LC-MS/MS analysis of okadaic acid analogues and other lipophilic toxins in single-cell isolates of several Dinophysis species collected in Hokkaido, Japan

Quantification of diarrhetic shellfish poisoning (DSP) toxins (okadaic acid analogues), and other lipophilic toxins in single-cell isolates of the dinoflagellates Dinophysis fortii, D. acuminata, D. mitra, D. norvegica, D. tripos, D. infundibulus and D. rotundata, collected in coastal waters Hokkaido, Japan in 2005, was carried out by liquid chromatography–tandem mass spectrometry (LC–MS/MS). Okadaic acid (OA), dinophysistoxin-1 (DTX1), 7-O-palmitoyldinophysistoxin-1 (DTX3), pectenotoxin-1 (PTX1), pectenotoxin-11 (PTX11), pectenotoxin-2 (PTX2), pectenotoxin-6 (PTX6), pectenotoxin-2 seco-acid (PTX2sa), yessotoxin (YTX) and 45-hydroxyyessotoxin (45-OHYTX) were quantified by LC–MS/MS. PTX2 was the dominant toxin in D. acuminata, D. norvegica and D. infundibulus whereas both DTX1 and PTX2 were the principal toxins in D. fortii. None of the toxins were detected in D. mitra, D. rotundata and D. tripos. These results suggest that D. fortii is the most important species responsible for DSP contamination of bivalves in Hokkaido. This is the first finding of PTX2 in D. infundibulus, and confirms the presence of PTX2 in Japanese D. acuminata and D. norvegica collected from natural seawater.