A sulfated galactofucan from the brown alga Hormophysa cuneiformis (Fucales, Sargassaceae)

• Published in: Carbohydrate research 2018-11, Vol.469, p.48-54
• Main Authors: Bilan, Maria I., Ustyuzhanina, Nadezhda E., Shashkov, Alexander S., Thanh, Thi Thu Thuy, Bui, Minh Ly, Tran, Thi Thanh Van, Bui, Van Nguyen, Nifantiev, Nikolay E., Usov, Anatolii I.
• Format: Article
• Language: English
• Subjects: Biological activity; Carbohydrate Sequence; Fucoidan; Fucose - chemistry; Galactose - chemistry; Hormophysa cuneiformis; Phaeophyceae - chemistry; Polysaccharides - chemistry; Sulfated galactofucan; Sulfates - chemistry
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/j.carres.2018.09.001

The brown alga Hormophysa cuneiformis collected from the coastal waters of Vietnam was used to isolate a mixture of sulfated polysaccharides FHC, which was fractionated further by anion-exchange chromatography on DEAE-Sephacel. The main fraction F3 eluted with 1.5 M NaCl contained essentially l-fucose, d-galactose and sulfate and has very complex NMR spectra. Desulfation to obtain F3deS followed by Smith degradation to obtain F3deS-Sm was used to simplify the structure of F3, and all these preparations were characterized by methylation analysis and NMR spectra. A linear (1 → 3)-linked backbone built up of α-l-fucopyranose residues was identified as the main structural motif of molecules. Some fucose residues attached to position 4 of its 3-linked neighbor were found as branches. Galactose residues having both α- and β-configurations were found mostly at the periphery of molecules. They are present as (1 → 6)-linked disaccharide of two β-d-Galp attached to position 4 of the backbone or as single α-d-Galp attached to the same position. Sulfate groups in F3 may probably occupy any positions of the molecule. F3 acts as anticoagulant and is about half as active as the standard low-molecular mass heparin (enoxaparin). FHC was practically inactive in cytotoxicity test against six human cancer cell lines. [Display omitted] •A fucoidan preparation was isolated from the brown alga Hormophysa cuneiformis.•Fractionation of fucoidan was carried out by anion-exchange chromatography.•Anticoagulant activity of fractions was shown to depend on degree of sulfation.•Polysaccharide structures were studied by chemical and spectral methods.•The presence of a sulfated branched galactofucan was detected.