A honokiol-derived cationic amphiphilic compound combats methicillin-resistant Staphylococcus aureus by disrupting...

Methicillin-resistant Staphylococcus aureus (MRSA) remains a major threat owing to limited therapeutic options and increasing antimicrobial resistance. In this study, a new honokiol-derived amphiphilic compound, 5D, was developed and evaluated for its anti-MRSA activity. 5D exhibited potent activity against clinical MRSA isolates (MIC = 0.5-1 μg/mL), and rapidly killed MRSA N315 in both early and late growth phases. It also disrupted established biofilms, retained activity after plasma exposure, and showed a low propensity for resistance development. Mechanistic analyses revealed that 5D damages bacterial morphology, dissipates membrane potential, increases membrane permeability, and causes leakage of intracellular DNA and proteins. Untargeted metabolomics indicated that 5D markedly perturbs glycerophospholipid metabolism, while phospholipid supplementation and isothermal titration calorimetry suggested preferential interaction with phosphatidylglycerol. In a Galleria mellonella infection model, 5D improved 7-day survival to approximately 33% and reduced bacterial burdens by 0.7-1.2 log₁₀ CFU/mL compared with untreated larvae. In a murine sepsis model, 5D increased survival to 83.3-100% and significantly reduced organ bacterial burdens. These findings identify 5D as a promising honokiol-derived anti-MRSA lead compound that acts mainly by disrupting membrane integrity and phospholipid homeostasis.