Liquid chromatographic methods for the isolation and identification of newpectenotoxin-2 analogues from marine phytoplankton and shellfish

Two acidic analogues of the polyether marine toxin, pectenotoxin-2 (PTX-2), responsible for diarrhetic shellfish poisoning (DSP), have been isolated f rom the toxic marine phytoplankton (Dinophysis acuta), collected in Irish w aters. Liquid chromatography with fluorimetric detection (LC-FLD) analyses of the extracts of bulk phytoplankton samples, following derivatisation wit h 9-anthryldiazomethane (ADAM) or 1-bromoacetylpyrene (BAP), showed a compl ex toxin profile with peaks corresponding to okadaic acid (OA) and its isom ers, dinophysistoxin-2 (DTX-2) and DTX-2C, as well as other unidentified li pophilic acids. LC-UV analysis showed the presence of a diene moiety in the se new compounds and two acids have been isolated. LC coupled with mass spe ctrometry (MS) and tandem mass spectrometry (LC-MS-MS) were used to gain st ructural information. Through flow injection analysis (FIA)-MS, both in pos itive and negative ion modes, the molecular weight of 876 for both compound s was determined. Collision Induced Dissociation (CID) from each parent ion , as performed both in positive and negative ion mode, produced mass spectr a which were very similar to those obtained for authentic PTX-2 (mw 858). T hese new compounds have been confirmed to be pectenotoxin-2 seco acids (PTX -2SAs) and they are closely related to PTX-2 except that they contain an op en chain carboxylic acid rather than a lactone ring. Toxic mussels also con tained these pectenotoxin-2 analogues. (C) 1999 Published by Elsevier Scien ce B.V. All rights reserved.