Diphenylurea derivatives for combating methicillin- and vancomycin-resistant Staphylococcus aureus

Area of Science:

• Medicinal Chemistry
• Microbiology
• Pharmacology

Background:

• Antibiotic resistance, particularly from strains like methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Staphylococcus aureus (VRSA), poses a significant global health threat.
• Existing treatments have limitations in efficacy and spectrum of activity against highly resistant bacterial isolates.

Purpose of the Study:

• To identify and develop novel antibacterial agents targeting resistant bacterial strains.
• To explore the structure-activity relationships (SARs) of a new diphenylurea scaffold for optimized antibacterial properties.

Main Methods:

• Synthesis and characterization of novel diphenylurea analogues.
• Evaluation of antibacterial activity against resistant Staphylococcus aureus isolates, including MRSA and VRSA.
• Pharmacokinetic parameter assessment and SAR analysis focusing on lipophilic side chains.
• In vitro assessment of efficacy against intracellular MRSA within macrophages.
• In vivo validation using a Caenorhabditis elegans infection model.

Main Results:

• A new class of diphenylurea compounds was identified as a potent antibacterial scaffold.
• The cycloheptyloxyl analogue (21n) emerged as a promising drug candidate with broad-spectrum activity.
• Compound 21n demonstrated rapid killing kinetics against MRSA and reduced intracellular MRSA burden in macrophages.
• In vivo studies in Caenorhabditis elegans confirmed the potent anti-MRSA activity of 21n.

Conclusions:

• Diphenylurea derivatives represent a viable scaffold for developing new antibiotics against resistant bacteria.
• Compound 21n exhibits significant advantages over current antibiotics like vancomycin and linezolid, particularly against MRSA.
• Further development of this diphenylurea class holds potential for addressing the challenge of antibiotic resistance.