Essential oils from Carex meyeriana Kunth: Optimization of hydrodistillation extraction by response surface methodology and evaluation of its antioxidant and antimicrobial activities

Essential oils from plants were reported with multiple bioactivities. To investigate the Carex meyeriana Kunth essential oils (CmkEos), the optimization of extraction by response surface methodology, chemical composition, antioxidant, and antibacterial activities of Carex meyeriana Kunth essential oils were reported. Carex meyeriana Kunth essential oils were extracted by hydrodistillation and the chemical components were determined via gas chromatography-mass spectrometry (GC-MS). Extraction time, ratio of liquid to material (v/w), and particle size were evaluated by single-factor experiments and response surface methodology based on Box-Behnken Design and which were optimized to be 9 h, 43:1 (mL/g), and 10 mesh, respectively, with the optimal yield of 0.13% (w/w). Twenty-five compounds were identified by gas chromatography-mass spectrometry, accounting for 94.94% of the total oils. The major components were palmitic acid (43.06%), linolenic acid (28.46%), and oleic acid (3.68%). The antioxidant activity of Carex meyeriana Kunth essential oils was evaluated by Diphenyl picryl hydrazinyl radical (DPPH), 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+), and reducing power assays, and Carex meyeriana Kunth essential oils showed moderate antioxidant activity with IC50/EC50 of 2.33, 10.79, and 12.59 mg/mL, respectively. In broth microdilution assays, Carex meyeriana Kunth essential oils demonstrated strong antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Bacillus pumilus, and Escherichia coli with minimum inhibitory concentrations (MIC) of 3.13, 100, 50, and 100 mg/mL, respectively. Carex meyeriana Kunth essential oils demonstrated strong antioxidant and antimicrobial activities, and shows great application potential in food, pharmaceutical, and chemical industries.