Optimization of the Essential Oil Extraction Process from Dong Van Marjoram (E. winitiana var. dongvanensis Phuong.) by Using Microwave Assisted Hydrodistillation, and the Bioactivities of the Oil Against Some Cancer Cell Lines and Bacteria

This study reports on the optimization of a microwave-assisted distillation process to obtain Dong Van marjoram essential oil, and the determination of its composition, content of constituents, and cytotoxic and antimicrobial activities. Using the response surface method (RSM), the optimal essential oil distillation conditions were determined as material size 0.74 (cm), water to material ratio 4.14:1 (mL/g), microwave power 302.4 (W), and distillation time 2.1 hours. At optimal conditions, the mass of Dong Van marjoram essential oil obtained was 0.887 ± 0.007 g, corresponding to a content of 0.6% essential oil in the material. GC-MS and GC-FID methods showed that the main chemical constituents of Dong Van marjoram essential oils obtained were rosefuran epoxide (44.9%), caryophyllene (10.8%), germacrene D (2.6%), and α-humulene (1.3%). The essential oil exhibited moderate inhibition against both tested cancer cell lines, with IC50 values of 23.9 µg/mL (for PC3) and 56.2 µg/mL (for A549). However, the oil exhibited strong effectiveness against three bacterial strains, Escherichia coli, Bacillus subtilis, and Staphylococcus aureus, and a yeast strain, Saccharomyces cerevisiae, with minimal inhibitory concentration (MIC) values ranged from 50 to 100 µg/mL.