DETERMINATION OF THE MYCOTOXIN FUMONISIN B-1 AND IDENTIFICATION OF ITS PARTIALLY HYDROLYZED METABOLITES IN THE FECES OF NONHUMAN-PRIMATES

A method has been developed for the determination of fumonisin B-1 (FB1) in the faeces of non-human primates (vervet monkeys). The animals were dosed with C-14-labelled FB1, and the radioactive compounds in faeces were recovered by repeated extractions with 0.1M ethylenediaminetetraacetic acid. The extracts were cleaned-up on a reversed-phase (C-18) solid-phase extraction cartridge, and FB1 was determined by o-phthaldialdehyde derivatization and reversed-phase HPLC. The analytical method for the determination of FB1 in the faecal extracts was reproducible [2.6% relative standard deviation (RSD)] and accurate (recovery from spiked blank extracts of 93 +/- 2.9% RSD). Confirmation of the identification of FB1 in faeces was achieved using HPLC and thin-layer chromatography, which showed that the radioactivity extracted corresponded mainly to FB1 and a new metabolite with chromatographic properties similar to those of the mycotoxin. The new metabolite was identified by mass spectrometry and nuclear magnetic resonance spectroscopy to be an equilibrium mixture of the two structural isomers of partially hydrolysed FB,, which are formed by hydrolysis of one of the ester groups of the mycotoxin.