Antimicrobial Cyclic Peptidomimetics

Area of Science:

• Medicinal Chemistry
• Microbiology
• Biomaterials Science

Background:

• Antimicrobial resistance (AMR) poses a significant global health threat, necessitating the discovery of novel antimicrobial agents.
• Existing treatments are increasingly ineffective against multidrug-resistant (MDR) bacteria.
• Development of new therapeutic strategies is urgently required to address the AMR crisis.

Purpose of the Study:

• To synthesize and characterize novel cationic amphipathic cyclic peptidomimetics.
• To evaluate their potential as antimicrobial agents against multidrug-resistant bacteria.
• To investigate the structure-activity relationships, including the impact of alkyl chain length on efficacy and toxicity.

Main Methods:

• Synthesis of cyclic oligomers via carbodiimide-mediated condensation using aza-crown ether.
• Evaluation of antimicrobial activity using minimum inhibitory concentration (MIC) assays.
• Assessment of membrane perturbation effects and in vitro toxicity.
• Testing resistance to proteolytic degradation.

Main Results:

• Novel cyclic peptidomimetics were successfully synthesized with varying alkyl chain lengths.
• Antimicrobial activity and membrane disruption were dependent on lipid chain length, with longer chains showing higher potency.
• The compound CYPEP-C16 exhibited potent bacteriostatic activity (MIC = 16 µg/mL) but also demonstrated toxicity.
• Compounds with a polyoxazoline-esque backbone showed resistance to proteolytic degradation and maintained antimicrobial efficacy.

Conclusions:

• Cyclic peptidomimetics represent a promising class of novel antimicrobial agents.
• Alkyl chain length is a critical factor influencing antimicrobial potency, membrane disruption, and biocompatibility.
• The stability of these peptidomimetics against proteolytic degradation offers an advantage over traditional polyamide systems.
• Further optimization is needed to balance efficacy and reduce toxicity for therapeutic applications.