Optimization of Hydrodistillation Extraction by Response Surface Methodology and Evaluation of the Antioxidant and Antimicrobial Activities of Essential Oils from Phragmites communis (Cav) Trin

The principal objectives of this study encompass three distinct aspects: firstly, to streamline the extraction process of Phragmites communis (Cav) Trin essential oil; secondly, to systematically analyze the essential oil’s chemical composition; and finally, to evaluate biological activity. Through the system optimization experiment, the optimal extraction process was determined: the crushing size was set to 10 mesh, the total solid-liquid ratio was 19:1 (mL/g), and the extraction time limit was 5 hours. Under this condition, the maximum yield of essential oil was 0.233% (mass fraction). In addition, the GC-MS (gas chromatography-mass spectrometry) composition of pure essential reed oil (PCT-Eos) was analysed, and 27 different compounds were detected. The major components included: 2-(2-ethylhexoxycarbonyl) benzoic acid (15.78%), 2,2'-methylenebis (6-tert-butyl- 4-methylphenol) (9.96%), pentacosane (4.97%), triacontane (4.96%), dibutyl phthalate (4.92%), dotriacontane (4.64%), and nonacosane (4.17%). The findings of the activity test demonstrated that this essential oil possessed a moderate antioxidant capacity, with IC₅₀/EC₅₀ values of 2.42 ± 0.311, 3.5 ± 0.306, 6.5 ± 0.395, and 9.8 ± 0.557 mg/mL. In both microdilution assessments, concurrently exhibiting significant inhibitory effects on various pathogenic bacteria, the respective minimum inhibitory concentrations (MICs) were determined to be 72.00, 72.00, 43.20, 9.33, and 120.00 mg/mL. These findings indicate that PCT-Eos possesses significant potential for applications in the food, pharmaceutical, and chemical sectors due to its notable antimicrobial and antioxidant properties.