Biomaterial Database

Effects of dietary antioxidants on human DNA ex vivo. 2002

Yim-Tong Szeto, and Iris F F Benzie

Department of Nursing and Health Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, People's Republic of China.

The protective effect of fruits and vegetables against cancer is well established. It is believed that this effect is mediated by antioxidants and decreased oxidative damage to DNA. However, the identity of the antioxidant(s) responsible is not clear. Moreover, a potentially damaging pro-oxidant effect of some antioxidants has been reported. In this study the ex vivo effects of several dietary antioxidants, including quercetin, various catechins, ascorbic acid and alpha-tocopherol, were investigated, at concentrations up to 200 microM, using the single cell gel electrophoresis (comet) assay for DNA damage. Lymphocytes from three healthy subjects were pre-incubated with these antioxidants, and the comet assay was performed on treated, untreated, challenged and unchallenged cells in parallel, oxidant challenge being induced by 5 min exposure to hydrogen peroxide (final concentrations H2O2: 30, 45, or 60 microM). Results using this ex vivo cellular assay showed protection by some antioxidants (quercetin, caffeic acid), no effect by some (catechin, epicatechin, catechin gallate, epicatechin gallate) and an apparently damaging effect by others (epigallocatechin, epigallocatechin gallate). Damage may have been caused by production of H2O2 from these polyphenolics. Neither ascorbic acid nor alpha-tocopherol protected or damaged DNA. Further study of the role of quercetin and caffeic acid in DNA protection is needed.

UI	MeSH Term	Description	Entries
D008214	Lymphocytes	White blood cells formed in the body's lymphoid tissue. The nucleus is round or ovoid with coarse, irregularly clumped chromatin while the cytoplasm is typically pale blue with azurophilic (if any) granules. Most lymphocytes can be classified as either T or B (with subpopulations of each), or NATURAL KILLER CELLS.	Lymphoid Cells,Cell, Lymphoid,Cells, Lymphoid,Lymphocyte,Lymphoid Cell
D008297	Male		Males
D011794	Quercetin	A flavonol widely distributed in plants. It is an antioxidant, like many other phenolic heterocyclic compounds. Glycosylated forms include RUTIN and quercetrin.	3,3',4',5,7-Pentahydroxyflavone,Dikvertin
D002109	Caffeic Acids	A class of phenolic acids related to chlorogenic acid, p-coumaric acid, vanillic acid, etc., which are found in plant tissues. It is involved in plant growth regulation.	Acids, Caffeic
D002392	Catechin	An antioxidant flavonoid, occurring especially in woody plants as both (+)-catechin and (-)-epicatechin (cis) forms.	Catechinic Acid,Catechuic Acid,(+)-Catechin,(+)-Cyanidanol,(+)-Cyanidanol-3,(-)-Epicatechin,(2R,3R)-2-(3,4-Dihydroxyphenyl)-3,5,7-chromanetriol,2H-1-Benzopyran-3,5,7-triol, 2-(3,4-dihydroxyphenyl)-3,4-dihydro-, (2R-cis)-,3,3',4',5,7-Flavanpentol,Catergen,Cianidanol,Cyanidanol-3,Epicatechin,KB-53,Z 7300,Zyma,Cyanidanol 3,KB 53,KB53
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D004247	DNA	A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).	DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D004249	DNA Damage	Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.	DNA Injury,DNA Lesion,DNA Lesions,Genotoxic Stress,Stress, Genotoxic,Injury, DNA,DNA Injuries
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D005260	Female		Females