The polysaccharide C prepared from gum tragacanth powder (U. S. P. grade) by the precipitation method with 85% ethanol was a neutral polysaccharide, [α]^30_D-72.2. The polysaccharide C consisted of L-rhamnose, D-xylose, L-arabinose and D-galactose in the molar ratio 2:1:17:9 (Table 1, 2, 3, ). The polysaccharide C was methylated with dimethylsulphate and 40% NaOH, and Purdies regent.
The hydrolyzate of fully methlated porduct ([α]^22_D-102 in chloroform, the methoxy content 40.6%) was composed of 2,3,5-tri-O-methyl-L-arabofuranose (Ⅰ), 3,4-di-O-methyl-L-rhamnop-yrancse (Ⅱ), 2,3-di-O-methyl-D-xylose (Ⅲ) 2,3,4-tri-O-methyl-D-galactopyranose (Ⅳ), 2,4-di-O-methyl-L-arabopyranose (Ⅴ). 2,4-di-O-methyl-D-galactose(Ⅵ), 2-O-methyl-D-arabinose (Ⅶ), and L-arabopyranose(Ⅷ) (Table 4, 5, and Fig. 4).
The first partial hydrolysis (A) of the polysaccharide C with 0.05N-HCl for 4.5 hours at 80-85℃ released only L-arabinose: the second hydrolysis (B) with 0.1N-HCl for 5 hours at 80-85℃, L-arabinose and D-galactose; and the third hydrolysis (C) with 0.3N-HCl at 90-95℃ in sealed tube, L-rhamnose, D-xylose, L-arabinose and D-galactose. From the unhydrolyzatz A´ were found L-rhamnose, D-xylose, L-arabinose, and D-galactose; from B´ L-rhamnose, d-xylose, L-arabinose and D-galactose; and from C´ D-xylose and D-galactose respectively (Table 6).
The periodate consumption and formic acid production of the polysaccharide C were measured at various time intervals. After 120 hours periodat was consumed by 1.23 mole per C_5H_8O₄ and formic acid was produced 0.78 mole per C_5H_8O₄ (Table 7).
Although a definite chemical structure for this polysaccharide C may not be formulated, experimental data, especially, from methylation, partial hydrolysie and determination of its molar ratio, and periodate analysis showed that the polysaccharide C is a highly branched polysaccharide and would be constructed of galactoaraban as a main chain residue and L-arabofuranose, D-galactopyranosyl (1→1)-L-arabofuranose, D-xylopyranosyl (1→2)-L-rhamnopyranosyl (1→1)-L-arabofuranose, and L-rhamnopyranosyl (1→1)-arabofuranose, and D-galactopyranosyl-(1→2)-L-arabopyranosyl - (1→1)-I-arabofuranose as a branch chain or end group (Page 21).
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