Rapid high-throughput assay to assess scavenging capacity index using DPPH

A new microplate-adapted DPPH rapid assay was developed to assess the antioxidant capacity of pure compounds and foods. The assay was carried out in buffered medium (methanol: 10 mmol/l Tris buffer pH 7.5, 1:1 v/v) and reaction was completed at 10 min. The scavenging capacity index (SCI), a theoretical antioxidant parameter directly related to the antioxidant capacity of samples, was calculated. SCI for pure compounds: gallic acid (6.76 ± 0.08), quercetin (7.89 ± 0.24), catechin (6.05 ± 0.23), trolox (2.32 ± 0.03), ascorbic acid (2.52 ± 0.15) and gluthatione (1.08 ± 0.08) and foods (μmol DPPH scavenged/100 ml): tropical juice (655.62 ± 12.18), mediterraneo juice (702.87 ± 11.13), apple juice (212.52 ± 17.22), pomegranate juice (319.83 ± 9.45), red grape nectar (1093.05 ± 18.69), Don Simon orange juice (632.94 ± 17.22) and date syrup (15992.34 ± 250.7) were comparable to those in previous reports using the classic DPPH assay. The relative standard deviation (RSD) for the SCI on the same and different days was less than 8.12% in all cases.