Synthesis and characterization of deoxy analogues of diphytanylglycerol phospholipids.

Abstract Novel analogues of diphytanyl phospholipids, 2,3-diphytanyl sn -1-glycerol-1-phosphoryl-1′-(1′,3′-propanediol) (dPG), 2,3-diphytanyl- sn -glycerol-1-phosphoryl-1′-propanol (ddPG) and 2,3-diphytanyl- sn -glycerol-1-phosphoryl-1′-(1′,3′-propanediol-3′-phosphate) (dPGP), were synthesized according to modifications of previously published procedures. The samples were TLC and analytically pure and were characterized by 13 C- and 1 H-NMR and negative FAB/MS. The p K values of dPGP in aqueous dispersions or in methanol/water (1 : 1, v/v) were determined by potentiometric titration and compared with those of 2,3-diphytanyl- sn -glycerol-1-phosphoryl-3′- sn -glycero-1′-phosphate (PGP). The dissociation constant of the third ionizable POH group of dPGP was more than 2 p K units higher than that of PGP, indicating that the free glycerol hydroxyl group plays an important role in headgroup conformation and stabilization, perhaps through hydrogen bonding with the phosphate group(s).