Metabolism of zearalenone in rat liver

The metabolism of zearalenone in rat liver has been investigated. The studies were performed mainly with liver homogenate, though isolated microsomes and hepatocytes have also been used. Zearalenone was metabolized along two principal pathways, conjugation with glucuronic acid, which was the main route and reduction to an isomer of zearalenol. In no case, however, could all zearalenone metabolized be accounted for as conjugated zearalenone and free and conjugated zearalenol. Therefore another, so far unknown metabolite cannot be excluded. Reduction to zearalenol could be increased three times by the addition of NADH (or NADPH) and is probably catalyzed by a hydroxysteroid dehydrogenase. Some 25-50 per cent of the zearalenol could be conjugated, depending on the incubation conditions. The capacity of hepatocytes to eliminate zearalenone was estimated to be about 100 microgram per gram of liver in one hour. With a liver homogenate the highest value obtained was 82 microgram.