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 (mu mol 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. (C) 2013 Elsevier Ltd. All rights reserved.