Synthesis and biological evaluation of a new sialyl Lewis X mimetic derived from lactose.

A sialyl Lewis X (sLe(x)) mimetic compound, 2-(trimethylsilyl)ethyl 3-O-carboxymethyl-beta-D-galactopyranosyl-(1-->4)-[alpha-L-fucosyl-(1-->6)]-beta-D-glucopyranoside (2a), has been synthesized in 14 steps from D-lactose. This synthesis features the use of the activated glycosylating donor, lactosyl iodide, in a Koenigs-Knorr sequence, the regioselective derivatization at the C-3 position of the galactose moiety, and the stereoselective construction of a fucose-alpha(1-->6)-lactose linkage. The mimetic was tested for its ability to inhibit human polymorphonuclear leukocyte (hPMNL) adhesion to immobilized recombinant human E-selectin under shear stress conditions.