Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/16920
Title: Effects of dietary antioxidants on DNA damage in lysed cells using a modified comet assay procedure
Authors: Szeto, YT
Collins, AR
Benzie, IFF 
Keywords: α-Tocopherol
Antioxidant
Caffeic acid
Comet assay
Oxidative stress
Quercetin
Issue Date: 2002
Source: Mutation research - Fundamental and molecular mechanisms of mutagenesis, 2002, v. 500, no. 1-2, p. 31-38 How to cite?
Journal: Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis 
Abstract: A modified version of the comet assay was employed to investigate the effect in vitro of dietary antioxidants in the subcellular environment. Human lymphocytes were isolated, embedded in agarose gel, lysed in high ionic strength solution with Triton X-100, and then incubated for 30min with antioxidants at different concentrations. Gels were washed, and the comet assay performed on cells stressed by 5min incubation with 45μM hydrogen peroxide and on unstressed cells in parallel. Results showed that α-tocopherol was protective against oxidant stress, whereas caffeic acid did not protect, and at high concentration (100μM) caused increased DNA damage. Results for quercetin suggested a direct damaging effect, but this did not reach statistical significance. However, at low concentration (3.1μM), quercetin appeared protective. Thus some dietary antioxidants that have been shown previously to have a protective effect in the 'standard', whole-cell, comet assay cause DNA damage in this lysed-cell version. The cell membrane may have an important role in limiting cellular access of these 'double-edged' antioxidants. Furthermore, the absolute concentration and the presence of complementary or synergistic intracellular antioxidants may delineate the type of action of a putative antioxidant. We suggest that, used in conjunction with the standard comet assay, this lysed-cell version is useful for assessing the effect of the cell membrane and intracellular systems on susceptibility of DNA to oxidative damage, and will help determine the mechanism of protection or damage by phytochemicals.
URI: http://hdl.handle.net/10397/16920
ISSN: 0027-5107
DOI: 10.1016/S0027-5107(01)00298-6
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