Synthesis of Fluorinated 2′-Fucosyllactose Analogues: Investigating the Roles of Primary and Anomeric Hydroxyl Groups in Norovirus Recognition

Human milk oligosaccharides (HMOs) inhibit norovirus attachment by acting as soluble decoy ligands. 2'-Fucosyllactose (2'-FL) is the most abundant component of HMOs and also one of the most studied, yet the contribution of individual hydroxyl groups in 2'-FL to molecular recognition remains unclear. To probe their roles, we synthesized a series of monofluorinated, difluorinated, and trifluoroethyl-substituted 2'-FL analogues bearing modifications at the primary and anomeric positions. The dissociation constants (Kd) of the fluorinated analogues toward the GII.4 Sydney norovirus P-domain were determined by chemical shift perturbation (CSP) NMR spectroscopy. All fluorinated derivatives exhibited binding affinities comparable to native 2'-FL, indicating that fluorination at these positions does not significantly perturb ligand recognition. These findings indicate that fluorination at the primary and anomeric positions of 2'-FL is well tolerated by the GII.4 Sydney norovirus P-domain, highlighting the utility of fluorinated 2'-FL analogues for probing carbohydrate-protein interactions.