Synthesis and antifungal activity of rhodopeptin analogues. 1. Modification of the east and south amino acid moieties.

Structure−activity relationships of the east and south amino acid modified analogues of rhodopeptins, novel antifungal cyclic tetrapeptides isolated from Rhodococcus species Mer-N1033, have been investigated. It was observed that a basic amino acid moiety (lysine or ornithine) as the east amino acid and a hydrophobic and bulky neutral amino acid (i.e., γ-methylleucine) as the south amino acid were indispensable structure motifs for antifungal activity of rhodopeptin analogues.