Short Photoswitchable Antibacterial Peptides.

Area of Science:

• Medicinal Chemistry
• Biochemistry
• Microbiology

Background:

• Antibiotic resistance in Staphylococcus aureus is a growing global health concern.
• Synthetic peptides offer a promising avenue for novel antibacterial drug development.
• Photoswitchable molecules allow for external control over biological activity.

Purpose of the Study:

• To design and synthesize photoswitchable tetrapeptides based on a known antibacterial scaffold.
• To investigate the antibacterial activity of these modified peptides against Staphylococcus aureus.
• To understand how the position of an azobenzene photoswitch influences antibacterial efficacy.

Main Methods:

• Synthesis of three photoswitchable tetrapeptides with azobenzene incorporated at different positions (N-terminal side chain, C-terminal side chain, C-terminus).
• Evaluation of antibacterial activity using minimum inhibitory concentration (MIC) assays against Staphylococcus aureus.
• Analysis of structure-activity relationships, considering factors like charge, hydrophobicity, and amphiphilicity.

Main Results:

• All synthesized tetrapeptides exhibited antibacterial activity against Staphylococcus aureus.
• The tetrapeptide with the azobenzene moiety at the C-terminus demonstrated the most potent activity, with an MIC of 1 μg/mL.
• Key physicochemical properties including net positive charge, hydrophobicity, and amphiphilicity were identified as crucial for membrane disruption and antibacterial efficacy.

Conclusions:

• The C-terminus incorporation of an azobenzene photoswitch significantly enhances antibacterial potency against Staphylococcus aureus.
• Physicochemical properties play a vital role in the mechanism of action, likely involving bacterial lipid membrane disruption.
• These photoswitchable antibacterial tetrapeptides serve as a valuable platform for the rational design of next-generation antibiotics.