Synthesis, bioactivity testing, and structure elucidation of antimicrobial peptide analogues derived from Synoicum Turgens

Abstract

A method was developed for synthesizing and isolating two DRPs, with varying levels of success affected by difficulties in the purification process and human error. However, it has shed light on some of the difficulties that may occur and suggestions on how they could be improved. The method developed structure elucidation through sequential reduction and alkylation of the disulfide bridges proved to be a promising method. The disulfide connectivity was elucidated for the two peptide isomers that were successfully isolated in sufficient amounts. This was done by analysis of the mass spectra that were produced from the reduced and alkylated peptide isomers.

The DRPs synthesized in this study have proven to be superior to the original peptide in terms of antimicrobial activity, suggesting that replacing amino acids with groups that are hydrophobic or can obtain positive charges is a valid strategy in improving an AMPs activity. From the bioactivity testing, the approach taken in Turg_JK_2 proved to be superior to the one taken in Turg_JK_1. The most potent isomer in this study was isomer I of Turg_JK_2, which had an equal or lower MIC against all the bacterial strains compared to the rest of the isomers that were synthesized. The disulfide connectivity for this is unfortunately unknown.