Inhibition of UV light- and Fenton reaction-induced oxidative DNA damage by the soybean isoflavone genistein.
We have investigated the effect of the soybean isoflavone genistein on 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation in calf thymus DNA exposed to either UV irradiation or the Fenton reaction system. Under the conditions used we observed that UV light and the Fenton reaction significantly increase 8-OHdG formation in DNA. Co-incubation with genistein inhibits the formation of 8-OHdG induced by either UV light irradiation or the Fenton reaction in a dose-dependent manner. The quenching effect of genistein on 8-OHdG formation induced by UV light is much more potent than that by the Fenton reaction, suggesting that the mechanisms of 8-OHdG formation may differ between the two systems. We further compared the antioxidant activities and quenching effect on 8-OHdG formation of genistein with biochanin A. Genistein potently scavenges both hydrogen peroxide in the medium and superoxide anion generated by xanthine/xanthine oxidase, whereas biochanin A has either a weak or no scavenging effect on these reactive oxygen species. However, both genistein and biochanin A display a similar quenching effect on UV light-induced 8-OHdG formation. These results suggest that the quenching effect of genistein and biochanin A on UV light-induced 8-OHdG formation is different from their ability to scavenge hydrogen peroxide and superoxide anion. The potent inhibition of UV light-induced oxidative DNA damage by genistein suggests its potential anticarcinogenic role in photocarcinogenesis.
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Department of Dermatology, Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
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D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D002417:Cattle; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D005609:Free Radicals; D019833:Genistein; D007529:Isoflavones / Q000494:pharmacology*; D017382:Reactive Oxygen Species; D014466:Ultraviolet Rays
D016588:Anticarcinogenic Agents; D005609:Free Radicals; D007529:Isoflavones; D017382:Reactive Oxygen Species; D000080242:8-Hydroxy-2'-Deoxyguanosine; D004247:DNA; D019833:Genistein; D003849:Deoxyguanosine