Ultrasonic-Assisted Extraction, Comparative Chemical Composition and Biological Activities of Essential Oils of Fresh and Dry Aboveground Parts of Artemisia annua L.

Abstract

The extraction of essential oil from Artemisia annua L. by ultrasonic-assisted steam distillation extraction (UASDE) was evaluated using the response surface methodology. The optimized conditions were steam distillation extraction time of 3.5 h, ultrasonic time of 0.5 h, and ratio of solid-liquid ratio of 1:10 (g/mL). Ultimately, we obtained an actual extraction rate of 0.71 % by UASD, which is higher than that by steam distillation (0.64 %). This method could be used to explore the optimum conditions of essential oil extraction and increase the extraction rate. The compounds of fresh A. annua essential oil (FE) and dry A. annua essential oil (DE) were identified by GC-MS. Results showed that the extraction ratio of FE and DE were 0.77 % and 0.73 %, respectively, and 25 compounds were identified. The relative content of each component varied, and different compounds were found in these two essential oils. Thujone was found only in DE at 0.8 %, and 0.3 % of isoeugenol was found only in FE. In-vitro antibacterial tests showed that the essential oils had different inhibitory effects on Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Salmonella typhimurium. Three antibacterial activity of DE was more effective than that of FE at low essential oil concentrations. The antioxidant activity of the FE and DE was evaluated using the DPPH, reducing power, and hydroxyl radical scavenging tests. Results demonstrated that DE had a higher antioxidant activity than FE.