Chemical composition and anticancer activity of Elsholtzia ciliata essential oils and extracts prepared by different methods

E. ciliata (Lamiaceae) is very interesting and promising herb mainly for chemical composition and pharmacological activities. The aim of this study was to determine chemical composition of the essential oils of fresh, frozen and dried herbal materials of E. ciliata and compare different extraction methods This is the first study on composition of E. ciliata volatile compounds from fresh, frozen and dried herbal samples. The samples were prepared by hydrodistillation (HD), extraction with polar solvent-ethanol (ESE) and dynamic headspace solid-phase micro extraction (SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS) method. A total of 48 compounds were identified by GC-MS. Dehydroelsholtzia ketone, elsholtzia ketone, sesquiterpenes beta-bourbonene, caryophyllene, a-caryophyllene, germacrene D and alpha-farnesene were identified and found to be predominant compounds in SPME composition of the fresh, frozen and dried herbal samples. The major amounts of ketones (dehydroelsholtzia and elsholtzia) were determined in dried herbal samples where they made up 24.94% (p < 0.05) and 71.34% (p < 0.05) of the SPME composition. Artemisia ketone was determined only in fresh herb. No previous report exists regarding this ketone in E. ciliate fresh, frozen and dried herbal materials or essential oil. There were 26 components identified in the essential oil obtained by HD. The main compounds of this essential oil were dehydroelsholtzia ketone (78.28%) and elsholtzia ketone (14.58%). Essential oil showed antiproliferative activity on three tested cancer cell lines (human glioblastoma (U87), pancreatic cancer (Panc-1) and triple negative breast cancer (MDA-MB231)) in vitro. EC50 (half maximal effective concentration) values of essential oil against those cells were in the range of 0.017-0.021%. The viability of human normal fibroblasts exposed to' the same concentrations of the essential oil was statistically significantly higher compared to the viability of cancer cells (p < 0.05). The extracts did not show any effect on U87 cells, and only slightly decreased MDA-MB231 cell viability (up to 76.4%) at the highest concentration of 10 mg/mL. The impact that different extraction methods have on the yield of the essential oil from the tested herbal materials requires a further research. It would enable production of pharmaceutical forms enriched by these essential oils, which are notable for their anticancer activity.