The IC50 value of seeds reported by Bozan, Tosun, and Özcan
(2008) ranged from 2.71 to 4.62 μg mL−1, showing a greater
antioxidation potential than in this study. Ruperto et al. (2007)
studied grape residues and found that methanolic extracts had IC50
values between 15.90 and 38.93 μg mL−1; these concentrations were
less effective in the inhibition of the DPPH radical than those found in
seeds in the present work; however, they were more effective than
the peel concentrations.