Suppression of sulfoconjugation reduces the protective effect of ortho-aminoazotoluene on hepatocarcinogenesis induced by diethylnitrosamine in mice.

The effects of ortho-aminoazotoluene on carcinogenic activity of diethylnitrosamine were studied in CBA and ICR mice. Injection of ortho-aminoazotoluene before and after diethylnitrosamine led to a significant reduction of its anticarcinogenic effect, judging from significantly lower level of liver tumors. Pentachlorophenol, inhibitor of sulfotransferase (catalyzing the terminal stage of ortho-aminoazotoluene metabolic activity), stimulated its carcinogenic effect on mouse liver. On the other hand, pentachlorophenol reduced the protective effect of ortho-aminoazotoluene on diethylnitrosamine-induced hepatocarcinogenesis in mice. Presumably, the carcinogenic and anticarcinogenic effects of ortho-aminoazotoluene were realized by its initial form or intermediate (non-sulfated) metabolites.