2.4. DPPH Radical (DPPH∙) and ABTS Cation Radical (ABTS∙+) Scavenging Assay
In the DPPH radical (DPPH∙) scavenging assay [15], fifty microliters of samples of various concentrations were mixed with 150 μl of DPPH∙ solution (0.1 mM) dissolved in methanol. Each mixture was allowed to stand for 30 min and measured at 517 nm using a multiplate spectrophotometer (μQuant, Bio-Tek, USA). The scavenging ability was calculated using the following formula: