Ring-Extended Gramicidin S Analogs Containing Cis D-Sugar Amino Acid Turn Mimetics With Varying Ring Size

This article presents a series of ring-extended gramicidin S derivatives, 914, that have four ornithine residues as polar protonated side chains and one modified turn region containing a mono-functionalized cis-d-oxetane, d-furanoid, or d-pyranoid sugar amino acid residue. Of the GS analogs evaluated, we identified compound 7, which contains the mono-benzyloxy cis-d-pyranoid sugar amino acid, as having a better biological profile than the clinically applied topical antibiotic gramicidin S.