Date of Award

1999

Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Dr. Kevin J. James

Abstract

There are three classes of polyether toxins responsible for Diarrhetic Shellfish Poisoning (DSP) world-wide. The causative toxins are okadaic acid (OA) and derivatives (DTXs), pectenotoxins (PTXs) and yessotoxins (YTXs). The origin of these toxins are phytoplankton from Dinophysis or Prorocentrum spp. OA has been demonstrated for most outbreaks in Europe and more recently a new isomer DTX-2 has been reported in Ireland.

Marine phytoplankton biomass samples consisting predominantly of Dinophysis acuta, were acquired using a large double plankton net from waters off the South-west coast of Ireland. Analysis of unialgal samples using high performance liquid chromatography (HPLC) with fluorescence and mass spectrometry detection revealed the presence of okadaic (OA; 58 pg/cell) and the rare isomer dinophysistoxin (DTX-2; 78 pg/cell). A dual-tag fluorimetric method was developed to confirm the presence of these toxins. The presence of pectenotoxin-2 (PTX-2) was also confirmed using HPLC with tandem mass spectroscopy (MS), this is the first time PTX-2 has been found in Irish waters.

Using extensive chromatographic procedures, four new polyether toxins were isolated and named AC 1-4. AC-4 was shown to be an isomer of OA using LC- MS-MS with an ionspray interface and therefore named DTX-2C. AC 1-3 were analysed using FIA-MS and FIA-MS-MS showed a very similar fragmentation pattern as PTX-2. Negative ion tandem fast atom bombardment (FAB) spectroscopy in conjunction with nuclear magnetic resonance (NMR) was used to unambiguously determine the structures of AC-2 and AC-3. AC-2 and AC-3 are related to PTX-2, except they contain an open chain carboxylic acid rather than a lactone ring and these compounds have been named pectenotoxin -2 seco acid (PTX-2-SA) and 7-epi-pectenotoxin-2 seco acid (7-epi-PTX-2-SA). An isolation protocol has also been established for YTX.

Using the isolated material as standards, PTX-2SA and 7-epi-PTX-2-SA have been identified in Irish, Italian, Croatian and Chinese mussel samples.

Comments

Submitted to the National Council for Education Awards for the Degree of Doctor of Philosophy - August 1999

Access Level

info:eu-repo/semantics/openAccess

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