Unmodified Polysaccharides Research Articles

Low Fouling Marine Coatings Based on Nitric Oxide-Releasing Polysaccharide-Based Hybrid Materials

Diethylenetriamine-modified heparin and alginates as well as unmodified polysaccharides were combined using sol–gel chemistry to construct hybrid material thin-film coatings. Due to the high density of amine groups, the hybrid material coatings are capable of binding nitric oxide when exposed to NO at elevated pressures, which were characterized by UV–Vis and ATR-FTIR spectroscopy. When exposed to aqueous environments, the hybrid material coatings showed nitrogen oxide release rates between 17 and 30 pmol·cm–2·s–1. Marine antifouling properties were tested against the marine bacterium Cobetia marina and the diatom Navicula perminuta. The diatom assays revealed a lower settlement on the nitric oxide-loaded hybrid materials compared to hybrid materials without nitrogen oxide release. All coatings readily suppressed attachment of the marine bacterium C. marina. The advantages of hybrid materials, composed purely of polysaccharides and siloxanes, are that their building blocks are environmentally friendly, biodegradable, and biocompatible. This makes them interesting candidates for environmentally benign marine protective coating applications. In particular, the binding of nitric oxide and release of nitrogen oxide species as naturally occurring signaling molecules were found to be promising mechanisms to add additional fouling inhibiting functionality to deter marine organisms from settlement.

Acetylation Modification, Characterization, and Anticomplementary Activity of Polysaccharides from Rhododendron dauricum Leaves.

This study focuses on the acetylation modification of polysaccharides from Rhododendron dauricum leaves (RDPs) with a high degree of substitution (DS) and then discusses their characterization and biological activity. The optimum acetylation conditions of RDPs were optimized by response surface methodology, which were reaction time 3 h, reaction temperature 50 °C, and the liquid-solid ratio 16 mL/g. Under the optima schemes, two eco-friendly acetylated polysaccharides from R. dauricum leaves (AcRDP-1 with DS of 0.439 ± 0.025 and AcRDP-2 with DS of 0.445 ± 0.022) were prepared. The results of structural characterization showed that the AcRDP-1 (9.3525 × 103 kDa) and AcRDP-2 (4.7016 × 103 kDa) were composed of mannose, glucose, galactose, and arabinose with molar ratios of 1.00:5.01:1.17:0.15 and 1.00:4.47:2.39:0.88, respectively. Compared with unmodified polysaccharides, the arabinose content and molecular weight of the two acetylated polysaccharides decreased, and their triple helix conformation disappeared, and further improved their anticomplementary activity. The two acetylated polysaccharides showed stronger a complement inhibition effect than the positive drug by blocking C2, C3, C4, C5, C9, and factor B targets in the classical and alternative pathways. This research indicated that acetylation modification could effectively enhance the anticomplementary activity of RDPs, which is beneficial for the development and utilization of R. dauricum leaves.

Facile Preparation of Polysaccharide-Polypeptide Conjugates via a Biphasic Solution Ring-Opening Polymerization.

Polysaccharide-polypeptide conjugates have gained a broad interest in mimicking the structure and bioactivity of peptidoglycans or proteoglycans for biomedical applications. Efficient and precise preparation of the conjugates is challenging and unresolved, mainly because of the mismatched solubility between polysaccharide initiators and N-carboxyanhydrides (NCAs), which frequently results in competing side reactions and oligomeric polypeptide chain. Herein, we report a facile and efficient strategy to prepare the conjugates with well-controlled polypeptide chain length (lp) directly from unmodified polysaccharides via a biphasic solution ring-opening polymerization. The effect of lp on surface antibacterial properties has been investigated. Elongating the lp can significantly potentiate the antibiofilm property of the conjugate coatings. Our results may provide opportunities to develop various polypeptide-based conjugates with well-defined structures toward versatile uses.

Structure characterization and antioxidant activity of carboxymethylated polysaccharide from Pholiota nameko.

The objective of this paper was to prepare the carboxymethyl polysaccharide of Pholiota nameko (CPPN) and further evaluate its structural characteristics, water solubility, and antioxidant activities. The optimal carboxymethylation conditions were as follows: 20% NaOH concentration, 1.5hr alkalization, 4hr etherification time, and 60°C with 2g chloroacetic acid. Under these conditions, a substitution degree of 0.72 and a yield of 88.3% were achieved. The results of NMR and FT-IR spectra showed that carboxymethylation modification was successful. The protein, total sugar, and total phenol content decreased, while the molecular weight increased, and the monosaccharide composition content and surface structure changed upon carboxymethylation. Compared with unmodified polysaccharides, CPPN had significant antioxidant activity and water solubility. Thus, this study could provide a potential antioxidant for functional foods and pharmaceuticals. PRACTICAL APPLICATIONS: Pholiota nameko is an edible and medicinal mushroom, rich in carbohydrates, cellulose, and minerals. Pharmacological studies have shown that P. nameko polysaccharides have many medicinal effects on the human body. In this study, CPPN was synthesized by carboxymethylation of P. nameko polysaccharides. Through structural characterization, antioxidant activity, and solubility studies, carboxymethylated polysaccharides shown significant antioxidant properties and increased solubility. Therefore, this research lays the foundation for the high-value application of P. nameko polysaccharides in functional food and pharmaceutical industry.

Preparation, structure characterization of carboxymethylated schisandra polysaccharides and their intervention in immunotoxicity to polychlorinated biphenyls

Carboxymethylation is a well-known modification process for polysaccharides. To evaluated structural features and biological availability of carboxymethyl, carboxymethylated schisandra polysaccharides (CSP) was synthesized using an optimized chloroacetic acid /NaOH method. Optimal modification parameters were reaction temperature of 62.67 ℃, reaction time of 4.27 h, and 0.83 g chloroacetic acid. The main fraction of CSP (CSPP) was obtained by purification using DEAE-52 column. Chemical analysis indicated that CSPP contained carboxymethyl groups with a Mw of 1.698 × 104 g/mol and degree of substitution of 0.88 and composed of mannose, glucose and galactose at ratio of 1: 44.8: 3.7. Moreover, CSPP have improved water solubility (12.56 ± 0.04 mg/mL) and existed as a slight extended flexible chain. CSPP exhibited higher immunomodulating activities to polychlorinated biphenyl-126 (PCB126) -exposure mice than unmodified polysaccharide, as shown by improving PCB 126-induced reduction of body weight gain and atrophy of the immune organ, diminishing PCB126-induced inhibition of cytokines production and reversing damage of spleen caused by oxidative stress in PCB126-treated mice. It could be concluded that introduction of carboxymethyl groups to polysaccharide can alter its physicochemical characteristic to enhance its immunoregulatory activity. This study suggested that CSPP potentially serve as an effective nutritional intervention agent to reverse the PCB126-induced immunosuppression.

Immunoregulatory activities of the selenylated polysaccharides of Lilium davidii var. unicolor Salisb in vitro and in vivo

Studies have demonstrated that the modification of selenylation can improve the activity of polysaccharides. Lilium davidii var. unicolor Salisb (known as “lily bulb”) is the dried succulent bulb of the genus Lilium in the family Liliaceae. We wished to investigate the immunoregulatory activities of the selenized polysaccharides of lily bulb (sLP). We undertook experiments in vitro and in vivo taking the unmodified polysaccharides of lily bulb (LP) as controls. The results of in vitro studies showed that sLP could promote the phagocytosis of RAW 264.7 cells significantly, increase the content of interleukin (IL)-1β and IL-2, enhance the activity of acid phosphatase, and increase the surface molecular expression of CD86 and CD80. The results of in vivo studies showed that sLP could improve the index of immune organs, increase the contents of interferon-γ, IL-6, immunoglobulin (Ig)G and IgM in serum, and promote lymphocyte proliferation. The immunoregulatory activities of sLP were significantly more robust than those of LP in vitro and in vivo. These results indicated that selenylation could enhance the immune-enhancement activity of LP significantly.

Preparation, characterization, antioxidant activity and protective effect against cellular oxidative stress of phosphorylated polysaccharide from Cyclocarya paliurus

In this study, a phosphorylated derivative of Cyclocarya paliurus polysaccharide (CP) was synthesized using sodium tripolyphosphate and sodium trimetaphosphate. Antioxidant activities and cytoprotective effects of unmodified polysaccharide and phosphorylated derivatives were investigated employing various in vitro systems. Results showed that phosphorylated modification caused a significant change in chemical composition and the apparent structure of CP. Phosphorylated Cyclocarya paliurus polysaccharide (P-CP) showed excellent scavenging capacities against DPPH and hydroxyl radical in a dose-dependent manner. P-CP provided a more significant protective effect against hydrogen peroxide-induced oxidative stress in RAW264.7 cells by a compositive oxidation defense mechanism than CP. P-CP could reduce oxidative stress by significantly enhancing the contents of antioxidant enzyme superoxide dismutase (SOD) and decreasing malondialdehyde (MDA) content in oxidative damaged cells, in addition to scavenging ROS directly and regulating cell cycle distribution, reducing apoptosis capacity and improving cell viability, consequently achieving the intracellular antioxidant activity. This study suggested that phosphorylated modification is an effective method to improve the antioxidant activities of CP, so as to expand the development and application of CP.

Understanding hemicellulose-cellulose interactions in cellulose nanofibril-based composites

Plant-based polysaccharides (cellulose and hemicellulose) are a very interesting option for the preparation of sustainable composite materials to replace fossil plastics, but the optimum bonding mechanism between the hard and soft components is still not well known. In this work, composite films made of cellulose nanofibrils (CNF) and various modified and unmodified polysaccharides (galactoglucomannan, GGM; hydrolyzed and oxidized guar gum, GGhydHox; and guar gum grafted with polyethylene glycol, GG-g-PEG) were characterized from the nano- to macroscopic level to better understand how the interactions between the composite components at nano/microscale affect macroscopic mechanical properties, like toughness and strength. All the polysaccharides studied adsorbed well on CNF, although with different adsorption rates, as measured by quartz crystal microbalance with dissipation monitoring (QCM-D). Direct surface and friction force experiments using the colloidal probe technique revealed that the adsorbed polysaccharides provided repulsive forces–well described by a polyelectrolyte brush model – and a moderate reduction in friction between cellulose surfaces, which may prevent CNF aggregates during composite formation and, consequently, enhance the strength of dry films. High affinity for cellulose and moderate hydration were found to be important requirements for polysaccharides to improve the mechanical properties of CNF-based composites in wet conditions. The results of this work provide fundamental information on hemicellulose-cellulose interactions and can support the development of polysaccharide-based materials for different packaging and medical applications.

Study of the selenizing Codonopsis pilosula polysaccharides protects RAW264.7 cells from hydrogen peroxide-induced injury

Codonopsis pilosula polysaccharides (CPPS) has been shown to possess a variety of biological activities. In previous study, CPPS was successfully modified to obtain its best selenizing Codonopsis pilosula polysaccharides (sCPPS5). The purpose of this study was to investigate the protective effect of the selenizing derivative of CPPS (sCPPS5) from H2O2-induced oxidative damage in RAW264.7 murine macrophages and the possible mechanism of this protection. Results showed that the sCPPS5 was significantly stronger than that of the corresponding unmodified polysaccharide, CPPS. Meanwhile, sCPPS5 treatment could improve the production of reactive oxygen species (ROS), antioxidant enzyme, MMP, caspases-3 and apoptosis capacity of H2O2-induced RAW264.7 cells. Moreover, the mechanism might be elucidated that sCPPS5 could increase expression level of Nrf2 and its downstream ARE gene battery, promote production of corresponding antioxidative enzymes and protein, and enhance Keap1-Nrf2/ARE signaling pathway to avoid male reproductive dysfunction. Overall, these results showed that sCPPS5 as a potent antioxidant could reduce reproductive oxidative stress damage related to Keap1-Nrf2/ARE pathway.

Immunomodulatory effects of hydroxyethylated Hericium erinaceus polysaccharide on macrophages RAW264.7

Hericium erinaceus polysaccharide (HEP) has been shown to possess a variety of biological activities. In present study, HEP was successfully modified to obtain its hydroxyethylated derivative hHEP. Its potential immunomodulatory activities on RAW264.7 macrophages were investigated. Results showed that the hHEP were significantly stronger than that of the corresponding unmodified polysaccharide, HEP. Meanwhile, the NO, IL-6 and TNF-α production activities of macrophages were enhanced in the RAW264.7 macrophages by stimulation of hHEP. In addition, the hHEP increase significantly higher iNOS expression than HEP. These results indicated that the hydroxyethylated derivative hHEP could enhance the activation of peritoneal macrophages, and hydroxyethylation modification can enhance the immunomodulation function of HEP.

Mucoadhesive properties of low molecular weight chitosan- or glycol chitosan- and corresponding thiomer-coated poly(isobutylcyanoacrylate) core-shell nanoparticles

The aim of the present work was to evaluate the mucoadhesive properties of poly(isobutyl cyanoacrylate) (PIBCA) nanoparticles (NPs) coated with Low Molecular Weight (LMW) chitosan (CS)- and glycol chitosan (GCS)-based thiomers as well as with the corresponding LMW unmodified polysaccharides. For this purpose, all the CS- and GCS-based thiomers were prepared under simple and mild conditions starting from the LMW unmodified polymers CS and GCS. The resulting NPs were of spherical shape with diameters ranging from 400 to 600nm and 187 to 309nm, for CS- and GCS-based NPs, respectively. The mucoadhesive characteristics of these core shell NPs were studied in Ussing chambers measuring the percentage of NPs stuck on the mucosal of fresh intestinal tissue after 2h of incubation. Moreover, incubation of nanoparticle formulations with the intestinal tissue induced changes in transmucosal electrical resistance which were measured to gain information into the opening of tight junctions and to control the integrity of the mucosa. Thus, it was found that PIBCA NPs coated with the GCS–Glutathione conjugate (GCGPIBCA NPs) possessed the most favorable mucoadhesive performances. Moreover, both GCGPIBCA- and GCS-N-acetyl-cysteine (GCNPIBCA)-core-shell NPs might induced an enlargement of the epithelial cell tight junctions. In conclusion, coating of PIBCA NPs with GCS-based thiomers may be useful for improving the mucoadhesive and permeation properties of these nanocarriers.

Immunomodulatory effects of an acetylated Cyclocarya paliurus polysaccharide on murine macrophages RAW264.7

Polysaccharides (CP) extracted from the leaves of Cyclocarya paliurus (C. paliurus) have been shown to possess a variety of biological activities. In present study, CP was successfully modified to obtain its acetylated derivative Ac-CP. Its potential immunomodulatory activities on RAW264.7 macrophages were investigated. Results showed that the acetylated polysaccharide Ac-CP could significantly stimulate macrophage proliferation, its actions were significantly stronger than that of the corresponding unmodified polysaccharide, CP. Meanwhile, the NO production activities of macrophages were not significantly enhanced by Ac-CP compared to CP group. In addition, both the phagocytic activity and levels of cytokines TNF-a, IL-1β and IL-6 were enhanced in the RAW264.7 macrophages by stimulation of Ac-CP. These results indicated that the acetylated derivative Ac-CP could enhance the activation of peritoneal macrophages, and acetylation modification can enhance the immunomodulation function of CP, indicating the potential application of acetylated polysaccharide as an immunotherapeutic adjuvant.

Conformational analysis of sulfated and unmodified levan polysaccharides via molecular dynamics simulations

Conformational analysis of sulfated and unmodified levan polysaccharides via molecular dynamics simulations

Carboxymethylation of polysaccharide from Cyclocarya paliurus and their characterization and antioxidant properties evaluation

In this study, three chemically carboxymethyl polysaccharides (CM-CPs) were derived from Cyclocarya paliurus polysaccharides. The physicochemical properties and antioxidant activity in vitro of carboxymethyl derivatives were determined. The results of degree of substitution and FT-IR analysis showed the carboxymethylation of polysaccharides were successful. Compared with unmodified polysaccharides, the contents of carbohydrate and protein were decreased while CM-CP3 with highest DS value had more uronic acid. The carboxymethyl derivatives was mainly composed of Ara, Gal, Glc, Man, GalA, with a molecular weight (Mw) of 1.03–1.08×106Da. Compared with the native polysaccharide, the CM-CP3 with highest DS and Mw exhibited the highest antioxidant activity in β-carotene–linoleic acid assay. However, the superoxide radical and hydroxyl radical scavenging activity were decreased by CM-CPs. These results demonstrated appropriate carboxymethylation modification could enhance the potential of C. paliurus polysaccharide as oxidation inhibitor.

Effect of phosphorylation on antioxidant activities of pumpkin (Cucurbita pepo, Lady godiva) polysaccharide

Phosphorylated derivatives of pumpkin polysaccharide with different degree of substitution were synthesized using POCl3 and pyridine. Antioxidant activities and cytoprotective effects of unmodified polysaccharide and phosphorylated derivatives were investigated employing various in vitro systems. Results showed that high ratio of POCl3/pyridine could increase the degree of substitution and no remarkable degradation occurred in the phosphorylation process. Characteristic absorption of phosphorylation appeared both in the IR and 31P NMR spectrum. The df values between 2.27 and 2.55 indicated the relatively expanded conformation of the phosphorylated derivatives. All the phosphorylated polysaccharides exhibited higher antioxidant activities. H2O2-induced oxidative damages on rat thymic lymphocyte were also prevented by the derivatives. In general, phosphorylation could improve the antioxidant activities of pumpkin polysaccharide both in vitro and in a cell system.

Preparation, characterization and antioxidant activities of acetylated polysaccharides from Cyclocarya paliurus leaves

In this study, polysaccharides extracted from Cyclocarya paliurus leaves were modified to obtain its three acetylated derivatives, Ac-CP1, Ac-CP2, and Ac-CP3. The physicochemical characteristics and antioxidant activities of acetylated derivatives were investigated. The results of chemical and FT-IR spectrum analysis showed differences between acetylated derivatives and native C. paliurus polysaccharide, which revealed that the acetylation were successful. Relative to unmodified polysaccharide, the protein contents of acetylated derivatives decreased, while carbohydrate values increased. The molecular weight (Mw) of acetylated derivatives were approximately 1.05–1.09×106Da and were mainly composed of Ara, Gal, Glc, Man, GalA. Ac-CP1 with relatively low degree of substitution (0.13±0.01) exhibited excellent antioxidant activity in DPPH radical assay (95.21±0.89%), and also had strong chelating activity on β-carotene–linoleic acid assay (34.64±2.07%) at 0.5mg/ml. In addition, scanning electron microscope (SEM) observations suggested that acetylation could change the morphology and structure of polysaccharides from C. paliurus leaves.

Molecular simulation of model sulfated polysaccharides of low molecular weight from Ganoderma lucidum and their interaction with human serum albumin

The extracellular polysaccharides from Ganoderma lucidum possess low molecular weight and are mainly composed of (1 → 3)/(1 → 6) linked-α-glucan and (1 → 3)/(1 → 6) linked-α-galactose. In the present study, conformations of the polysaccharides were simulated and investigated using Discovery studio 2.5. Their sulfated derivatives were also taken into account. The simulation was performed using CHARMM force field. The results show that the polysaccharides exist as random coil conformations, while the sulfated derivatives adopt more extensive and stiffer conformations in most cases. In addition, the molecular docking between polysaccharide and human serum albumin (HSA) was also investigated using ZDOCK module in Discovery studio 2.5. It is shown that the unmodified polysaccharide possesses higher affinity with HSA than the sulfated derivatives do due to its higher ZDOCK score.

Stabilization of pluronic gels in the presence of different polysaccharides

ABSTRACTSeveral different polysaccharides have been added to pluronic F127 (poloxamer 407) gels to test their ability to stabilize the gels against dissolution in aqueous media over time. The studied polysaccharides include κ‐carrageenan, chitosan, hyaluronic acid, pectin, alginate, hydroxyethylcellulose, and ethyl(hydroxyethyl)cellulose. Although all the considered polysaccharides slowed down the dissolution time of the pluronic gels, unmodified polysaccharides only had a modest stabilization effect. However, hydrophobic modification of polysaccharides with a sufficiently long hydrocarbon chain (C16) was found to partly prevent the gels from dissolving for more than 6 months. Shorter hydrocarbon chains did not have the same effect, even at high degrees of hydrophobicity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40465.

Facile grafting of bioactive cellulose derivatives onto PVC surfaces

Bioactive methyl cellulose and hydroxyethyl cellulose were successfully grafted onto PVC films using a two-step pathway. PVC surface was first modified with isothiocyanate in DMSO/water medium. Then, unmodified polysaccharides were directly grafted onto the thiocyanated surface in acetonitrile/DMSO mixture, in presence of DBTL as catalyst. The polysaccharide grafting onto the PVC surface was evidenced by contact angle measurements, AFM and XPS.

Effect of acetylation on antioxidant and cytoprotective activity of polysaccharides isolated from pumpkin (Cucurbita pepo, lady godiva)

Acetylation of pumpkin (Cucurbita pepo, lady godiva variety) polysaccharide using acetic anhydride with pyridines as catalyst under different conditions was conducted to obtain different degrees of acetylation on a laboratory scale. Furthermore, antioxidant activities and cytoprotective effects of pumpkin polysaccharide and its acetylated derivatives were investigated employing various established in vitro systems. Results showed that addition of pyridine as catalyst could increase the degree of substitution, whereas volume of acetic anhydride had little effect. The acetylated polysaccharides in DPPH scavenging radical activity assay, superoxide anion radical activity assay and reducing power assay exhibited higher antioxidant activity than that of unmodified polysaccharide. H2O2-induced oxidative damages on rat thymic lymphocyte were also prevented by pumpkin polysaccharide and its acetylated derivatives and the derivatives presented higher protective effects. On the whole, acetylated polysaccharide showed relevant antioxidant activity both in vitro and in a cell system.