Ostreopsis ovata along the Campania coasts: determination of putative palytoxin and ovatoxin-a by LC-MS

Over the last few years, microalgae belonging to Ostreopsis genus have been blooming along Italian coastlines, causing serious concerns to both environment and public health. In fact, concurrently to the algal blooms, environmental sufferings involving mostly epibenthos were observed and symptoms of respiratory distress occured in people exposed to marine aerosols by recreational or working activities. Such a phenomenon was recorded for the first time during summer 1998 along the north-western Tuscanian coasts, but reached alarming proportions in late July 2005, when about 200 people exposed to marine aerosols on the beach and promenade of Genoa required extended hospitalization. Human illness was concurrent with a massive bloom of Ostreopsis ovata along the Genoa coasts and disappeared as O. ovata population decreased. From 2006 onwards, O. ovata outbreaks have been observed every single year along the whole Tyrrhenian coasts from Liguria to Sicily as well as in the Adriatic Sea. These episodes caused great concern as Ostreopsis species are reported to produce palytoxin-like compounds. Palytoxin is a complex polyhydroxylated water-soluble compound and one of the most potent non-protein marine toxins so far known. A method for determination of palytoxin, based on combination of liquid chromatography and mass spectrometry (LC-MS), was developed by our group and used to investigate toxin profile of plankton collected along the Genoa coasts during 2005 and 2006 toxic outbreaks. In all O. ovata samples, the presence of two main toxins was highlighted: putative palytoxin and a much more abundant palytoxin-like compound never reported so far, ovatoxin-a; this latter shares part structure A with palytoxin. In 2007, Regione Campania has started a monitoring program to investigate the presence of O. ovata along the Campania coastlines. In this frame, we set up extraction methods for fast and accurate analyses of both seawater and seafood samples. A relevant number of plankton, mussels and sea-urchins samples collected at various sites were analyzed by LC-MS and the presence of putative palytoxin and ovatoxin-a was ascertained, indicating that both toxins had entered the marine food web with potential risk for the health of seafood consumers