Seasonal variation in the chemical composition, antioxidant activity, and total phenolic content of Artemisia absinthium essential oils

Background: The genus Artemisia belonging to the Compositae (Asteraceae) family and many traditional uses from the Artemisia species were reported. Artemisia absinthium is one of the species in this genus and commonly used in the food industry in the preparation of aperitifs, bitters, and spirits. Objective: Evaluation of the effect of different harvesting stages on the composition of essential oil and antioxidant capacity of A. absinthium. Materials and Methods: Essential oils from the aerial parts of A. absinthium, collected in three stages (preflowering, flowering, and after‑flowering) from plants grown in the North Khorasan province of Iran were obtained by steam distillation and the chemical composition of the oils was analyzed by gas chromatography‑mass spectrometry and antioxidant activity and total phenolic content were determined by 2‑diphenyl‑1‑picrylhydrazyl assay and Folin‑Ciocalteu method. Results: Analysis of the isolated oils revealed the presence of 44 compounds, mainly alpha‑pinene, sabinene, beta‑pinene, alpha‑phellandrene, p‑cymene and chamazulene. Alpha‑phellandrene, and chamazulene were major compounds in preflowering stage, but beta‑pinene and alpha‑phellandrene were major in flowering and past‑flowering stages. Flowering stage had highest yield and after flowering stage had lowest yield. The essential oil of preflowering stage had the highest amount of antioxidant compound (chamazulene). Preflowering stage with highest amount of phenolic compounds had the strongest antioxidant activity with the lowest amount of EC₅₀. Conclusion: This study showed that the harvesting stage had significant effects on chemical composition and antioxidant properties of essential oils, and chamazulene is main compound for antioxidant activity in A. absinthium.