Cyclic D,L-α-peptide nanotubes as potential therapeutic agents

ORGN 913

Shai Rahimipour, rahimis@mail.biu.ac.il, Department of Chemistry, Bar-Ilan University, Ramat-Gan, 52900, Israel, Leila Motiei, coleila@wisemail.weizmann.ac.il, Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, 76100, Israel, and M. Reza Ghadiri, ghadiri@scripps.edu, Departments of Chemistry and Molecular Biology and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037.
We have previously shown that appropriately designed cyclic peptides with an even number of alternating D- and L-α-amino acids can adopt a flat and ring-shaped conformation that under conditions favoring hydrogen bonding can stack to form hollow and β-sheet like tubular structures known as peptide nanotubes. These cyclic peptides selectively self-assemble in bacterial membranes and exert antibacterial activity by increasing membrane permeability. In this study, we have rationally designed and synthesized several cyclic D,L-α-peptide and cyclic D,L-α-glycopeptide combinatorial libraries that were screened for potent and selective anticancer and antibacterial activity. We demonstrate that these cyclic peptides increase membrane permeation and exert impressive anticancer and antibacterial activity with low toxicity to normal cells. In the case of cyclic D,L-α-glycopeptides, we have discovered that, depending on the position and the type of sugar residue employed, the toxicity of these compounds may significantly be attenuated toward erythrocytes and normal mammalian cells.