Phytochemical identification of volatile fraction, essential oil and screening of antioxidant, antibacterial, allelopathic and insecticidal potential from Artemisia herba-alba leaves

In the present paper, the essential oil and the volatiles emitted in vivo by leaves of A. herba alba, which grows wild in center of Tunisia, were analyzed by GC-MS and SPME, respectively. The essential oil was characterized by the predominance of oxygenated monoterpenes (93.3%) with alpha-thujone as the major compound (45.5%) followed by beta-thujone (11.4%), trans-sabinyl acetate (10.1%) and 1,8-cineole (7.4%). The SPME analyses showed that oxygenated monoterpenes were the most representative compounds (64.9%). The major ones were alpha-thujone (37.9%), germacrene D(16.5%), 1,8-cineole (8.4%) followed by beta-thujone (7.8%). Moreover, different activities (antioxidant, antibacterial, allelopathic and insecticidal) of the leaf essential oil were investigated. The antioxidant activity was ascertained by evaluating its inhibitory effect against DPPH and ABTS. The results showed that the essential oil had a strong activity and it was more effective against the DPPH radical (IC50 = 6 mu g/mL) than the ABTS radical (IC50 = 40 mu g/mL). In antibacterial screening, it inhibited the growth of all bacteria tested except Salmonella anatum and Salmonella salamae which were resistant to this oil type. Staphylococcus aureus and Vibrio cholera were found to be extremely sensitive with the lowest MIC value (0.007 mg/mL). In addition, allelopathic activity was evaluated against Lactuca sativa and Raphanus sativus. Data showed that, with essential oil, seed germination was completely inhibited for both of them, suggesting a potent allelopathic potential for the evaluated oil. Insecticidal activity was investigated against Culex pipiens larvae and a weak activity (LC50 241.1 ppm) for this A. herba alba essential oil.