Chemical Composition of Essential Oil (GC-FID and GC-MS), Phenolic Compounds Content (LC–ESI–MS), and Antioxidant Activity of Eucalyptus marginata Leaves from Northern Tunisia: Effect of Season

Eucalyptus marginata is an aromatic and medicinal plant species used in several industrial sectors, owing to the chemical properties of its essential oil. The present study aimed to evaluate the chemical composition and antioxidant activities of Eucalyptus marginata leaves collected in three seasons of the year (winter, spring and summer). Therefore, essential oil yields, total phenolic, flavonoid, tannin and chlorophyll contents have been evaluated. Essential oil chemical composition was carried out by combination of GC-FID and GC–MS. While, individual phenolic quantification has been done using LC–ESI–MS. This study demonstrated that spring seasons presented the highest contents of total phenolic compounds (491.01 mg GAE/g DW), chlorophyll α (134.55 mg/g DW), chlorophyll β (216.61 mg/g DW), chlorophyll α + β (350.61 mg/g DW), DPPH (1.099 mg/g DW) and ABTS (0.909 mg/g DW). The major compounds of Eucalyptus marginata essential oil for the three seasons were 1,8-Cineol (22.42 − 30.52%), while, the quantification of the identified phenolic compounds showed a significant difference between the three season (p < 0.05). Results revealed that Eucalyptus marginata is a nature source of compounds with antioxidant proprieties, and the difference in chemical composition leads to change in the antioxidant activity of plant, which contributes to seasonal change.