Synthesis and intermembrane transfer of pyrene-labelled liponucleotides: ceramide phosphothymidines

Phospholipid conjugates of 3'-azido-3'-deoxythymidine (AZT) show activity a gainst human immunodeficiency virus (HIV) in vitro. Here we report on the s ynthesis and characterization of two pyrene containing conjugates: 2-N-(4-( pyren-1-yl)butanoyl)ceramide 5'-phosphothymidine (Pbs-Cer-P-T) (XII) and 2- N-(10-(pyren-1-yl)decanoyl)ceramide 5'-phosphothymidine (Pds-Cer-P-T) (XIII ). These fluorescent labelled conjugates served as model compounds to study incorporation of sphingoliponucleotides into membranes. The complex compou nds were prepared by condensation of 3'-acetylthymidine and labelled cerami des using the phosphite triester coupling procedure. UV absorption, fluorim etry as well as H-1-, P-31-, C-13-NMR analyses were used for structure conf irmation of the synthesized substances. When incorporated into small unilam ellar 1-palmitoyl-2-oleoyl-glycerophosphatidyl choline (POPC) vesicles and incubated with unlabelled acceptor POPC vesicles, the compounds (XII) and ( XIII) exhibited spontaneous transfer. Kinetic data suggest that transfer fr om donor to acceptor vesicles occurred via the intervening aqueous phase. T he non-specific lipid transfer protein from bovine liver stimulated the tra nsfer of Pds-Cer-P-T between phospholipid vesicles in a concentration depen dent manner. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.