Comparative mutagenicity of aflatoxins using a Salmonella/trout hepatic enzyme activation system

Abstract

A modification of the Ames assay using rainbow trout (Salmo gairdneri) liver postmitochondrial fraction (PMF) was developed to investigate the relative mutagenic potential of a series of aflatoxins (AFs). Preliminary experiments revealed that the 20 000 × g (S20) liver fraction contained a higher metabolic activity than either the S9 or S30 fractions, and that 5 mg of S20 protein/plate gave the highest mutagenic response. A 9–24 h preincubation period at 25°C was also required. The results from comparative mutagenicity experiments showed the following relative potencies: AFB₁ > AFL > AFG₁ > AFM₁ > AFB₂ > AFP₁ > AFQ₁. The relative potencies observed with this in vitro system qualitatively correlated with the in vivo carcinogenic activity seen in trout, indicating that this assay is of value in predicting the carcinogenic potential of mycotoxins in this species.