Abstract

• We examined pattern of covalent modification of DNA produced in rat liver after exposure to single dose of aflatoxin B₁. DNA-bound aflatoxin B₁ adducts obtained from rat liver microsomes were hydrolyzed with weak acid to yield 2, 3-dihydro-3-hydroxy-(N⁷-guanyl) aflatoxin B₁ as major product. This adduct was derived from the aflatoxin B₁, 2, 3-dioxide and accounted for approximately 80% of the carcinogen-derived radioactivity incorporated into DNA. Acid hydrolysis of the nucleic acid-aflatoxin B₁, adducts also yielded 2,3-dihydro-2,3-dihydroxy-aflatoxin B₁ and other minor products. Vitamin A and E pretreatment of rats resulted in reduction in the level of hepatic AFB₁-DNA adducts to two-third of the control value. Therefore, administration of vitamin A and E to rats chages in AFB₁ metabolism probably decreased modification of DNA during this experiment.