SULFATION OF POLYSACCHARIDES WITH SULFURIC-ACID MEDIATED BY DICYCLOHEXYLCARBODIIMIDE

Starch, agarose, kappa-carrageenan and porphyran were sulfated by sulf uric acid with dicyclohexylcarbodiimide as a condensation reagent. In all the cases, the sulfation at O-6 appeared to be predominant on the basis of results from methylation analyses. Although the reactivities of the other hydroxyl groups towards the present sulfation reaction we re less than that at C-6, they varied depending on the position in the sugar residue of the polysaccharides. The sulfated agarose was furthe r fractionated in terms of the difference in the solubility of its cet ylpyridinium salt to KCl solution. The major fraction resembled the ma in polysaccharide of funoran (agarose 6-sulfate) on the basis of the b ehavior of its cetylpyridinium salt, C-13 NMR measurements and methyla tion analyses.