The excretion of fumonisin B1 (FB1), hydrolyzed FB1 (HFB1), and FB1−fructose addition products (FB1−fructose) was determined in male Fisher 344/NHsd rats. Rats were dosed by gavage with 0.69, 6.93, or 69.3 μmol/kg of body weight FB1, HFB1, or FB1−fructose. Excretion of unchanged FB1, HFB1, and HFB1 after hydrolysis was determined in urine and feces by analytical reverse phase HPLC and fluorometric detection of the o-phthaldialdehyde derivatives. Average total FB1 backbone excretion in feces was 101, 76, and 50% of the dose for FB1, HFB1, and FB1−fructose, respectively. No effect of dose level was found on the percentage of the dose excreted as total FB1 after hydrolysis. FB1−fructose appears to be absorbed to the highest extent, followed by HFB1. FB1 appears to be excreted nearly completely in the feces. The greater absorption of HFB1 may explain the greater toxicity of HFB1 compared to FB1 on a molar basis. However, the detoxification of FB1 by formation of the fructose adduct cannot be explained by reduced absorption. Average total FB1 backbone excretion in urine was 2.7, 5.0, and 5.3% of the dose for FB1, HFB1, or FB1−fructose, respectively.
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