Fusarin C, a fungal metabolite, was recently isolated and identified from corn meal inoculated with Fusarium moniliforme which was one of the most common fungi associated with corn in Linxian county, a high-incidence area of esophageal cancer. In the presence of S-9 mix, fusarin C significantly increased the number of revertants in Salmonella typhimurium TA 100, and induced SCE, micronuclei, chromosome aberrations and 6-TG resistant mutants in V79 cells. The toxic action of fusarin C on V79 cells was much stronger in the absence of S-9 mix. However, fusarin C did not show, at the largest concentration used, any significant mutagenic or clastogenic effect on the cells without the addition of S-9 mix. The possible relationship between the consumption of corn contaminated with F. moniliforme and the cause of esophageal cancer was discussed.

Fusarin C (FC) is a potent mutagen which has been isolated from Fusarium moniliforme culture extracts (FME). We have confirmed that the mutagenicity of these extracts is enhanced by phenobarbital- or Aroclor-induced microsomes and shown that: (i) additional, direct-acting, mutagens are present in crude extracts from F. moniliforme cultures; (ii) Salmonella typhimurium TA 100 exposed to FME in the presence of S9 mixtures shows an increased number of DNA strand breaks as detected by intercalation of ethidium bromide; (iii) exposure of polyoma-transformed rat fibroblast cells to HPLC-purified FC induced asynchronous replication of polyoma DNA sequences, a phenomenon also observed when these cells were exposed to a variety of other carcinogens; (iv) FME can alkylate 4-(p-nitrobenzyl)pyridine in the absence of S9 mix, although less efficiently than styrene oxide; and (v) these additional direct-acting mutagens, present in crude extracts from F. moniliforme cultures, may be responsible for the DNA adducts formed by reaction with calf thymus DNA in the absence of metabolic activation and detected by the 32P-postlabeling assay. All of these observations suggest that significant health effects may be associated with human exposure to F. moniliforme and that further studies on its metabolites are needed.