Cellular evaluation of the antioxidant activity of U.S. pecans [Carya illinoinensis (Wangenh.) K. Koch]
Kellett, Mary Elizabeth
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Clinical trials have shown an inverse relationship between consumption of antioxidant-rich tree nuts and the development of several chronic diseases. As the USDA considers pecans to be a top antioxidant-rich food, their biological antioxidant efficacy was evaluated using an adapted cellular antioxidant activity (CAA) assay. The CAA assay was performed in HepG2 cells and modified for use in Caco-2 cells due to their common use as a model of the intestinal barrier. Crude phenolic extracts from raw and roasted pecans, as well as fractions abundant in proanthocyanidins (PACs), were analyzed. This activity was measured by monitoring the fluorescence of 2′,7′-dichlorofluorescein; this fluorescence is highest when the cells are devoid of antioxidants. Significant reductions in fluorescence showed that raw and roasted pecans are effective antioxidants in biological systems. The primary active phenolic constituents in the extracts were determined to be (epi)catechin dimers and trimers via HPLC-ESI-MS/MS.