Physical properties and barrier functions of synthetic glyceroglycolipids

Four glyceroglycolipids containing dipalmitylglycerol were synthesized. The thermotropic behavior and barrier function of aqueous suspensions of these glyceroglycolipids were studied. The gel to liquid crystalline phase transition temperatures of these glycolipids were higher than that of dipalmitoylphosphatidylcholine. The interaction between headgroups in glyceroglycolipids might be stronger than that in dipalmitoylphosphatidylcholine. Diglycosyl dipalmitylglycerols could form liposomes and function as a barrier against water-soluble small molecules (glucose, UmP, and H+) when assayed below their phase transition temperatures, like dipalmitoylphosphatidylcholine liposomes. The fundamental properties of glyceroglycolipid membranes so far examined were rather similar to those of phospholipid membranes, with the exception that the permeability rate of water through glycolipid membranes was higher than that through phospholipid membranes. This property might cause the apparent sensitivity difference between liposomes prepared from glycolipids and those from phospholipids to amphotericin B.