DPPH· radical scavenging activity

The DPPH^· radical scavenging method involves neutralization of free radicals of DPPH^· by the antioxidant compounds. The procedure was same as that described by Bimakr et al. [21] with minor modification. In short, 2 mL of sample (0.1 mg/mL) (dissolved in ethanol) was mixed with 2 mL of an ethanolic solution of DPPH^· (0.1 mM) and the sampleʼ s absorbance was measured at 517 nm for 60 min with 10-min intervals using a UV–Vis spectrophotometer (Specord 250, Jena, Germany). Ethanolic DPPH^· solution was used as a blank sample. The inhibition percent of scavenged DPPH^· (%DPPH_sc) was calculated as 100 × (A_b − A_s)/A_b, where A_b is the absorbance of the blank and A_s is the absorbance of the sample.