Bakhtiari savory (Satureja bachtiarica Bunge.) essential oil and its chemical profile, antioxidant activities, and leaf micromorphology under green and conventional extraction techniques

Bakhtiari savory (Satureja bachtiarica Bunge.) belonging to the Lamiaceae family is an important Iranian herb, which its leaves is used as herbal medicine, spice, and nutraceuticalS. bachtiarica is widly distributed in the central Zagros Mountains of Iran. The essential oil from the aerial parts of the herb contains significant amounts of phenolic compounds. The effects of two extraction techniques, including the traditional hydro-distillation (HD) and microwave-assisted steam hydro-diffusion (MSHD) on some properties of quantity and quality essential oil and the antioxidant activities (DPPH and FRAP assays) of the essential oils and micromorphology of the plant leaves (Scanning Electron Microscopy, SEM) were investigated. The maximum amounts of oxygenated monoterpenes and active phenolic compounds with the highest level antioxidant activities were obtained from the HD technique after 150 min and the MSHD technique after 20 min. The same essential oil yield was achieved from both extraction techniques (1.8 ± 0.012 v/w dry weight basis). Results of SEM images of the leaves showed that 60, 90, and 150 min after extraction by the HD and 10, 20, and 75 min after extraction by the MSHD visible physical changes at different rupture degrees were obtained. The HD technique after 150 min extraction and the MSHD after 20 min, the oil glands rich in essential oil in the leaves were completely ruptured. In conclusion, the microwave-assisted steam hydro-diffusion technique with high quantity and quality of essential oil, saving time, energy consumption, and reduction of waste water (environmental impacts) in comparison to the traditional method, it can be as a green technique and suitable for extraction of essential oil, usable in food, cosmetic, and pharmaceutical industries.