Lanxangia tsaoko sesquiterpenes inhibit methicillin-resistant Staphylococcus aureus by targeting the arginine biosynthesis pathway

Methicillin-resistant Staphylococcus aureus (MRSA), pose a major global health challenge as a difficult-to-treat pathogen. Lanxangia tsaoko is a well-known aromatic herb traditionally used in Chinese medicine. Historically, it has been applied for its antimicrobial and antiparasitic properties, including the treatment of malaria. L . tsaoko essential oil (LEO) exhibit potent anti-MRSA activity both in vitro and in vivo; however, its active components and mechanisms remain unelucidated. We investigated the inhibitory effect and mechanism of bioactive components from LEO on MRSA infection. Bioactive constituents of LEO were retrieved from the literature, and the major bioactive constituents responsible for the anti-MRSA activity were identified through network pharmacology. The antibacterial efficacy of the predicted constituents was subsequently evaluated using in vitro experiments and a mouse model of MRSA infection. Untargeted metabolomics and molecular docking identified potential targets and pathways, which were validated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting (WB). Notably, five constituents predicted by network pharmacology were all sesquiterpenoids, with trans-farnesol (FAR) exhibiting the strongest anti-MRSA activity (minimum inhibitory concentration = 0.039 mg/mL; minimum bactericidal concentration = 0.078 mg/mL). FAR showed additive effects with antibiotics, inhibited MRSA biofilm formation, and showed preventive efficacy in MRSA-infected mice in vivo. Metabolomics revealed disruption of the arginine biosynthesis pathway, with molecular docking indicating strong binding of FAR to argG and argH. This interaction was further confirmed with RT-qPCR and WB confirming downregulation of argG/argH mRNA in MRSA and upregulation of argininosuccinate synthase (ASS1)/argininosuccinate lyase (ASL) proteins in infected mice. The findings of this study present FAR as the primary active component of LEO, highlighting its potent anti-MRSA effects via the arginine biosynthetic pathway, argG/argH mRNA downregulation in MRSA, and ASS1/ASL upregulation in infected mice.