Fumonisin concentration and ceramide synthase inhibitory activity of corn, masa, and tortilla chips.

Nixtamalization removes fumonisins from corn and reduces their amounts in masa and tortilla products. Fumonisin concentrations and potential toxicity could be underestimated, however, if unknown but biologically active fumonisins are present. Therefore, the relative amounts of fumonisins in extracts of fumonisin-contaminated corn and its masa and tortilla chip nixtamalization products were determined with an in vitro ceramide synthase inhibition bioassay using increased sphinganine (Sa) and sphinganine to sphingosine ratio (Sa/So) as endpoints. African green monkey kidney cells (Vero cells ATCC CCL-81) were grown in 1-ml wells and exposed to 4 microl of the concentrated extracts for 48 h. The corn extract inhibited ceramide synthase as Sa (mean = 132 pmol/well) and Sa/So (mean = 2.24) were high compared to vehicle controls (Sa = 9 pmol/well; Sa/So = 0.10). Inhibitory activity (mean Sa = 14-24 pmol/well; mean Sa/So = 0.17-0.28) of the masa and tortilla chip extracts were reduced > or = 80% compared to the corn extract. Results were corroborated in a second experiment in which Sa and Sa/So of the wells treated with masa or tortilla chip extracts were reduced > or = 89% compared to those treated with the corn extract. Masa and tortilla chip FB1 concentrations (4-7 ppm) were reduced about 80-90% compared to the corn (30 ppm) when the materials were analyzed by high-performance liquid chromatography (HPLC). Therefore, nixtamalization reduced both the measured amount of FB1 and the ceramide synthase inhibitory activity of masa and tortilla chips extracts. The results further suggest that the masa and tortilla chip extracts did not contain significant amounts of unknown fumonisins having ceramide synthase inhibitory activity.

Toxicity and Role of Fumonisins in Animal Diseases and Human Esophageal Cancer.

Fumonisins are secondary metabolites of Fusarium moniliforme , Fusarium proliferatum and several other Fusaria that commonly contaminate corn. Only recently discovered in 1988, these mycotoxins appear to be the causative agents of several toxicoses in animals that result from ingestion of moldy corn or corn-based feeds. The syndromes observed vary considerably among the different species affected and include brain lesions in equids, lung edema in swine, and nephrotoxicity, hepatotoxicity and hepatocellular carcinoma in laboratory rats. There is also evidence that suggests that F. moniliforme and fumonisins may also be responsible for esophageal cancer in humans in certain areas of the world where moldy corn is frequently consumed. Studies are currently underway to determine the extent of the hazards posed by fumonisins, and whether controls in the form of regulatory action levels may be necessary.

Ammonia Treatment to Destroy Aflatoxins in Corn.

Aflatoxin contamination of corn can result in financial disaster to farmers, and is a serious health hazard to both livestock and human populations. Atmospheric ammoniation of contaminated corn appears to be an economically feasible detoxification procedure. Feeding trials conducted in livestock, and relay toxicity studies in which meat or egg tissue from the corn-fed livestock was fed to rats, have not revealed any adverse effects produced by ammoniation of contaminated corn. However, complete histopathologic examinations have not been completed. Other studies, including feeding corn to rats for 21 months, dosing rats with single doses of corn containing large quantities of ammoniated aflatoxin by-products, and using radiolabelled aflatoxin to determine tissue distribution and excretion of ammoniated aflatoxin, have indicated that ammoniation is an effective method for salvaging aflatoxin-contaminated corn.