Designing Novel Antimicrobial Agents from the Synthetic Antimicrobial Peptide (Pep-38) to Combat Antibiotic...

Background/Objectives: The rise of antibiotic-resistant bacteria presents a major global health challenge, highlighting the need for novel antimicrobial agents such as antimicrobial peptides (AMPs). AMPs are promising due to their broad-spectrum activity, membrane-disruptive mechanisms, and low development of resistance. This study aimed to design and evaluate novel AMPs derived from a synthetic parent peptide (PEP-38). Methods: Novel peptides were designed using bioinformatics tools, including CAMP_R3 and Peptide Ranker. Their antimicrobial potential was validated through in vitro assays, including bacterial susceptibility, antibiofilm activity, cytotoxicity, hemolysis, and time-kill kinetics. Results: Among the designed peptides, Hel-4K-12K showed potent activity against both Gram-positive and Gram-negative bacteria, with MICs ranging from 3.125 to 6.25 µM. It also effectively eradicated biofilms of resistant Staphylococcus aureus at an MBEC of 6.25 µM. Time-kill assays confirmed rapid bactericidal action, achieving complete bacterial elimination within one hour at its MIC. Moreover, Hel-4K-12K exhibited low toxicity toward mammalian MDCK cells (>82% viability at MIC) and minimal hemolytic activity on human erythrocytes. Conclusions: Hel-4K-12K demonstrates strong antibacterial and antibiofilm activities with a favorable safety profile, indicating its potential as a therapeutic candidate for treating infections caused by resistant bacteria. These findings support further development of this peptide as a basis for new antimicrobial drug strategies. In addition to its promising in vitro profile, future studies will investigate Hel-4K-12K in animal models and evaluate strategies for attaining stable formulations, such as peptide encapsulation or PEGylation. These steps are critical to ensure its therapeutic viability in systemic applications.