Enzyme-assisted deep eutectic solvent extraction of Litsea cubeba essential oil and its anti-Aspergillus flavus activity

The essential oil of Litsea cubeba demonstrates notable antibacterial properties and holds considerable promise for various applications. To explore green and effective extraction method for L. cubeba essential oil, we introduced enzyme-assisted natural deep eutectic solvents (DESs). The optimization of DESs was performed using response surface methodology with a Box-Behnken design (BBD), and the optimal parameters were determined as follows: a choline chloride to citric acid (ChCl/CA) ratio of 1:0.97, water content of 73%, and cellulase(0.5%) enzymolysis temperature of 45°C. Compared to traditional steam distillation, the DESs method significantly increased the essential oil yield from 3.20% to 4.70% and expanded the chemical profile of the essential oil, identifying a total of 79 compounds. Five new aromatic compounds, including methyl geranate, geranic acid, p-mentha-1,5-dien-8-ol, α-terpinyl acetate, and terpinyl acetate, were identified. Antifungal activity against Aspergillus flavus was confirmed by scanning electron microscopy. At a concentration of 1,000 μL/L, after 96 hours of incubation, essential oils extracted using enzyme-assisted DESs method demonstrated substantial inhibition against A. flavus , with the ChCl/EG formulation achieving a 100% inhibition rate. The content of citral, citronellal, citronellol, linalool, and new compound methyl geranate showed a positive correlation with the anti- A. flavus inhibition rate. The enzyme-assisted DESs extraction method proves to be an effective and efficient approach for extracting L. cubeba essential oil and provides a valuable reference for future research and application in essential oil extraction. • We introduced enzyme-assisted DESs extraction for Litsea cubeba essential oil. • Enzyme-assisted DESs method increased the essential oil yield from 3.20% to 4.70%. • Five new compounds were first identified in Litsea cubeba essential oil. • ChCl/EG formula obtained 100% inhibition rate against Aspergillus at 1,000 μL/L.