Synthetic Strategies to Prepare Bioactive Lysine and Peptide Conjugates with Triazolium Derivatives

Peptides conjugated with organic molecules can be useful tools for the development of novel bioactive compounds. The lysine side-chain is an interesting functional group to act as a linker to connect small molecules in peptide conjugates. Herein we present the design and synthesis of four Safirinium derivatives, their facile conjugation to lysine in solid phase, and incorporation in peptides. The compounds differing in the functionalization of nitrogen N2 of the condensed triazolyl moiety are novel building blocks to design conjugates to perform structure-activity relationship studies of elastase inhibitors. Consequently, structural investigations of the lysine building blocks and of the corresponding peptide conjugates were performed. We present herein the potential of the Safirinium analogs to act as elastase inhibitors in assays performed on porcine pancreas elastase.