Fine chemical structure of carrageenan from the commercially cultivated Kappaphycus striatum (sacol variety) (Solieriaceae, Gigartinales, Rhodophyta)

The polysaccharide extracted from Kappaphycus striatum (Schmitz) Doty (sacol variety), a recently farmed eucheumoid seaweed, was characterized by Fourier transform infrared and NMR spectroscopy. The extract is composed mainly of 3-linked beta -d-galactopyranosyl-4-sulfate residues alternating with 4-linked 3,6-anhydro-alpha -d-galactopyranosyl residues (kappa-carrageenan). Minor components include 3,6-anhydrogalactopyranosyl-2-sulfate residues (iota-carrageenan) and 6-O -methylgalactopyranosyl-4-sulfate residues (methylated carrageenan). The substitution pattern of carrageenan in the tribe Eucheumatoideae and the family Solieriaceae is revisited in terms of chemotaxonomic affiliation.