STRUCTURAL ANALYSIS OF CARRAGEENANS FROM BURMESE AND THAI SAMPLES OF CATENELLA NIPAE ZANARDINI

摘要

The carrageenans extracted from samples of the red seaweed Catenella nipae Zanardini from Burma and Thailand have been characterised by recently developed chemical derivatisation procedures (utilising reductive hydrolysis and reductive partial-hydrolysis techniques) combined with GLC-MS analysis and by IR and NMR spectroscopy. Both polysaccharides are linear polymers composed primarily of 4-linked 3,6-anhydro-alpha-D-galactopyranosyl-2-sulfate residues alternating with 3-linked beta-D-galactopyranosyl residues that are either unsubstituted (alpha-carrageenan) or 4-sulfated (iota-carrageenan). The Burmese sample has a somewhat higher proportion of alpha-carrageenan residues. The Thai C. nipae carrageenan was shown to have minor proportions of beta- and kappa-carrageenan residues. H-1-H-1 COSY, C-13-H-1 COSY and TOCSY NMR spectroscopic examinations of polymer segments produced from this polysaccharide as well as iota-carrageenan itself, have permitted the H-1 and C-13 NMR assignments for iota-carrageenan to be independently verified and for characteristic H-1 and C-13 chemical shifts for alpha-carrageenan to be identified and assigned for the first time. (C) 1996 Elsevier Science Ltd. [References: 29]