Combinatorial Effects of CPP-Modified Antimicrobial Peptides: Synergistic and Additive Interactions Against...

Area of Science:

• Biochemistry
• Microbiology
• Drug Discovery

Background:

• Multidrug resistance (MDR) in pathogenic bacteria poses a significant global health threat.
• Antimicrobial peptides (AMPs) are a potential therapeutic avenue due to their broad-spectrum activity.
• Enhancing cellular uptake of AMPs is crucial for improving their efficacy.

Purpose of the Study:

• To investigate the antimicrobial activity of three designed peptides incorporating an amyloidogenic fragment and cell-penetrating peptide (CPP) fragments.
• To evaluate the efficacy of these peptides and their combinations against key Gram-positive and Gram-negative bacteria.
• To explore potential synergistic interactions between peptide combinations.

Main Methods:

• Design and synthesis of three novel peptides (R44K^S*, V31K^S*, R23F^S*) with integrated CPP fragments.
• Antimicrobial susceptibility testing against *Pseudomonas aeruginosa*, *Escherichia coli*, *Staphylococcus aureus*, MRSA, and *Bacillus cereus*.
• Determination of minimum inhibitory concentrations (MICs) and fractional inhibitory concentration index (FICI) for peptide combinations.

Main Results:

• All designed peptides demonstrated significant, concentration-dependent antibacterial activity.
• R44K^S* exhibited the highest potency among the individual peptides.
• Combinations, especially V31K^S*/R23F^S* and R44K^S*/V31K^S*, showed enhanced inhibition and synergistic/additive effects based on FICI analysis.

Conclusions:

• Cell-penetrating peptide (CPP)-modified antimicrobial peptides (AMPs) show considerable potential as therapeutic agents against multidrug-resistant bacteria.
• Optimizing combinations of these engineered peptides can lead to enhanced antimicrobial efficacy.
• Further research into peptide combinations is warranted for developing novel antibacterial strategies.