Synthesis and characterization of deoxynivalenol glucuronide : its comparative immunotoxicity with deoxynivalenol
Deoxynivalenol (DON) is a mycotoxin commonly contaminating corn, wheat and barley. DON glucuronide (DONGLU) was synthesized with rat liver microsomes, uridine-5'-dephosphoglucuronic acid (UDPGA) and DON. DONGLU was purified with a Sephadex LH-20 column and HPLC (revere phase column, UV at 220 nm). [Beta]- glucuronidase hydrolysis formed a product with retention time and UV spectrum identical with DON. HPLC chromatography of DONGLU reaction mix with/without UDPGA or with/without microsomes showed that only in the complete reaction mix was there a peak more hydrophilic than DON but with similar UV spectrum, putatively DONGLU. DONGLU was further identified by mass spectrometry in negative ionization mode and NMR. The molecular mass (M-1) was 471g/mol, in agreement with DONGLU's expected molecular weight of 472 g/mol. [Beta]- glucuronidase hydrolysis, MS and NMR indicated that the glucuronide moiety was conjugated with the carbon- 3 -hydroxyl group of DON. The cytotoxicity of DON and DONGLU were compared in cell culture using human erythroleukemia cell line K562. 50% inhibition of cell proliferation was observed with a DON concentration of 1.31 [Mu]M using CellTitre96 detection, whereas no significant cytotoxicity was observed for DONGLU at up to 270[Mu]M. DONGLU did not influence DON toxicity at low, medium and high concentration combinations (0.5 [Mu]M, 1.3 [Mu]M and 8.4 [Mu]M) of each compound. These data show that DONGLU is a detoxification product of DON, and that measuring DON without DONGLU in human urine or plasma would be a suitable biomarker of DON exposure and toxicity.