Applications of arginine-rich amphiphilic peptides as cell-penetrating peptides and in drug delivery are subjects of major interest. We have previously shown that cyclic and linear peptides containing arginine and tryptophan can be used as molecular transporters of small molecules and siRNA. We hypothesized that conjugation of hydrophobic fatty acids with positively-charged arginine-containing peptides could facilitate interaction of the peptide with the cellular phospholipid bilayer, improve the binding with siRNA, and enhance the cellular delivery of siRNA. Herein, we describe the solid-phase synthesis of cyclic and linear peptides containing arginine and lysine residues conjugated with dicarboxylic and monocarboxylic fatty acids. The linear peptides were assembled on the solid-phase Wang arginine resin. Then two lysine side chain amino groups were unprotected selectively and conjugated with the fatty acids. The final cleavage from the resin in the presence of reagent R generated twelve linear peptide-fatty acid conjugates. Alternatively, assembling of linear peptides on the trityl resin, cleavage of the corresponding linear peptide from the resin, followed by the cyclization, and fatty acid conjugation afforded twelve cyclic peptide-fatty acid conjugates. All the compounds were purified by reverse-phase HPLC and characterized by high-resolution MALDI mass spectroscopy. The cytotoxicity of peptides was evaluated in MDA231 human breast cancer cells. For example, the linear peptide-fatty acid conjugates did not exhibit any significant toxicity at a concentration of 5 µg/mL. The binding assay demonstrated that the peptides had an affinity for siRNA at a ratio of 2:1 possibly due to ionic interactions. These studies provide information about the structural requirements for the optimal interactions between peptides and siRNA.

Synthesis of amphiphilic cyclic and linear peptide-fatty acid conjugates and studying their interactions with siRNA

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.