Molecules (Oct 2022)

Comparing Variants of the Cell-Penetrating Peptide sC18 to Design Peptide-Drug Conjugates

  • Joshua Grabeck,
  • Tamara Lützenburg,
  • Pia Frommelt,
  • Ines Neundorf

DOI
https://doi.org/10.3390/molecules27196656
Journal volume & issue
Vol. 27, no. 19
p. 6656

Abstract

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Herein, the design and synthesis of peptide-drug conjugates (PDCs) including different variants of the cell-penetrating peptide sC18 is presented. We first generated a series of novel sequence mutants of sC18 having either amino acid deletions and/or substitutions, and then tested their biological activity. The effects of histidine substituents were found to be not meaningful for sC18 uptake and cell selectivity. Moreover, building a nearly perfect amphipathic structure within a shortened sC18 derivative provided a peptide that was highly membrane-active, but also too cytotoxic. As a result, the most promising analog was sC18ΔE, which stands out due to its higher uptake efficacy compared to parent sC18. In the last set of experiments, we let the peptides react with the cytotoxic drug doxorubicin by Thiol–Michael addition to form novel PDCs. Our results indicate that sC18ΔE could be a more efficient drug carrier than parent sC18 for biomedical applications. However, cellular uptake using endocytosis and resulting entrapment of cargo inside vesicles is still a major critical step to overcome in CPP-containing peptide-drug development.

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