Structural analysis of a novel sulfated galacto-fuco-xylo-glucuronomannan from Sargassum fusiforme and its anti-lung cancer activity

Polysaccharide (HFSGF) was purified from Sargassum jusiforme. Autohydrolysis and gel column chromatography were performed to fractionate HFSGF into three components (HFSGF-S, HFSGF-L and HFSGF-H). Compositional analysis, mass spectrometry and nuclear magnetic resonance spectroscopy were used to elucidate the structural features of HFSGF. HFSGF-S was a mixture of sulfated galacto-fuco-oligomers, from the branches terminal ends; in HFSGF-L, the branches of HFSGF, was a sulfated galactofucan, containing a backbone of 1,3-linked alpha-L-fucan sulfated at C2/4 and/or C4 and interspersed with galactose (Gal); and in HFSGF-H, the backbone of HFSGF, was composed of alternating 12-linked alpha-D-mannose (Man) and 1,4-linked beta-D-glucuronic acid (GIcA). branched with sulfated galactofucan or sulfated fucan, 1,3-linked alpha-L-fucan sulfated at C2/4 and/or C4 and partly interspersed with Gal. Some fucose (Fuc) residues were also partially branched with xylose (Xyl). The anti-lung cancer activities of HISGF-L and HISGF-H against human lung cancer A549 cells in vitro and A549 xenograft tumor growth in vivo were determined. HFSGF-H had higher activity in vitro (IC50 similar to 12 mg/mL for 24 h) and in vivo (tumor inhibition similar to 51%.) than HFSGF-L, indicating that HFSGF-H might be a leading compound for a potential new therapeutics for the treatment of lung cancer. (C) 2020 Elsevier B.V. All rights reserved.