In vitro metabolism of aflatoxin B2 by animal and human liver.

The metabolism of aflatoxin B2 by postmitochondrial supernatant fractions of duck, rat, mouse, and human livers was studied in an in vitro system. Duck liver had a much higher level of activity than had tissues from other species. Postmitochondrial supernatant equivalent to 0.2 g whole liver metabolized 40 to 80% of the initial substrate in 30 min, compared to less than 6% for the other species. Among several metabolites formed by duck liver, aflatoxin B1 was produced in amounts equivalent to 2 to 8% of the initial substrate, and metabolites having chromatographic properties postualted for aflatoxicols 1 and 2 and aflatoxins M1 and M2 were also formed in small amounts. In contrast, rat, mouse, and human liver preparations produced no detectable aflatoxin B1 and only small amounts of compounds thought to be aflatoxins Q2 and P2. The greater susceptibility of duck liver to the toxicity of aflatoxin B2 may be attributable to its ability to form aflatoxin B2 may be attributable to its ability to form aflatoxin B1, which could then be activated through further metabolism.