Teaching various methods of extracting mountain thymus essential oil and studying the antioxidant properties of the extracted essences

Essential oil of a species of mountain thymus, extracted by three methods. In the first method through distillation, the extracted essential oil and its compounds were analyzed and identified using gas chromatography-mass spectrometry (GC/MS), showing that the main compounds of the plant are linalool 75.24%, alpha-terpinol 45.11%, limonene 13.9%, and trans-beta-ocimene 52.7%. In the second method, the essential oil was extracted without solvent using a microwave device, and the main compounds of the plant were analyzed and identified using gas chromatography-mass spectrometry (GC/MS), showing that the main compounds of the plant are linalool 32.30%, alpha-terpinol 12.14%, limonene 38.11%, and nerolidol 85.9%. In the third method, a combination of ultrasound and water distillation was used for extracting the essential oil, and the main compounds of the plant were analyzed and identified using gas chromatography-mass spectrometry (GC/MS), showing that the main compounds of the plant are linalool 45.23%, 1,8-cineole 98.13%, alpha-terpinol 49.12%, and trans-beta-ocimene 26.6%. In all three methods, the highest percentage corresponds to oxygenated monoterpenes, which are 42% in distillation, 59.87% in microwave, and 50.38% in ultrasound treatment. Then, based on the extraction of the essential oil in each method and their abundance percentage, the antioxidant property of the obtained essences was evaluated using the DPPH free radical scavenging test. The method was chosen based on its non-toxic solvent and its inhibitory time, and the best inhibitory percentage belongs to the microwave extraction method with 5.54% and the distillation method with 40% at a concentration of 5ppm.