because they are an accessible and renewable sourceof polysaccharides, including fucoidans,
which are biologicallyactive fucose-containing sulfated gomo- and heteropolysaccha-rides. Although the number of publications on the biologicalactivity of new fucoidans has increased, the number of struc-tural studies is considerably less due to the complexity ofthe structure of these polysaccharides. Elucidating the struc-ture fucoidans–heteropolysaccharides by NMR-spectroscopy isnot always productive, because these polysaccharides are oftenbranched and have no regular patterns. We have proposed an alter-native approach to the depolymerization of fucoidan with minimalloss of their structural features using autohydrolysis, with furtheranalysis of the products by instrumental methods (Anastyuk et al.,2010). In some cases, this approach allowed us to isolate and char-acterize the main chain of fucoidan, consisting of fucose, and toinvestigate low molecular weight derivatives, consisting of galactose and fucose (Menshova et al., 2015; Shevchenko et al., 2015).However, in the investigation of galactofucans, containing a signif-icant amount of galactose, the galactan part has not been studiedenough.