Backbone Alterations in Cyclic Peptides Influence Both Membrane Permeability and Biological Activity

Area of Science:

• Medicinal Chemistry
• Biochemistry
• Molecular Biology

Background:

• Cyclic peptides show promise for targeting difficult biological interactions like protein-protein interactions.
• However, their clinical application is hindered by poor passive membrane permeability.

Purpose of the Study:

• To investigate how minor structural modifications affect the membrane permeability and biological activity of Sanguinamide A analogues.
• To understand the relationship between cyclic peptide structure, membrane transport, and cellular effects.

Main Methods:

• Utilized cell-permeability assays to quantify passive membrane transport.
• Employed a target-agnostic cell-painting assay to assess biological activity and cellular morphology changes.
• Applied Nuclear Magnetic Resonance (NMR) spectroscopy to analyze conformational dynamics in response to varying environmental polarity.

Main Results:

• Observed significant variations in membrane permeability among different Sanguinamide A analogues.
• NMR data indicated that permeable analogues underwent conformational changes influenced by environmental polarity.
• Cell-painting assays revealed that while permeability correlated with general morphological changes, specific biological activities varied based on backbone modifications.

Conclusions:

• The choice of backbone modification critically influences the balance between membrane permeability and biological efficacy in cyclic peptides.
• These findings provide essential guidance for designing improved cyclic peptide-based therapeutics.
• Tailoring cyclic peptide structures is key to overcoming delivery challenges and enhancing therapeutic potential.