Determination of DPPH radical scavenging activity

The free DPPH radical scavenging activity was spectrophotometrically evaluated according to the method described by Sharma et al. [19]. This assay is based on the principle that the purple color of DPPH changes to yellow on accepting a hydrogen atom (H) from the scavenger molecule, i.e., the antioxidant. Fruit juice (100 µL, diluted 20-fold using distilled water) was mixed with an aliquot of 3.9 mL of freshly prepared 6 × 10⁻⁵ M DPPH radical in methanol. The reaction tubes were wrapped in aluminum foil and kept in the dark at 25 °C for 30 min. Absorbance at 520 nm was measured using methanol as a blank. The inhibition of the DPPH radical was calculated according to the Eq. (2):

where A₀ is the absorbance of DPPH (control sample) and A is the absorbance of the sample with DPPH.