Helical peptide-polyamine and -polyether conjugates as synthetic ionophores.

Two new synthetic ionophores in which the hydrophobic portion is represented by a short helical Aib-peptide (Aib=α-amino-isobutyric acid) and the hydrophilic one is a poly-amino (1a) or a polyether (1b) chain have been prepared. The two conjugates show a high ionophoric activity in phospholipid membranes being able to efficiently dissipate a pH gradient and, in the case of 1b, to transport Na(+) across the membrane. Bioactivity evaluation of the two conjugates shows that 1a has a moderate antimicrobial activity against a broad spectrum of microorganisms and it is able to permeabilize the inner and the outer membrane of Escherichia coli cells.

Albumin-directed stereoselective reduction of 1,3-diketones and β-hydroxyketones to anti diols.

The reduction of 1,3-diketones and β-hydroxyketones with NaBH(4) in aqueous acetonitrile is highly stereoselective in the presence of stoichiometric amounts of bovine or human albumin, giving anti 1,3-diols with d.e. up to 96%.

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.

Albumin-controlled stereoselective reduction of 1,3-diketones to anti-diols.

An unprecedented combination of high chemo- and stereoselectivity in the NaBH4 reduction of 1:1 complexes between albumin and aromatic 1,3-diketones results in the formation of anti 1,3-diols with de up to 96%.