A study of the glucofructofuranan from the New Zealand cabbage tree Cordyline austrulis

Extraction of the roots of the New Zealand cabbage tree Cordyline australis with water gave a glucofructofuranan in 60% yield (dry-weight basis). Viscosity measurements on aqueous solutions of the polysaccharide, and vapor pressure osmometry of the polysaccharide peracetate, showed the number average molecular weight of the glucofructofuranan to be similar to 3000. Complete hydrolysis with dilute acid gave only D-fructose and D-glucose, in the ratio of 16:1. The polysaccharide was methylated by using dimethyl sulfoxide-sodium hydroxide-methyl iodide, and the methylated polymer was hydrolyzed to give 1,3,4,6-tetra-O-methylfructose (5.6 mol), 2,3,4,6-tetra-O-methylglucose (1 mol), 1,3,4-tri-O-methyl-fructose (8.4 mol), 2,3,4-tri-O-methylglucose (0.1 mol), and 3,4-di-O-methyl-fructose (2.7 mol). These results, supported by C-13-n.m.r. analyses, showed that the polymer is a highly branched glucofructofuranan containing mainly (1 -> 2)-linked ss-D-fructofuranosyl residues, with branching at O-6 of 15% of the D-fructosyl residues.