Antibacterial cyclopeptides targeting acinetobacter and other gram-negative pathogens

A compound having a structure represented by a formula:

• wherein R1 is selected from C1-C24 alkyl and C2-C24 alkenyl
• wherein each of R2, R6, and R9 is independently a side chain of a D-amino acid residue;
• wherein R3 is a polar uncharged side chain of an amino acid residue;
• wherein R4 is a hydrophobic side chain of an amino acid residue;
• wherein R5 is a side chain of an amino acid residue selected from cysteine, selenocysteine, glycine, and proline;
• wherein R7 is a side chain of a homo-amino acid residue selected from homoserine, homothreonine, homoasparagine, and homoglutamine;
• wherein R8 is a hydrophobic side chain of an amino acid residue;
• wherein R10 is an electrically charged side chain of an amino acid residue;
• wherein each of R11a and R11b is independently selected from hydrogen and C1-C4 alkyl;
• and
• wherein each of R12, R13, and R14 is independently selected from —OH, —SH, and —NH2,
• or a pharmaceutically acceptable salt thereof, provided that the compound does not have a structure represented by a formula:
• wherein R4 is valine, R6 is D-alloisoleucine, R8 is alanine, R11a is methyl, R11b is hydrogen, and R14 is —OH.