Optimization, chemical constituents and bioactivity of essential oil from Iberis amara seeds extracted by ultrasound-assisted hydro-distillation compared to conventional techniques

In this study, ultrasound-assisted hydro-distillation (UAHD) extraction of essential oil (EO) from Iberis amara seeds was optimized using response surface methodology (RSM). The maximum recovery of EO was 0.42 +/- 0.05% (v/w) using the optimal extraction parameters (extraction time of 240 min, ultrasonic power of 75 W and solvent-to-sample ratio of 6.7 mL/g). UAHD showed a significantly higher amount of EO compared to the traditional methods hydro-distillation (HD) (0.26 +/- 0.07% (v/w)) and steam distillation (SD) (0.19 +/- 0.04% (v/w)) (P < 0.05). Scanning electron microscope (SEM) images revealed that the seeds were crushed into tiny particles after UAHD, which is believed to facilitate secretion of EO. Subsequently, 28 kinds of compounds were identified by GC-MS for the EOs extracted by UAHD, HD and SD and with similar quantitative characters. The principal constituents were 4-Carvomenthenol (18.75 - 22.13%), Menthone (10.95 - 12.36%), Neodihydrocarveol (9.78 - 11.38%) and alpha-Curcumene (9.37 - 10.81%). Further study on bioactivity of EO samples was carried out. The oils obtained with the three techniques exerted slightly different but good antioxidant and anti-inflammatory effects, cytotoxicity on human colon cancer cells, as well as antibacterial and anti-feedant effects against Pieris rapae larvea. In conclusion, this study suggests that UAHD is an excellent technology for EO extraction and may have industrial applications. In addition, Iberis amara seed extracts can become more available as a natural resource for food and pharmaceutical industries.