Identification of the okadaic acid-based toxin profile of a marine dinoflagellate strain Prorocentrum lima by LC-MS/MS and NMR spectroscopic data

The marine dinoflagellate Prorocentrum lima can produce toxins of okadaic acid and its congeners, which are mainly responsible for diarrhetic shellfish poisoning syndrome. Since 1990s, cells of P. lima have been reported as epiphytes to seaweeds distributed along the coast of Hainan Island. However, its toxin profile has not hitherto been investigated. We report herein the first description and unequivocal evidence of diarrhetic shellfish poisoning toxin production in a cultured strain of P. lima isolated from the coast of Sanya, Hainan Island. Okadaic acid and its two longest diol esters, viz. okadaic acid-D10a and okadaic acid-D10b, have been characterized as the main diarrhetic shellfish poisoning toxin congeners of this strain by liquid chromatographytandem mass spectrometry and NMR spectroscopic data. Okadaic acid-D10a and okadaic acid-D10b are first identified by NMR spectroscopic data from the dinoflagellate P. lima. The simultaneous presence of okadaic acid-D10a and okadaic acid-D10b in P. lima enlarges the range of target molecules that must be considered in future diarrhetic shellfish poisoning monitoring programs of Hainan Island, China.