2.2. Antioxidant Activity—DPPH Method

The antioxidant activities were determined by DPPH (2,2-diphenyl-1-picrylhydrazyl) assay according to the methodology described by Brand-Williams [52]. Briefly, 100 μL of plant extract was added to 0.9 mL methanol and 2 mL of DPPH solution (0.1 mM) and the mixtures were incubated in the dark for 30 min at room temperature. The blank was prepared in parallel from 1 mL of methanol and 2 mL of DPPH solution. The absorbance was measured at 517 nm using UV-Vis spectrophotometer Cary 60 (Agilent Technologies, Santa Clara, CA, USA), and the scavenging activity percentage (AA%) was determined according to Equation (1):

where A_sample is the absorbance of the plant extract with DPPH solution and A_blank is the negative control (methanol replacing the plant extract). The data were expressed as an average of triplicates ± standard deviation (SD).