Inhibition by Dietary Organoselenium, P-Methoxybenzene-Selenol, of Hepatocarcinogenesis Induced by Azoxymethane in Rats*1

The effect of dietary p-methoxybenzeneselenol, a new organoselenium compound, on azoxymethane(AOM)-induced hepatocarcinogenesis was examined in female F344 rats. Semipurified diets containing 0 and 5 ppm p-methoxybenzeneselenol were fed to the rats, starting at 5 weeks of age until one week after the carcinogen treatment.At 7 weeks of age, all animals except the vehicle-treated controls were given weekly sc injections of AOM (15 mg/kg body weight, 3 times). At 34 weeks after the last AOM treatment, the liver neoplasm incidence and liver tumor multiplicity as well as the incidence of altered liver cell foci were significantly lower in AOM-treated rats fed the diet containing 50 ppm p-methoxybenzeneselenol (tumor incidence 19%, tumor multiplicity 0.45/rat, foci incidence 3.47/cm2) than in AOM-treated animals fed the diet without p-methoxybenzeneselenol (tumor incidence 66%, tumor multiplicity 2.24/rat, foci incidence 12.08/cm2). These results indicate that dietary p-methoxybenzeneselenol at a dose of 50 ppm inhibits AOM-induced hepatic tumorigenesis.