Description
Polymyxin B is a mixture of polymyxin B1, B2, B3 and B1-1 sulfates; polymyxin B is a cationic lipid oligopeptide derived from Bacillus polymyxa that displays antibacterial activity against all gram-negative bacteria except species of Proteus. Polymyxin B kills both proliferative and quiescent cells in vitro. Polymyxin B inhibits cellular respiration by inhibiting type II NADH-quinone oxidoreductase activity. This compound also induces aggregation of lipopolysaccharide (LPS) in bacterial cell membranes, altering membrane potential and causing leakage of cellular components. Polymyxin B has been used to treat septic shock induced by LPS of gram-negative bacteria, preventing LPS-induced caspase activity, Fas expression, Bax/Bcl-2 ratio alteration, and apoptosis.