Incrementally increasing the length of a peptide backbone: effect on macrocyclisation efficiency

Area of Science:

• Medicinal Chemistry
• Organic Synthesis
• Peptide Chemistry

Background:

• Sansalvamide A is a cyclic pentapeptide with potential biological activities.
• The synthesis of cyclic peptides can be challenging due to low cyclization efficiency.
• Modifying amino acid residues is a common strategy to alter peptide properties.

Purpose of the Study:

• To synthesize novel analogues of sansalvamide A.
• To investigate the effect of replacing a leucine residue with glycine, beta-alanine, or GABA on cyclization efficiency.
• To understand the relationship between cyclization efficiency and effective molarity.

Main Methods:

• Solid-phase peptide synthesis.
• Chemical synthesis of linear peptide precursors.
• Cyclization reactions in solution.
• Analysis of cyclization efficiency and effective molarity.

Main Results:

• Three novel analogues of sansalvamide A were successfully synthesized in high yield.
• Replacing leucine with glycine, beta-alanine, or GABA in the linear precursor significantly improved cyclization efficiency.
• Increased effective molarity was observed for the cyclization reactions of the modified peptides.

Conclusions:

• The replacement of leucine with specific residues enhances the cyclization efficiency of sansalvamide A analogues.
• Effective molarity is a key factor influencing the success of cyclic peptide synthesis.
• These findings provide insights for the rational design of cyclic peptides with improved synthetic accessibility.