3-Cyanochromone is a potent gram-negative bacteria WcbL protein inhibitor with IC50 of 28 uM in a competitive enzyme-inhibition model.

Rosoxacin shows antibacterial activities against a broad spectrum of Gram-negative bacteria including Neisseria gonorrhoeae (MIC90 = 0.03mg/ml).

Polymyxin B nonapeptide, a cationic cyclic peptide derived by enzymatic processing from the naturally occurring peptide polymyxin B, is able to increase the permeability of the outer membrane of Gram-negative bacteria toward hydrophobic antibiotics probably by binding to the bacterial lipopolysaccharide (LPS)