Polysaccharides from the seeds of Senna multijuga

Abstract

The seeds of Senna multijuga were extracted with water or 1% acetic acid and treated with ethanol, resulting in two insoluble fractions. After purification, the major one (FIA, 23%) was shown to be a galactomannan (Man:Gal 2.3:1;[α] = + 54.6;[η]=1340mlg −1). It consists of a main chain of (1 → 4)-linked β- d-mannopyranosyl residues substituted at 06 by single-unit α- d-galactopyranosyl side chains. The second fraction (FIB, 2.5%) was an O-acetyl-glucuronoarabinoxylan from the seed coats ( O-acetyl 8.3 mol%; glucuronic acid 11.7%, Xyl:Ara ratio 20:1), which showed a predominance of 4- O-substituted Xylp units (84.4%), branched at 03 with non-reducing end units of Xylp, Araf and glucuronic acid. The O-acetyl positions in d-xylosyl units are at 02 (4.8%), 03 (4.4%) and 02,3 (0.9%). The ratio between 03 and 02 determined by 13C-nuclear magnetic resonance spectroscopy is 1.5:1.