Fumonisin contamination of a corn sample associated with the induction of hepatocarcinogenesis in rats—role of dietary deficiencies

A corn sample associated with a field outbreak of equine leukoencephalomalacia in Pennsylvania, USA, during 1983/1984 and induced hepatotoxic and hepatocarcinogenic effects when fed to male Fischer rats was analyzed mycologically and chemically for the presence of fumonisins (FB), hydrolysed FB derivatives and aflatoxins (AFB). Fusarium verticillioides was found to be the predominant fungal contaminant in the corn sample but Aspergillus flavus was also present. Trace amounts (0.1 μg/kg) of AFB1 and AFB2 and a total FB level of 33.5 mg/kg (FB1:FB2:FB3 ratio of 9:2.3:1) were found. No hydrolysed FB derivatives or AFG1 and AFG2 were detected. Based on the chemical stability of the fumonisins in different corn cultures of F. verticillioides kept at 4 °C over a period of 13–20 years, a level of approximately 55 mg/kg of total FB is estimated in the original corn sample. A possible role of certain dietary constituents such as the high protein content and deficiencies in certain micronutrients is evaluated to address differences in the organ-specific toxicity of FB1 in rats using commercial, semi-purified, purified and corn-only diets.