Putative Palytoxin and its new analogue, Ovatoxin-a, in Ostreopsis ovata collected along the Ligurian coasts during the 2006 toxic outbreak

In this paper we report on the liquid chromatography tandem mass spectrometry (LC-MS) investigation of plankton samples collected in summer 2006 along the Ligurian coasts, in coincidence with a massive bloom of the tropical microalga Ostreopsis ovata. LC-MS analyses indicated the occurrence of putative palytoxin along with a much more abundant palytoxin-like compound never reported so far, that we named ovatoxin-a. On the basis of molecular formula, fragmentation pattern, and chromatographic behaviour, the structure of ovatoxin-a appeared to be strictly related to palytoxin’s. We report also on the analysis of cultured O. ovata which was most necessary to unequivocally demonstrate that putative palytoxin and ovatoxin-a contained in field samples were actually produced by O. ovata itself.