An arabino(glucurono)xylan isolated from immunomodulatory active hemicellulose fraction of Salvia officinalis L.

From the aerial parts of sage (Salvia officinalis L) an arabino-(4-O-methyl-glucurono)-xylan (AGX) was isolated by alkaline extraction followed by precipitation with barium hydroxide solution. Polymer was isolated from sage as a light brown polysaccharide material of molecular mass (M-p) 84,000. Compositional analyses of sage AGX revealed xylose (81%), arabinose (10%), glucuronic acid (8%) and small amounts of hexoses (1%). Linkage sugar analyses showed the (1 -> 4)-linked xylopyranosyl backbone with low degree of substitution (9-10%) at O-2 and O-3. Arabinofuranose residues were found as the terminal, 1,3-, 1,5-and 1,3,5-linked. NMR structural analyses of acidic oligomers, generated by partial acidic hydrolysis of AGX, confirmed a substitution of xylose residues by glucuronic acid and its 4-O-methyl derivate at O-2 at an average on every fourteenth xylose residue. NMR and FT-IR measurements, as well as a high negative optical rotation confirmed the 13 configuration of glycosidic linkages in AGX backbone. (C) 2013 Elsevier B.V. All rights reserved.