Related Experiment Video
Updated: Feb 2, 2026

Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids
Published on: May 4, 2018
Structure-Activity Relationships of Photoswitchable Diarylethene-Based β-Hairpin Peptides as Membranolytic
Oleg Babii1, Sergii Afonin1, Aleksandr Yu Ishchenko2,3
1Institute of Biological Interfaces (IBG-2) , Karlsruhe Institute of Technology (KIT) , POB 3640, 76021 Karlsruhe , Germany.
Abstract:
Five series (28 structures) of photoswitchable β-hairpin peptides were synthesized based on the cyclic scaffold of the natural antibiotic gramicidin S. Cell-type selectivity was compared for all activated (diarylethene "ring-open") and deactivated ("ring-closed") forms in terms of antibacterial activity (MIC against Escherichia coli and Bacillus subtilis), anticancer activity (IC50 against HeLa cell line), and hemolytic cytotoxicity (HC50 against human erythrocytes). Correlations between the conformational plasticity of the peptides, their hydrophobicity, and their bioactivity were also analyzed. Considerable improvements in selectivity were achieved compared to the reference compound. We found a dissociation of the anticancer activity from hemolysis. Phototherapeutic indices (PTI), HC50(closed)/MIC(open) and HC50(closed)/IC50(open), were introduced for the peptides as safety criteria. The highest PTI for HeLa-selective toxicity were observed among analogues containing hydroxyleucine on the hydrophobic face. For one compound, high PTIs were demonstrated across a range of different cancer cell lines, including a doxorubicin-resistant one.
Related Concept Videos
Structure-Activity Relationships and Drug Design
SAR studies the intricate relationship between a drug's chemical structure and biological activity. It focuses on understanding how modifications to a drug's structure can influence...
Local Anesthetics: Chemistry and Structure-Activity Relationship
Cholinergic Antagonists: Chemistry and Structure-Activity Relationship
Adrenergic Agonists: Chemistry and Structure-Activity Relationship
Aromatic ring substitutions: Substituting the aromatic ring with –OH groups at positions 3 and 4 yields catecholamines (e.g., epinephrine), which have a high affinity for adrenoceptors. Hydrogen bonding between –OH groups and receptors enhances adrenergic activity.
Separation of...
Indirect-Acting Cholinergic Agonists: Chemistry and Structure-Activity Relationship
Reversible inhibitors display short to medium durations of action. Short-acting agents include simple alcohols with...
Direct-Acting Cholinergic Agonists: Chemistry and Structure-Activity Relationship
The direct-acting...

