Lactoferricin

Lactoferricin is a cationic antimicrobial peptide released from the N-terminal region of lactoferrin through pepsin-mediated proteolysis in the stomach. Lactoferrin is an iron-binding glycoprotein abundant in milk, particularly colostrum, as well as in various exocrine secretions and neutrophil granules. The bovine form (Lactoferricin B, LfcinB) is a 25-amino acid peptide that has been the most extensively studied variant.

The antimicrobial mechanism of lactoferricin involves direct interaction with microbial cell membranes. The peptide's amphipathic structure — with positively charged and hydrophobic domains — allows it to bind to negatively charged components of bacterial membranes (such as lipopolysaccharides in Gram-negative bacteria and lipoteichoic acid in Gram-positive bacteria). This interaction disrupts membrane integrity, leading to increased permeability and ultimately cell death. Notably, this mechanism of action makes it difficult for bacteria to develop resistance.

Beyond its direct antimicrobial activity, lactoferricin exhibits immunomodulatory properties. It can enhance the activity of natural killer cells, stimulate the proliferation of lymphocytes, and modulate cytokine production. Research has also demonstrated antifungal activity against Candida species, antiviral effects against certain enveloped viruses (including herpes simplex and cytomegalovirus), and antiparasitic activity against protozoa such as Giardia.

Lactoferricin has also attracted attention for its anticancer properties. Studies have shown it can selectively kill cancer cells through mechanisms involving membrane disruption and induction of apoptosis while showing relatively less toxicity toward normal cells. This selectivity is attributed to differences in membrane composition between cancer cells and normal cells. Research continues to explore lactoferricin and its derivatives as potential therapeutic agents.