Comparison of the free radical scavenging activity of six Iranian Achillea species

This study was designed to evaluate and determine the free radical scavenging activity and total flavonoid content of the ethanol extract of six Iranian Achillea species (A. micrantha Willd Asteraceae, A. filipendula Lam., A. millefolium L., A. tenuifolia Lam., A. vermicularis Trin and A. wilhelmsii C. Koch.) (Asteraceae) and investigate the possible composition-activity relationship. The free radical scavenging activity of the extracts was characterized by the DPPH scavenging test. The total flavonoid content of the extracts was determined using the colorimetric technique by AlCl3 reagent. Two of six extracts [A. micrantha (IC50 = 32.92 mu g/ml) and A. millefolium (IC50 = 49.43 mu g/ml)] revealed a suitable free radical scavenging activity. The strongest activity was found for A. micrantha (IC50 = 32.92 mu g/ml), whereas the activity of A. wilhelmsii (IC50 = 118.90 mu g/ml) was significantly lower than the others. On the other hand, the extracts of A. vermicularis (58.17 mu g/mg) and A. wilhelmsii (55.96 mu g/mg) had very high content of flavonoid, but the lowest content was determined in A. tenuifolia (35.66 mu g/mg). However, a favorable correlation was not found between the scavenging activity and the total flavonoid content of the extracts. The study suggests that A. micrantha and A. millefolium are the possible sources of natural radical scavengers.