A synthetic route for the preparation of symmetrical and unsymmetrical archaeal tetraether-like analogues has been described. The syntheses are based upon the elaboration of hemimacrocyclic tetraether lipid cores from versatile building blocks followed by simultaneous or sequential introduction of polar head groups. Functionalizations of the tetraether lipids with neutral lactose or phosphatidylcholine
cationic lipid and the resulting formulations were tested in transfection assays after complexation with plasmid DNA. All four novel co-lipids afforded efficient in vitro gene transfection. Moreover, the FA-equipped derivatives permitted ligand/receptor-based targeted transfection; their activity was inhibited when free FA was added to the transfection medium. These novel archaealderivatives equipped