59 research outputs found
Anti-Metastatic Properties of a Marine Bacterial Exopolysaccharide-Based Derivative Designed to Mimic Glycosaminoglycans
Osteosarcoma is the most frequent malignant primary bone tumor characterized by a high potency to form lung metastases. In this study, the effect of three oversulfated low molecular weight marine bacterial exopolysaccharides (OS-EPS) with different molecular weights (4, 8 and 15 kDa) were first evaluated in vitro on human and murine osteosarcoma cell lines. Different biological activities were studied: cell proliferation, cell adhesion and migration, matrix metalloproteinase expression. This in vitro study showed that only the OS-EPS 15 kDa derivative could inhibit the invasiveness of osteosarcoma cells with an inhibition rate close to 90%. Moreover, this derivative was potent to inhibit both migration and invasiveness of osteosarcoma cell lines; had no significant effect on their cell cycle; and increased slightly the expression of MMP-9, and more highly the expression of its physiological specific tissue inhibitor TIMP-1. Then, the in vivo experiments showed that the OS-EPS 15 kDa derivative had no effect on the primary osteosarcoma tumor induced by osteosarcoma cell lines but was very efficient to inhibit the establishment of lung metastases in vivo. These results can help to better understand the mechanisms of GAGs and GAG-like derivatives in the biology of the tumor cells and their interactions with the bone environment to develop new therapeutic strategies
Sterilization of Exopolysaccharides Produced by Deep-Sea Bacteria: Impact on Their Stability and Degradation
Polysaccharides are highly heat-sensitive macromolecules, so high temperature treatments are greatly destructive and cause considerable damage, such as a great decrease in both viscosity and molecular weight of the polymer. The technical feasibility of the production of exopolysaccharides by deep-sea bacteria Vibrio diabolicus and Alteromonas infernus was previously demonstrated using a bioproduct manufacturing process. The objective of this study was to determine which sterilization method, other than heat sterilization, was the most appropriate for these marine exopolysaccharides and was in accordance with bioprocess engineering requirements. Chemical sterilization using low-temperature ethylene oxide and a mixture of ionized gases (plasmas) was compared to the sterilization methods using gamma and beta radiations. The changes to both the physical and chemical properties of the sterilized exopolysaccharides were analyzed. The use of ethylene oxide can be recommended for the sterilization of polysaccharides as a weak effect on both rheological and structural properties was observed. This low-temperature gas sterilizing process is very efficient, giving a good Sterility Assurance Level (SAL), and is also well suited to large-scale compound manufacturing in the pharmaceutical industry
Antiviral Activities of Sulfated Polysaccharides Isolated from Sphaerococcus coronopifolius (Rhodophytha, Gigartinales) and Boergeseniella thuyoides (Rhodophyta, Ceramiales)
Water-soluble sulfated polysaccharides isolated from two red algae Sphaerococcus coronopifolius (Gigartinales, Sphaerococcaceae) and Boergeseniella thuyoides (Ceramiales, Rhodomelaceae) collected on the coast of Morocco inhibited in vitro replication of the Human Immunodeficiency Virus (HIV) at 12.5 ÎŒg/mL. In addition, polysaccharides were capable of inhibiting the in vitro replication of Herpes simplex virus type 1 (HSV-1) on Vero cells values of EC50 of 4.1 and 17.2 ÎŒg/mL, respectively. The adsorption step of HSV-1 to the host cell seems to be the specific target for polysaccharide action. While for HIV-1, these results suggest a direct inhibitory effect on HIV-1 replication by controlling the appearance of the new generations of virus and potential virucidal effect. The polysaccharides from S. coronopifolius (PSC) and B. thuyoides (PBT) were composed of galactose, 3,6-anhydrogalactose, uronics acids, sulfate in ratios of 33.1, 11.0, 7.7 and 24.0% (w/w) and 25.4, 16.0, 3.2, 7.6% (w/w), respectively
Les sucres de l'extrĂȘme pour la mĂ©decine de demain
Ă la fin des annĂ©es 1980, l'Ifremer a initiĂ© des recherches sur les micro-organismes des Ă©cosystĂšmes hydrothermaux ocĂ©aniques profonds. Parmi les Ă©chantillons prĂ©levĂ©s â environ 1330 isolats â, des bactĂ©ries productrices de biopolymĂšres dâintĂ©rĂȘt biotechnologique, comme des exopolysaccharides (EPS) et des polyhydroxyalcanaotes (PHA), ont Ă©tĂ© identifiĂ©es. De genres connus, elles appartiennent Ă des espĂšces ignorĂ©es jusquâalors (Alteromonas infernus, Alteromonas macleodii subsp. fijiensis biovar deepsane ou Vibrio diabolicus)
Préparation, caractérisation et activités biologiques de fucanes extraits d'algues brunes
Fucoldans are a family of high molecular weight sulfated polysaccharides (from 8x105 to 1 x106 g/mol) widely dispersed in brown seaweed cell wall. When extracted from several brown algae, they exhibit anticoagulant properties. The chemical degradation of a crude extract, from Pelvetia canaliculata undertaken to obtain a low molecular weight polysaccharide (4 x 104 g/mol) with the purpose of a possible clinical use. Its anticoagulant potency was investigated through the inhibition of factor IIa and factor Xa in the presence of antithrombin III or heparin cofactor II. The degraded fucoidan revealed a potent antithrombin activity, although weaker than heparin. In the presence of either antithrombin III depleted plasma or purified heparin cofactor II, the fucoidan was as efficient as heparin or dermatan sulfate on heparin cofactor II potentiation, at the same ponderal concentration. In whole plasma or in presence of the purified inhibitor, an inhibition of factor Ila activity mediated by antithrombin III was detected (30 times less potent than heparin, on a weight to weight basis). No inhibition of factor Xa activity was detected in the same experimental conditions,
Chemical degradations of various crude extracts, from four brown seaweeds; have given low molecular weight fucoidan fractions (almost 2 x 104 g/mol). In plasma or in presence of purified heparin cofactor II, these fractions have revealed a same anticoagulant activity and mode of action that the previous fraction extracted from Pelvetia canaliculata.
These fucoidans, by-products of alginates preparation in the food and cosmetologic industries, are obtained easily. Thus, they may represent a cheap and easy source of a new type of anticoagulants.Les fucanes, polysaccharides sulfatés extraits de la paroi extracellulaire des algues brunes sont décrits depuis plus d'une trentaine d'années comme présentant une activité anticoagulante vis à vis du plasma sanguin. Le mécanisme d'action du fucane sur le systÚme de la coagulation sanguine n'a pas donné lieu à des études trÚs approfondies jusqu'en 1989.
AprĂšs l'extraction et la caractĂ©risation de fucanes issus de diffĂ©rentes algues brunes, les polysaccharides de trĂšs haute masse molaire (1 x 105 g/mol) isolĂ©s ont montrĂ© des propriĂ©tĂ©s anticoagulantes sur plasma pauvre en plaquettes qui confirment les travaux antĂ©rieurs. Une Ă©tude approfondie du mĂ©canisme de l'activitĂ© anticoagulante a Ă©tĂ© ensuite rĂ©alisĂ©e sur une fraction de fucane dĂ©gradĂ©e par hydrolyse acide et bien caractĂ©risĂ©e de masse molaire de 40 000 g/mol. Cette Ă©tude a montrĂ© que le fucane de faible masse molaire dĂ©nommĂ© F2 accĂ©lĂšre l'inhibition de la thrombine, principale enzyme procoagulante du systĂšme de la coagulation, par l'intermĂ©diaire de ses deux principaux inhibiteurs physiologiques qui sont l'antithrombine III et le deuxiĂšme cofacteur de l'hĂ©parine. Aucune accĂ©lĂ©ration de l'inhibition du facteur Xa, autre enzyme procoagulante de la coagulation, n'a Ă©tĂ© dĂ©tectĂ©e en plasma pauvre en plaquettes. L'originalitĂ© du fucane Ă©tudiĂ© rĂ©side dans le fait qu'il inhibe fortement la thrombine en prĂ©sence du deuxiĂšme cofacteur de l'hĂ©parine et pour des concentrations pondĂ©rales Ă©quivalentes Ă celles de l'hĂ©parine. L'autre originalitĂ© du fucane est due aussi Ă sa capacitĂ©, Ă mĂȘme concentration pondĂ©rale, d'inactiver spĂ©cifiquement la thrombine par l'intermĂ©diaire du deuxiĂšme cofacteur de l'hĂ©parine et de l'antithrombine III.
La méthode de dégradation par hydrolyse acide comparée à une autre méthode de dégradation par radiolyse a montré que ces deux méthodes conduisaient à des fucanes de faible masse molaire conservant en grande partie l'activité anticoagulante initiale. La préparation d'un fucane "optimal" par dégradation acide, à partir de l'algue Ascophyllum nodosum, a permis l'obtention d'une fraction de fucane dénommée D2, de masse molaire de 18 000 g/mol. L'étude in vivo réalisée chez le lapin montre que cette fraction est plus active, par rapport à l'héparine, en expérimentation in vivo qu'en essais in vitro
Modifications d'un exopolysaccharide biosynthétisé par une bactérie issue des écosystÚmes hydrothermaux profonds
Le travail concerne la modification d'un exopolysaccharide (EPS) biosynthĂ©tisĂ© par une bactĂ©rie issue des Ă©cosystĂšmes hydrothermaux profonds. Ce polysaccharide complexe, de haute masse molaire, est constituĂ© d'oses neutres et d'acides uroniques. La rĂ©duction de sa masse molaire est la premiĂšre Ă©tape dans la conception de molĂ©cules d'intĂ©rĂȘts variĂ©s. Deux voies de dĂ©polymĂ©risation ont Ă©tĂ© envisagĂ©es : physique avec les ultrasons et chimique avec la catalyse mĂ©tallique. Les facteurs influents ont Ă©tĂ© dĂ©terminĂ©s pour ces deux voies. La derniĂšre partie du mĂ©moire est consacrĂ©e Ă la faisabilitĂ© de modifications chimiques de l'EPS natif ou dĂ©polymĂ©risĂ© par ajout de groupements classiques. Des rĂ©sultats de caractĂ©risation et de quantification des modifications par des techniques d'analyses adaptĂ©es Ă chaque manipulation sont prĂ©sentĂ©s.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF
Potentiel des exopolysaccharides marins en ingénierie des tissus squelettiques
Les lĂ©sions dĂ©gĂ©nĂ©ratives des tissus squelettiques affectent une part importante de la population et reprĂ©sentent un enjeu majeur de santĂ© publique. Cependant, les approches thĂ©rapeutiques mises en place pour la rĂ©paration de ces tissus, souffrent de nombreuses limitations. Dans ce contexte, des efforts pluridisciplinaires pour dĂ©velopper des solutions thĂ©rapeutiques alternatives ont conduit Ă une nouvelle discipline, l ingĂ©nierie tissulaire. Cette discipline se donne pour objectif de dĂ©velopper des substituts biologiques aux tissus squelettiques en dĂ©veloppant des constructions hybrides associant des matrices tridimensionnelles avec des cellules. L objectif de cette thĂšse a Ă©tĂ© d Ă©valuer le potentiel de deux exopolysaccharides (EPS) marins HE800 et GY785, en ingĂ©nierie des tissus squelettiques. Lors d une premiĂšre Ă©tude nous avons mis en place un mode de stĂ©rilisation adaptĂ© aux EPS marins. Dans le but de dĂ©velopper des matrices tridimensionnelles physiquement et biologiquement compĂ©tentes nous avons dĂ©montrĂ© dans une deuxiĂšme Ă©tude que l association d EPS marins Ă un hydrogel auto rĂ©ticulant Ă base d hydroxypropyl mĂ©thylcellulose silanisĂ©e (HPMC-Si) permettait d augmenter ces propriĂ©tĂ©s mĂ©caniques. Une troisiĂšme Ă©tude plus approfondie sur la construction associant l EPS GY785 Ă l hydrogel d HPMC-Si Ă montrer les capacitĂ©s de cette matrice Ă favoriser la prolifĂ©ration et le maintien du phĂ©notype de chondrocytes articulaires de lapin tout en fournissant un microenvironnement adĂ©quate pour la production d une matrice extracellulaire cartilagineuse. Les rĂ©sultats de ces travaux montrent l intĂ©rĂȘt des EPS marins en ingĂ©nierie tissulaire et plus particuliĂšrement de l EPS GY785 en ingĂ©nierie tissulaire du cartilageDegenerative hurts of skeletal tissue affect an important part of the population and represent a major stake in health care. However, the therapeutic approaches for the repair of these tissues, suffer from numerous limitations. In this context, a multidisciplinary efforts has been done to develop alternative therapeutic solutions, leading to a new discipline; tissue engineering. This discipline has for objective to develop biological substitutes, by developing hybrid constructs associating three-dimensional matrices with cells. The goal of this thesis was to estimate the potential of two exopolysaccharides (EPS) from marine origin HE800 and GY785 in skeletal tissue engineering. During a first study, we set up a sterilization method adapted to marine EPS. Then, toward the development of physically and biologically competent 3 D matrices, we demonstrated in the second study that the association of EPS to a sililated hydroxypropyl methylcellulose (Si-HPMC) increases the mechanical properties of the scaffold. The third study deepened on the biological properties of the GY785/Si-HPMC scaffold on cartilage tissue engineering with rabbit articular chondrocytes (RAC). Results indicate the ability of this scaffold to maintain and to recover a chondrocytic phenotype as well as the production of cartilage-like extracellular matrix. The results of these works show the interest of marine EPS in tissue engineering and more particularly, the significance of GY785 EPS in cartilage tissue engineeringNANTES-BU Sciences (441092104) / SudocSudocFranceF
Flow Field-Flow fractionation for an accurate characterization of polysaccharides Â
As size exclusion chromatography (SEC), Flow Field Flow Fractionation is a separation technique that assesses the size distribution of the molecules via theoretical equations or representative standards. In FFF technique, high-resolution separation is achieved within a very thin flow against which a perpendicular force field is applied. It takes place in an asymmetrical flat channel (A4F) or in a hollow fiber (HF5). Separation depends on the Brownian diffusion coefficient of the molecule / particle, and thus on its size. Multi Angle Light Scattering detector (MALS) is used for the determination of the absolute molar mass and size determination of macromolecules / nanoparticles. In FFF separation, no stationary phase is required that avoids interferences with the samples. Consequently, for very high molar weight polymers, shearing forces do not apply. The entire separation is smooth, fast, and non-destructive without a stationary phase that may interact, degrade, or alter the sample.
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Field-Flow Fractionation-based techniques are powerful tools for characterizing polysaccharides and for monitoring the potential polydispersity and/or polymodality. They are powerful tools especially in the case of drug delivery. In a Pharmacopeia approach, these techniques must be coupled to complementary techniques for a full characterization of products. Viscosity measurements have been conducted together with A4F-UV-MALS and to study the size and size distribution of exopolysaccharides.
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