O-acetylated xyloglucan in extracellular polysaccharides from cell-suspension cultures of Mentha.

Extracellular polysaccharide produced by suspension-cultured Mentha cells consisted of 50% neutral sugars, 32% uronic acid and 10% of protein. The ammonium oxalate-soluble fraction of this polysaccharide contained 30% hemicellulose and 70% pectic substances. The purified hemicellulose contained xylose, glucose, arabinose, galactose, mannose and fucose residues in a molar ratio of 41.6:31.3:13.1:11.1:1.3:1.6. It was identified as a xyloglucan from its neutral sugar composition and by methylation analysis and cellulase treatment: the principal neutral sugar was arabinose. The presence of O-acetyl residues was confirmed with 1H NMR, 13C NMR and GC-mass spectrometry. The total acetyl content in the polysaccharide was 4%. The point of attachment of the O-acetyl residue was shown to be at position 6 of the galactosyl residue.