Efficient extraction of essential oil compounds from agarwood using low eutectic solvents assisted by molecular simulation

The characteristics of natural aromatic compounds have promoted the research of efficient extraction methods. In this study, quantum chemical (QC) calculation, molecular dynamics (MD) simulation and experimental verification were combined to solve the problems of low extraction rate and solvent pollution of agarwood essential oil, and the screening and extraction mechanism of green extractants were systematically analyzed. Based on the mechanism of ethanol extraction of the main components of agarwood essential oil, through QC calculation, extraction experiments and Fourier transform infrared spectroscopy (FT-IR), it was found that choline chloride:ethylene glycol (ChCl:EG) at 1: 4, T = 40  °C , under the condition of 8 h, the extraction rate reached 24.2 %, which was 226 % higher than that of traditional ethanol solvent, and maintained good stability in five reuse cycles. In addition, the extraction mechanism of the process was clarified. The hydroxyl group in ChCl:EG forms additional interaction sites with the oxygen atoms on the ring structure of the target compound, which enhances the hydrogen bond and van der Waals force, and significantly improves the selective dissolution of the target compound. The effects of different ChCl:EG ratios and temperatures on the extraction efficiency were evaluated by MD simulation. The results show that the effect of temperature on the interaction of the system is greater than that of the proportion, and ethylene glycol in Deep Eutectic Solvents (DES) plays a major role. This research provides new insights into the use of DES for green extraction of natural products and establishes a theoretical and experimental basis for future industrial applications.