*2.6. Antioxidant Activity*

The antioxidant potential of ADR1 metabolites was assessed by measuring reduction of DPPH (1, 1-diphenyl-2-picrylhydrazyl) free radicals as reported earlier [36]. Briefly, DPPH solution (0.1 mM) was prepared in methanol; 100 μL of this solution was added to 100 μL of the ADR1 metabolite preparations at different concentrations varying from 1000 to 7.81 μg/mL in 96-well microtitre plate. The plate was then incubated at 25 ◦C for 20 min in dark and the absorbance was measured at 517 nm. The scavenging strength was calculated using the following formula [36].

$$\% \text{scavenging activity} = \{ (\text{absorbrane of DPPH} \cdot \text{control} - \text{absorbrane of DPPH} \cdot \text{in}) \}\tag{3}$$
  $\text{the presence of metabolism of DPPH} \cdot \text{control} \ge 100$ 
