Synthesis of a series of multivalent homo-, and heteroglycosides and their anti-adhesion activities.

Adhesion of leukocytes to endothelium plays an important role in inflammatory diseases. We previously found that the tetravalent lactoside Gu-4 was able to inhibit leukocyte-endothelial cell adhesion significantly and that CD11b was the target of Gu-4 on the surface of leukocytes. In this report, we aimed to explore the relationship between structural characteristics of glycoclusters and anti-adhesion activity. Using selective glycosylation method and convergent strategy, we synthesized a new series of homoglycoclusters and heteroglycoclusters with diverse structures. And the bioactivities of these compounds were assessed by a static state cell-based adhesion assay. We found that when the linked saccharide fragments are the same, the anti-adhesion activities of compounds with flexible linkers were stronger than those with rigid scaffold such as the benzene ring, and the best flexible linker in the tested compounds was L-glutamic acid. When l-glutamic acid was employed as the linker, glycoclusters with four valences, but not other valences, exhibited the most significant anti-adhesion activity; however, no significant differences in anti-adhesion activity were found among the tetravalentglycosides that were made by linking glucose (32), mannose (TMa-4), cellobiose (34), or lactose (Gu-4). Thus, we conclude that a flexible linker with proper length, such as that of L-glutamic acid, and the linking of four saccharide fragments might be the preferable structural characteristics for the glycocluster compounds with potent anti-adhesion activity.