Structure of a fucoidan from the brown seaweed Fucus evanescens C.Ag. Original Research Article

A fucoidan consisting of l-fucose, sulfate and acetate in a molar proportion of 1:1.23:0.36 was isolated from the Pacific brown seaweed Fucus evanescens. The structures of its desulfated and de-O-acetylated derivatives were investigated by 1D and 2D 1H and 13C NMR spectroscopy, and the data obtained were confirmed by methylation analysis of the native and desulfated polysaccharides. The fucoidan was shown to contain a linear backbone of alternating 3- and 4-linked α-l-fucopyranose 2-sulfate residues: →3)-α-l-Fucp(2SO3−)-(1→4)-α-l-Fucp(2SO3−)-(1→. Additional sulfate occupies position 4 in a part of 3-linked fucose residues, whereas a part of the remaining hydroxyl groups is randomly acetylated.