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      Assays for hydrophilic and lipophilic antioxidant capacity (oxygen radical absorbance capacity (ORAC(FL))) of plasma and other biological and food samples.

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          Abstract

          Methods are described for the extraction and analysis of hydrophilic and lipophilic antioxidants, using modifications of the oxygen radical absorbing capacity (ORAC(FL)) procedure. These methods provide, for the first time, the ability to obtain a measure of "total antioxidant capacity" in the protein free plasma, using the same peroxyl radical generator for both lipophilic and hydrophilic antioxidants. Separation of the lipophilic and hydrophilic antioxidant fractions from plasma was accomplished by extracting with hexane after adding water and ethanol to the plasma (hexane/plasma/ethanol/water, 4:1:2:1, v/v). Lipophilic and hydrophilic antioxidants were efficiently partitioned between hexane and aqueous solvents. Conditions for controlling temperature effects and decreasing assay variability using fluorescein as the fluorescent probe were validated in different laboratories. Incubation (37 degrees C for at least 30 min) of the buffer to which AAPH was dissolved was critical in decreasing assay variability. Lipophilic antioxidants represented 33.1 +/- 1.5 and 38.2 +/- 1.9% of the total antioxidant capacity of the protein free plasma in two independent studies of 6 and 10 subjects, respectively. Methods are described for application of the assay techniques to other types of biological and food samples.

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          Author and article information

          Journal
          J Agric Food Chem
          Journal of agricultural and food chemistry
          American Chemical Society (ACS)
          0021-8561
          0021-8561
          May 21 2003
          : 51
          : 11
          Affiliations
          [1 ] U.S. Department of Agriculture, Agriculture Research Service, Arkansas, Children's Nutrition Center, 1120 Marshall Street, Little Rock, Arkansas 72202, USA. priorronaldl@uams.edu
          Article
          10.1021/jf0262256
          12744654
          9a888bfd-0f29-4538-bf42-dc3253b3e783
          History

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