Steroid-based Head to Tail Amphiphiles as Effective Iono- and Protonophores.

The synthesis of five steroid-oligo(ethyleneglycol) conjugates (1–5) has been accomplished starting from commercially available epi-androsterone (8) and known 3beta-[(tert butyldiphenylsilyl)oxy]-5a-23,24-bisnorchol-16-en-6alfa,7beta,22-triol (27). The synthetic strategy was based on a convergent approach including stereoselective C-17 side chains construction and standard coupling reactions. The activitiesof the head-to-tail amphiphiles, once incorporated in 95:5 egg PC/PG vesicular membranes, have been assessed by direct determination of transported species by NMR techniques (23NaC) and fluorescence spectroscopy (HC). The sodium and proton transmembrane transport was compared to those evaluated for the polyene macrolide antibiotic amphotericin B and those shown by the known related C2-symmetric sterolpolyether conjugates 6 and 7

Calix[4]arene-Cholic Acid Conjugates: A New Class of Efficient Synthetic Ionophores

The synthesis of a new class of amphiphilic calix[ 4] arene-based ionophores, relying on direct reductive amination as a key step, and the evaluation of their H+ and Na+ transporting properties is described

Calix[4]arene-cholic acid conjugates: a new class of efficient synthetic ionophores

The synthesis of a new class of amphiphilic calix[4]arene-based ionophores, relying on direct reductive amination as a key step, and the evaluation of their H+ and Na+ transporting properties is described