A highly regular fraction of a fucoidan from the brown seaweed Fucus distichus L

Structure of a fucoidan consisting of trisulfated disaccharide repeating units has been elucidated mainly by 1D and 2D 1H and 13C NMR spectroscopy: → 3)-α- l-Fuc p(2,4-di-SO 3 −)-(1 → 4)-α- l-Fuc p(2SO 3 −)-(1 →. A fucoidan fraction consisting of l-fucose, sulfate, and acetate in a molar proportion of 1:1.21:0.08 was isolated from the brown seaweed Fucus distichus collected from the Barents Sea. The 13C NMR spectrum of the fraction was typical of regular polysaccharides containing disaccharide repeating units. According to 1D and 2D 1H and 13C NMR spectra, the fucoidan molecules are built up of alternating 3-linked α- l-fucopyranose 2,4-disulfate and 4-linked α- l-fucopyranose 2-sulfate residues: → 3)-α- l-Fuc p-(2,4-di-SO 3 −)-(1 → 4)-α- l-Fuc p-(2SO 3 −)-(1 →. The regular structure may be only slightly masked by random acetylation and undersulfation of several disaccharide repeating units.