Extraction, modification enzymatique et caractérisation chimique de nouvelles structures pectiques (application de la relation structure/activité à la dermocosmétique)

Les polysaccharides et plus particulièrement les pectines sont des molécules d'intérêt biologique dont nos travaux démontrent qu'elles peuvent être utilisées par l'industrie dermocosmétique. C'est sur ce thème que la société SILAB et le Laboratoire de Chimie des Substances Naturelles ont décidé d'engager une étude prospective. Dans une première partie, nous nous sommes intéressés au rhamnogalacturonane de type I dont la variabilité chimique a été approchée après screening réalisé sur 11 matières végétales. Les protocoles ont été transférés puis optimisés à une échelle permettant, pour trois de ces matières (son de châtaigne, marc de pomme et marc de raisin) leur industrialisation, et pour l'une d'elles (son de châtaigne), leur commercialisation. La structure chimique des RG-I testés explique par ailleurs leur capacité à moduler la prolifération de kératinocytes. Dans une deuxième partie, un galacturonane substitué de la famille des apiogalacturonanes est étudié. Extrait de Zostera marina, sa structure a été caractérisée par spectroscopie RMN et ses propriétés précisées dans le domaine de l'oncologie cellulaire et moléculaire.Polysaccharides and, more particularly, pectins are molecules of biological interest that, as exemplified by the present work, can be used by the dermocosmetic industry. The SILAB company and the Laboratoire de Chimie des Substances Naturelles mounted a joint prospective study on this theme. Firstly, we studied the chemical variability of type I rhamnogalacturonans (RG-I) extracted from 11 different plant materials. Experimental protocols designed for three of these materials (chestnut bran, apple marc and grape marc) have been transferred and optimised at a scale allowing their industrialization and, for one of them (chestnut bran), its marketing. The chemical structure of the tested RG-I explained their ability to modulate keratinocyte proliferation. In a second part, we studied a substituted galacturonan of the apiogalacturonan family, extracted from the seaweed Zostera marina. We characterized the chemical structure of this polysaccharide by the means of NMR spectroscopy and we studied its properties in relation to cellular and molecular oncology.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Structural patterns of rhamnogalacturonans modulating Hsp-27 expression in cultured human keratinocytes

International audiencePolysaccharide extracts were obtained from chestnut bran (Castanea sativa), grape marc (Vitis vinifera) and apple marc (Malus spp.) and fractionated by size exclusion chromatography after endopolygalacturonase degradation. Compositional and linkage analyses by GC and GC-MS showed the characteristic rhamnogalacturonan structure with specific arabinan (apple marc) and type II arabinogalactan (chestnut bran, grape marc) side chains. Type II arabinogalactan rhamnogalacturonan from chestnut bran significantly stimulated the in vitro differentiation of human keratinocytes, giving evidence of a tight structure-function relationship. This molecule comprises short and ramified 3- and 3,6-β-D-galactan and 5- and 3,5-α-L-arabinan side chains, but also contains significant amounts of t-Xyl and 4-Xyl with a characteristic 2:1 ratio. Enzymatic hydrolysis of this polysaccharide produced fragments of lower molecular weight with unchanged xylose content which conserved the same ability to stimulate human keratinocyte differentiation. It could be then speculated that dimeric xylosyl-xylose and/or longer oligomeric xylose side chains attached to a galacturonan and closely associated to hairy rhamno-galacturonan domains are essential patterns that could determine the biological activity of pectins

Article Structural Patterns of Rhamnogalacturonans Modulating Hsp-27 Expression in Cultured Human Keratinocytes

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Structural characterization and cytotoxic properties of an apiose-rich pectic polysaccharide obtained from the cell wall of the marine phanerogam Zostera marina

International audienceZosterin, an apiose-rich pectic polysaccharide, was extracted and purified from the sea grass Zostera marina. Structural studies conducted by gas chromatography and NMR spectroscopy on a purified zosterin fraction (AGU) revealed a typical apiogalacturonan structure comprising an α-1,4-d- galactopyranosyluronan backbone substituted by 1,2-linked apiofuranose oligosaccharides and single apiose residues. The average molecular mass of AGU was estimated to be about 4100 Da with a low polydispersity. AGU inhibited proliferation of A431 human epidermoid carcinoma cells with an approximate IC50 value of 3 μg/mL (0.7 μM). In addition, AGU inhibited A431 cell migration and invasion. Preliminary experiments showed that inhibition of metalloproteases expression could play a role in these antimigration and anti-invasive properties. Autohydrolysis of AGU, which eliminated apiose and oligo-apiose substituents, led to a virtual disappearance of cytotoxic properties, thus suggesting a direct structure-function relationship with the apiose-rich hairy region of AGU