Current issues in research on fumonisins, mycotoxins which may cause nephropathy?

The fumonsins are a series of mycotoxins produced by the ubiquitous corn (m aize) contaminant, Fusarium moniliforme, and several other Fusarium species . Fumonisin B-1 (FB1), the major component of the fumonisins, causes leukoe ncephalomalacia in horses, pulmonary edema in swine and hepatocellular carc inoma, cirrhosis and chronic interstitial nephritis in rats. Also, consumpt ion of corn-derived food products contaminated with F. moniliforme has been correlated with increased risk of human esophageal cancer in epidemiologic al studies in South Africa and China. In the kidneys of rodents, dietary ex posure to FB1 produces a dose-related non-inflammatory nephrosis with regen eration at low doses. Individual cells die by induction of apoptosis. The f umonisins have chemical structures analogous to sphingosine, a putative int racellular regulatory molecule, and a component of sphingolipids. The alkyl amine structure of FB1 makes possible sensitive high performance liquid chr omatography (HPLC) assays based on pre-column derivatization of the amino g roup with fluorogenic reagents. These assays have been used to demonstrate that FB1 contaminates most corn and corn-derived processed food products in tended for human consumption. Conventional thermal food processing techniqu es reduce FB1 levels, but do not completely eliminate it. Structure-activit y relationship studies carried out in our laboratories on natural and synth etic fumonisins indicate that extensive alterations in structure are possib le without loss of biological activity. This observation raises the concern that the FB1 eliminated during food processing may actually be converted t o other biologically active forms. The full extent of the threat to food sa fety posed by fumonisins will not be known until it is determined what subs tances the toxin is converted to during food processing, the bioavailabilit y of those substances, the extent they retain biological activity and the a dditivity of their toxic effects with other nephrotoxic myeotoxins such as ochratoxins A and B.