Comparative evaluation of 2,2-diphenyl-1-picryl-hydrazylhydrate (DPPH) free radical- and oxygen radical absorbance capacity (ORAC) assays in measuring the antioxidant capacities of pigmented rice varieties
2017
Xiaoqiong Chen | Kohei Irifune | Dingqian Yang | Norio Nagao | Yuuki Chikawa | Xianju Wu | Tomio Itani
This study aimed to compare different experimental approaches for measuring antioxidant capacities of pigmented rice varieties. Samples of red, black, and white rice varieties were analyzed. The anti-oxidative activities of the rice samples were assessed by the 2,2-diphenyl-1-picryl-hydrazylhydrate (DPPH) free radical and oxygen radical absorbance capacity (ORAC) assays, respectively. The total phenolic contents and the extraction efficiencies of the methanol and ethanol solvents were compared. Although the DPPH free radical and ORAC assays yielded different results, the same trends were observed with regard to their antioxidant capacities, with ranges of 1492.7-2065.8 (highest value), 713.7-1587.4, and 23.9-92.5 mumol Trolox 100/mg corresponding to red, black and white varieties, respectively. The most efficient extraction solvent was 1% HCI in methanol, which yielded extracts with the highest antioxidant capacity and total phenolic content. Extraction with 1% HCI in methanol was found to be suitable for analyzing antioxidant compounds and total phenolic contents.
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