Inhibition effect of aggregation of phospholipid vesicles by incorporation of glycolipids

Oligosaccharide fatty acid esters (glycolipids) [G_kmC_n; k, number of α-1,4-bound glucose unit (G) (k = 2, 5, 7); m, number of fatty acid (C) (m = 1, 2); and n, number of methylene unit (n = 12, 16, 22)] were synthesized. Aggregation of unilamellar vesicles of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) below a gel-to-liquid crystalline phase transition temperature (43°C) were inhibited by incorporation of glycolipids into bilayer membrane and G₅1C₁₆ was clarified to be the most effective structure. The complete inhibition by G₅1C₁₆ could be achieved by the addition of 2 mol% of G₅1C₁₆ to less than 0.5 wt% of DPPC liposomes at room temperature. This glycolipid also restricts the aggregation of liposomes induced by polyethyleneglycol or polysaccharide and improves the packing of lipids in the bilayer membrane.