Inhibition by an antioxidant of the carcinogenic effect of nitrosomorpholine formed in vivo.

In earlier studies, it was found that the new antioxidant, MTDQ-DA ((6,6-methylene-bis)2,2-dimethyl-4-methane-sulphonic acid sodium salt-1,2-dihydroquinoline) (Patent No. 3172) prevented in vivo nitrosation and the acute hepatotoxicity of morpholine plus sodium nitrite in rats. The aim of the present experiments was to examine whether MTDQ-DA could decrease the frequency of tumours induced by simultaneous administration of morpholine and nitrite in the lung adenoma assay. Forty CFLP mice were used in each group and they were killed 8 months after treatment. In group A, treated with 1000 mg/kg morpholine i.g., and in Group B (untreated control) a similar frequency of lung adenomas could be observed (0.13 adenomas/mouse). After the combined i.g. treatment in Group C (MOR, 1000 mg/kg + nitrite, 125 mg/kg), the incidence of lung adenomas was found to be 16.58/mouse. A single dose of MTDQ-DA (500 mg/kg) added to the group C treatment reduced the lung adenoma frequency to 2.47/mouse (Group D). As MTDQ-DA shows neither toxic nor mutagenic effects and inhibits the in vivo nitrosation in both hepatotoxicity and lung adenoma assays, it may be considered to be a potential food additive.