A cytotoxicity assay for the detection and differentiation of two familiesof shellfish toxins

There is an urgent need for an alternative to the mouse bioassay for the de tection of algal toxins in shellfish on both analytical and animal welfare grounds. Several alternative methodologies have been described, but have no t gained widespread acceptance to date, because each assay measures only on e or a small number of related phycotoxins out of the increasing range that needs to be detected. A simple cytotoxicity assay using either the HepG2 o r ECV-304 cell lines is described with two end-point measurements, which ca n detect and distinguish between two unrelated classes of phycotoxins. Morp hological examination following 3 h exposure to the sample enables the dete ction of the diarrhetic shellfish poisons, including okadaic acid and relat ed toxins. Viability testing using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-di phenyl tetrazolium bromide), following 24 h exposure of the same cells to t he sample, reveals a second class of toxin, which is most probably the newl y-described toxin, azaspiracid. This assay should play an important role in shellfish monitoring in the future. (C) 2001 Elsevier Science Ltd. All rig hts reserved.