Achillea eriophorea, Asteraceae is an endemic species in Khorassan province of Iran [1], which is greatly used in folk medicine. Medicinal plants are the source of a wide variety of natural antioxidants [2]. An increasing interest has been attracted for phenolics in recent years because of their significant bioactivities, such as scavenging free radicals, chelating metals, regulating enzyme activity, and modulating cell proliferation which have been associated with the beneficial effects of polyphenol-rich diets on human health [3]. In this study, phenol and flavonoid contents of A. eriophora were measured and regression between phenolics and antioxidant activity was evaluated. Extraction process was carried out on dry powders of leaves, flowers, stems and aerial parts of A. eriophora with maceration and shaking methods, separately. Total phenol and flavonoid for each extract were determined by colorimetric methods [4,5], and then antioxidant properties were measured depending on their 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities [6]. Methanolic extracts of flower and leaves prepared by maceration method, showed the highest level of phenolics. Total phenol and flavonoids were determined as 1050.829 and 244.06 mg/100 g dry leaves, and 812.23 and 216.56 mg/100 g dry flowers, respectively. Methanolic leaf and flower extracts efficiently reduced DPPH radicals in a dose-dependent manner, and the IC50 values were reported as 0.82 and 1.8 mg/ml, respectively (20 μg/ml for Ascorbic acid as positive control). There was an inverse regression between phenolic concentrations with DPPH scavenging activity (r2=0.951 for leaf extract and r2=0.976 for flower extract).

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