Structural characterization of bacterial fucose-containing tetrasaccharide and its potential enhancement on intestinal barrier function

Fucose-containing oligosaccharides possess prospective application in diverse industries owing to their antiinflammatory, prebiotic, anticoagulant, and hypoglycemic activities. In this study, an exopolysaccharide (EPS) with a fucose content of 49.48 +/- 0.70 mol% and a molecular weight of 1.62 x 106 Da was extracted from Clavibacter michiganensis. Then, an EPS-degrading bacterium was isolated and used for the preparation of EPSdegrading enzyme. Subsequently, fucose-containing oligosaccharide was obtained using EPS-degrading enzyme to depolymerize EPS. Structural characterization demonstrated that the fucose-containing oligosaccharide was a tetrasaccharide (704 Da) composed of glucose, galactose, fucose, and pyruvic acid (Pyr), and its backbone was identified to be alpha-L-Fucp-(1 -> 3)-alpha-L-Fucp-(1 -> 3)-beta-D-Glcp, branched by Pyr-4,6-beta-D-Galp at O-4 position of the second alpha-L-Fucp. This study investigated the bioavailability of the fucose-containing tetrasaccharide (FTe) using a Caco-2 cell monolayer model, and results revealed that the transportation of FTe involved both passive and active transport. Furthermore, FTe and 2 '-fucosyllactose (2 '-FL) was exposed to Caco-2 cell monolayer and Ls174T cell. The results demonstrated that FTe could up-regulate the gene expression of claudin-1, occludin, and zonula occludens of Caco-2, and promoted more mucin secretion of Ls174T than 2 '-FL did. This work revealed a novel fucose-rich oligosaccharide and its preparation method, and the obtained tetrasaccharide have good potential in the development and application of foods or drugs that enhance intestinal barrier function.