The cyclic peptide KTKCKFLKKC has ben shown to form a strong complex with lipid A, the toxic component of the endotoxin lipopolysaccharide (LPS) with Ka = 0.56 · 10⁷ M⁻¹. It detoxifies LPS in vitro and prevents LPS-induced cytokine release and lethality in vivo. Furthermore, it shows neither antibiotic activity nor toxicity and might therefore be useful in the prophylaxis and treatment of LPS-mediated diseases. KTKCKFLKKC bears a structural resemblance to the peptide antibiotic and endotoxin inhibitor polymyxin B. It could be of use as an adjuvant for antibiotic therapy.
M.Vaara and M.Porro, Antimicrob. Agents Chemother., 40, 1801 (1996) A.Rustici et al., Science, 259, 361 (1993)