Reduction of ochratoxin A toxicity by heat-induced epimerization. In vitro effects of ochratoxins on embryonic chick meningeal and other cell cultures.

The widespread contamination of food by mycotoxins may present a serious hazard to human and animal health. The present study was designed to determine the toxic potential of three structurally related ochratoxins: ochratoxin A (OTA), ochratoxin B (OTB) and the heat-induced 3S-epimer of OTA (3S-OTA) recently discovered in roasted coffee and human serum. The toxicity was determined using serum-free cell cultures of embryonic chick meningeal fibroblasts, taking the effects on mitochondrial and lysosomal activity and culture protein content as an index for toxicity. OTA, OTB and 3S-OTA were toxic. However, the concentration necessary to induce comparable effects were nearly 19- and 10-fold higher for OTB and 3S-OTA, respectively, than those for OTA. In a next step the sensitivity of serum-free cell cultures of embryonic chick neural retina and brain were compared in relation to meningeal cell cultures. In the present study, no indications for differences in sensitivity could be detected. Furthermore, our study suggest that the OTA-induced toxic effects are not due to the inhibition by OTA of phenylalanine-tRNA synthetase.