Rational designing and synthesizing an antimicrobial peptide from bovine milk casein and evaluating its biological properties

The overuse of antibiotics has led to a growing crisis—antimicrobial resistance, making it harder to treat infections and pushing scientists to find new solutions. Among the most promising alternatives are bioactive peptides, especially antimicrobial peptides, which offer broad-spectrum activity with a lower risk of resistance. One exciting source of these peptides is milk, particularly casein-derived peptides, which naturally possess antimicrobial properties. This study focused on bovine milk casein to design and synthesize a novel antimicrobial peptide. We evaluated several properties, such as antimicrobial activity, cytotoxicity, stability, and structure, using computational predictions to select the most promising candidate. The peptide NCP1 emerged as the best option and was synthesized for lab testing. Our results showed that NCP1 has antifungal activity and effectively stops the growth of Candida albicans with a minimum fungicidal concentration (MFC) of 250 µg/mL in less than four hours. It also prevented biofilm formation, interacted with DNA, and bound to ergosterol, ultimately damaging the fungal cell wall. Additionally, NCP1 demonstrated feeble antibacterial effects, particularly against Staphylococcus aureus and Pseudomonas aeruginosa. However, its antibacterial impact weakened over time due to interactions with environmental salts. Since the NCP1 peptide has low cytotoxicity and kills the yeasts selectively, further refinements to improve its potency and stability could pave the way for our future study of the presentation of a potent antimicrobial peptide.