performed by FT-IR, UV–vis, DSC, NMR (1D and 2D), GC-MS, and SEC analysis. The polysaccharide extracted from Coriandrum sativum (CPS) seeds was characterized to evaluate its antioxidant and hepatoprotective capacities in rats. Results showed that CPS was composed of arabinose, rhamnose, xylose, mannose, fructose, galactose, and glucose in molar percentages of 6.2%, 3.6%, 8.8%, 17.7%, 5.2%, 32.9%, and 25.6%, respectively. Further, CPS significantly hindered cadmium-induced oxidation damage and exercised a protective effect against Cd hepatocytotoxicity, with a considerable reduction in MDA production and interesting CAT and SOD enzyme levels. Results suggest that CPS might be employed as a natural antioxidant source.

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Asensio, Amparo. « Structural studies of a hemicellulose B fraction (B-2) from the cork of Quercus suber ». Canadian Journal of Chemistry 66, n^o 3 (1 mars 1988) : 449–53. http://dx.doi.org/10.1139/v88-078.

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Polysaccharide B-2 contains xylose, arabinose, glucose, galactose, 4-O-methylglucuronic acid, and rhamnose in the molar ratio of 17:12:12:6:4:1. The polysaccharide has a backbone of β(1 → 4)- and β(1 → 3)-linked glucopyranosyl, β(1→ 4)-linked xylopyranosyl, and (1 → 4)- and (1 → 6)-linked galactopyranosyl residues. Arabinofuranosyl, rhamnopyranosyl, and some xylopyranosyl and galactopyranosyl groups are present as nonreducing end units. Glucopyranosyluronic acid side chains are attached at O-2 of some xylose residues. The anomeric configurations of the different glycosyl groups were determined by a study of the chromium trioxide oxidation of the acetylated polysaccharide and by nuclear magnetic reasonance spectra of the methylated polysaccharide.

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Shiekh, Khursheed Ahmad, Kittaporn Ngiwngam et Wirongrong Tongdeesoontorn. « Polysaccharide-Based Active Coatings Incorporated with Bioactive Compounds for Reducing Postharvest Losses of Fresh Fruits ». Coatings 12, n^o 1 (22 décembre 2021) : 8. http://dx.doi.org/10.3390/coatings12010008.

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This review reports recently published research related to the application of polysaccharide-based biodegradable and edible coatings (BECs) fortified with bioactive compounds obtained from plant essential oils (EOs) and phenolic compounds of plant extracts. Combinations of polysaccharides such as starches, pectin, alginate, cellulose derivatives, and chitosan with active compounds obtained from clove, lemon, cinnamon, lavender, oregano, and peppermint have been documented as potential candidates for biologically active coating materials for retardation of quality changes in fresh fruits. Additionally, polysaccharide-based active coatings supplemented with plant extracts such as cashew leaves, pomegranate peel, red roselle, apple fiber, and green tea extracts rich in phenolic compounds and their derivatives have been reported to be excellent substituents to replace chemically formulated wax coatings. Moreover, EOs and plant polyphenolics including alcohols, aldehydes, ketones phenols, organic acids, terpenes, and esters contain hydroxyl functional groups that contribute bioactivity to BECs against oxidation and reduction of microbial load in fresh fruits. Therefore, BECs enriched with active compounds from EOs and plant extracts minimize physiological and microbial deterioration by reducing moisture loss, softening of flesh, ripening, and decay caused by pathogenic bacterial strains, mold, or yeast rots, respectively. As a result, shelf life of fresh fruits can be extended by employing active polysaccharide coatings supplemented with EOs and plant extracts prior to postharvest storage.

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Lukasiewicz, Marcin, Szczepan Bednarz et Anna Ptaszek. « Environmental friendly polysaccharide modification - microwave-assisted oxidation of starch ». Starch - Stärke 63, n^o 5 (17 février 2011) : 268–73. http://dx.doi.org/10.1002/star.201000124.

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Zou, Yang, Yuye Zhong, Houbin Li, Fuyuan Ding et Xiaowen Shi. « Electrodeposition of Polysaccharide and Protein Hydrogels for Biomedical Applications ». Current Medicinal Chemistry 27, n^o 16 (4 juin 2020) : 2610–30. http://dx.doi.org/10.2174/0929867326666191212163955.

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In the last few decades, polysaccharide and protein hydrogels have attracted significant attentions and been applied in various engineering fields. Polysaccharide and protein hydrogels with appealing physical and biological features have been produced to meet different biomedical applications for their excellent properties related to biodegradability, biocompatibility, nontoxicity, and stimuli responsiveness. Numerous methods, such as chemical crosslinking, photo crosslinking, graft polymerization, hydrophobic interaction, polyelectrolyte complexation and electrodeposition have been employed to prepare polysaccharide and protein hydrogels. Electrodeposition is a facile way to produce different polysaccharide and protein hydrogels with the advantages of temporal and spatial controllability. This paper reviews the recent progress in the electrodeposition of different polysaccharide and protein hydrogels. The strategies of pH induced assembly, Ca2+ crosslinking, metal ions induced assembly, oxidation induced assembly derived from electrochemical methods were discussed. Pure, binary blend and ternary blend polysaccharide and protein hydrogels with multiple functionalities prepared by electrodeposition were summarized. In addition, we have reviewed the applications of these hydrogels in drug delivery, tissue engineering and wound dressing.

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He, Feng, Guang Yang et Longjiang Yu. « Structural Investigation of an Antibacterial Polysaccharide from Streptomyces virginia H03 ». Zeitschrift für Naturforschung C 65, n^o 5-6 (1 juin 2010) : 317–21. http://dx.doi.org/10.1515/znc-2010-5-602.

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The chemical structure of a polysaccharide from the broth of cultured Streptomyces virginia H03 was investigated. There might be 1→2 and 1→4 and no 1→6 glycosidic linkages in the polysaccharide according to periodate oxidation and Smith degradation. Four fragments including 2,3,4,6-Me4-Man, 2,3,6-Me3-Gal, 2,4,6-Me3-Glc, and 3,6-Me2-Man were found in the methylated polysaccharide. Furthermore, the polysaccharide has a β-Glc(1→4)- α-Man(1→4)-α-Gal(1→3)-linked backbone and a branch at the C-2 position of (1→2)-linked mannose residues as determined by the method of nuclear magnetic resonance (NMR) spectroscopy. The assumed structure of the polysaccharide is [→3)-β-Glc(1→4)-α-Man (1→4)-α-Gal(1→]n. 2 ↑ α-Man(1 Additionally, the polysaccharide has a wide antibiogram and was found to be most effective against Bacillus subtilis, Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli.

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Laus, Marc C., Trudy J. Logman, Anton A. N. van Brussel, Russell W. Carlson, Parastoo Azadi, Mu-Yun Gao et Jan W. Kijne. « Involvement of exo5 in Production of Surface Polysaccharides in Rhizobium leguminosarum and Its Role in Nodulation of Vicia sativa subsp. nigra ». Journal of Bacteriology 186, n^o 19 (1 octobre 2004) : 6617–25. http://dx.doi.org/10.1128/jb.186.19.6617-6625.2004.

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ABSTRACT Analysis of two exopolysaccharide-deficient mutants of Rhizobium leguminosarum, RBL5808 and RBL5812, revealed independent Tn5 transposon integrations in a single gene, designated exo5. As judged from structural and functional homology, this gene encodes a UDP-glucose dehydrogenase responsible for the oxidation of UDP-glucose to UDP-glucuronic acid. A mutation in exo5 affects all glucuronic acid-containing polysaccharides and, consequently, all galacturonic acid-containing polysaccharides. Exo5-deficient rhizobia do not produce extracellular polysaccharide (EPS) or capsular polysaccharide (CPS), both of which contain glucuronic acid. Carbohydrate composition analysis and nuclear magnetic resonance studies demonstrated that EPS and CPS from the parent strain have very similar structures. Lipopolysaccharide (LPS) molecules produced by the mutant strains are deficient in galacturonic acid, which is normally present in the core and lipid A portions of the LPS. The sensitivity of exo5 mutant rhizobia to hydrophobic compounds shows the involvement of the galacturonic acid residues in the outer membrane structure. Nodulation studies with Vicia sativa subsp. nigra showed that exo5 mutant rhizobia are impaired in successful infection thread colonization. This is caused by strong agglutination of EPS-deficient bacteria in the root hair curl. Root infection could be restored by simultaneous inoculation with a Nod factor-defective strain which retained the ability to produce EPS and CPS. However, in this case colonization of the nodule tissue was impaired.

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Richards, James C., Malcolm B. Perry et Peter J. Kniskern. « Structural analysis of the specific capsular polysaccharide of Streptococcuspneumoniae type 22F ». Canadian Journal of Chemistry 67, n^o 6 (1 juin 1989) : 1038–50. http://dx.doi.org/10.1139/v89-158.

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The structure of the specific capsular polysaccharide produced by Streptococcuspneumoniae type 22F (American type 22) was investigated by high-field 1H and 13C nuclear magnetic resonance spectroscopy, composition, methylation analysis, and periodate oxidation studies. The polysaccharide was found to be a high molecular weight acidic polymer composed of D-glucose, D-galactose, D-glucuronic acid, and L-rhamnose residues to form a regular repeating hexasaccharide unit having the structure[Formula: see text]in which the β-L-rhamnopyranosyl residues were substituted by O-acetyl groups in 80% of the repeating units. The 1H and 13C nmr resonances of the O-deacetylated type 22F polysaccharide were completely assigned by application of two-dimensional homo- and heteronuclear chemical shift correlation techniques. Keywords: Streptococcuspneumoniae polysaccharide, NMR analysis.

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Kanclerz, Drozińska et Kurek. « Microencapsulation of Camelina sativa Oil Using Selected Soluble Fractions of Dietary Fiber as the Wall Material ». Foods 8, n^o 12 (13 décembre 2019) : 681. http://dx.doi.org/10.3390/foods8120681.

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The aim of the study was to prove the usefulness of microencapsulation of Camelina sativa oil regarding its vulnerability to oxidation caused by oxygen, temperature, and other factors. Pectin, inulin, gum arabic, and β-glucan, each of them mixed with maltodextrin, were used as wall materials and their appropriability to reduce oxidation of the core material was examined. Microcapsules were prepared by spray drying, which is the most commonly used and very effective method. The research confirmed results known from literature, that gum arabic and inulin are most proper wall materials, because they ensure small oxidation increase during storage (4.59 and 5.92 eq/kg after seven days respectively) and also provide high efficiency of process (83.93% and 91.74%, respectively). Pectin turned out to be the least appropriate polysaccharide because it is not able to assure sufficient protection for the core material, in this case Camelina sativa oil, due to low efficiency (61.36%) and high oxidation (16.11 eq/kg after seven days). β-glucan occurred to be the coating material with relatively high encapsulation efficiency (79.26%) but high humidity (4.97%) which could negatively influence the storage of microcapsules. The use of polysaccharides in microencapsulation, except performing the role of wall material, has the advantage of increasing the amount of dietary fiber in human diet.

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Li, Ping, Chuan Xiong et Wenli Huang. « Gamma-Irradiation-Induced Degradation of the Water-Soluble Polysaccharide from Auricularia polytricha and Its Anti-Hypercholesterolemic Activity ». Molecules 27, n^o 3 (7 février 2022) : 1110. http://dx.doi.org/10.3390/molecules27031110.

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The water-soluble polysaccharides (APPs) isolated from the edible mushroom Auricularia polytricha were irradiated by γ-ray at doses of 10, 100, and 1000 kGy. The effect of gamma irradiation on the degradation of the polysaccharide was investigated. After irradiation treatment, the viscosity and molecular weight of APPs decreased with the increase in the irradiation dose. The changes in the enthalpy of APPs after irradiation treatment were observed. Meanwhile, SEM showed that R-APPs were crushed into fragments and the surfaces became smooth and wrinkled after irradiation. In further spectrum analysis, it was found that the glycoside bonds of the polysaccharides were broken and accompanied by the formation of double bonds. This suggested that gamma irradiation could cause the depolymerization and oxidation of polysaccharides. In addition, irradiated APPs could reduce the body weight of hyperlipidemia mice. The levels of serum and liver TC, TG, and serum LDH-c significantly decreased in hyperlipidemia mice after treatment by irradiated APPs. It indicated that gamma irradiation significantly improved the anti-hypolipidemic activity of APPs. The relationship between the physicochemical properties and hypolipidemic activity of polysaccharides was interpreted, which provides a theoretical basis for the further development of APP products. Gamma irradiation is a viable technology for macromolecular modification for degradation.

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Perry, Malcolm B., et Leann L. MacLean. « Structural characterization of the O-polysaccharide of the lipopolysaccharide produced by Salmonella milwaukee O:43 (group U) which possesses human blood group B activity ». Biochemistry and Cell Biology 70, n^o 1 (1 janvier 1992) : 49–55. http://dx.doi.org/10.1139/o92-007.

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The O-polysaccharide of the lipopolysaccharide produced by Salmonella milwaukee O:43 (group U) was shown by composition analysis, methylation, periodate oxidation and 1H and 13C nuclear magnetic resonance spectroscopic analytical methods to be a polymer of branched pentasaccharide repeating units having the structure:[Formula: see text]The blood-group activity of the O-polysaccharide was established by its serological reactivity with a specific monoclonal antibody to human blood group B, using passive hemaglutination and ELISA assays, indicating the common antigenic epitope to be a nonreducing terminal trisaccharide unit composed of L-Fucp and D-Galp (1:2) residues.Key words: Salmonella milwaukee, lipopolysaccharide, blood group B, polysaccharide, nuclear magnetic resonance.

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Саркисян, Варужан Амбарцумович, Юлия Владимировна Фролова, Роман Владимирович Соболев et Алла Алексеевна Кочеткова. « Comparative analysis of polysaccharide properties and their effect on oxidative stability of food emulsions ». Food processing industry, n^o 11 (5 novembre 2021) : 50–53. http://dx.doi.org/10.52653/ppi.2021.11.11.013.

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Полисахариды являются многофункциональными пищевыми ингредиентами, применяемыми в различных типах пищевых продуктов. Особый интерес вызывает изучение роли полисахаридов в качестве потенциальных про- или антиоксидантов в составе пищевых эмульсий. Основным недостатком традиционных способов оценки развития окислительных процессов в эмульсиях является необходимость предварительной экстракции жировой фазы, что может сопровождаться искажением реальных значений показателей окисления. В данной работе влияние полисахаридов на окислительную стабильность эмульсий изучено при помощи реактора окислительной устойчивости Oxitest, который позволяет проводить прямое измерение потребления кислорода в процессе окисления липидов, тем самым исключая необходимость экстракции и повышая достоверность полученных данных. Проведен сравнительный анализ 6 различных полисахаридов (альгинат натрия, i-каррагинан, камедь рожкового дерева, пектин амидированный, пектин высокоэтерифицированный, картофельный крахмал) в составе пищевых эмульсий. Методами ИК-Фурье спектроскопии и дифференциально-сканирующей калориметрии охарактеризованы состав и свойства исходных полисахаридов. Изучена вязкость 0,5%-ных растворов полисахаридов при помощи метода ротационной вискозиметрии. В результате проведенного анализа полисахаридов выявлены и охарактеризованы основные отличия в колебательных спектрах поглощения функциональных групп. Методом дифференциально-сканирующей калориметрии определены энтальпии теплового эффекта отделения влаги и начала термической деградации полисахаридов. Проведен многомерный статистический анализ полученных данных, выявивший основные закономерности между структурой и свойствами полисахаридов в составе эмульсий. Наибольшую окислительную стабильность проявили эмульсии на основе камеди рожкового дерева и амидированного пектина. Polysaccharides are multifunctional food ingredients used in various types of food products. The role of polysaccharides as potential pro- or antioxidants in food emulsions is of particular interest is. The main drawback of traditional methods for assessing the development of oxidative processes in emulsions is the need for preliminary extraction of the fat phase, which may be accompanied by a distortion of the real values of oxidation indices. In this work, the effect of polysaccharides on the oxidative stability of emulsions was studied using the Oxitest oxidative stability reactor, which allows the direct measurement of oxygen consumption during lipid oxidation, thereby eliminating the need for extraction and increasing the reliability of the obtained data. Comparative analysis of 6 different polysaccharides (sodium alginate, i-carrageenan, locust bean gum, amidated pectin, highly esterified pectin, potato starch) in food emulsions was performed. The composition and properties of the initial polysaccharides were characterized by FTIR spectroscopy and differential scanning calorimetry methods. The viscosity of 0.5% solutions of polysaccharides was studied using the rotary viscometry method. The analysis of polysaccharides revealed and characterized the main differences in the vibrational absorption spectra of functional groups. The enthalpies of the thermal effect of moisture separation and the beginning of thermal degradation of polysaccharides were determined by differential scanning calorimetry. A multivariate statistical analysis of the obtained data revealed the main relations between the structure and properties of polysaccharides in emulsions. Emulsions based on locust bean gum and amidized pectin exhibited the highest oxidative stability.

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Ahmedov, O. R., N. Sh Rahmatova, H. S. Talipova, Z. S. Alihonova et A. S. Turaev. « SYNTHESIS AND RESEARCH OF NITROGEN-CONTAINING XANTHANE GUM DERIVATIVES ». EurasianUnionScientists 9, n^o 5(74) (14 juin 2020) : 57–62. http://dx.doi.org/10.31618/esu.2413-9335.2020.9.74.792.

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This study presents the results concerning the synthesis of nitrogen-containing derivatives of xanthan gum. The authors obtained xanthan gum derivatives with various oxidation states through the preliminary reaction of periodic oxidation of the polysaccharide. Through the physicochemical methods of analysis, the structure and established quantitative content of aldehyde groups in the macromolecular chain of the polysaccharide were proved. It was possible to carry out a condensation reaction with guanidine and to synthesize new macromolecular derivatives in the presence of reactive aldehyde groups in the structure of xanthan gum. The synthesized derivatives were further investigated through IR spectroscopy, thermogravimetry, differential scanning calorimetry, and elemental analysis for nitrogen content. Furthermore, it is found that the amount of guanidine and the degree of substitution in the synthesized compounds are 15.3-39.0% and 34-85 mol.%. Finally, when using modified xanthan gum with a different degree of oxidation it is possible to vary the quantitative content of guanidine and the degree ofsubstitution in the reaction products.

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Zhang, Min, Qian Ma et Jian Wang. « Purification, Analysis of Structure of a Polysaccharide From the Fruit of Lycium barbarum L. » Advanced Materials Research 550-553 (juillet 2012) : 1719–23. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.1719.

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A polysaccharide, coded as LBP5a, was extracted from the Lycium barbarum L. with distilled water. LBP5a was precipitated repeated by ethanol and purified by DEAE-52, Sephadex G-75. The structure of LBP5a was detected by FT-IR spectrometer, Ultraviolet spectrophotometer, experiments of periodate oxidation and Smith degradation. The results show that LBP5a is testified to be homogeneous polysaccharide, and does not contain nucleic acid or protein. Pyranose with 1→3, 1→4 glycosyl linkages mainly exist in LBP5a.

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Zhang, Chi, et Xing Ping Liu. « Antioxidant Activity In Vitro of Selenium Polysaccharide of Thlaspi caerulescens L. Rich in Selenium ». Advanced Materials Research 518-523 (mai 2012) : 5518–22. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.5518.

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The antioxidant capacity of the human body is closely related to its ability of disease resistance and anti-aging. It is a current research focus to find effective anti-oxidants used in medicine, food, health care, beauty make-up from natural plants. In this paper, we studied the content of selenium in selenium polysaccharide and its antioxidant activity in vitro of Thlaspi caerulescens L. produced from Yutangba of Enshi selenium mining area. The double tracts atomic fluorescence spectrometry is used to detect the total selenium content in the sample and that of selenium polysaccharide in the active ingredient of the sample. The salicylic acid method and pyrogallol autoxidation method are used to detect the scavenging activity of selenium polysaccharide on hydroxyl radicals and superoxide anion. Experiments show that the total amount of selenium in Thlaspi caerulescens L. is 708ug.g-1, while the amount of selenium in selenium polysaccharide is 98.1ug.g-1, accounting 13.86% of the total selenium content. Meanwhile, selenium polysaccharide in samples is with significant antioxidant capacity, and it shows a certain dose-effect relationship. Selenium polysaccharide has stronger anti-oxidation ability than pure polysaccharide compared with non-selenium polysaccharide. Therefore, plants rich in selenium are better natural antioxidants. This study will provide the necessary experimental basis for the effective and rational development and utilization of Thlaspi caerulescens L. rich in selenium

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Cunha, Pablyana L. R., Jeanny S. Maciel, Maria Rita Sierakowski, Regina C. M. de Paula et Judith P. A. Feitosa. « Oxidation of cashew tree gum exudate polysaccharide with TEMPO reagent ». Journal of the Brazilian Chemical Society 18, n^o 1 (2007) : 85–92. http://dx.doi.org/10.1590/s0103-50532007000100009.

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Bao, Jiaqi, Li Chen et Tiantian Liu. « Dandelion polysaccharide suppresses lipid oxidation in Antarctic krill (Euphausia superba) ». International Journal of Biological Macromolecules 133 (juillet 2019) : 1164–67. http://dx.doi.org/10.1016/j.ijbiomac.2019.04.205.

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Sun, R., J. M. Fang, L. Mott et J. Bolton. « Fractional Isolation and Characterization of Polysaccharides from Oil Palm Trunk and Empty Fruit Bunch Fibres ». Holzforschung 53, n^o 3 (10 mai 1999) : 253–60. http://dx.doi.org/10.1515/hf.1999.043.

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Summary The polysaccharides in oil palm trunk fibre and empty fruit bunch (EFB) fibre were fractionated into cold water solubles, hot water solubles, 1% NaOH solubles, and 17.5% NaOH soluble fractions. Cellulose (approximately 42%) and hemicelluloses (approximately 33%) were the major polysaccharides in the palm trunk fibre and EFB fibre. Extractions of the lignified fibres with cold water, hot water, and 1% NaOH produced the hemicellulosic fractions, which were enriched in xylose and glucose and to a lesser extent, arabinose-, galactose-, mannose-, rhamnose-, and ribose-containing polysaccharides, together with noticeable amounts of associated lignin (4.5–31.2%). Further extraction of the delignified fibre residues with aqueous 17.5% NaOH removed the hemicellulosic fractions, which were strongly enriched in xylose-containing polysaccharides and relatively free of associated lignin (0.3–0.7%). Eight phenolic acids and aldehydes, including p-hydroxybenzoic acid, p-hydroxybenzaldehyde, vanillic acid, syringic acid, vanillin, syringaldehyde, p-coumaric acid, and ferulic acid, were detected in the mixtures of alkaline nitrobenzene oxidation of associated lignin in all the sixteen polysaccharide fractions. The results obtained showed that hemicelluloses in the cell walls of oil palm trunk and EFB fibres, are mainly bonded with lignin by syringyl units.

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Shan, Junwen, Thomas Böck, Thorsten Keller, Leonard Forster, Torsten Blunk, Jürgen Groll et Jörg Teßmar. « TEMPO/TCC as a Chemo Selective Alternative for the Oxidation of Hyaluronic Acid ». Molecules 26, n^o 19 (1 octobre 2021) : 5963. http://dx.doi.org/10.3390/molecules26195963.

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Hyaluronic acid (HA)-based hydrogels are very commonly applied as cell carriers for different approaches in regenerative medicine. HA itself is a well-studied biomolecule that originates from the physiological extracellular matrix (ECM) of mammalians and, due to its acidic polysaccharide structure, offers many different possibilities for suitable chemical modifications which are necessary to control, for example, network formation. Most of these chemical modifications are performed using the free acid function of the polymer and, additionally, lead to an undesirable breakdown of the biopolymer’s backbone. An alternative modification of the vicinal diol of the glucuronic acid is oxidation with sodium periodate to generate dialdehydes via a ring opening mechanism that can subsequently be further modified or crosslinked via Schiff base chemistry. Since this oxidation causes a structural destruction of the polysaccharide backbone, it was our intention to study a novel synthesis protocol frequently applied to selectively oxidize the C6 hydroxyl group of saccharides. On the basis of this TEMPO/TCC oxidation, we studied an alternative hydrogel platform based on oxidized HA crosslinked using adipic acid dihydrazide as the crosslinker.

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Levy-Ontman, Oshrat, Eliraz Stamker, Vital Mor et Adi Wolfson. « Pd-Based Polysaccharide Hydrogels as Heterogeneous Catalysts for Oxidation of Aromatic Alcohols ». Organics 2, n^o 1 (17 mars 2021) : 50–56. http://dx.doi.org/10.3390/org2010005.

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Immobilization of Pd(OAc)2(TPPTS)2 in various renewable polysaccharides hydrogels, yielded heterogeneous catalysts that were successfully used, for the first time, in the aerobic oxidation of benzylic alcohol. The new catalysts were easily removed from the reaction mixture and recycled with some loss of activity. Among all tested polysaccharides, iota-carrageenan was found to be the most suitable support, using calcium chloride as a gelation agent.

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Das, Debsankar, Subhas Mondal, Debabrata Maiti, Sadhan K. Roy et Syed S. Islam. « Structural Characterization of Dietary Fiber of Green Chalcumra (Benincasa Hispida) Fruit by NMR Spectroscopic Analysis ». Natural Product Communications 4, n^o 4 (avril 2009) : 1934578X0900400. http://dx.doi.org/10.1177/1934578x0900400421.

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A water-soluble dietary fiber was isolated from the hot aqueous extract of Chalcumra ( Benincasa hispida) fruit. The polysaccharide was found to contain D-galactose and D-methyl galacturonate in a molar ratio of 2:1. On the basis of acid hydrolysis, methylation analysis, periodate oxidation, and NMR spectroscopic studies (1H, 13C, TOCSY, DQF-COSY, NOESY, ROESY, HMQC, and HMBC), the repeating unit of the polysaccharide was established as →4)-β-D-Gal p-(1→4)-β-D-Gal p-(1→2)-α-D-Gal pA6Me-(1→.

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Masoud, Hussein, et Malcolm B. Perry. « Structural characterization of the O-antigenic polysaccharide of Escherichia coli serotype O17 lipopolysaccharide ». Biochemistry and Cell Biology 74, n^o 2 (1 mars 1996) : 241–48. http://dx.doi.org/10.1139/o96-025.

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The structure of the O-poly saccharide component of the lipopolysaccharide produced by Escherichia coli O17 (ATCC 23512) was determined by the use of methylation, periodate oxidation, one- and two-dimensional nuclear magnetic resonance spectroscopy, and mass spectrometric methods. The O-polysaccharide was found to be a high molecular weight polymer of repeating branched pentasaccharide units composed of D-mannose, D-glucose, and 2-acetamido-2-deoxy-D-glucose residues (3:1:1) and had the structure[Formula: see text]Key words: Escherichia coli, lipopolysaccharide, polysaccharide, NMR.

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Lin, Yanna, et Huiqin Wu. « Research Progress in the Application of Lycium Barbarum Polysaccharide in Ophthalmic Diseases ». Proceedings of Anticancer Research 6, n^o 3 (20 mai 2022) : 17–22. http://dx.doi.org/10.26689/par.v6i3.3885.

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Lycium barbarum polysaccharides (LBP) are widely used in age-related macular degeneration, glaucoma, diabetic retinopathy, and other eye diseases. With further studies on the pharmacological action of Lycium barbarum polysaccharides in recent years, researchers have found that Lycium barbarum polysaccharides (LBP) play a protective role in the treatment of various eye diseases through anti-oxidation, scavenging oxygen free radicals, and inhibiting inflammatory reaction as well as cell senescence. This paper reviews the application of Lycium barbarum polysaccharides in ophthalmology.

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Chouikhi, Aicha, Naourez Ktari, Sirine Ben Slima, Imen Trabelsi, Farida Bendali et Riadh Ben Salah. « Effects of a Novel Lin Seed Polysaccharide on Beef Sausage Properties ». Polymers 15, n^o 4 (17 février 2023) : 1014. http://dx.doi.org/10.3390/polym15041014.

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Functional ingredients are substances that offer health benefits beyond their nutritional value. A novel heteropolysaccharide, named Linum water soluble polysaccharide (LWSP) was purified from Linum usitatissimum L. seeds powder and identified, via TLC and NMR, as a polymer composite of α1-2-L-arabinose, β1-2-D-xylose, β1-2-D-mannose and α1-2-D-glucose. The effect of incorporating LWSP on the quality of beef sausages, stuffed into collagen casings after 15 days of storage at 4 °C, was evaluated for texture profile analysis, color, sensory analysis and oxidation attributes. The new sausages formulated with LWSP recorded good textural attributes via reduction of cohesiveness, hardness and chewiness and improved the sensory features, especially texture, color and general acceptability. In addition, substituting ascorbic acid, a synthetic antioxidant, via the biological ingredient LWSP, retarded lipid oxidation and improved the oxymyoglobin rate until 15 days of storage. LWSP was proved to be a good natural substituent to synthetic antioxidants that definitely improves the oxidation stability and quality of sausages.

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Richards, James C., et Malcolm B. Perry. « Structure of the specific capsular polysaccharide of Streptococcus pneumoniae type 23F (American type 23) ». Biochemistry and Cell Biology 66, n^o 7 (1 juillet 1988) : 758–71. http://dx.doi.org/10.1139/o88-087.

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The specific capsular polysaccharide of Streptococcus pneumoniae serotype 23F (American type 23) is composed of a repeating tetrasaccharide unit containing D-glucose (one part), D-galactose (one part), L-rhamnose (two parts), glycerol (one part), and phosphate (one part). By composition analysis, optical rotation, partial hydrolysis, periodate oxidation, methylation, and high-resolution 1H and 13C nuclear magnetic resonance studies, the elucidated unambiguous structure was in agreement with our earlier proposal but is at variance with structures proposed later by other authors. The structure of the type 23F pneumococcal polysaccharide is[Formula: see text]

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Górska, Sandra, Anna Maksymiuk et Jadwiga Turło. « Selenium-Containing Polysaccharides—Structural Diversity, Biosynthesis, Chemical Modifications and Biological Activity ». Applied Sciences 11, n^o 8 (20 avril 2021) : 3717. http://dx.doi.org/10.3390/app11083717.

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Selenosugars are a group of sugar derivatives of great structural diversity (e.g., molar masses, selenium oxidation state, and selenium binding), obtained as a result of biosynthesis, chemical modification of natural compounds, or chemical synthesis. Seleno-monosaccharides and disaccharides are known to be non-toxic products of the natural metabolism of selenium compounds in mammals. In the case of the selenium-containing polysaccharides of natural origin, their formation is also postulated as a form of detoxification of excess selenium in microorganisms, mushroom, and plants. The valency of selenium in selenium-containing polysaccharides can be: 0 (encapsulated nano-selenium), IV (selenites of polysaccharides), or II (selenoglycosides or selenium built into the sugar ring to replace oxygen). The great interest in Se-polysaccharides results from the expected synergy between selenium and polysaccharides. Several plant- and mushroom-derived polysaccharides are potent macromolecules with antitumor, immunomodulatory, antioxidant, and other biological properties. Selenium, a trace element of fundamental importance to human health, has been shown to possess several analogous functions. The mechanism by which selenium exerts anticancer and immunomodulatory activity differs from that of polysaccharide fractions, but a similar pharmacological effect suggests a possible synergy of these two agents. Various functions of Se-polysaccharides have been explored, including antitumor, immune-enhancement, antioxidant, antidiabetic, anti-inflammatory, hepatoprotective, and neuroprotective activities. Due to being non-toxic or much less toxic than inorganic selenium compounds, Se-polysaccharides are potential dietary supplements that could be used, e.g., in chemoprevention.

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Rincon, Esther, Araceli Garcia, Antonio A. Romero, Luis Serrano, Rafael Luque et Alina M. Balu. « Mechanochemical Preparation of Novel Polysaccharide-Supported Nb2O5 Catalysts ». Catalysts 9, n^o 1 (3 janvier 2019) : 38. http://dx.doi.org/10.3390/catal9010038.

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Polysaccharides extracted from natural sources can be used as starting material for the preparation of nanoparticle supported composites. A novel family of bio-nanocomposites was mechanochemically synthesized by using niobium oxide and enzymatically produced polysaccharides. The structural, textural and surface properties of nanomaterials, were determined by X-Ray diffraction (XRD), nitrogen adsorption-desorption (N₂ porosimetry), pulse chromatography, infrared spectroscopy (ATR-IR) and dynamic light scattering (DLS). Selective oxidation of isoeugenol to vanillin was carried out to demonstrate the catalytic activity of the Nb-polysaccharides nanocomposites. Interestingly, most of our material showed high conversion of isoeugenol (60–70%) with selectivity to vanillin over 40%. The optimum conversion and selectivity were achieved with a reaction time between 8 and 24 h.

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Mikkonen, Kirsi S., Kirsti Parikka, Jussi-Petteri Suuronen, Abdul Ghafar, Ritva Serimaa et Maija Tenkanen. « Enzymatic oxidation as a potential new route to produce polysaccharide aerogels ». RSC Advances 4, n^o 23 (2014) : 11884. http://dx.doi.org/10.1039/c3ra47440b.

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Ahmed, Gamal Abdel-Whab, Khalid Suliman Khairou et Refat Moustafa Hassan. « Kinetics and mechanism of oxidation of Chitosan Polysaccharide by Permanganate Ion in Aqueous Perchlorate Solutions ». Journal of Chemical Research 2003, n^o 4 (avril 2003) : 182–83. http://dx.doi.org/10.3184/030823403103173598.

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The kinetics of oxidation of chitosan as polysaccharide by permanganate in aqueous perchlorate media at a constant ionic strength was found to have second-order overall kinetics and to be first-order in the concentration of both reactants, the results obtained showed that the reaction is acid catalysed.

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Bey, Mathieu, Simeng Zhou, Laetitia Poidevin, Bernard Henrissat, Pedro M. Coutinho, Jean-Guy Berrin et Jean-Claude Sigoillot. « Cello-Oligosaccharide Oxidation Reveals Differences between Two Lytic Polysaccharide Monooxygenases (Family GH61) from Podospora anserina ». Applied and Environmental Microbiology 79, n^o 2 (2 novembre 2012) : 488–96. http://dx.doi.org/10.1128/aem.02942-12.

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ABSTRACTThe genome of the coprophilic ascomycetePodospora anserinaencodes 33 different genes encoding copper-dependent lytic polysaccharide monooxygenases (LPMOs) from glycoside hydrolase family 61 (GH61). In this study, two of these enzymes (P. anserinaGH61A [PaGH61A] andPaGH61B), which both harbored a family 1 carbohydrate binding module, were successfully produced inPichia pastoris. Synergistic cooperation betweenPaGH61A orPaGH61B with the cellobiose dehydrogenase (CDH) ofPycnoporus cinnabarinuson cellulose resulted in the formation of oxidized and nonoxidized cello-oligosaccharides. A striking difference betweenPaGH61A andPaGH61B was observed through the identification of the products, among which were doubly and triply oxidized cellodextrins, which were released only by the combination ofPaGH61B with CDH. The mass spectrometry fragmentation patterns of these oxidized products could be consistent with oxidation at the C-6 position with a geminal diol group. The different properties ofPaGH61A andPaGH61B and their effect on the interaction with CDH are discussed in regard to the proposedin vivofunction of the CDH/GH61 enzyme system in oxidative cellulose hydrolysis.

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Kärkönen, Anna, Alain Murigneux, Jean-Pierre Martinant, Elodie Pepey, Christophe Tatout, Bernard J. Dudley et Stephen C. Fry. « UDP-glucose dehydrogenases of maize : a role in cell wall pentose biosynthesis ». Biochemical Journal 391, n^o 2 (10 octobre 2005) : 409–15. http://dx.doi.org/10.1042/bj20050800.

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UDPGDH (UDP-D-glucose dehydrogenase) oxidizes UDP-Glc (UDP-D-glucose) to UDP-GlcA (UDP-D-glucuronate), the precursor of UDP-D-xylose and UDP-L-arabinose, major cell wall polysaccharide precursors. Maize (Zea mays L.) has at least two putative UDPGDH genes (A and B), according to sequence similarity to a soya bean UDPGDH gene. The predicted maize amino acid sequences have 95% similarity to that of soya bean. Maize mutants with a Mu-element insertion in UDPGDH-A or UDPGDH-B were isolated (udpgdh-A1 and udpgdh-B1 respectively) and studied for changes in wall polysaccharide biosynthesis. The udpgdh-A1 and udpgdh-B1 homozygotes showed no visible phenotype but exhibited 90 and 60–70% less UDPGDH activity respectively than wild-types in a radiochemical assay with 30 μM UDP-glucose. Ethanol dehydrogenase (ADH) activity varied independently of UDPGDH activity, supporting the hypothesis that ADH and UDPGDH activities are due to different enzymes in maize. When extracts from wild-types and udpgdh-A1 homozygotes were assayed with increasing concentrations of UDP-Glc, at least two isoforms of UDPGDH were detected, having Km values of approx. 380 and 950 μM for UDP-Glc. Leaf and stem non-cellulosic polysaccharides had lower Ara/Gal and Xyl/Gal ratios in udpgdh-A1 homozygotes than in wild-types, whereas udpgdh-B1 homozygotes exhibited more variability among individual plants, suggesting that UDPGDH-A activity has a more important role than UDPGDH-B in UDP-GlcA synthesis. The fact that mutation of a UDPGDH gene interferes with polysaccharide synthesis suggests a greater importance for the sugar nucleotide oxidation pathway than for the myo-inositol pathway in UDP-GlcA biosynthesis during post-germinative growth of maize.

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Gonzalez Toledo, Selene Yadira, et Jianping Wu. « Impact of Adding Polysaccharides on the Stability of Egg Yolk/Fish Oil Emulsions under Accelerated Shelf-Life Conditions ». Molecules 26, n^o 13 (30 juin 2021) : 4020. http://dx.doi.org/10.3390/molecules26134020.

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Polysaccharides can form interfacial complexes with proteins to form emulsions with enhanced stability. We assessed the effect of adding gum guar or gum arabic to egg yolk/fish oil emulsions. The emulsions were produced using simple or high-pressure homogenization, stored for up to 10 days at 45 °C, and characterized for their particle size and distribution, viscosity, encapsulation efficiency, oxidative stability, and cytotoxicity. Emulsions containing gum guar and/or triglycerides had the highest viscosity. There was no significant difference in the encapsulation efficiency of emulsions regardless of the polysaccharide used. However, emulsions containing gum arabic displayed a bridging flocculation effect, resulting in less stability over time compared to those using gum guar. Emulsions produced using high-pressure homogenization displayed a narrower size distribution and higher stability. The formation of peroxides and propanal was lower in emulsions containing gum guar and was attributed to the surface oil. No significant toxicity toward Caco-2 cells was found from the emulsions over time. On the other hand, after 10 days of storage, nonencapsulated fish oil reduced the cell viability to about 80%. The results showed that gum guar can increase the particle stability of egg yolk/fish oil emulsions and decrease the oxidation rate of omega-3 fatty acids.

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Shen, Mingyue, Ruixin Cai, Zhedong Li, Xiaodie Chen et Jianhua Xie. « The Molecular Mechanism of Yam Polysaccharide Protected H2O2-Induced Oxidative Damage in IEC-6 Cells ». Foods 12, n^o 2 (6 janvier 2023) : 262. http://dx.doi.org/10.3390/foods12020262.

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Oxidative stress is involved in maintaining homeostasis of the body, and an in-depth study of its mechanism of action is beneficial for the prevention of chronic illnesses. This study aimed to investigate the protective mechanism of yam polysaccharide (CYP) against H2O2-induced oxidative damage by an RNA-seq technique. The expression of genes and the function of the genome in the process of oxidative damage by H2O2 in IEC-6 cells were explored through transcriptomic analysis. The results illustrated that H2O2 damaged cells by promoting cell differentiation and affecting tight junction proteins, and CYP could achieve cell protection via restraining the activation of the MAPK signaling pathway. RNA-seq analysis revealed that H2O2 may damage cells by promoting the IL-17 signaling pathway and the MAPK signaling pathway and so forth. The Western blot showed that the pretreatment of CYP could restrain the activation of the MAPK signaling pathway. In summary, this study demonstrates that the efficacy of CYP in modulating the MAPK signaling pathway against excessive oxidative stress, with a corresponding preventive role against injury to the intestinal barrier. It provides a new perspective for the understanding of the preventive role of CYP on intestinal damage. These findings suggest that CYP could be used as oxidation protectant and may have potential application prospects in the food and pharmaceutical industries.

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