Aflatoxin Structure and Hepatocarcinogenicity in Rainbow Trout (Salmo gairdneri)

The extreme carcinogenicity of aflatoxin B1 was found to depend on the bifunctional activity of the molecule with a requirement for both the dihydrofurofuran ring system and the unsaturated δ-lactone moieties. The 12-month incidence of liver tumors in trout fed the following 8 lactones was: 4 parts per billion (ppb) aflatoxin B1, 25%; 8 ppb aflatoxin B1, 70%; 20 ppb aflatoxin B1, 78%; 20 ppb aflatoxin B2, 5%; 20 ppb aflatoxin G1, 5%; 20 ppb aflatoxin G2, 0%; 20 ppb 7-ethoxy-4-methylcoumarin, 0%; 20 ppb isobergaptene, 0%; 20 ppb tetrahydrodeoxo-aflatoxin B1, 1%; 20 ppb 5,7-dimethoxycyclopentenone (2,3-c)-coumarin, 0%; and 4 ppb aflatoxin B1 plus 4 ppb aflatoxin B2, 43%. There was a synergistic effect on tumor incidence between aflatoxin B2 and B1.