Abstract
Produced by marine microalgae, okadaic acid is a highly selective inhibitor of protein phosphatases, as well as being a potent tumour promoter. In this paper, we report on a comparison of the toxin profiles in mussels and oysters by protein phosphatase inhibition assay (PP2A) and liquid chromatography with fluorescence detection (HPLC). Samples of Mytilus galloprovincialis and Crassostrea gigas, were harvested from Bizerta lagoon during 8 months. All of the mussel samples (November excepted) were found to be contaminated with OA to levels of about 10.2 eq µg/100 g wet weight (PP2A assay). However, OA-group in oysters were detected only from April to July to a maximum limit of 1.45 eq µg/100 g wet weight (PP2A assay). Overall, levels were 10–70 times greater in mussels. The results showed that OA-group toxins appeared to be reduced at a faster rate in oysters (t1/2 = 9 days) compared with mussels (t1/2 = 18 days).
Highlights
IntroductionOkadaic acid is a highly selective inhibitor of protein phosphatases, as well as being a potent tumour promoter
Produced by marine microalgae, okadaic acid is a highly selective inhibitor of protein phosphatases, as well as being a potent tumour promoter
C. gigas may be regarded as a low-risk species for diarrhetic shellfish toxins (DST), contamination compared to M. galloprovincialis
Summary
Okadaic acid is a highly selective inhibitor of protein phosphatases, as well as being a potent tumour promoter. We report on a comparison of the toxin profiles in mussels and oysters by protein phosphatase inhibition assay (PP2A) and liquid chromatography with fluorescence detection (HPLC). Introduction Episodes of poisoning occasionally occur when toxic phytoplankton are filtered from the water as food by shellfish (mussels, oysters, clams) which accumulate the algal toxins to levels which can be lethal to humans. No serious acute toxicities of Okadaic acid were reported, the chronic effects of the toxins, such as tumor promotion resulting from the inhibition of protein phosphatase (Suganuma et al 1988), caused much concern. The aim of this study was the comparison of oyster (Crassostrea gigas) and blue mussel (Mytilus galloprovincialis) contamination by OA-like toxins during the investigation period from April through November 2006. The PP2A inhibition assay using p-nitrophenylphosphate (p-NPP) as substrate, and HPLC methods using ADAM as fluorimetric derivatizing agents were used to quantify the diarrheic OA-like toxins in shellfish
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