Antimicrobial peptides are produced by plants and most organisms throughout the animal kingdom including humans. Antimicrobial peptides protect against a broad range of infectious agents, as bacteria, fungi, and viruses. The amphibian skin is an especially rich source of antimicrobial peptides. See also the product families: Hepcidins LL-37 and Fragments Tuftsin and Analogs (subfamily).

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.