Development of Membrane-Targeting Osthole Derivatives Containing Pyridinium Quaternary Ammonium Moieties with Potent...

Area of Science:

• Medicinal Chemistry
• Microbiology
• Pharmacology

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) presents a significant global health challenge, driving the urgent need for new antibacterial agents.
• Existing treatments face limitations due to rising resistance and potential side effects.

Purpose of the Study:

• To design, synthesize, and evaluate novel osthole derivatives as potential anti-MRSA therapeutics.
• To assess the in vitro and in vivo efficacy and safety of lead compounds against MRSA.

Main Methods:

• Synthesis of 30 osthole derivatives incorporating pyridinium quaternary ammonium moieties.
• In vitro antibacterial assays against S. aureus and clinical MRSA isolates, including MIC determination, hemolytic activity, and resistance induction studies.
• In vivo efficacy evaluation in MRSA-induced skin abscess and sepsis mouse models.
• Mechanistic studies investigating membrane targeting, ROS generation, and content leakage.

Main Results:

• Compounds 8u and 8ac displayed potent in vitro activity against S. aureus and MRSA isolates (MIC = 0.5-1 μg/mL).
• These compounds exhibited low hemolytic activity, rapid bactericidal effects, and minimal resistance induction.
• In vivo studies showed 8u and 8ac possessed excellent antibacterial effects and safety profiles comparable to vancomycin.
• Mechanistic investigations revealed selective bacterial membrane targeting via phosphatidylglycerol (PG) binding, leading to increased ROS, content leakage, and bacterial death.

Conclusions:

• Osthole derivatives 8u and 8ac are effective against MRSA through bacterial membrane disruption.
• These compounds demonstrate significant potential as novel therapeutic candidates for combating MRSA infections.
• Further development of 8u and 8ac could lead to new treatments for challenging staphylococcal infections.