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SECTION I: MOLECULAR GENETIC ENGINEERING AND BIOCHEMICAL TECHNOLOGY 113into contact with the cooling system, immediately condensing into drops and condensing into a layered mixture of 2 liquids. Distill the sample for 2 days (6 hours each day) to ensure the optimal amount of essential oil is distilled. On the 3rd day, let the distillation system return to a stable state at normal temperature, and open the soxhlet valve. The essential oil obtained has 2 forms including the floating part on top and the part that sinks to the bottom of the water. After that, these two essential oils are separated to obtain two essential oil forms (LO as upper layer, HO as bottom layer of oil).2.3. Antioxidant activityPrinciple of the Assay: The compound 1,1-diphenyl-2-picrylhydrazyl (DPPH) is a free radical generator commonly used to evaluate the antioxidant activity of test compounds. Antioxidant activity is demonstrated by a reduction in DPPH color intensity, which can be quantified spectrophotometrically at a wavelength of %u03bb = 515 nm [6].Procedure: A DPPH solution at 1 mM concentration is prepared in methanol (MeOH), while the test compound is dissolved in deionized water. In a 96-well plate, different concentrations of the test compound are combined with the DPPH solution and incubated for 30 minutes at 37%u00b0C. The absorbance of the reacted DPPH solution is measured using a Biotek spectrophotometer at 517 nm [7]. The percentage of DPPH radical scavenging (%SC) by the sample is calculated using the following formula:SC% = (ODblank %u2013 OD sample)/ ODblank (%)The EC50 value, representing the concentration at which 50% of DPPH radicals are scavenged, is derived from the %SC values across different concentrations of the test compound, with each