Convergent Synthesis of Sialyl Lewis- O-Core-1 Threonine.

Selectins are a class of cell adhesion molecules that play a critical role during the initial steps of inflammation. The N-terminal domain of P-selectin glycoprotein ligand-1 (PSGL-1) binds to all selectins, but with the highest affinity to P-selectin. Recent evidence suggests that the blockade of P-selectin/PSGL-1 interactions provides a viable therapeutic option for the treatment of many inflammatory diseases.

Synthesis of Lewis-O-Core-1 threonine: A building block for O-linked Lewis glycopeptides.

Lewis (Le) is a branched trisaccharide Galβ1→4(Fucα1→3)GlcNAc that is expressed on many cell surface glycoproteins and plays critical roles in innate and adaptive immune responses. However, efficient synthesis of glycopeptides bearing Le remains a major limitation for structure-function studies of the Le determinant. Here we report a total synthesis of a Le pentasaccharide 1 using a regioselective 1-benzenesulfinyl piperidine/triflic anhydride promoted [3 + 2] glycosylation.

Glycopeptide analogues of PSGL-1 inhibit P-selectin in vitro and in vivo.

Blockade of P-selectin (P-sel)/PSGL-1 interactions holds significant potential for treatment of disorders of innate immunity, thrombosis and cancer. Current inhibitors remain limited due to low binding affinity or by the recognized disadvantages inherent to chronic administration of antibody therapeutics. Here we report an efficient approach for generating glycosulfopeptide mimics of N-terminal PSGL-1 through development of a stereoselective route for multi-gram scale synthesis of the C2 O-glycan building block and replacement of hydrolytically labile tyrosine sulfates with isosteric sulfonate analogues.