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Title: | Caractérisation structurale et activités biologiques des polysaccharides d'Astragalus gombo bunge. |
Authors: | Noria SMAIL-SAADOUN Ingrid FRUITIER-ARNAUDIN CHOUANA, Toufik |
Keywords: | Astragalus polysaccharide galactomannane Sahara Astragalus polysaccharide galactomannan Sahara |
Issue Date: | 2017 |
Series/Report no.: | ;2017 |
Abstract: | Astragalus gombo Bunge (Fabaceae) est une plante bien representee dans le Sahara
Septentrional Est Algerien (region de Ouargla, Algerie) et couramment utilisee comme
fourrage pour les animaux ou en medecine traditionnelle. Malgre de nombreuses publications
sur la richesse en polysaccharides d fautres especes appartenant au genre Astragalus et la
description de leurs proprietes biologiques putatives ou averees, aucune etude ne s fest
interessee a l fespece gombo. L fobjectif de ce travail de these a donc ete de realiser des
investigations sur plusieurs parties de cette plante en vue d fextraire, identifier et caracteriser
son contenu en polysaccharides. Dans un second temps les proprietes biologiques et
rheologiques de ces polymeres ont ete etudiees afin d fidentifier d feventuelles voies de
valorisation. Les resultats obtenus ont permis de detecter la presence de composes pectiques
et hemicellulosiques dans la tige d fAstragalus gombo et celle d fun galactomannane dans les
graines. Le galactomannane est de haute masse moleculaire (1,1x106 Da) et est constitue
d fune chaine principale de ƒÀ-(1 ¨4)-D-mannane ramifiee en ƒ¿-(1 ¨6) par des residus Dgalactopyranoses
avec un rapport M/G de 1,7. La caracterisation de ses proprietes
rheologiques a revele un comportement typique rheofluidifiant et des proprietes
viscoelastiques. L fetude des activites biologiques associees a ce biopolymere a revele son
potentiel comme prebiotique et antioxydant. Astragalus gombo Bunge (Fabaceae) is a terrestrial plant occuring in the East Septentrional Sahara (Ouargla, Algeria). It is commonly used as fodder or in traditional medicine by local populations. Despite numerous publications focusing on polysaccharidic contents of Astragalus species and the designation of their putative or proved biological activities, no study has examined those of A. gombo. The objective of this thesis was firstly to investigate several organs of this plant for their polysaccharide contents. In a second step, the biological and rheological properties of these biopolymers have been studied to identify ways of adding value. Results led to the identification of pectic compounds and hemicelluloses in the rods of Astragalus gombo whereas a galactomannan was detected in its seeds. This galactomannan was a high molecular weight macromolecule composed of a ƒÀ-(1 ¨4)-D-mannan skeleton ramified by residues of D-galactopyranoses. The M/G ratio was of 1.7. The characterization of its rheological behavior was typic of that of a rheofluidifiant fluid with viscoelastic properties. The study of its biological properties showed its potential as prebiotic and antioxidant agent. |
Description: | Sciences des Aliments |
URI: | http://dspace.univ-ouargla.dz/jspui/handle/123456789/16334 |
Appears in Collections: | Département des Sciences Agronomiques - Doctorat |
Files in This Item:
File | Description | Size | Format | |
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CHOUANA-Toufik.pdf | 6,87 MB | Adobe PDF | View/Open |
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