Palytoxin and related compounds are neurotoxic
phycotoxins produced by benthic microalgae belonging to the genus Ostreopsis. For several years this family of
phycotoxins has been posing a threat to human health since they can bioaccumulate in shellfish. With the aim of replacing current
biological assays, such as the mouse or hemolytic assays, we investigated using the Neuro-2a
neuroblastoma cell line to detect
palytoxin and related compounds. Cell death induced by the effects of PlTX and analogues on Na+, K+-
ATPase were measured using the 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan (MTT) assay for mitochondrial
reductase activity as a surrogate for cell number. The specificity of the Neuro-2a cell-based assay for
palytoxin detection was confirmed by using
ouabain, which also acts on Na+, K+-
ATPase. Pre-treatment of the Neuro-2a cells with
ouabain minimizes the effects of
palytoxin. The specificity of the Neuro-2a assay was confirmed by the finding that cell death was not detected when Neuro-2a cells were exposed to other
phycotoxins with unrelated cellular targets. When the Neuro-2a assay was used to detect
palytoxin in mussel extracts spiked with levels of
palytoxin around the proposed regulatory value of 250 microg
palytoxin/kg shellfish, a good correlation was observed between the levels found and the expected values. We conclude by proposing an experimental design for functional assays using the Neuro-2a cell line for the specific detection of four neurotoxic phycotoxin families: saxitoxins, brevetoxins,
ciguatoxins and palytoxins.