Antioxidant properties and principal phenolic phytochemicals of Iranian tarragon (Artemisia dracunculus L.) accessions

Artemisia dracunculus L. (tarragon), a common spice and vegetable grown throughout Iran, is an economically important species of the Asteraceae family. The free radical-scavenging activities of 12 Iranian A. dracunculus accession extracts were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric-reducing antioxidant power (FRAP) assays. The total phenolic and flavonoid contents were measured using spectrophotometric techniques. Reversed-phase highperformance liquid chromatography (RP-HPLC) with UV detection was also used to identify the major phenolic compounds, revealing the presence of chlorogenic, syringic, and caffeic acids, while the predominant flavonoid was quercetin. Herniarin was the main coumarin in the extracts. Although a high antioxidant capacity was observed in all extracts, their antioxidant activities varied significantly, with the Birjand and Varamin accessions having the highest and the lowest capacities, respectively. The obtained total phenolic and flavonoid values similarly varied among tarragon accessions. Positive linear correlations were found between total antioxidant capacities (DPPH and FRAP assays) and total phenolic as well as flavonoid contents, indicating that phenolic compounds were the dominant antioxidant constituents in the tested plant extracts. Tarragon could therefore be a good source of natural antioxidants and has potential as a valuable dietary supplement.