Inter-species variability of okadaic acid group toxicity in relation to the content of fatty acids detected in different marine vectors

ABSTRACT

Okadaic acid group (OA-group) is a set of lipophilic toxins which are characterised by being produced by species associated with the genera Dinophysis and Prorocentrum. OA-group has been regularly detected in endemic shellfish species from the southern zone of Chile only through the mouse bioassay. The purpose of this work was to determine the variability of OA-group toxins in endemic aquatic organisms (bivalves, crabs, gastropods and fish) and to establish the relationship with the concentration of fatty acids (FAs) detected in the evaluated species. The toxicity of OA-group and the FA profiles were determined using LC-MS/MS and gas chromatography with flame-ionisation detection, respectively. In the study area, the dinoflagellate Dinophysis acuta was detected in densities ≈2000 cells ml⁻¹ with a toxicity ≈18.3 pg OA equiv cel⁻¹. The analysis identified OA and dinophysistoxin-1 in shellfish in a range of ≈90 to ≈225 μg OA eq kg⁻¹, where no toxins in fish were detected. A positive relationship between the FA level and the concentration of OA-group toxins in the digestive glands of bivalves and gastropods was established, noted for high levels of saturated FAs (C14:0 and C16:0). The toxic variability of OA-group toxins determined in the different species allowed us to establish that the consumption of these vectors, regulated by non-analytical methods, can be harmful when consumed by humans, thus suggesting that the sanitary regulations for the control of OA-group in Chile should be updated.

Graphical Abstract

KEYWORDS:

• OA-group
• okadaic acid
• dinophysistoxin-1
• fatty acids
• toxin compartmentalisation
• Dinophysis acuta
• Mytilus chilensis
• Chile

Acknowledgements

The authors would like to thank the Secretaría Regional Ministerial de Salud de la Región de Aysén (Aysén Regional Secretariat of the Health Ministry) and Capitanía de Puerto Aguirre, Armada de Chile (Port Authority of Puerto Aguirre, Chilean Navy). We would like to thank Mrs. Carolina Valencia for her contributions and comments in the drawing up of this paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was funded by the Fondo Nacional de Desarrollo Científico y Tecnológico (National Science and Technology Fund) (FONDECYT) (granted to C. García) [1160168].