Determination of the variability of both hydrophilic and lipophilic toxins in endemic wild bivalves and carnivorous gastropods from the Southern part of Chile

Abstract

The aim of this study was to analyse and determine the composition of paralytic shellfish poisoning (PSP) toxins and lipophilic toxins in the Region of Aysén, Chile, in wild endemic mussels (Mytilus chilensis, Venus antiqua, Aulacomya ater, Choromytilus chorus, Tagelus dombeii and Gari solida) and in two endemic carnivorous molluscs species (Concholepas concholepas and Argobuccinum ranelliforme). PSP-toxin contents were determined by using HPLC with fluorescence detection, while lipophilic toxins were determined by using LC-MS/MS. Mean concentrations for the total of PSP toxins were in the range 55-2505 μg saxitoxin-equivalent/100 g. The two most contaminated samples for PSP toxicity were bivalve Gari solida and carnivorous Argobuccinum ranelliforme with 2505 ± 101 and 1850 ± 137 μg saxitoxin-equivalent/100 g, respectively (p < 0.05). The lipophilic toxins identified were okadaic acid, dinophysistoxin-1 (DTX-1), azaspiracid-1 (AZA-1), pectenotoxin-2 (PTX-2) and yessotoxins (YTX). All analysed molluscs contained lipophilic toxins at levels ranging from 56 ± 4.8 to 156.1 ± 8.2 μg of okadaic acid-equivalent/kg shellfish together with YTX at levels ranging from 1.0 ± 0.1 to 18 ± 0.9 μg of YTX-equivalent/kg shellfish and AZA at levels ranging from 3.6 ± 0.2 to 31 ± 2.1 μg of AZA-equivalent/kg shellfish. Furthermore, different bivalves and gastropods differ in their capacity of retention of lipophilic toxins, as shown by the determination of their respective lipophilic toxins levels. In all the evaluated species, the presence of lipophilic toxins associated with biotransformation in molluscs and carnivorous gastropods was not identified, in contrast to the identification of PSP toxins, where the profiles identified in the different species are directly related to biotransformation processes. Thus, this study provides evidence that the concentration of toxins in the food intake of the evaluated species (Bivalvia and Gastropoda class) determines the degree of bioaccumulation and biotransformation they will thereafter exhibit.

Saxitoxins and okadaic acid group: accumulation and distribution in invertebrate marine vectors from Southern Chile

“…Therefore, once these toxins are filtered, they are epimerized (>C2/<C1) and then subjected to enzymatic reactions (hydrolysis) in shellfish, favouring a rapid conversion to more stable toxic forms, such as α-epimers (GTX3/GTX2) (Guéguen et al 2011). The results are more characteristic of toxic profiles identified in the assessed marine organisms (Zamorano et al 2013).…”

“…Additionally, species from soft bottom showed profiles with varying levels of carbamates (STX and neoSTX); thus, Venus antiqua showed 14.6% of STX in digestive glands, while Gari solida showed 3.7% of STX and 0.2% of neoSTX in digestive glands and 0.4% of neoSTX in the foot, which demonstrates that the N 1 -hydroxy-carbamate toxic form (neoSTX) represented less than 1% of the molar toxins, showing that the reduction of the N 1 -OH toxic forms is faster than the C 11 -OHSO 3 . In both species, high levels of GTXs (α-epimers) were detected, causing them to stand out in the GTX5 profile (79 μg 100 g -1 and 1,691 μg 100 g -1 , respectively), a profile variability that is directly related to the contribution of toxins from the dinoflagellate (Alexandrium catenella) (Krock et al 2007) and from exogenous forms such as feces and pseudofeces coming from other bivalves (Zamorano et al 2013). …”

“…Said factors may be explained by the specific micro-geographies of the area studied which favour individual oceanographic factors that generate blooms (water quality, temperature, pH and salinity). These factors directly cause the marine species to have different feeding rates, physiological differences between individuals and varying sensitivities to the presence of the STX-group and/or OA-group (Zamorano et al 2013). Such variable blooms cycles (with low and high contributions of toxic cells) may also allow a variable and simultaneous accumulation of toxins (STX-group and OA-group) ) with a high contribution of non-toxic cells, which would explain the varying toxicity levels (mixed accumulation) in the different marine organisms obtained in the micro-zones of the austral fjords.…”

“…Chromatograms and mass spectra were acquired according to the and LOQ for all the studied toxin groups are expressed in micrograms per kilogram of whole tissue: OA, 0.9 and 3.8; DTX-1, 0.8 and 3.5; PTX-2, 0.15 and 0.7; AZA-1, 0.25 and 0.9; YTX, 0.35 and 1.2. We considered the smaller signal of the sample as the signal with amplitude equal to or bigger than three times the amplitude of the noise of the LC-MS/MS system, which was determined using the OA-group toxin analytical standard (Zamorano et al 2013).…”

“…In Chile, both groups of toxins have been identified in recent years (García et al 2012;Zamorano et al 2013), and the production of STX-group toxins have been associated with the dinoflagellate Alexandrium catenella (Krock et al 2007;Varela et al 2012), and OA-group toxins with dinoflagellates Dinophysis acuta and Dinophysis acuminata (Seguel & Sfeir 2010;Alves de Souza et al 2014). The identification of these toxins has been associated with southern regions of Chile, which are areas of great abundance of marine species resources with high commercial value that are mostly exported to different parts of the world, mainly Europe and Asia .…”