Design of novel analogues of t-DPH1 with reduced cytotoxicity, taking the three conserved characteristics of the dermaseptin family as the feasible starting point

In recent years, there has been growing scientific interest in balancing the bioactivity and cytotoxicity of antimicrobial peptides (AMPs) for more comprehensive research and application. In this study, we focused on t-DPH1, a representative member of the dermaseptin family, as a template. We synthesized five analogues were synthesised to to assess the impact of three conserved features of the dermaseptin family (1. the tryptophan residue at 3rd position, 2. the consensus motif at mid-region, and 3. C-terminal amidation) on the bioactivity of t-DPH1 and their potential to reduce cytotoxicity. Our results demonstrated that analogues lacking an amino group at the C-terminus, specifically t-DPH1-NH2, exhibited potent antimicrobial activity against Gram-negative bac-teria, including Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae). Furthermore, t-DPH1-NH2 retained its robust antiproliferative activity against the human non-small lung cancer cell line H157. Regarding cytotoxicity, t-DPH1-NH2 displayed lower levels of haemolytic activity and cytotoxicity against two normal cell lines. Notably, we employed C. elegans as an in vivo model to assess the cytotoxicity of peptides, and the results revealed no induction of in vivo toxicity by t-DPH1-NH2. Collectively, t-DPH1-NH2 provides valuable insights for further investigation as promising bioactive peptide templates in the development of antibiotic and anticancer prototype drugs. The modifications implemented based on the conserved structure of the peptide family offer a new direction for reducing the cytotoxicity of peptides.