Stapled β‑Hairpin Antimicrobial Peptides with Improved Stability and Activity against Drug-Resistant Gram-Negative Bacteria

Different stapling techniques have been used recently
to address
the subpar performance of antimicrobial peptides (AMPs) in clinical
trials with ample focus on α-helical AMPs. In comparison, a
systematic evaluation of such strategies on β-hairpin AMPs is
lacking. Herein, we report the design, synthesis, and evaluation of
a library of all-hydrocarbon-stapled β-hairpin AMPs with variation
in key parameters intended as potent therapeutics against drug-resistant
pathogens. We observed an interesting interplay between the activity,
stability, and structural strength. Single-stapled peptides with a
6-carbon staple at peptide termini such as 5(c6) displayed
the most potent activity against colistin-resistant clinical isolates.
Using imaging techniques, we observed translocation of 5(c6) across bacterial membranes without causing extensive damage. Overall,
we have engineered novel all-hydrocarbon-stapled β-hairpin AMPs
with structural and functional proficiency that can effectively combat
resistant pathogens, with findings from this study a point of reference
for future interests in developing novel β-hairpin AMPs.