Polymyxin B nonapeptide (86408-36-8) is a cationic cyclic peptide consisting of 9 amino acids. The sequence contains 5 Dabs. Its main functional group is amino. It is a peptide derived from the antibiotic polymyxin B. Polymyxin B nonapeptide can interact with the outer membrane of Gram-negative bacteria to increase the permeability of the membrane by promoting hydrophobic diffusion.