Influence of extraction methods on total phenolic, flavonoids and antioxidant activity of Thymus kotchyanus L. extract in Semnan Province, Iran

Thymus kotchyanus L. is an aromatic plant belonging to Lamiaceae family and has promising traditional uses to treat some rural disorders. This species like other wild species of thyme is an aromatic plant and has been extensively used as an antiinflammatory, expectorant, spasmolitic, sedative, antibacterial, antifungal, antioxidant and anti-infection agent. The present work concerned with ethnopharmacology as well as the influence of extraction methods on total phenolic contents (TPC), total flavonoids contents (TFC) and antioxidant activity of of Thymus kotchyanus L. extract in Semnan Province, Iran. In this regard, the aerial parts of plant were collected in the blooming period from Tash Mountain (2120 msl) in September 2015. Then, ethanol extracts of the plant were obtained by maceration and ultrasound-assisted methods. In addition, TPC and TFC were determined through the standard spectrophotometric methods using the Folin-Ciocalteu and AlCl3 approaches, respectively. The antioxidant capacity was evaluated in vitro by the methods basing on 1,1-diphenyl-2-picryl hydrazyl radical scavenging (DPPH), total antioxidant capacity (TAC) and reducing power (RP) assays. The ultrasonic extract of plant was found to have higher amounts of TFC (81.17±1.07 mgQUE/g) and TPC contents (103.14±2.5 mgGAE/g) accounting for its high potential antioxidant activity (IC50=14.12±0.1 mg/mL) especially using the DPPH method. There was a strong positive correlation between influence of extraction methods on TPC, TFC and antioxidant activity of plant indicating that T. kotchyanus posess remarkable antioxidant activity and can be used potentially as a good source of natural antioxidant activities.