Essential oils extracted from Mexican giant hyssop (Agastache mexicana subsp. xolocotziana) by a central composite face-centered (CCF) design

Abstract Mexican giant hyssop ( Agastache mexicana subsp. xolocotziana ) is an endemic Mexican plant traditionally used as a sleeping inducer. The aim of this study was to evaluate the effect of selected processing variables on the extraction of essential oil (EO) using surfactant-assisted hydrodistillation (SAH). Response surface methodology (RSM), coupled with a face-centered central composite design, was used to optimize the oil extraction process. The factors studied included the concentration of Tween 20 (0.001 – 0.007 g/mL), the solid–liquid ratio (15.8 – 45.8 g/L), and the extraction time (0.5 – 3.0 h). The experimental data obtained were fitted to a second-order polynomial model. The results showed that the concentration of Tween 20 and the solid–liquid ratio had a significant effect ( P < 0.005) on the essential oil yield. Additionally, all three factors studied significantly affected ( P < 0.005) the antioxidant activity, as measured by the DPPH radical scavenging activity. The optimal conditions for extracting oil from Agastache mexicana subsp. xolocotziana ( AMX ) were determined to be 0.001 g/mL of Tween 20, a solid–liquid ratio of 45.8 g/L, and an extraction time of 2.86 h. The GC-MS analysis of the essential oil showed that nerol was the main component, whose presence was confirmed by infrared spectroscopy. The antibacterial activity of EO was evaluated by determining the inhibition diameter, with results indicating that the antibacterial activity was higher when using hydrodistillation compared to SAH. The study concluded that the AMX essential oil showed significant DPPH radical scavenging activity and antibacterial activities. Additionally, surfactant-assisted hydrodistillation (SAH) was identified as a sustainable method for essential oil extraction, due to its reduced environmental impact. Graphical abstract