Antimicrobial and antioxidant activities of essential oils extracted from leaves of Vinh orange, Dao lime and Thanh Tra pomelo in Vietnam
Pham Thi Lan Chi, Vu Kieu Chinh, Pham Van Hung, Nguyen Thi Lan Phi
Essential oils (EOs) are mixtures containing complex biologically active substances, and they are being used as flavoring agents, as well as preservatives for a number of commercial products. Antimicrobial and antioxidant activities are two important characteristics when determining the potential of essential oils. In this study, essential oils from leaves of three citrus varieties including Dao Lime, Vinh orange and Thanh Tra pomelo were extracted using hydro-distillation method. For antimicrobial capacity, the EOs of leaf of Vinh orange showed the strongest capacity against S. aureus, with an inhibition zone of 22.25 mm and the lowest capacity against F. flavus with the inhibition zone of 11.08. In contrast, Dao lime leaf EOs showed the lowest antimicrobial capacity, with an inhibition zone of 12.67 mm against S.aureus and the strongest capacity against F. flavus with the inhibition zone of 11.4 mm. Against P. aeruginosa, S. typhi, B. cereus and A. flavus, Vinh orange leaf EOs also showed the highest result, withthe inhibition zone corresponding to 21.42 mm, 12.58 mm, 18.08 mm and 15 mm, respectively. Thanh Tra Pomelo leaf EOs showed the lowest result against P. aeruginosa with an inhibition zone of 14.67 mm and S. typhi with the inhibition zone of 10.17 mm. Otherwise, Dao lime leaf EOs showed the weakest capacity against B. cereus andA. flavus, corresponding to 11.17 mm and 10.2 mm of diameter inhibition zone. Theminimal inhibition capacity (MIC) was a range of 10.5-84 mg/ml for orange leaf EOs, 84-168 mg/ml for lime leaf EOs and 21 – 168 mg/ml for pomelo leaf EOs. For antioxidant capacity, orange leaf EOs also showed the highest, similar to antimicrobial activities. The results of this study showed that essential oils of citrus leaves could be widely used as flavoring and preservatives in food, cosmetic and pharmaceutical industries.