Impact of Conjugation of the Reactive Oxygen Species (ROS)-Generating Catalytic Moiety with Membrane-Active Antimicrobial Peptoids: Promoting Multitarget Mechanism and Enhancing Selectivity

Antimicrobial peptides (AMPs) represent promising therapeutic modalities against multidrug-resistant bacterial infections. As a mimic of natural AMPs, peptidomimetic oligomers like peptoids (i.e., oligo-<i>N</i>-substituted glycines) have been utilized for antimicrobials with resistance against proteolytic degradation. Here, we explore the conjugation of catalytic metal-binding motifs─the amino terminal Cu(II) and Ni(II) binding (ATCUN) motif─with cationic amphipathic antimicrobial peptoids to enhance their efficacy. Upon complexation with Cu(II) or Ni(II), the conjugates catalyzed hydroxyl radical generation, and <b>22</b> and <b>22-Cu</b> exhibited over 10-fold improved selectivity compared to the parent peptoid, likely due to reduced hydrophobicity. Cu-ATCUN-peptoids caused bacterial membrane disruption, aggregation of intracellular biomolecules, DNA oxidation, and lipid peroxidation, promoting multiple killing mechanisms. In a mouse sepsis model, <b>22</b> demonstrated antimicrobial and anti-inflammatory efficacy with low toxicity. This study suggests a strategy to improve the potency of membrane-acting antimicrobial peptoids by incorporating ROS-generating motifs, thereby adding oxidative damage as a killing mechanism.