title: Glutathione and ascorbate are negatively correlated with oxidative DNA damage in human lymphocytes.
abstract: Intracellular antioxidants, glutathione and ascorbate, and two molecular markers of oxidative DNA damage, 5-hydroxy-2'-deoxycytidine (5-OH-dCyd) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGuo), were measured in lymphocytes from 105 healthy volunteers. The analysis of 5-OH-dCyd and 8-oxo-dGuo was carried out by HPLC with electrochemical detection such that both compounds were detected on the same chromatography run. There was no significant difference in oxidative DNA damage when the extraction of DNA from cells using phenol was carried out under anaerobic conditions or in the presence of metal ion chelators. This indicates that auto-oxidation of DNA during sample preparation was minimal. Using the above methods, the average level of oxidative DNA damage in lymphocytes was 2.9 +/- 1.4 for 5-OH-dCyd and 4.5 +/- 1.8 for 8-oxo-dGuo lesions per 10(6) dGuo (n = 105). It is unlikely that artifactual oxidation contributed to the observed damage because the level of 5-OH-dCyd was comparable with that of 8-oxo-dGuo in lymphocyte DNA, whereas 8-oxo-dGuo outnumbers 5-OH-dCyd by a ratio of >5:1 when DNA is exposed to various oxidants, including ionizing radiation or Fenton reagents. Rather, the nearly equal levels of 5-OH-dCyd and 8-oxo-dGuo in cellular DNA implies that 8-oxo-dGuo may be more efficiently removed by DNA repair. Finally, and most importantly, the correlation of our endpoints revealed that the naturally occurring level of intracellular antioxidants was negatively correlated to the level of oxidative DNA damage with the strongest correlation observed for glutathione and 8-oxo-dGuo (r = -0.36; P < 0.001). These results strongly suggest that intracellular glutathione and ascorbate protect human lymphocytes against oxidative DNA damage.
authors.affiliation: Centre de recherche, Institut Universitaire de Gériatrie de Sherbrooke, Québec, Canada.
authors.forename: K J
authors.initials: KJ
authors.lastname: Lenton
authors.forename: H
authors.initials: H
authors.lastname: Therriault
authors.forename: T
authors.initials: T
authors.lastname: Fülöp
authors.forename: H
authors.initials: H
authors.lastname: Payette
authors.forename: J R
authors.initials: JR
authors.lastname: Wagner
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000693:Anaerobiosis; D000975:Antioxidants / Q000032:analysis*; D001205:Ascorbic Acid / Q000032:analysis* / Q000502:physiology; D015415:Biomarkers; D002614:Chelating Agents / Q000494:pharmacology; D005591:Chemical Fractionation / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification; D004249:DNA Damage; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000032:analysis; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000032:analysis; D005260:Female; D005978:Glutathione / Q000032:analysis* / Q000502:physiology; D006098:Granulocytes / Q000737:chemistry; D006801:Humans; D019169:Jurkat Cells / Q000737:chemistry; D008214:Lymphocytes / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000737:chemistry; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010100:Oxygen / Q000737:chemistry / Q000494:pharmacology; D012016:Reference Values; D012997:Solvents / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D002614:Chelating Agents; D012997:Solvents; D003841:Deoxycytidine; C074071:5-hydroxy-2'-deoxycytidine; D000080242:8-Hydroxy-2'-Deoxyguanosine; D004247:DNA; D003849:Deoxyguanosine; D005978:Glutathione; D001205:Ascorbic Acid; D010100:Oxygen