Structural Characterization and Heparanase Inhibitory Activity of Fucosylated Glycosaminoglycan from Holothuria floridana

Unique fucosylated glycosaminoglycans (FG) have attracted increasing attention for various bioactivities. However, the precise structures of FGs usually vary in a species-specific manner. In this study, HfFG was isolated from Holothuria floridana and purified by anion exchange chromatography with the yield of similar to 0.9%. HfFG was composed of GlcA, GalNAc and Fuc, its molecular weight was 47.3 kDa, and the -OSO3-/-COO- molar ratio was 3.756. HfFG was depolymerized by a partial deacetylation-deaminative cleavage method to obtain the low-molecular-weight HfFG (dHfFG). Three oligosaccharide fragments (Fr-1, Fr-2, Fr-3) with different molecular weights were isolated from the dHfFG, and their structures were revealed by 1D and 2D NMR spectroscopy. HfFG should be composed of repeating trisaccharide units -{(L-FucS-alpha 1,3-)D-GlcA-beta 1,3-D-GalNAc(4S6S)-beta 1,4-}-, in which sulfated fucose (FucS) includes Fuc(2S4S), Fuc(3S4S) and Fuc(4S) residues linked to O-3 of GlcA in a ratio of 45:35:20. Furthermore, the heparanase inhibitory activities of native HfFG and oligosaccharide fragments (Fr-1, Fr-2, Fr-3) were evaluated. The native HfFG and its oligosaccharides exhibited heparanase inhibitory activities, and the activities increased with the increase of molecular weight. Additionally, structural characteristics such as sulfation patterns, the terminal structure of oligosaccharides and the presence of fucosyl branches may be important factors affecting heparanase inhibiting activity.

Automated summary

This study isolated and characterized a unique fucosylated glycosaminoglycan (FG) from a species of sea cucumber, revealing its composition, structure, and heparanase inhibitory activities. The low molecular weight FG obtained through depolymerization showed potential as an inhibitor of heparanase, with the inhibitory activities increasing with molecular weight. Structural characteristics such as sulfation patterns and the presence of fucosyl branches were identified as important factors affecting the inhibitory activity of heparanase.