Truncated Pleurocidin Derivative with High Pepsin Hydrolysis Resistance to Combat Multidrug-Resistant Pathogens

The global prevalence of antimicrobial resistance calls for the development of novel antimicrobial agents, particularly for these orally available drugs. Structural modifications of the natural antimicrobial peptides (AMPs) provide a straightforward approach to develop potent antimicrobial agents with high specificity and low toxicity. In this study, we truncated 11-amino-acids at the C-terminus of Pleurocidin, an AMP produced by Pleuronectes americanus, and obtained four peptide analogues termed GK-1, GK-2, GK-3 and GK-4. Minimum inhibitory concentration (MIC) tests showed that GK-1 obtained by direct truncation of Pleurocidin has no antibacterial activity, while GK-2, GK-3 and GK-4 show considerable antibacterial activity with Pleurocidin. Notably, GK-4 displays rapid bacteriostatic activity, great stability and low hemolysis, as well as enhanced hydrolytic resistance to pepsin treatment. Mechanistic studies showed that GK-4 induces membrane damage by interacting with bacterial membrane-specific components, dissipates bacterial membrane potential and promotes the generation of ROS. SEM and CD analysis further confirmed the ability of GK-4 to resist pepsin hydrolysis, which may be attributed to its stable helicity structure. Collectively, our findings reveal that GK-4 is a potential orally available candidate to treat infections caused by multidrug-resistant pathogens.

Automated summary

This study focuses on modifying the natural antimicrobial peptide Pleurocidin to develop potent and orally available antimicrobial agents. By truncating 11 amino acids at the C-terminus of Pleurocidin, four peptide analogues were obtained. Among them, GK-4 exhibited rapid bacteriostatic activity, stability, low hemolysis, and enhanced resistance to pepsin treatment. Mechanistic studies revealed that GK-4 induced membrane damage, dissipated bacterial membrane potential, and promoted ROS generation. SEM and CD analysis confirmed the resistance of GK-4 to pepsin hydrolysis. Overall, GK-4 shows promise as a potential orally available candidate for treating infections caused by multidrug-resistant pathogens.