4.8. DPPH Radical Scavenging Assay

The DPPH radical scavenging assay was conducted using the published protocol method [57]. Briefly, the compound (100 μL) was added to 100 μL of 2 mM DPPH solution in 50% ethanol. The mixtures were mixed well and incubated in the dark for 30 min. The reduction of DPPH absorption was measured at 520 nm using a microplate spectrophotometer (Bio-Tek). Ascorbic acid (100 μM) was used as a positive control. All determinations were performed in triplicate. The DPPH radical scavenging activity was calculated using Equation (1):