Submitted to: Journal of the Japanese Association of Mycotoxicology
Publication Type: Abstract Only
Publication Acceptance Date: October 15, 2003
Publication Date: February 15, 2004
Citation: Voss, K.A., Riley, R.T., Gelineau-Van Waes, J.B., Bacon, C.W. 2004. Fumonisins: toxicology, emerging issues, and prospects for detoxification [abstract]. Japanese Association of Mycotoxicology - International Symposium of Mycotoxicology in Kagawa. November 4, 2003, Kagawa, Japan. p. 5. Interpretive Summary: Abstract only
Technical Abstract: Fumonisins are produced mainly by Fusarium verticillioides and F. proliferatum and are found in corn-based feeds and foods. Fumonisin B1 (FB1), the most common fumonisin, causes the animal diseases associated with the consumption of F. verticillioides-contaminated feed including leukoencephalomalacia in horses, pulmonary edema in swine, and liver and kidney toxicity and cancer in rodents. FB1 and other fumonisins inhibit ceramide synthase, thereby disrupting sphingolipid metabolism and disrupting various sphingolipid-dependent functions in cells and tissues. Increased tissue sphinganine concentrations (one consequence of ceramide synthase inhibition) and toxicity have been repeatedly correlated in animal studies. The significance of fumonisins for human health has not been established, however, they are considered risk factors for esophageal cancer in parts of southern Africa and, more recently, evidence has emerged suggesting that they might be a risk factor for neural tube defects (NTDs). While FB1 caused developmental abnormalities in rodent embryos and interferes with folate transport in vitro, FB1 was not teratogenic and did not cross the placenta when given to pregnant rats, rabbits and mice. In more recent studies using the inbred LMBc mouse as an in vivo model, intraperitoneal injections of up to 20 mg/kg BW FB1 to pregnant females on gestation days 7.5-8.5 caused a dose-related increase in the incidence of fetal NTDs (ca. 80% incidence at the high-dose). The effect was partially reversed by folinic acid, whereas administration of the ganglioside GM1 to the dams reduced the incidence of NTDs in the fetuses by about 95%. In contrast to previous reports, FB1 crossed the placenta in the LMBc mouse studies. These results establish the LMBc mouse as a useful in vivo model for further studies to determine the relationships between fumonisins, folate transport, and NTDs. Cooking decreases the measurable fumonisin concentration in foods; the amount of reduction depends upon a number of factors including the particular cooking method, temperature, cooking time, and recipe. It has been shown that nixtamalization, the method for making masa and tortillas, removes fumonisins from corn during the cooking and steeping (in alkaline water) steps of the process. Other experiments have also shown that, as long as the cooking liquid is discarded, cooking in water reduces both fumonisin concentration and toxicity of cooked products. However, the chemical fate of fumonisins in cooked food matrices is in most cases unknown, as is the effect of cooking on the toxicity of fumonisin-contaminated corn products. While evidence suggests that conversion of fumonisins to their hydrolyzed forms or the formation of fumonisin-sugar reaction products during cooking reduces toxicity, the formation of "hidden", matrix-bound fumonisins or novel toxins not detectable by routinely used analytical methods has not been ruled out. The effect of baking, pan-frying and deep-frying on the toxicity of fumonisins in cornmeal was therefore investigated using a rat feeding study as a bioassay. No differences in the type or severity of kidney and liver lesions were found among groups fed low (2% w/w) amounts or among groups fed high (20% w/w) amounts of the three cooked products or the uncooked cornmeal. The results of this bioassay therefore provided no indication that unknown toxins with fumonisin-like biological activity were formed during baking or frying. Research to modify cooking methods and develop other strategies to reduce fumonisins in corn and food products is continuing.