Aqueous enzyme-ultrasonic pretreatment for efficient isolation of essential oil from Artemisia argyi and investigation on its chemical composition and biological activity

Abstract

The in-depth study of plant essential oil (EO) to provide valuable resources for the development of natural medicinal products is one of the current research hotspots. The present work realized the efficient isolation of EO from Artemisia argyi leaves using aqueous enzyme-ultrasonic pretreatment followed by microwave-assisted hydrodistillation (EUP-MHD). Because of the synergistic reaction mechanism, the combination of enzyme and ultrasound doubly improved the separation of EO. After the optimization process (single factor experiments, Plackett–Burman design, and Box–Behnken design), mixed enzyme (cellulose + pectinase + papain), concentration of 10 U/mg, ultrasonic frequency of 45 kHz, ultrasonic power of 200 W, ultrasonic time of 20 min, reaction temperature of 50 °C, pH of 5, microwave power of 650 W, microwave time of 10 min, and liquid-solid ratio of 10 mL/g performed best, with the yield of EO of 5.32 ± 0.20 mg/g. A distinct advantage of this technique was found as compared with other techniques, which highlighted the positive influence of the pretreatment process. Additionally, the oxygenated components of EO from EUP-MHD accounted for a higher proportion than other methods, including eucalyptol, borneol, camphor, neointermedeol, and terpinen-4-ol. Finally, the evaluation of the biological activity of A. argyi EO pointed out that the EO had excellent antioxidant activity and higher inhibitory activity against Phytophthora capsica but presented weaker cytotoxic activity. In general, the technique used in this study is promising in the field of separating EO from crop materials.