Comparative Molecular Transporter Properties of Cyclic Peptides Containing Tryptophan and Arginine Residues Formed through Disulfide Cyclization.

We have previously reported cyclic cell-penetrating peptides [WR] and [WR] as molecular transporters. To optimize further the utility of our developed peptides for targeted therapy in cancer cells using the redox condition, we designed a new generation of peptides and evaluated their cytotoxicity as well as uptake behavior against different cancer cell lines. Thus, cyclic [C(WR)C] and linear counterparts (C(WR)C), where x = 4-5, were synthesized using Fmoc/Bu solid-phase peptide synthesis, purified, and characterized.