4.2. DPPH Radical Scavenging Assay

The 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging activity was tested as described previously [26]. The compounds were dissolved in MeOH, and the solutions (120 µL) were dispensed into wells of a 96-well microplate. The DPPH (Sigma-Aldrich, Germany) was dissolved in MeOH at a concentration of 7.5 × 10⁻³ M and the solution (30 μL) was added to each well. The concentrations of tested compounds in the mixtures were 10 and 100 μM. Pure MeOH was used as a negative control and ascorbic acid was used as a positive control. The mixtures were shaken and left for 30 min. The absorbance of the resulting solutions was measured at λ = 520 nm with a Multiscan FC plate reader (Thermo Scientific, Waltham, MA, USA). The results were presented as percent of the negative control (MeOH) data.