[[Protective action of biphenyl dimethyl dicarboxylate (DDB) against liver nuclear DNA damage induced by carcinogens]]

The protective effect of DDB against carcinogen-induced DNA damage was examined in the present investigation. Preincubation of rat liver nuclei with DDB (1 mmol/L) resulted in inhibition of binding of 3H-benzo (a) pyrene to nuclear DNA. The inhibition rate was about 60%. Unscheduled DNA synthesis (UDS) of freshly isolated rat hepatocytes induced by aflatoxin B1 (10(-7) mol/L) was also dose dependently inhibited by DDB (10(-6)-10(-3) mol/L). Oral administration of DDB at 200 mg/kg once daily for 3 days was effective to induce increase of liver cytosol glutathione-S-transferase and microsomal UDPG-transferase in mice. The results indicate that DDB is able directly or indirectly to antagonize certain carcinogen-induced DNA damages.