DPPH Radical Scavenging Assay

The 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging activity was tested as described previously [39 (link)]. The compound solutions (120 µL) were dispensed into wells of a 96-well microplate. The DPPH (Sigma-Aldrich, Germany) was dissolved in MeOH at concentration of 7.5 µM and the solution (30 µL) was added to each well. The concentrations of tested compounds in the mixtures were 10 µM. The mixtures were shaken and left for 30 min. The absorbance of the resulting solutions was measured at λ = 520 nm with a MultiscanFC plate reader (Thermo Fisher Scientific, Waltham, MA, USA). The scavenging of the DPPH radical in comparison with control (MeOH) (%) was calculated for each compound. Ascorbic acid at 10 µM was used as positive control.