Quenching of DPPH radical

The DPPH radical scavenging activity of the VAS was measured following the method reported earlier (Manna et al., 2008; Dutta et al., 2016). Various concentrations of VAS (10, 30, 50, 70, 80 and 100 μM) were added to DPPH solution in methanol (125 μM, 1 mL). The solution was shaken and incubated at 37°C for 30 minutes in dark. The final volume was adjusted to 2 ml by adding water. The decrease in absorbance was measured at 517 nm against methanol blank using microplate reader (BioTek, USA). Percent inhibition was calculated by using the equation, I=(A₀–A₁/A₀)×100, where A₀ is the absorbance of the blank and A₁ is the absorbance of test sample. Ascorbic acid was used as a positive control.