New Antimicrobial Peptides with Repeating Unit against Multidrug-Resistant Bacteria

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Antimicrobial resistance (AMR) is a growing global health threat.
• Antimicrobial peptides (AMPs) offer a potential alternative to conventional antibiotics.
• Developing novel AMPs with improved efficacy and reduced toxicity is crucial.

Purpose of the Study:

• To design and synthesize novel de novo antimicrobial peptides.
• To evaluate the antimicrobial activity, selectivity, and resistance potential of these peptides.
• To investigate the therapeutic efficacy and toxicity of lead candidates in vivo.

Main Methods:

• De novo peptide design and synthesis.
• Antimicrobial activity assays against diverse bacterial strains, including multidrug-resistant isolates.
• Selectivity assays using bacterial and mammalian cell membranes.
• Mechanism of action studies (membrane disruption, nucleic acid leakage, DNA binding, ROS generation).
• In vivo therapeutic efficacy and toxicity studies.

Main Results:

• A series of novel peptides based on the (WRX)n repeating unit were synthesized.
• Most designed peptides exhibited broad-spectrum antimicrobial activity, particularly against multidrug-resistant bacteria.
• (WRK)4 and (WRK)5 showed high selectivity for bacterial over mammalian membranes, with potent antimicrobial activity and low toxicity.
• These peptides demonstrated rapid killing kinetics and a low propensity for resistance development compared to conventional antibiotics.
• Mechanism of action involves membrane disruption and intracellular targets like nucleic acid leakage, DNA binding, and ROS generation.
• (WRK)4 exhibited significant in vivo therapeutic effects comparable to polymyxin B but with substantially lower toxicity.

Conclusions:

• The designed peptides (WRK)4 and (WRK)5 represent promising novel antimicrobial candidates.
• Their broad-spectrum activity, high selectivity, low toxicity, and unique mechanisms of action address the challenge of antimicrobial resistance.
• These findings support the potential of (WRK)4 and (WRK)5 for clinical development as alternatives to existing antibiotics.