Composition of polysaccharides and radiosensitizing activity of native and sulfated laminarans from the Tаuуа basicrassa Kloczc. et Krupn

•Polysaccharide composition of brown alga Tauya basicrassa was studied.•Alginate and laminarans had typical structures for those substances.•Fucoidans were low- and medium-sulfated heterogeneous polysaccharides.•The main chain of fucogalactan 1TbF1 consisted of 1,6-linked β-D-Galp.•Laminaran 2TbL and its sulphated derivative had radiosensiting activity. Polysaccharide fractions of alginate, laminarans and fucoidans were obtained from the brown alga Tauya basicrassa. Yields of alginate and laminarans were large (19.7 % and 5.62 %, respectively), whereas the content of fucoidans (0.52 %) was not significant. Alginate and laminarans had typical structures for those substances. Fucoidans were low- and medium-sulfated heterogeneous polysaccharides. The fucoidan fraction 1TbF1 was sulfated fucogalactan containing a backbone from 1,6-linked residues of β-d-galactopyranose with branches at C3 and C4, terminal fucose and galactose residues and fragments from 1,3-; 1,4-; and 1,2-fucose residues. Sulfate groups were found at positions 2 and 4 of fucose, and positions 2, 3 and 4 of galactose residues. Laminaran 2TbL was subjected to a sulfation to obtain the derivative 2TbLS with partial sulfation (46 %) at C2, C4 and C6. It was shown that 2TbL and 2TbLS inhibited colony formation of sensitize-tested colon cancer cells HT-29 and HCT-116 to X-ray radiation.