Copper turns designer peptides into selective cancer-cell killers in lab tests

Chemists have designed and synthesized two functionalized peptides built around non-canonical amino acids, and found that binding copper ions to one of them markedly increases its ability to kill cancer cells in laboratory tests, while leaving normal human dermal fibroblasts unaffected across the concentration range tested. The study, published as an open-access original article in the journal Amino Acids, was led by Agnieszka Rombel-Bryzek together with colleagues including Hayarpi Simonyan, Anna Mkrtchyan, Tatevik Sargsyan, Satenik Petrosyan, Karolina Kapłon, Szymon Wenta, Joanna Wątły and Danuta Witkowska.

Unusual, non-canonical amino acids are prized tools in peptidomimetic design because they can accommodate diverse substituents while preserving a chiral center. According to the researchers, incorporating them into peptides allows fine-tuning of physicochemical and biological properties, and also provides versatile functional handles for further structural modification. In this study, the team chose specific non-canonical residues with the aim of improving peptide stability and conferring predicted biological activity.

The researchers pursued two complementary strategies for modulating peptide activity. The first was structural: designing the peptides themselves around the non-canonical building blocks. The second was coordination chemistry: binding the peptides to copper(II) ions, an approach that has previously been associated with enhanced antimicrobial, antioxidant and therapeutic potential in metal–peptide systems. The team investigated in detail how the two synthetic peptides coordinate Cu(II) ions, mapping the coordination behavior of each compound.

The biological evaluation covered both the free peptides and their copper complexes, tested in cancer cell lines and in normal fibroblasts. The central result was selective: copper(II) coordination markedly increased the in vitro cytotoxic activity of one of the two tested compounds, while the other did not show the same enhancement. No reduction of viability was detected in normal human dermal fibroblasts within the concentration range tested, a point the authors highlight as evidence that the active copper–peptide complex can discriminate between cancerous and healthy cells under the conditions of the assay.

The findings are limited to in vitro experiments on cell lines, and the article is being shared early as a peer-reviewed, accepted manuscript that is citable and carries a permanent DOI, subject to further edits before the final version of record.

Subject of Research: Copper(II) coordination of peptides incorporating non-canonical amino acids and its effect on cytotoxic activity in cancer cell lines

Article Title: Functionalized peptides incorporating non-canonical ɑ–amino acids: copper(II) coordination and cytotoxic activity

Article References: Rombel-Bryzek, A., Simonyan, H., Mkrtchyan, A., Sargsyan, T., Petrosyan, S., Kapłon, K., Wenta, S., Wątły, J., & Witkowska, D. (2026). Functionalized peptides incorporating non-canonical ɑ–amino acids: copper(II) coordination and cytotoxic activity. Amino Acids. https://doi.org/10.1007/s00726-026-03555-9

Image Credits: AI Generated

DOI: 10.1007/s00726-026-03555-9

Keywords: non-canonical amino acids, peptidomimetics, copper(II) coordination, cytotoxicity, cancer cell lines, normal fibroblasts, peptide design, coordination chemistry, in vitro study, Amino Acids journal, Functionalized, peptides