Detection of Genotoxic Nucleosides, 8-Hydroxydeoxyguanosine, 8-Hydroxyguanosine and Free Base 8-Hydroxyguanine, in Fish Food Products

8-Hydroxydeoxyguanosine (8-OH-dG) is a DNA base modiˆcation induced by reactive oxygen species (ROS), and is analyzed in cellular DNA and urine as a marker of oxidative stress.We now report that 8-OH-dG, the ribonucleoside 8-OH-Guo and the free base 8-OH-Gua were detected in ˆsh food products, such as salted dried sardines (Maruboshi) and dried small ˆshes (Iriko and Shirasu), which are often consumed in Japan.Water extracts of these ˆsh products were analyzed by an HPLC-ECD method, using anion exchange-and reverse phasecolumns.Various amounts of 8-OH-Gua (25 ng-22 mg/g), 8-OH-Guo (28-406 ng/g) and 8-OH-dG (5-60 ng/g) were detected in these foods.The amounts of 8-OH-dG and 8-OH-Guo increased upon heating or broiling of these ˆsh products.This is the ˆrst report on the presence of genotoxic nucleoside analogues in food.These results provide the warnings that these nucleosides analogues might be food carcinogens, because they are incorporated into DNA by a salvage pathway and show genotoxicity.