Determination of cytotoxic trichothecenes in corn by cell culture toxicity assay.

The great sensitivity of some cell species to toxins has been adapted to a direct biological determination of trichothecene contamination of food and feeds. The murine spleen lymphocyte stimulated by PHA (Phaseolus vulgaris phytohaemagglutinin) appeared to be the most convenient cells because of their particular sensitivity to cytotoxic trichothecenes and the opportunity to translate this cytotoxicity to immunosuppressive hazard, one of the most important concerns for trichothecenes. In this paper, the use of cell cultures was adapted for a survey of corn. The toxins were extracted by aqueous methanol, and the extract was defatted with hexane and purified on a silica gel/Florisil column. This extract was then used for a gas chromatographic (GC) determination and the biological test. The growth of cells was measured by the incorporation of tritiated thymidine (3H Tdr), and the inhibition was expressed by the IC50: concentration of corn extract inhibiting by half the 3H Tdr incorporation. We have tested pure toxins, control corn, corn spiked with T-2 toxin, corn experimentally inoculated with toxigenic Fusarium strains, and naturally contaminated corn. A good correlation exists between IC50 and the T-2 toxin concentration as determined by GC analysis. The response is not affected by the presence of zearalenone or by small amounts of deoxynivalenol. A quantitative evaluation of cytotoxic trichothecenes in corn is valuable in the range of 100 ppb to 10 ppm, expressed as T-2 toxin equivalents. The result is obtained in 48 h.