Structure--activity relationships of sialyl Lewis x-containing oligosaccharides. 1. Effect of modifications of the fucose moiety.

Leukocyte adhesion to the vasculature is mediated by E-, P-, and L-selectins. The natural ligands for E- and P-selectins have not been fully characterized but have been shown to contain the tetrasaccharide sialyl Lewis x structure (SLe(x)). To determine the importance of the fucose moiety of SLe(x), various analogs of SLe(x) containing modifications thereof were prepared and tested as inhibitors of E-selectin-mediated cell adhesion. Cellular experiments indicate that replacement of the hydroxyl groups of fucose by hydrogen abrogated E-selectin binding. However, the arabinose analog of fucose (CH3 delta H) inhibited cell adhesion but was 5-fold less potent than native SLe(x). This data suggests that modifications of fucose on SLe(x) are generally deleterious toward E-selectin binding.