Fucosyled neoglycolipids: synthesis and interaction with a phospholipid

The interfacial behavior of the neoglycolipids formed of Guerbet alcohol (G(28)) bound to a triethylene glycol spacer (E(3)) and to a sugar moiety (alpha- and beta-fucose) spread at the air/water interface has been studied under dynamic conditions of compression. Although the alpha (alpha-FucE3G28)- and beta-fucose (beta-FucE3G28) derivatives possessed the same chemical structure, the positioning of the sugar moiety relative to the whole molecule had a significant influence on the organization of neoglycolipid molecules in the spread monolayers. Thus, beta-fucose molecules exhibited higher compressibilities and larger molecular areas than a alpha/beta (84/16%) mixture (alpha(84)-FucE3G28). The comparison of the compressional behavior of the fucose derivatives with that of Guerbet alcohol in the absence and in the presence of the triethylene glycol spacer shows that the presence of the E(3) chain is necessary to stabilize the lipid at the interface and that the incorporation of a sugar moiety into the molecule resulted in an important expansion of a monolayer. Despite their different interfacial behaviors, the two sugar derivatives formed ideal mixtures when cospread at the air/water interface. Conversely, in the presence of a phospholipid, such as DMPC, repulsive interactions were observed and appeared to be stronger for DMPC/alpha(84)-FucE3G28 mixed monolayers. The membrane fluidity of DMPC liposomes bearing the studied amphiphilic molecules was assessed by fluorescence depolarization measurements. The results reveal that whereas G(28) was deeply inserted into the liposome bilayers, the presence of a E(3) chain and of a sugar moiety in these bilayers induced a transfer of the amphiphilic derivatives from the hydrophobic core towards polar headgroups of phospholipid molecules.