EFFECTS OF GLUTATHIONE ON FENTON REAGENT-DEPENDENT RADICAL PRODUCTIONAND DNA OXIDATION

The effects of glutathione (GSH) on the generation of radicals and the oxidation of DNA by Fenton reagent were studied. Hydroxyl radicals an d thiyl radicals were detected by electron spin resonance spin trappin g when GSH-Fe(II) reacted with H2O2; however, the mixture was ineffect ive at promoting the hydroxylation of 2'-deoxyguanosine in calf thymus DNA. When the concentrations of ferrous iron and hydrogen peroxide we re both 100 mu M, the concentration of GSH required to inhibit 8-hydro xy-2'-deoxyguanosine (8-OHdG) production by 92% was 1mM. Other thiol c ompounds were also effective at inhibiting 8-OHdG formation; however, mannitol and benzoate were ineffective at inhibiting 8-OHdG formation when present at the same concentration. Single strand breaks were dete cted in phi X174 plasmid DNA treated with 2 mu M Fe(II) and 2 mu M H2O 2; furthermore, the addition of 50 mu M GSH to this system inhibited s ingle strand break formation by 95%. In conclusion, GSH protected DNA from oxidation by FE(II) and H2O2 even though it did not completely in hibit the production of radicals by the Fenton reaction. (C) 1995 Acad emic Press, Inc.