Modifying role of dietary factors on the mutagenicity of aflatoxin B1: in vitro effect of trace elements.

Using Salmonella typhimurium strains TA100 and TA98 tests have been carried out to detect the inhibitory activity of various trace elements on mutagenesis induced by aflatoxin B1 (AFB1) in the presence of a rat liver microsomal activation system. Several trace elements have shown significant modulating activity in both the strains, while a few show inhibition only in a particular strain. Among the most effective elements are copper, manganese, zinc and selenium, all of which exhibit an inhibition pattern which is dose-dependent. Copper, in particular, shows exceptional activity, since the molar excess dose of this element required to inhibit AFB1 mutagenicity by 50% has been observed to be very low. The action of trace elements is possibly mediated through interaction with microsomal enzymes, thereby modulating the formation of the reactive metabolite before modification of DNA. These results suggest that certain trace elements notably copper may have potential anticarcinogenic activity against AFB1.