Hepatocarcinogenic activities of hydroxymethyl derivatives of 4-(N,N-dimethylamino)azobenzene in ACI/N rats.

The hepatocarcinogenic potencies of three newly identified hydroxymethyl derivatives of 4-(N,N-dimethylamino)azobenzene [(DAB) CAS: 60-11-7], i.e., 2'-CH2OH-DAB, 3'-CH2OH-DAB, and 4'-CH2OH-DAB, were strictly evaluated in a long-term test (400 days) and compared to the potency of 3'-CH3-DAB. ACI/N rats, known to be less sensitive to azo dye carcinogenesis, were given one of these compounds in their diets for 120 days. The incidence of hepatocellular carcinoma in group 2 (20/20), which was given 3'-CH2OH-DAB, was much higher than that in any of the other groups: group 1 (2'-CH2OH-DAB; 4/19), group 3 (4'-CH2OH-DAB; 1/25), or group 4 (3'-CH3-DAB; 3/24). These data suggest that 3'-CH2OH-DAB is the most potent hepatocarcinogen in the series of azo dyes. Possible reasons for the potency of the chemical are discussed.