Synthesis and ionophoric activities of functionalized bis(choloyl) conjugates with a rigid core.

Three bis(choloyl) conjugates bearing a rigid p-phenylenediamine/p-bis(aminomethyl)benzene linker and amino/acetamido groups were synthesized, and fully characterized on the basis of (1)H NMR, ESI-MS and HRMS. Their ionophoric activities were investigated by means of pH discharge assay. The results indicate that these conjugates exhibit potent ionophoric activities across egg-yolk l-α-phosphatidylcholine (EYPC)-based liposomal membranes, via a cation/proton antiport mechanism. They show moderate ion selectivity among alkali metal ions. Of the three conjugates, the ones having amino groups transport alkali metal ions in the order of Na(+)>Li(+)>K(+)≈Rb(+)≈Cs(+), whereas the one having acetamido groups functions in the order of Li(+)>Na(+)>K(+)≈Rb(+)≈Cs(+).