Sulfo-Fluorous Affinity Tag Assisted Regio-Selective Fucosylated Human Milk Oligosaccharide Synthesis

Human milk oligosaccharides (HMOs) are a family of structurally diverse unconjugated glycans unique to mother’s milk and are strongly correlated to the health benefits of breastfeeding in infants. The fucosylated portion of HMOs resemble Lewis antigen glycan structures, which not only play an important role in antiadhesive antimicrobial functions, inflammation, and tumor metastasis, but also serve as prebiotics for beneficial bacteria. Herein, we develop a sulfo-fluorous affinity (SOFA) tag-assisted enzymatic synthesis that facilitates the purification of HMOs using fluorous solid-phase extraction (FSPE).[1] Surprisingly, comparing to the azidohexyl glycosides that we reported previously, the catalytic efficiency of SOFA tagged glycoside by bacterial glycosyltransferases were higher. By the combination of SOFA strategy and limited number of bacterial glycosyltransferases (HP1105, HP0826, WbgO, FutC, and Bf13FT),[2] the facile preparation of seven HMOs and nine fucosylated HMOs were achieved. The anomeric linker[3] of the SOFA tag enabling the easy release of HMOs with a free-reducing end under mild acidic hydrolysis;[4] the SOFA tag recovered by FSPE could be recycled for glycosylation of next round.