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

Abstract 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.