Changes in essential oil compositions, total phenol, flavonoids and antioxidant capacity of Achillea millefolium at different growth stages

Achillea millefolium L. is one of the most important medicinal and aromatic plants that is used for the food, perfumery, cosmetic, and pharmaceutical industries. The volatile oil quantity and quality as well as the antioxidant capacity of A. millefolium at different growth stages including vegetative, flowering, and fruit set are investigated. The essential oils content (% v/w) of aerial parts was depended on the plant growth stage and was in the order of: vegetative (0.17 %), flowering (0.24 %), and fruit set (0.14 %). According to oils analysis by GCFID and GC-MS, 28 components were characterized that accounting for 92.89-97.28 % of the total volatile oil composition. The main constituent at all samples was 1,8-cineole (21.28-34.51 %) as an oxygenated monoterpene compound; followed by camphor (7.27-14.07 %), chamazulene (4.18-11.34 %), and a-eudesmol (2.09-9.63 %). Results showed that the constituents of the volatile oil A. millefolium were varied in regards to the amount of monoterpene and sesquiterpenes at different phenological stages. A considerable decrease and increase were observed respectively in monoterpene and sesquiterpene contents of essential oils during growth season. The total phenol content and antioxidant activity of A. millefolium extract gradually decreased during the plant growth period; however, the total flavonoids content did not show great changes at different growth stages. Based on obtained results, the flowering stage is suggested as the best stage for the production of A. millefolium with the optimal essential oil quantity and quality as well as antioxidant capacity in the extract.