Highly Potent Antibacterial Organometallic Peptide Conjugates

Area of Science:

• Medicinal Chemistry
• Antimicrobial Peptides
• Organometallic Chemistry

Background:

• Increasing antibiotic resistance necessitates novel therapeutic strategies.
• Existing antibiotics often face resistance, driving the need for compounds with new mechanisms of action.
• Antimicrobial peptides (AMPs) are a promising class, but their mechanisms are not fully understood.

Purpose of the Study:

• To develop novel metal-based antibiotics by modifying antimicrobial peptides (AMPs) with organometallic agents, creating organometallic AMPs (OM-AMPs).
• To investigate the antibacterial activity and elucidate the mode of action of these novel OM-AMPs.
• To explore potential applications of OM-AMPs in combating antibiotic-resistant bacteria.

Main Methods:

• Synthesis of organometallic-peptide conjugates using solid-phase peptide synthesis, incorporating group 8 and 9 metallocenes.
• Systematic optimization of peptide sequence, organometallic group, and amino acid chirality.
• Characterization of antibacterial activity against resistant strains like MRSA and elucidation of mechanism using physicochemical properties of ruthenocene.

Main Results:

• Several OM-AMPs demonstrated significantly enhanced antibacterial activity, with one derivative showing an 18-fold increase, achieving submicromolar activity.
• Optimized OM-AMPs rivaled vancomycin's efficacy against methicillin-resistant Staphylococcus aureus (MRSA).
• Detailed mechanistic studies revealed OM-AMPs disrupt bacterial membranes, leading to the detachment of essential enzymes like cytochrome c and MurG.

Conclusions:

• Organometallic modification of AMPs is a viable strategy for developing potent new antibiotics against resistant bacteria.
• OM-AMPs exhibit a novel mechanism of action involving bacterial membrane disruption.
• OM-AMPs show promise for topical applications, including wastewater treatment and synergistic therapy for infections like Pseudomonas aeruginosa.