Correlation Analyses of Phytochemical Composition, Chemical, and Cellular Measures of Antioxidant Activity of Broccoli (Brassica oleracea L. Var. italica)

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• 作者：Marian V. Eberhardt ; Kanta Kobira ; Anna-Sigrid Keck ; John A. Juvik ; and Elizabeth H. Jeffery
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2005
• 出版时间：September 21, 2005
• 年：2005
• 卷：53
• 期：19
• 页码：7421 - 7431
• 全文大小：318K
• 年卷期：v.53,no.19(September 21, 2005)
• ISSN：1520-5118

文摘

Chemical measures of antioxidant activity within the plant, such as the oxygen radical absorbancecapacity (ORAC) assay, have been reported for many plant-based foods. However, the extent towhich chemical measures relate to cellular measures of oxidative stress is unclear. The naturalvariation in the phytochemical content of 22 broccoli genotypes was used to determine correlationsamong chemical composition (carotenoids, tocopherols and polyphenolics), chemical antioxidantactivity (ORAC), and measures of cellular antioxidation [prevention of DNA oxidative damage and ofoxidation of the biomarker dichlorofluorescein (DCFH) in HepG2 cells] using hydrophilic and lipophilicextracts of broccoli. For lipophilic extracts, ORAC (ORAC-L) correlated with inhibition of cellularoxidation of DCFH (DCFH-L, r = 0.596, p = 0.006). Also, DNA damage in the presence of the lipophilicextract was negatively correlated with both chemical and cellular measures of antioxidant activity asmeasured by ORAC-L (r = -0.705, p = 0.015) and DCFH-L (r = -0.671, p = 0.048), respectively.However, no correlations were observed for hydrophilic (-H) extracts, except between polyphenolcontent and ORAC (ORAC-H; r = 0.778, p < 0.001). Inhibition of cellular oxidation by hydrophilicextracts (DCFH-H) and ORAC-H were ~ 8- and 4-fold greater than DCFH-L and ORAC-L, respectively.Whether ORAC-H has more biological relevance than ORAC-L because of its magnitude or whetherORAC-L bears more biological relevance because it relates to cellular estimates of antioxidant activityremains to be determined. Chemical estimates of antioxidant capacity within the plant may notaccurately reflect the complex nature of the full antioxidant activity of broccoli extracts within cells.Keywords: ORAC; antioxidant; dichlorofluorescein; Comet assay; quinone reductase; thioredoxinreductase; broccoli; Brassica oleracea L. var. italica