Aquilaria sinensis essential oil inhibits biofilm formation and virulence of Staphylococcus aureus

<i>Staphylococcus aureus</i> is a major foodborne pathogen characterized by strong virulence and biofilm-forming ability, posing a persistent threat to food safety. <i>Aquilaria sinensis</i> (Lour.) Gilg, a medicinal and edible plant found in tropical regions such as Hainan, has rarely been investigated for its quorum-sensing inhibitory (QSI) potential. In this study, four types of <i>A. sinensis</i> essential oils were systematically evaluated for their ability to inhibit quorum sensing and related virulence in <i>S. aureus</i>. Among them, the Tong-Ti-Xiang type supercritical essential oil (TTC) exhibited the strongest activity. At a sub-inhibitory concentration of 125 μg/mL (1/4 MIC), TTC reduced biofilm formation by up to 78% without affecting bacterial growth. Confocal laser scanning Microscopy and scanning electron microscopy analyses further confirmed that TTC compromised the density and structural integrity of the biofilms. Moreover, TTC suppressed α-hemolysin activity and significantly downregulated quorum-sensing-regulated genes involved in biofilm formation and adhesion, including <i>icaA</i>, <i>icaD</i>, <i>clfA</i>, <i>clfB</i>, and <i>agrA</i>. Gas chromatography mass spectrometry analysis revealed that TTC is rich in chromone derivatives, among which 2-phenethyl-4H-chromen-4-one showed strong binding affinity toward the adhesion-associated IcaA protein and the QS-associated AgrA protein in molecular docking analysis, suggesting it as a key active compound responsible for the observed QSI effect. Overall, these findings highlight TTC as a promising natural anti-biofilm and anti-virulence agent for controlling foodborne pathogens.