Study of two-stage ohmic hydro-extraction of essential oil from Artemisia aucheri Boiss.: Antioxidant and antimicrobial characteristics.

The effect of two-stage ohmic-assisted hydrodistillation (TSOH) on the extraction and characteristics of essential oils (EOs) from the Artemisia aucheri Boiss. was studied, and the results were compared to conventional hydrodistillation (HD). According to the results, the yield of EOs obtained through TSOH was almost 30% higher than those extracted by HD in nearly one-quarter of a time used by the HD. Scanning electron micrographs of A. aucheri leaves showed almost complete eruption of EO glands and their surrounding area in TSOH extraction method, hence achieving higher yield. The components of the EOs obtained through TSOH were only slightly different from those of HD. GC/MS analysis indicated some differences in the quantity of the main components, too. The main components of EOs were identified as Thymol, Linalool, Geraniol, Camphor, and 1, 8-Cineole, Davana ether and Cis-Davanone. Thymol (~17%) and Cis-Davanone (~23%) were the highest quantity in the EOs extracted from TSOH and HD, respectively. The variation of antioxidant and antimicrobial activities of the EOs may be attributed to these differences in the percentage of the main components. The radical scavenging activity of the EOs obtained by TSOH was almost twice that of HD. Based on antimicrobial activity assays, the EOs were efficient against S. aureus (a Gram-positive), E. coli (a Gram-negative), and S. cerevisiae (yeast). However, the efficacy was higher in gram-positive than gram-negative bacteria and yeast. The results indicate TSOH has a potential to produce EOs from herbal plants at a faster rate, higher yield, being probably more efficient in terms of energy although having similar antimicrobial and antioxidant efficacy.