Structure characterization and multi-target inhibitory activities of fucosylated chondroitin sulfate from sea cucumber Thelenota anax.

A fucosylated chondroitin sulfate (FCS) was extracted from the body wall of Thelenota anax (FCSTx). Physicochemical characterization confirmed its typical FCS structural features, and monosaccharide composition analysis revealed the presence of Gal. Combined NMR spectroscopic analysis of native FCSTx and fifteen oligosaccharides prepared by partial acid hydrolysis and β-elimination depolymerization comprehensively established that FCSTx possesses a chondroitin sulfate E backbone with branches composed of 60% Fuc2S4S, 8% Fuc4S, and 32% D-Gal4S(6S)-α1,2-L-Fuc3S, all attached at the O-3 of GlcA. Notably, this represents the second confirmation in nature of D-Gal-α1,2-L-Fuc-type disaccharide branches, following the initial report from T. ananas. This branch type has thus far been identified exclusively in the genus Thelenota, providing valuable clues for investigating the relationship among FCS structure, biosynthesis, and species taxonomy. Pharmacologically, FCSTx exhibited potent inhibition against intrinsic Xase (iXase), heparanase, and P-selectin, with the strongest inhibition observed against iXase. SAR analysis of low-molecular-weight derivatives revealed distinct molecular weight-dependent patterns: heparanase and P-selectin inhibitory activities increased with chain length, whereas iXase inhibitory activity initially increased upon depolymerization followed by a decrease. Further glycosylation of fucose branch diminished the inhibition potency. Notably, fractions with molecular weights above approximately 6 kDa exhibited stronger iXase inhibitory activity than native FCSTx.