This article presents a series of ring-extended gramicidin S derivatives, 9- 14, that have four ornithine residues as polar protonated side chains and one modified turn region containing a mono-functionalized cis- δ-oxetane, δ-furanoid, or δ-pyranoid sugar amino acid residue. Of the GS analogs evaluated, we identified compound 7, which contains the mono-benzyloxy cis-δ-pyranoid sugar amino acid, as having a better biological profile than the clinically applied topical antibiotic gramicidin S. [ABSTRACT FROM AUTHOR]