We examined pattern of covalent´ modification of DNA produced in rat liver after exposure to single dose of aflatoxin BI . 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 B 1 as major product. This adduct was derived from the aflatoxin B1, 2, 3dioxide 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,.3dihydro 2, 3-dihydroxyaflatoxinB, and other minor products.
Vitamin A and E pretreatment of rats resulted in reduction in the level of hepatic AFBI -DNA adducts to two-third of the control value. Therefore, administration of vitamin A ,and E to rats changes in AFBI metabolism probably decreased modification of DNA during this experiment.
|