The 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity of the extracts was measured as described by Butsat and Siriamornpun (2010) with some modifications. Briefly, sample extract (0.1 mL) was mixed with 1.9 mL of a 0.1 mM DPPH in ethanol. The mixture was vortexed (1 min), left to stand at room temperature in dark (30 min) and then the absorbance of this
solution was read at 517 nm. The percent inhibition activity was
calculated as [(Ao Ae)/Ao] 100 (Ao = absorbance without
extract; Ae = absorbance with extract)