Extraction of artemisinin using natural deep eutectic solvent selected by COSMO-RS

Natural deep eutectic solvent (NADES) has become an alternative and environmentally friendly solvent. This study designed new eutectic systems for the extraction of artemisinin from the leaves of Artemisia annua L. with the aid of conductor-like screening model for real solvents (COSMO-RS). The performance of the benzoic acid/fenchyl alcohol-based NADES was studied comprehensively under different extraction conditions, including hydrogen-bond donor (HBD)/hydrogen-bond acceptor (HBA) molar ratio, solid-liquid ratio, extraction temperature, and extraction time. It was found that artemisinin extraction should be performed using HBD/HBA 1:4 at 50 °C within 1.5 h. The extraction yield of the target could reach 11.08 mg/g. Artemisinin and the NADES were recovered from the final extract. Furthermore, the extraction mechanism was elucidated by the combination of 1H nuclear magnetic resonance (1H NMR) and scanning electron microscopy (SEM). The hydrogen bond reformation and the plant tissue destruction play vital roles during the extraction process. Therefore, the proposed NADES could serve as a green solvent to effectively extract natural bioactive compounds. The application of the NADESs proved their promise as designable solvents with stronger extraction capabilities than traditional organic solvents.