Prevention of nephrotoxicity of ochratoxin A, a food contaminant

Abstract

Ochratoxin A (OTA) is a mycotoxin produced by ubiquitous Aspergilli, mainly by Aspergillus ochraceus and also by Penicilium verrucosum. It is found all over the world in feed and human food and blood as well as in animal blood and tissues. The most threatening effects of OTA are its nephrotoxicity and carcinogenicity, since this mycotoxin is nephrotoxic to all animal species studied so far and is increasingly involved in the Balkan endemic nephropathy (BEN), a human chronic interstitial nephropathy which is most of the time associated to urinary tract tumours. Since it seems impossible to avoid contamination of foodstuffs by toxigenic fungi, detoxification and detoxication for OTA are needed. To reduce or abolish the OTA-induced toxic effects, several mechanisms were investigated. The results of these investigations showed that some of the potential antidotes were efficient in preventing the main OTA toxic effects whereas some others were not. Promising compounds are structural analogues of OTA, and/or compounds having a high binding affinity for plasma proteins such as piroxicam, a non-steroidal anti-inflammatory drug (NSAID). Some enzymes such as Superoxide dismutase (SOD) and catalase, radical scavengers, vitamins, prostaglandin (PG) synthesis inhibitors, (such as piroxicam), pH modificators, adsorbant resin such as cholestyramine etc. are efficient in vivo. Some of the results obtained in vivo were already confirmed in vitro and gave useful information on how to safely use these antidotes. The most generally acting compound seems to be A19 (Aspartame ®), a structural analogue of OTA and phenylalanine. When given to rats A19 (25 mg/kg/48 h) combined to OTA (289 μg/kg/48 h) for several weeks largely prevented OTA nephrotoxicity and genotoxicity. When given after intoxication of animals with OTA it washes out the toxin efficiently from the body. In vitro, A19 (10 μg/ml) prevents OTA (20–500 μg/ml) binding to plasma proteins. Its general action without any known side effect in humans and in animals, points at A19 to be the best candidate for preventing the OTA-induced subchronic effects.