Effects of solvent‐free microwave extraction on the chemical composition of essential oil of Calamintha nepeta (L.) Savi compared with the conventional production method

Abstract

The essential oil of Calamintha nepeta has been obtained by solvent-free microwave extraction (SFME) and by classical hydrodistillation (HD). A comparative qualitative-quantitative study on the composition of the oils was carried out. A total of 38 compounds, constituting 97.6% of the oil, were identified in the oil obtained by SFME, whereas 46 compounds, representing 95.4% of the oil, were characterized in the HD oil. SFME-distilled oil is richer in lightly oxygenated monoterpenes (LOM) than HD oil. It also has a higher amount of sesquiterpenes and a lower quantity of hydrocarbon monoterpenes. HD oil seems to be affected by chemical changes more than SFME oil.

Essential Oil Extraction, Chemical Analysis and Anti-Candida Activity of Calamintha nepeta (L.) Savi subsp. glandulosa (Req.) Ball—New Approaches

“…It was particularly abundant in the August (84.7%) and July harvest (77.7%) samples. These findings are in compliance with previous reports [11,12,13,14,17,21,22,26,28,29,31,32,33,34]. PUL is a monoterpene ketone (Figure 2b) with a fresh odor reminiscent of mint, found in many Lamiaceae species.…”

“…Limonene (LIM, 19 ) is the characteristic component of the first fraction (and exceptionally in the second) of each month (J1h, A1h, S1h and O1h), reaching the maximum percentage (13.6%) in the flowering material gathered in the September harvest as described in previous reports [11,13,14,19,21,22,31,32,33]. As a part of each CG chemotype, LIM could be considered as the common component, likely responsible for the plant fragrance [32].…”

“…This chemical compound was not reported to be an important constituent of CG oils. There are only few reports about its occurrence [33] and none is even close to the percentage found in TEOCG, indicating that the Tarquinia plants belong to a PUL/MEN chemotype variant. Considering the average distillation process duration (usually up to two–three hours) in most cases, CRY un-detection is not surprising, as it becomes significant between 3 and 6 h of extraction.…”

Microwave Assisted Extraction of Essential Oil FromCymbopogon Flexuosus(Steud.) Wats.: A Parametric and Comparative Study

“…This phenomenon caused the release of volatiles from the cell wall, thus, emptying the cells. Similar morphological changes were also observed by Riela et al (18) and Ferhat et al (32).…”

“…Also, fewer chemical changes of original plant components were observed in case of MAE compared to hydrodistillation (18,19). Essential oil obtained by microwave radiation has higher antimicrobial as well as antioxidant activities compared to the oil obtained by hydrodistillation (20).…”