In vitro investigation of the genotoxicity of portimine, a cyclic imine toxin produced by the dinoflagellate Vulcanodinium rugosum, on human hepatic HepaRG cells.

Portimine, a recently identified cyclic imine produced by the dinoflagellate Vulcanodinium rugosum, has been described as a potent apoptotic agent in contrast to most of the cyclic imines that are well-known to be neurological toxins. As apoptosis can be a consequence of a high level of DNA lesions, we investigated the responses of portimine on several endpoints aimed at detecting DNA damage in the hepatic cell line HepaRG. Portimine induced phosphorylation of H2AX, which could possibly be consistent with the previously published induction of apoptosis with this toxin. In addition, detection of apoptosis through the activation of caspase-3, the induction of strand breaks detected by the comet assay as well as chromosome and genome mutations using the micronucleus assay were addressed. Surprisingly, portimine treatment resulted in increases in only γH2AX in differentiated HepaRG cells whereas no effects on the other endpoints were detected. These increases in γH2AX in the absence of genotoxic effects in the other tests could indicate that portimine could possibly induce a DNA replication stress and/or that the compound can be detoxified by the HepaRG cells.