Search

Polysaccharides have been extensively studied in recent decades. Their conjugation with phenolic compounds of natural origin has demonstrated high added value, not only enhancing certain inherent properties but also introducing new ones. Recently, a sustainable approach utilizing oxidoreductase enzymes (Oxredases) (laccases (Lac), tyrosinases (Tyr) and peroxidases (Per)) has been employed, and interesting progress has been made. This review aims to provide a comprehensive understanding of the various Oxredases employed and the reaction mechanisms involved in the grafting of phenolic compounds (PCs) onto polysaccharides (PSs). We provide a detailed analysis of these reaction mechanisms based on modified polymer structural analysis techniques and supported by model reactions. The impacts of different reaction parameters on the final products are thoroughly discussed. Additionally, the properties of conjugated PS-PC are extensively explored to provide an overview of their physicochemical and functional behaviours. A comparison of the PS-PC conjugates obtained via the Oxredase approach and other existing chemical- and radical-mediated approaches is also presented, emphasizing the benefits of this enzymatic pathway. Finally, a critical analysis is proposed to identify areas of improvement, aiming to further refine this environmentally friendly approach for conjugating PSs and PCs and its scalability for industrial applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Allium roseum is amongst the most important wild medicinal plants. It is known for its diverse biological properties, including antioxidant, antibacterial and antidiabetic activities. In this work, the polysaccharides (PARLs) were ultrasonically extracted from Allium roesum leaves then purified and analyzed by several techniques. Chemical composition and GC-MS analysis showed that the obtained polysaccharides were composed mainly of glucose (40.20 %), mannose (25.30 %), fructose (10.60 %) and galacturonic acid (15.11 %). Moreover, PARLs exhibited a potent antioxidant effect with higher capacities up to 69.61 % and 71.72 % for DPPH and ABTS free radicals, respectively. Furthermore, PARLs significantly modulated inflammatory response by reducing TNF-α, IL-6, and IL-8 pro-inflammatory mediators and promoting the anti-inflammatory IL-10 mediator in LPS stimulated THP-1 derived macrophages. The in-vivo tests proved that the extract was able to decrease carrageenan-induced rat paw swelling by around 68.15 % after 4 h of treatment. PARLs, significantly reduced the growth of U87 (glioblastoma) and IGROV-1 cancer cells with IC 50 values of about 4.27 and 7.89 mg/mL respectively. This research clearly shows that Allium roseum polysaccharides can be used as natural antioxidants with anti-inflammatory and anticancer properties., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The fishing and aquaculture industries generate a huge amount of waste during processing and preservation operations, especially those of tuna. Recovering these by-products is a major economic and environmental challenge for manufacturers seeking to produce new active biomolecules of interest. A new hyaluronic acid was extracted from bluefin tuna's vitreous humour to assess its antioxidant and pharmacological activities. The characterization by infrared spectroscopy (FT-IR), nuclear magnetic resonance (( 1 D 1 H) and 2D ( 1 H COSY, 1 H/ 13 C HSQC)) and size exclusion chromatography (SEC/MALS/DRI/VD) revealed that the extracted polysaccharide was a hyaluronic acid with high uronic acid content (55.8 %) and a weight average molecular weight of 888 kDa. This polymer possesses significant anti-radical activity and ferrous chelating capacity. In addition, pharmacological evaluation of its anti-inflammatory and analgesic potential, using preclinical models, in comparison with reference drugs (Dexamethasone, diclofenac, and acetylsalicylate of lysine), revealed promising anti-inflammatory activity as well as interesting peripheral and central antinociceptive activity. Therefore, our new hyaluronic acid compound may therefore serve as a potential drug candidate for the treatment of pain sensation and inflammation of various pathological origins., Competing Interests: Declaration of competing interest I declare that there are no conflicts of interest associated with this work. We have no financial or personal relationships with any individuals or organizations that could influence our work or the interpretation of the data., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Marine algae are the most abundant resource in the marine environment and are still a promising source of bioactive compounds including hydrocolloids. This study contributes to the evaluation of the biological and biotechnological potentials of two water soluble polysaccharides, namely alginates (AHS) and fucoidan (FHS), extracted and purified from Halopteris scoparia, an abundant Tunisian brown macroalgae collected in Tunisia (Tabarka region). The total sugars, neutral monosaccharides, uronic acids, proteins, polyphenols, and sulfate groups contents were quantified for both fractions, as well as their functional groups and primary structural features by Fourier transform infrared spectroscopy, ionic and/or gas chromatography and nuclear magnetic resonance analyses. AHS and FHS showed significant anti-inflammatory (IC 50  ≈ 1 mg/mL), anticoagulant (e.g., 27-61.7 for the activated partial thromboplastin time), antihyperglycemic (0.1-40 μg/mL) and anti-trypsin (IC 50  ≈ 0.3-0.4 mg/mL) effects. FHS and a hydrolyzed fraction showed a very promising potential against herpes viruses (HSV-1) (IC 50  < 28 μg/mL). Besides, AHS and two hydrolyzed fractions were able to stimulate the natural defenses of tomato seedlings, assessing their elicitor capacity, by increasing the activity of phenylalanine ammonia-lyase (66-422 %) but also significantly changing the polyphenol content in the leaves (121-243 %) and roots (30-104 %) of tomato plants., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Guillaume Pierre reports financial support was provided by Campus France. Slim Abdelkafi reports financial support was provided by Tunisian Ministry of Higher Education and Scientific Research., (Copyright © 2023 Elsevier B.V. All rights reserved.)

This paper describes the structural elucidation of Leuconostoc mesenteroides P35 exopolysaccharide (EPS-LM). Ln. mesenteroides P35 strain was isolated from a French goat cheese for its capacity to produce EPS increasing the viscosity of a whey-based fermentation medium. The chemical structure of EPS-LM analysis was elucidated by determination of optical rotation degree, macromolecular characterization, sugar units and methylation analyses, FT-IR, 1D NMR spectroscopy ( 1 H and 13 C NMR), 2D NMR spectroscopy ( 1 H 1 H COSY, HSQC and HMBC). EPS-LM was a high molecular weight (ranging from 6.7 × 10 6  Da to 9.9 × 10 6  Da) dextran that is composed of only d-glucose units containing α (1 → 6) linkages and paltry α (1 → 3) branches. Since polysaccharide-protein interactions can be exploited to control and design food matrices, EPS-LM interactions with bovine serum albumin (the main constituent of bovine plasma) were investigated by surface plasmon resonance (SPR). Kinetic properties of EPS-LM binding with immobilized BSA via showed an increase of EPS-LM affinity (equilibrium constant (K d )) for BSA from (2.50 ± 0.01) × 10 -5  M -1 at 298 K to (9.21 ± 0.05) × 10 -6  M -1 at to 310 K. The thermodynamic parameters revealed that van der Waals and hydrogen binding forces play a major role in the interaction of EPS-LM with BSA. However, EPS-LM-BSA interaction was non-spontaneous, entropy driven and an EPS-LM - BSA binding process was endothermic (ΔG > 0). The structural findings suggested that Ln. mesenteroides P35 α-D-glucan might find widespread technological applications in the biopolymer, medical and food industries., Competing Interests: Declaration of competing interest The authors confirm that they have no conflicts of interest with respect to the work described in this manuscript., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Gelatin (G) cross-linked with oxidized pectin (OP) was studied as a potential scaffold material for tissue engineering. The effect of oxidation on the chemical properties of pectin was investigated by determining the carbonyl and carboxyl amounts. The OP treatment led to a significant decrease of all values (Mn, Mw, [η] and Rh) determined by size exclusion chromatography (SEC) coupled on line with multiangle light scattering and viscometer detectors. Cross-linking parameters were elucidated by FTIR and TNBS assay. In general, the degree of crosslinking increased with the oxidation of pectin. It was found that the presence of the crosslinking agents caused a reduction in swelling and in the gelatin release which was determined by the BCA kit assay. From the hemolysis test, the membrane of red blood cells was not disrupted by the contact of films and the rate of release of hemoglobin was lower than 5%. The coagulation properties were evaluated by the dynamic blood clotting test. The G/OP hydrogels manifested a good activity of wound healing in the albino rats' model. Moreover, the films did not produce any unwilling symptoms. So, it was concluded that studied films have the potentiality to be used as wound healing biomaterials., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Accurate determinations of particle size and particle size distribution (PSD) are essential to achieve the clinical translation of medical nanoparticles (NPs). Herein, dextran-based NPs produced via a water-in-oil emulsification/crosslinking process and developed as nanomedicines were studied. NPs were first characterized using traditional batch-mode techniques as dynamic light scattering (DLS) and laser diffraction. In a second step, their analysis by frit-inlet asymmetrical flow field-flow fractionation (FI-AF4) was explored. The major parameters of the AF4 procedure, namely, crossflow, detector flow, crossflow decay programming and relaxation time were set up. The sizes of the particle fractions eluted under optimized conditions were measured using DLS as an online detector. We demonstrate that FI-AF4 is a powerful method to characterize dextran-NPs in the 200 nm -1 µm range. It provided a more realistic and comprehensive picture of PSD, revealing its heterogenous character and clearly showing the ratio of different populations in the sample, while batch-mode light scattering techniques only detected the biggest particle sizes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A Box-Behnken design was used to optimize extraction temperature, extraction time and concentration of the salicylic acid to obtain a maximum polysaccharide yield from Citrus sinensis peels. The optimal settings were: extraction time 3 h, extraction temperature 80 °C and concentration of the salicylic acid 1.5%. Under these conditions, the experimental yield and uronic acid content were 11.74% and 66.9% respectively. Preliminary characterization was performed via FT-IR, SEC/MALS/VD/DRI and GC-MS after hydrolysis. SEC analysis showed that the extracted polysaccharide had a weight average molar mass of 350 kDa and an intrinsic viscosity of 640 mL/g. The GC-MS results revealed that the extracted polysaccharide was composed of arabinose 56.7%, galactose 17.8%, xylose 13.8%, rhamnose 5.1%, mannose 2.5% and glucose 1.5% suggested a rhamnogalacturonan pectin type I with a degree of esterification of 50.9% (IRTF). The flow curve and the dynamic frequency sweep were obtained at 10, 20, 30 and 40 g/L in water and at 30 g/L in presence of CaCl 2 or NaCl at 1 mol/L. The solutions showed shear-thinning behavior fitted with Ostwald-De Waele model, except 10 g/L with a Newtonian behavior. The apparent viscosity and, the G' and G" moduli increase with PACO concentration in agreement with a slow-down of the dynamic chain. In the presence of CaCl 2 or NaCl the reduction of electrostatic repulsions between pectin chains decreases the rheological parameters. The effect is less sensitive with CaCl 2 due to intermolecular interactions. The antiproliferative activity of the extracted pectin on human Caco-2 and Hep-2 cells was very interesting with an IC 50 1.4 and 1.8 μg/mL respectively., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A water-soluble polysaccharide (PSPC) was extracted from the seeds of Plantago ciliata Desf., a spontaneous Algerian Saharan plant by a hot aqueous extraction then purified by successive ethanolic precipitations. The final extraction yield for PSPC was close to 18.6% (w/v). PSPC was then investigated regarding its global composition, structural features and rheological properties. PSPC is a neutral arabinoxylan, composed of a β-(1,3)/β-(1,4)-d-xylan backbone with side chains of Xylp, and Araf residues attached in O-2 and O-3 positions. The macromolecular characteristics of PSPC in water was determined by SEC/MALLS, with a high molecular weight (Mw) of 700 kDa, a low polydispersity index (PDI) of 1.47 and an intrinsic viscosity [η] close to 157 mL/g. PSPC showed a pseudoplastic behavior in semi-dilute media and the critical overlay concentration (C*) was estimated around 0.32-0.37% (w/v). This current research has supplied original structural information on a new arabinoxylan which could be particularly useful as a novel source of soluble fiber belonging to psyllium., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Spinacia is an interesting medicinal halophyte plant that is employed as a food and therapeutic agent in traditional medicine. In this work, water-soluble polysaccharides from Spinacia oleracea were extracted and preliminary characterization was established via FT-IR, UV-vis, 1 H NMR and SEC/MALS DRI technics. The extracted polysaccharide, with an average molecular mass of 408 kDa, was composed of arabinose, galactose, mannose, glucose, rhamnose and xylose in the molar percentage of 49.3%, 28.1%, 4.9%, 7.8%, 8.2% and 1.7%, respectively. The polysaccharide showed significant antioxidant activity. Moreover, Spinacia polysaccharide, significantly prevented oxidation-induced Cd damage and exhibited a protective effect against Cd cytotoxicity on HEK293 and HCT116 cells, with an important cell viability decrease, an important reduction of MDA production and ROS levels. The outcomes obtained suggest that the Spinacia polysaccharides may be used as an accessible source of natural antioxidants and as potential phytochemicals against kidney and colon cancer., (Copyright © 2019 Elsevier B.V. All rights reserved.)

As a health-beneficial fruit, watermelon is widely consumed by people around the world. However, components responsible for the health benefits are not yet determined. As watermelon contains a large amount of polysaccharides, these carbohydrates might play an important role in the health benefits. In this work, polysaccharide from watermelon rinds (PWR) was extracted by papain digestion, purified and characterized by GC-MS, SEC/MALS/VD/DRI, FTIR and 1D and 2D NMR which revealed the glycosidic linkages, their locations in branches and backbone. The monosaccharide composition revealed that the extracted polysaccharide was composed of galactose (38.26%), arabinose (26.12%), rhamnose (17.86%), mannose (9.94%), xylose (5.10%) and glucose (2.70%) with a percentage of uronic acid of 45%. A combination of CPG and NMR analysis showed that the extracted polysaccharide is arabinogalactan linked to type I rhamnogalacturonan. we notice that the arabinogalactan was formed by →6)-β-D-Galp-(1→ as backbone with short branching of arabinose linked in α 1 → 3, rhamnose linked in α 1 → 4, mannose linked in β 1 → 6 and galactose branches linked in β 1 → 3. Furthermore, PWR exhibited obvious cytotoxicity ability to human laryngeal carcinoma Hep-2 cells in a dose-and time-dependant manner., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In order to develop new and low cost anticoagulants as potential heparin alternatives, sulfation of a pectin-like polysaccharide from Opuntia ficus indica cladodes using SO 3 -DMF complex was performed with a significant sulfate content (7%). FTIR and NMR assays indicated that the sulfation reaction had occurred. In addition, GC-MS analyses demonstrated that sulfation was carried out on the arabinose units of native polysaccharide. Moreover, Physico-chemical characterization indicated an evident decrease of the average molecular weight (M w ) and sugar rates after sulfation. Finally, anticoagulant assays demonstrated that the anticoagulant activity was significantly enhanced by the addition of sulfate groups. Thus, sulfated polysaccharides exhibited the most potent anticoagulant activity by prolonging activated partial thromboplastin time (APTT) and thrombin time (TT)., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Prunus amygdalus is used in the folk medicine that proved the interest of this plant which cures many diseases. Many researchers are interested to valorize almond waste (hull and shell) and to evaluate their biological and pharmacological activities. In this work, polysaccharides from Prunus amygdalus shell were extracted sequentially by water, ammonium oxalate and hydrochloric acid. The monosaccharide composition of polysaccharides fractions was performed by GC-MS. Water-soluble polysaccharide was found to be the most effective extracting agent with an extracted yield of 9%. The acid Soluble Polysaccharides (ASP) exhibited the highest galacturonic acid content (31.95%), the highest polysaccharides extractability (88.57%) and the lowest degree of esterification (31.76%). The different polysaccharides fractions were characterized by FTIR, 1 H NMR and SEC/MALS/VD/DRI. The antioxidant tests (DPPH, ABTS and FRAP) indicated that ASP showed even better antioxidant activities. Moreover, the result of the antiproliferative activity against Caco-2 and B-16 cells showed that ASP exhibited strong cytotoxicity ability which confirmed that the Prunus amygdalus peels may comprise the natural raw materials for new drug and functional food., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Central composite design was performed to optimize uronic acid rate, esterification degree, total antioxidant ability and antiglycation capacity of carbohydrates from Arthrocnemum indicum leaves. Three independent variables were opted: extraction temperature, time and ratio (solvent/material). The optimal settings were: extraction temperature of 80°C, time of 288min and (solvent/solid) ratio of 40mL/g. Under these settings, uronic acid rate and esterification degree were 49.29%, 30.24%, respectively, whereas total antioxidant activity and antiglycation capacity was 35.81mg ascorbic acid equivalents/g matter and 69.81%, respectively. Colorimetric assays showed that total sugar and uronic acid contents for polysaccharide were 71.78% and 49.24%, respectively. Furthermore, Preliminary structure study was performed via various methods including FT-IR, NMR and UV-vis analysis. SEC analyzes revealed that polysaccharide had an average molecular weight of 2179kDa. Moreover, GC-MS analyzes showed that extracted polysaccharide was a pectic polysaccharide which formed of arabinose, mannose, galactose, rhamnose, glucose and xylose in the molar percentage of 66.68%, 3.93%, 12.71%, 6.31%, 6.08% and 4.29%, respectively. This results revealed that extracted polysaccharide can be employed as source of natural antioxidants and as possible antiglycated agents., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The aim of this study is to isolate pectin from peel (WNPE) and pulp (WNPU) of Opuntia microdasys var. rufida's (OMR) cladodes and to characterize these polysaccharides by size exclusion (SEC/MALS/VD/DRI), gas chromatography coupled to mass spectrometer (GC-MS), nuclear magnetic resonance ( 1 H NMR), and Fourier transform infrared spectroscopy (FTIR) analysis. The polysaccharides were extracted in neutral aqueous media followed by ethanol precipitation and dialysis. Both WNPE and WNPU are mainly composed of uronic acids and some neutral sugars such as arabinose, galactose, rhamnose and mannose. Their molecular weight range from 2,180,000 and 4,920,000g/mol. The in-vivo pharmacological activities (anti-inflammatory, analgesic and gastroprotective activities) have been performed. The extracted pectin (50-100mg/kg, i.p. (intraperitoneal)) inhibited, in a dose-related manner, both carrageenan-induced paw edema in rats and Xylene-induced ear edema in mice. A dose-dependent action was obtained against chemical (writhing test) and thermic (hot plate test) stimuli, respectively, with doses of 50 and 100mg/kg. Moreover, a considerable gastroprotective effect was observed with these two biopolymers, the gastric ulcer was attenuated until 67.67% for WNPE and 81.93% for WNPU, at the dose of 100mg/kg., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The isolation, purification and ozone depolymerization of polysaccharides from Arthrocnemum indicum as well as the evaluation of their antiproliferative capacities were investigated. The ozone treatment for various reaction times (0, 15, 30, 45 and 60min) was employed as degradation method in order to attain lower molecular weight product with stronger antiproliferative property. According to FTIR, 1 H NMR and UV-vis analysis, the main chain of ozonolytic degraded polysaccharides could be preserved. The monosaccharide composition, which was determined via GC/MS analysis, showed that extracted polysaccharides were of type of arabinan-rich pectic polysaccharides. Macromolecular characteristics as well as intrinsic viscosity of the degraded polysaccharides were performed by size exclusion chromatography before and after ozone treatment. These experiments showed that intrinsic viscosity and molecular weight (Mn and Mw) of degraded samples decreased with increase in reaction time. Furthermore, preliminary antiproliferative tests indicated that degraded polysaccharide for 1h showed even better antiproliferative capacity., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Pectin has been widely used in a variety of biomedical applications. In this study, it was modified with sodium periodate as an oxidant and characterized by physicochemical methods Periodate oxidation increased the contents of dialdehyde units and carboxyl groups in pectin, and a decrease in pectin viscosity was measured. The oxidization reaction led to a significant decrease in all values of molecular weight and size (Mn, Mw, [η] and Rh) as determined by size exclusion chromatography (SEC), which allowed the selection of the oxidized pectin to be added to chitosan. Chitosan-based films were characterized by infra-red spectroscopy (FTIR), X-ray diffractometry (XRD), and differential scanning calorimetry (DSC) measurements. Thermal behaviour studies demonstrated that interactions existed between chitosan and oxidized pectin. The haemolysis percentages of films were found to be less than 5%, which indicated their good blood compatibility. Finally, the antibacterial activity was clearly improved. Cross-linking reactions between pectin and chitosan through ionic bonds and amide bonds and between chitosan and oxidized pectin through Schiff base formation were evidenced, which opens the way to extend applications of these polysaccharides; notably, the biocompatibility and biodegradability of these new networks is convenient for pharmaceutical, biomedical or cosmetic applications., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The elaboration of chemically crosslinked hydrogels based on collagen (C), hyaluronanic acid (HA) and sericin (S) with different polymer ratios was investigated by in-situ rheology. This reaction was performed via amide or ester bond reaction activated by carbodiimide, in pure water. Prior to molecule crosslinking, the rheological behaviour of the biopolymers (alone or in mixture) was characterized in a semi-dilute concentration regime. Both flow and dynamic measurements showed that uncrosslinked collagen alone appears to be rather elastic with yield stress properties, whereas uncrosslinked HA alone appears to be rather shear thinning and viscoelastic in agreement with entangled polymer behaviour. Sericin exhibited Newtonian low viscosity behaviour according to its very low molar mass. Before crosslinking, HA exhibited viscoelastic behaviour at concentrations above the critical entangled concentration (C*) in the mixtures, thus HA shows promise as a matrix for future crosslinked networks, whereas sericin did not significantly modify the rheology. During the reaction, followed by rheology, the kinetics were slower for pure HA systems compared with the mixtures (i.e., with added collagen and/or to a lesser extent sericin). At the same time, the final network of hydrogels (i.e., the elastic modulus) was more structured in the mixture based systems. This result is explained by ester bonds (the only possibility for pure HA systems), which are less favourable and reactive than amide bonds (possible with sericin and collagen). The presence of collagen in the HA matrix reinforced the hydrogel network. SEM studies confirmed the structure of the hydrogels, and in vitro degradability was globally consistent with the effect of the selected enzyme according to the hydrogel composition. All the elaborated hydrogels were non-cytotoxic in vitro., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The extraction, purification and degradation of polysaccharides from Opuntia ficus indica cladodes, as well as the evaluation of their antioxidant and antiglycated activities in vitro were investigated. The optimization of the extraction showed that extraction by ultrasound at 40 °C presented the best carbohydrates yield. The degradation of the extracted polysaccharides was achieved by free radical depolymerization with H2O2 in the presence of copper(II) acetate for various reaction times. Sugar contents were determined by colorimetric assays. The macromolecular characteristics of the different isolated and degraded carbohydrates were carried by size exclusion chromatography (SEC/MALS/VD/DRI). These experiments showed that all samples are polysaccharides, which are probably pectins and that molecular weight (Mw) has decreased from 6,800,000 to 14,000 g/mol after 3 h of depolymerization without changing the structure. Preliminary antioxidant and antiglycated tests indicated that degraded polysaccharides for 2 and 3 h showed even better antioxidant and antiglycated activities., (Copyright © 2015 Elsevier B.V. All rights reserved.)

In the present work, a new particulate controlled release system was prepared, by coating alginate-g-PCL/Ca(2+) beads with chitosan. The swelling behaviour and controlled release of a poorly water-soluble drug (theophylline) model were studied in media of varying pH, by simulating human fluids at 37 degrees C. In a simulated gastric fluid (SGF, pH 1.2), coated beads presented weak swelling (8-22%) and weak release rates (24-32% within 120min), and were able to protect the drug from this harsh environment. In a simulated intestinal fluid (SIF, pH 6.8), the swelling rates of amphiphilic beads (before disintegration) were strongly reduced (300-1100%) comparatively with those of uncoated beads (700-1700%). This can be explained by the strong electrostatic interactions between the amino groups of chitosan and the carboxylate groups of alginate-g-PCL, leading to the formation of a protective membrane of strong polyelectrolyte complex around the beads. This outermost layer effectively promoted the stability of beads under gastro-intestinal tract conditions, while the hydrophobic interactions between theophylline and PCL grafts allowed a considerable slowing down of the drug release. It was found out that combination of the protective effect of the polyelectrolyte membrane in SIF associated with the hydrophobicity of PCL grafts allowed to release a poorly water-soluble drug, in a controlled manner, for 7h, along a simulated gastro-intestinal tract., (Copyright 2010 Elsevier B.V. All rights reserved.)

The extracellular polysaccharide hyaluronan (HA) controls cell migration, differentiation and proliferation, and contributes to the invasiveness of human cancers. In order to investigate the sensitivity of cancer cells to antimitotic agents, we developed a cross-linked HA hydrogel, a three-dimensional matrix in which cells can invade and grow. We have studied three cell lines (SA87, NCI-H460 and H460M), from primary tumors and metastases, that migrated into the HA hydrogel and proliferated giving rise to clusters and colonies. Concurrently, we studied the growth of these cell lines in a usual monolayer culture system. In these two models, increasing concentrations of doxorubicin and 5-fluorouracil were evaluated for their ability to inhibit tumor cell growth and colony formation. Taken together, our data suggest that the cancer cells were more resistant in the three-dimensional model than in monolayer cell systems. The antimitotic drugs were efficient after 24h of treatment in the monolayer cultures, whereas they were significantly efficient only after one week of incubation in the HA hydrogels. Herein, we show that this cross-linked matrix provides a three-dimensional model particularly appropriate for investigating mechanisms involved in cancer cell line sensitivity to antimitotic drugs.

Water soluble polyelectrolyte complexes (PECs) formed between polyaspartate (anionic polymer) and poly(trimethylammonium propyl methacrylamide chloride) (cationic polymer) were studied by flow field flow fractionation with on-line coupling multi-angle laser light scattering-quasi elastic light scattering-differential refractive index determination (F4/MALLS/QELS/DRI). The separation technique permits to characterize polydisperse PECs. The molar mass of the polycation (PC) influences the stiffness of the PECs and the proportion between single PECs (i.e. nPA/1PC) and multiple PECs (i.e. nPA/n'PC). High ionic strength with NaCl (>0.1 M) tends to break the multiple PECs while CaCl2 destroys PECs and leads to the formation of complexes polyaspartate/Ca2+. The studied PECs can be used as inhibitors to the calcite formation in the drilling fluids.

An NMR spectroscopy study ((31)P, (1)H, (13)C) of the postulated crosslinking mechanism of sodium trimetaphosphate (STMP) on polysaccharides is reported using methyl alpha-D-glucopyranoside as a model. In a first step, reaction of STMP with Glc-OMe gives grafted sodium tripolyphosphate (STPP(g)). On the one hand, STTP(g) can react with a second alcohol functionality to give a crosslinked monophosphate. On the other hand, a monophosphate (grafted phosphate) could be obtained by alkaline degradation of STPP(g). NMR spectroscopy allows to detect the various species formed and to obtain the crosslinking density of STMP-polysaccharides hydrogels.

Hyaluronan (HA) has different biological functions according to its molar mass; short HA fragments are involved in inflammation processes and angiogenesis, whereas native HA is not. Physicochemically, studies of native HA hydrolysis catalyzed by bovine testicular hyaluronidase (HAase) have suggested that kinetic parameters depend on HA chain length. To study the influence of HA chain length in more detail, and to try to correlate the physicochemical and biological properties of HA, HA hydrolysis catalyzed by HAase was used in a new procedure to obtain HA fragments of different molar masses. HA fragments (10-mg scale) with a molar mass from 800 to 300,000 g mol(-1) were prepared, purified using low-pressure size exclusion chromatography (SEC), lyophilized, and characterized in molar mass by either mass spectrometry or HPLC-SEC-multiangle laser light scattering. The polydispersity index of the purified fractions was less than 1.25. The complete set of HA standards obtained was used to calibrate our routine HPLC-SEC device using only a refractive index (RI) detector. We showed that the N-acetyl-d-glucosamine reducing end assay and the calibrated HPLC-SEC-RI gave equivalent kinetic data. In addition, the HPLC-SEC-RI furnished the mass distribution of the polysaccharide during its hydrolysis.

The extracellular polysaccharide hyaluronan (HA) controls cell migration, differentiation and proliferation, and contributes to the invasiveness of human cancers. The roles of HA cell surface receptors and hyaluronidases (HAses) in this process are still controversial. In order to investigate their involvement in cancer pathogenesis, we developed a reticulated HA hydrogel, a three-dimensional matrix in which cells can invade and grow. We have studied thirteen cell lines, from primary tumors or metastases, that migrated into the HA hydrogel and proliferated giving rise to clusters and colonies. The number of colonies, which reflects tumor cell invasiveness, ranged from 7 to 193 after 5 days of culture. Invasion was dependent on the production of HAse as well as other factors. Optimal colonization occurred when cells released HAse, lacked HA-binding sites and did not secrete HA. Moreover, we describe for the first time a HAse activity at physiological pH that may be responding to the confinement of the enzyme in a three-dimensional structure. We show here that this reticulated matrix provides a three-dimensional model for investigating mechanisms involved in malignant invasion.

Size-exclusion chromatography (SEC) is a useful steric separation technique for the analysis of water-soluble polysaccharides in aqueous solution. However, in the case of amphiphilic derivatives, the usefulness is limited because of interactions between hydrophobic segments and the stationary phase. Alkyl-bearing pullulans differing from the extent and the length of alkyl groups were characterized using flow-field flow fractionation with on-line coupling multi-angle laser light scattering (F4/MALLS). Comparison of SEC and F4 is presented and the interest of F4 in the field of amphiphilic derivatives is demonstrated.