URONIC ACIDS IN A HYDROLYZATE OF SAPOTE GUM

The molar ratios of d-xylose, l-arabinose, d-glucuronic acid, and 4-O-methyl-d-glucuronic acid in the hydrolyzates of ten nodules of sapote gum obtained from two different commercial batches were very similar and averaged 2.2:1.0:0.42:0.58. A small proportion of nonacidic polysaccharide material was associated with the gum, and accounted for the trace quantities of galactose, glucose, and mannose detected in chromatograms of its hydrolyzate. Partial hydrolysis with acid gave two groups of acidic fragments, containing 4-O-methyl-d-glucuronic acid and d-glucuronic acid, respectively. Of these, the aldotriouronic acids, O-(4-O-methyl-α-d-glucopyranosyl-uronic acid)-(1→2)-O-β-d-xylopyranosyl-(1→4)-d-xylopyranose (1 and O-α-d-glucopyranosyluronic acid-(1→2)-O-β-d-xylopyranosyl-(1→4)-d-xylopyranose (2), crystallized after isolation by paper chromatography. Compound (1) was identified by comparison with an authentic sample. Compound 2 yielded O-α-d-glucopyranosyl-uronic acid-(1→2)-d-xylopyranose on partial hydrolysis. Reduction of 2, followed by methylation and methanolysis yielded a 1,2,3,5-tetra-O-methylxylitol, as well as other methanolysis products identical to those obtained from reduced 1 after methylation and methanolysis. © 1968.