Purification, toxicity, and antiendotoxin activity of polymyxin B nonapeptide.
Polymyxin B, a relatively toxic antibiotic, has potent endotoxin-neutralizing properties that may be beneficial as adjunctive therapy in gram-negative sepsis. Polymyxin B nonapeptide (deacylated polymyxin B) is devoid of antibiotic activity but retains the capacity to disorganize the outer membrane of gram-negative bacteria. To evaluate the potential therapeutic usefulness of this derivative, we produced purified polymyxin B nonapeptide, tested its in vivo toxicity in animals, and evaluated its in vitro antiendotoxin activity. Effectiveness as an antiendotoxin agent was assessed by examining the ability of polymyxin B nonapeptide to block the enhanced release of toxic oxygen radicals induced by lipopolysaccharide in human neutrophils (priming). In vivo, at doses of 1.5 and 3.0 mg/kg, polymyxin B nonapeptide did not exhibit the neuromuscular blocking, neurotoxic, or nephrotoxic effects that were observed with polymyxin B sulfate. Both polymyxin B and polymyxin B nonapeptide inhibited lipopolysaccharide-induced neutrophil priming in a concentration-dependent manner, but the parent compound, polymyxin B, was 63 times more effective on a weight basis. The inhibitory activity of both compounds, however, diminished rapidly when they were added after the start of the lipopolysaccharide-neutrophil incubation. We conclude that polymyxin B nonapeptide is less toxic than polymyxin B and, at the doses tested, lacks the neurotoxicity and nephrotoxicity of the parent compound. Polymyxin B nonapeptide retains the antiendotoxin activity of polymyxin B but is much less potent. The findings suggest that these compounds block an early step in the neutrophil priming process, possibly lipopolysaccharide attachment to or insertion into the neutrophil membrane.
Danner
R L
RL
Critical Care Medicine Department, National Institutes of Health, Bethesda, Maryland 20892.
Joiner
K A
KA
Rubin
M
M
Patterson
W H
WH
Johnson
N
N
Ayers
K M
KM
Parrillo
J E
JE
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D004285:Dogs; D006801:Humans; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D008070:Lipopolysaccharides / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D011112:Polymyxin B / Q000031:analogs & derivatives; D011113:Polymyxins / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology / Q000633:toxicity; D051381:Rats; D011919:Rats, Inbred Strains; D013056:Spectrophotometry, Ultraviolet; D013481:Superoxides / Q000378:metabolism
D007202:Indicators and Reagents; D008070:Lipopolysaccharides; D011113:Polymyxins; D013481:Superoxides; C038934:polymyxin B nonapeptide; D011112:Polymyxin B