| Abstract | Polysaccharides of the red seaweed Apophloea lyallii were extracted with hot water in a yield of 63.6% w/w of the dry seaweed. The polysaccharides were non-sulphated and were composed of various proportions of D-xylose, 2-O-methyl D-galactose, D-glucuronic acid, D- and L-galactose, 3-O-methyl galactose, and D-glucose. The aldobiuronic acid 3-O-(β-D-glucopyranosyluronic acid)-D-xylopyranose was isolated from the acid hydrolysate of the polysaccharides. The polysaccharides were fractionated by DEAE-sephadex ion exchange chromatography, and two of the fractions obtained were characterised by neutral sugar analyses, linkage analyses, and NMR[?] spectroscopy. A major fraction obtained was shown to be largely composed of a unique (2-O-methyl galacto)-glucurono-xylo-glycan with a repeating unit represented by [α-D-(2-O-Me-Galp)-(1 → 4)-β-D-GlcAp-(1 → 3)-α-D-Xylp-(1 → 4)-]n. The structure of this new glycan was explored by beta-elimination analyses. A minor fraction obtained by ion exchange chromatography contained (1 → 4)-linked xylose, (1 → 4)-linked galactose, (1 → 4)-linked 3-O-methyl galactose, (1,3,4)-linked galactose, and terminal uronic acid in a ratio of approximately 1:0.3:0.5:0.4:0.4. © 2002 Elsevier Science Ltd. All rights reserved. |
