Optimization of ultrasound pretreatment combined with solvent-free microwave for extracting volatile oil from Atractylodes lancea and its chemical composition and antimicrobial activity.

As a traditional method of volatile oil extraction, hydrodistillation (HD) method is energy-intensive and time-consuming. In the context of environmental pollution, excessive energy consumption, and increasing climate warming, a new extraction method-ultrasound pretreatment combined with solvent-free microwave extraction (UP-SFME)-has been adopted for the extraction of volatile oil from Atractylodes lancea (Thunb.) DC. Key parameters-ultrasonic temperature (60 °C), power (400 W, 15 min), and microwave power (540 W, 35 min)-are identified to maximize yield while minimizing time and energy consumption. The UP-SFME method achieves a volatile oil yield of 1.77 ± 0.088 %, surpassing traditional HD and standalone SFME method by 59.46 % and 31.11 %, respectively. Notably, UP-SFME method reduces extraction time by 70 min and energy consumption to 12.8 % of HD. Kinetic analysis reveals that the process followed a first-order model. GC-MS analysis demonstrates enhanced contents of key bioactive compounds, including agarospirol (+8.40 %, +2.57 %), β-eudesmol (+7.23 %, +6.81 %), and α-bisabolol (+1.84 %, +1.82 %) compared to HD and SFME methods. In vitro assays confirm superior antibacterial activity against S. aureus for UP-SFME-extracted oil. Molecular docking simulations further supports these findings, with stable binding (ΔG < -6 kcal/mol) of bioactive compounds to S. aureus DNA gyrase. Critical interactions include hydrogen bonds with GLN-B:1267 and π-alkyl contacts with VAL-B:1123. This strong binding affinity, comparable to known gyrase inhibitors, supports their potential as lead compounds for developing novel antibacterial agents targeting this validated therapeutic target.