The experimental method in this study was that of Kuo et al. (2002). A 400 μM solution of DPPH was prepared in 100% methanol. Instead of reading samples spectrophotometrically, the assay was performed in a microplate. 50 μl of sample (methanolic or ethanolic extract, final concentration 0–3000 μg/ml) and 150 μl of DPPH· solution were added to a well in a 96-well flat-bottom EIA microtitration plate. After thorough mixing, the solutions were kept in the dark for 90 min. The absorbency of the samples was measured using an Optimax automated microplate reader (Molecular Devices, CA) at 517 nm against methanol without DPPH· as the blank reference. Each sample was tested four times and the values were averaged. For the determination of EC50 (which is the efficient concentration of antioxidant, defined as 50% of the initial DPPH concentration), each sample was measured at more than five different concentrations in the DPPH· test. EC50 was obtained by interpolation from linear regression analysis