Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2004
Publication Date: 3/7/2005
Citation: Eberhardt, M.V., Kobira, K., Keck, A.S., Finley, J.W., Juvik, J.A., Jeffery, E.H. 2005. Correlations of chemical composition, antioxidant capacity and cellular oxidative stress in extracts from broccoli cultivars [abstract]. The Federation of American Societies for Experimental Biology Journal. 19(5):A1475.
Technical Abstract: Broccoli contains numerous antioxidants as well as the anti-carcinogen sulforaphane. Antioxidants scavenge free radicals, reduce cellular damage to proteins, lipids, DNA, and overall oxidative stress. Many assays measure direct antioxidant capacity of food extracts, however, it is not clear how well these assays relate to cellular measures of oxidative stress. The objective of this study was to determine correlations among chemical composition (tocopherol, carotenoid and polyphenols), direct chemical antioxidant capacity (ORAC & ABTS), inhibition of cellular oxidative stress (Comet assay & DCFH), and cellular antioxidant enzyme induction (quinone reductase and thioredoxin reductase) using hydrophilic and lipophilic extracts of broccoli (12 cultivars, 3 samples each). For lipophilic extracts, chemical composition did not correlate with any antioxidant, cellular oxidative stress or enzyme activities. Significant correlations were found between cellular DCFH and ORAC (R = 0.58, p = 0.01) and DNA damage and ABTS (R =-0.69, p = 0.01). For hydrophilic extracts there was a significant correlation between hydrophilic ORAC and polyphenol content (R = 0.78, p < 0.01) whereas antioxidant assays did not correlate with any cellular assays. These data suggest that chemical assays for antioxidant activity may not accurately reflect the antioxidant capacity of broccoli extracts in cells.