Researchers created two new short peptides, Catoid and its dimer Dicatoid, based on the human antimicrobial peptide LL‑37. In lab tests they killed eye‑infecting bacteria better than the original LL‑37 and were much less toxic to eye and skin cells, suggesting they could be safer eye‑drop ingredients, though they’re not yet approved for human use.

The human body produces two classes of antimicrobial peptides (AMPs), namely defensins and cathelicidins. In this study, a novel decapeptide (Catoid) and its dimer (Dicatoid) based on human cathelicidin (LL-37) have been designed by bioinformatics tools to be used in the treatment of bacterial keratitis. After the selection and synthesis of peptide sequences, their antimicrobial activities against the standard and resistant strains of <i>Pseudomonas aeruginosa</i> and <i>Staphylococcus aureus</i> were evaluated. This test was performed with LL-37, gentamicin, ciprofloxacin, amikacin, and penicillin for a more accurate comparison. Furthermore, the cytotoxicity levels of the specified compounds on fibroblast cells and bovine corneal endothelial cells were investigated. The results demonstrated that the designed peptides had a superior antimicrobial activity on <i>P. aeruginosa</i>, compared to LL-37; however, Catoid had a better effect on the <i>S. aureus</i> strain. Additionally, a significant achievement is the very low toxicity level of Catoid and Dicatoid on the human skin fibroblast cell line and bovine corneal endothelial cells, compared to that of LL-37 as the initial design model.