3.8.1. DPPH Free-Radical Scavenging Assay

The DPPH free radical scavenging activity was carried out by the method previously described [43]. Briefly, 2 mL of DPPH solution (0.1 mmol/L) was mixed with 0.5 mL of sample solutions or Trolox solution (100 μg/mL in methanol). Then, the mixture was incubated for 30 min in the dark at room temperature. Absorbance of the mixture was measured at 517 nm using a SpectraMax M5 microplate reader. DPPH radical scavenging activity of each extract was expressed as nmol Trolox equivalent (TE) per mg of extract (nmol TE/mg extract).