E-selectin (endotherial-leukocyte adhesion molecule-l), P-selectin (GMP-140) and L-selectin (leukocyte adhesion molecule-l) belong to a family of adhesion molecules that mediate the binding of leucocytes to endothelial cells and platelets, as well as to lymphocyte-homing receptors. The ligand recognized by E-selectin is the SLe x type determinant [1] which is found as the terminal carbohydrate structure in both glycolipids and glycoproteins. From this background, Hasegawa and co-workers have reported the synthesis of sialyl Le x gangliosides and analogues to clarify structure-activity relationships in this epitope [2].
Sialyl dimeric Le x exhibits high potency among the naturally occurring E-selectin binding molecules, but nobody has reported its synthesis as the naturally occurring glycolipid structure due to its molecular complexity, although the carbohydrate portion was synthesized by Nicolaou et al. [3]. It is noteworthy that glycononaosyl ceramide 1 is identified as tumor-associated ganglioside that accumulates in human colonic adenocarcinoma but is absent in normal colonic mucosa [4]. Owing to the biological importance of 1, an efficient chemical synthesis is in demand.
* For a preliminary report, see M.