Antioxidant and Bacteriostatic Activities of Essential Oil from Ligustrum robustum (Rxob.) Blume

Antioxidant and bacteriostatic effects of the essential oil from Ligustrum robustum (Rxob.) Blume (EOL) were investigated. L. robustum was used as the crude material to prepare EOL by steam distillation method. The volatile components of EOL were identified by gas chromatography mass spectrometry (GC-MS). Then, its antioxidant activity was analyzed by some chemical methods in vitro, and its bacteriostatic activity was evaluated by using bacteria, fungi and yeast. Furthermore, peanut oil and orange juice were selected as food models to determine its antioxidant and bacteriostatic effects during storage period. Results showed that 22 of volatile components were identified from EOL, such as 4-terpined, γ-terpinene, and 4-carene, etc.. In addition, EOL could scavenge ABTS⁺ free radical (EC₅₀: 395.9 μg/mL), DPPH free radical (EC₅₀: 165.45 μg/mL), inhibit lipid peroxidation (IC₅₀: 420.1 μg/mL) and showed strong reduce power. Meanwhile, EOL could effectively slow down the increasing of peroxide value of peanut oil, and inhibit the oxidative deterioration of oil during storage. Moreover, EOL showed the favorable broad-spectrum bacteriostatic activities (MIC: 0.31~5.0 μg/mL, MBC: 1.25~20.0 μg/mL), and it inhibited the growth of all testing microorganisms during logarithmic growth period effectively. Specifically, the inhibition of bacteria was obvious, especially for Escherichia coli (the inhibition zone was 29.85 mm). EOL had remarkable abilities to restrain the spoilage and prolong the shelf life of orange juice during storage. All results suggested that the essential oil from L. robustum showed the high value and potential to be developed and utilized in food industry.