The Chemical Structure of Galactans from Sarcodia montagneana and from Sarcodia flabellata

Abstract

The polysaccharides from Sarcodia montagneana and from Sarcodia flabellata were examined by 1 3 C NMR spectroscopy. Analysis of these spectra showed the 3-linked D-galactosyl units were mostly substituted at the 2-position by sulfate ester, and at the 4,6-position by pyruvate acetal. The 4-linked galactosyl units were almost entirely in the L-configuration, the 3-position was almost entirely substituted by sulfate ester, and a high percentage of these were substituted at the 2-position by sulfate ester. However, there was also a significant fraction of the 4-linked units with 2,3,6-trisubstitution by sulfate ester, and these units appeared to be linked to 3-linked units substituted with 2-sulfate ester and pyruvate, that is, these diads had no non-substituted hydroxyl group. A previous report that Sarcodia polysaccharides are equivalent to λ-carrageenan is wrong, but the polysaccharide is similar to the polysaccharides previously isolated from Trematocarpus species, confirming an association suggested previously on the basis of gene sequencing.