Dietary exposure to
aflatoxin B1 (AFB1) is a significant contributor to the incidence of
hepatocellular carcinomas globally. AFB1 exposure leads to the formation of AFB1-N7-guanine (AFB1-N7-Gua) and two diastereomers of the
imidazole ring-opened
8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl-formamido)-9-hydroxyaflatoxin B1 (AFB1-FapyGua) in
DNA. These adducts lead to G → T transversion mutations with the ring-opened adduct being more mutagenic than the cationic species. Accurate measurement of these three adducts as
biomarkers in
DNA and urine will help identify dietary exposure to AFB1 as a risk factor in the development of
hepatocellular carcinoma worldwide. Herein, we report an improved methodology for the measurement of AFB1-N7-Gua and the two diastereomers of AFB1-FapyGua using liquid chromatography-tandem mass spectrometry with
isotope dilution. We measured the levels of these compounds in liver
DNA of six control mice and six AFB1-treated mice. Levels varying from 1.5 to 45 lesions/106
DNA bases in AFB1-treated mice were detected depending on the compound and animal. No background levels of these adducts were detected in control mice. We also tested whether the AFB1 treatment caused oxidatively induced
DNA base damage using gas chromatography-tandem mass spectrometry with
isotope dilution. Although background levels of several
pyrimidine- and
purine-derived lesions were detected, no increases in these levels were found upon AFB1 treatment of mice. On the other hand, significantly increased levels of (5' R)- and (5' S)-8,5'-cyclo-2'-deoxyadenosines were observed in liver
DNA of AFB1-treated mice. The impact of this work is expected to achieve the accurate measurement of three AFB1-DNA adducts and oxidatively induced DNA lesions as
biomarkers of AFB1 exposure as germane to investigations designed for the prevention of
aflatoxin-related
hepatocellular carcinomas and for determining the effects of genetic deficiencies in human populations.