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Ability of retinoic and ascorbic acid to interfere with the binding of benzo(a)pyrene to DNA in explants from donors with bronchial cancer.

The capability of ascorbic acid (AA) and transretinoic acid (RA) to interfere with 3H-benzo(a)pyrene [B(a)P] binding to DNA has been evaluated in cultured bronchial mucosa explants from patients with bronchial cancer. The results show that the DNA-bound 3H-B(a)P is smaller in treated cultures than in controls. To explain this finding, it is proposed that AA, acting as antioxidant, inhibits the oxidative degradation of B(a)P, and that RA, a lipophilic compound interacting with the lipid components of mixed function oxidases, could modify the activities of these enzymes. Both vitamins decrease the concentration of ultimate carcinogen metabolites, which can interact with DNA. Furthermore, the treatment with RA does not increase DNA synthesis, while AA inhibits 3H-thymidine incorporation.