Complex Toxin Profile of French Mediterranean Ostreopsis cf. ovata Strains, Seafood Accumulation and Ovatoxins Prepurification

Abstract

Ostreopsis cf. ovata produces palytoxin analogues including ovatoxins (OVTXs) and a putative palytoxin (p-PLTX), which can accumulate in marine organisms and may possibly lead to food intoxication. However, purified ovatoxins are not widely available and their toxicities are still unknown. The aim of this study was to improve understanding of the ecophysiology of Ostreopsis cf. ovata and its toxin production as well as to optimize the purification process for ovatoxin. During Ostreopsis blooms in 2011 and 2012 in Villefranche-sur-Mer (France, NW Mediterranean Sea), microalgae epiphytic cells and marine organisms were collected and analyzed both by LC-MS/MS and hemolysis assay. Results obtained with these two methods were comparable, suggesting ovatoxins have hemolytic properties. An average of 223 μg·kg−1 of palytoxin equivalent of whole flesh was found, thus exceeding the threshold of 30 μg·kg−1 in shellfish recommended by the European Food Safety Authority (EFSA). Ostreopsis cells showed the same toxin profile both in situ and in laboratory culture, with ovatoxin-a (OVTX-a) being the most abundant analogue (~50%), followed by OVTX-b (~15%), p-PLTX (12%), OVTX-d (8%), OVTX-c (5%) and OVTX-e (4%). Ostreopsis cf. ovata produced up to 2 g of biomass per L of culture, with a maximum concentration of 300 pg PLTX equivalent cell−1. Thus, an approximate amount of 10 mg of PLTX-group toxins may be produced with 10 L of this strain. Toxin extracts obtained from collected biomass were purified using different techniques such as liquid-liquid partition or size exclusion. Among these methods, open-column chromatography with Sephadex LH20 phase yielded the best results with a cleanup efficiency of 93% and recovery of about 85%, representing an increase of toxin percentage by 13 fold. Hence, this purification step should be incorporated into future isolation exercises.

The novel ovatoxin-g and isobaric palytoxin (so far referred to as putative palytoxin) from Ostreopsis cf. ovata (NW Mediterranean Sea): structural insights by LC-high resolution MSn

“…Toxin content on a per-cell basis was in most cases higher than that reported for the other Mediterranean O. cf. ovata strains (7.5 to 75 pg/cell) [2,3,29,31,32] and quite similar to that recently reported for a French Mediterranean strain (up to 300 pg/cell) [15].…”

“…Recently, an O. cf. ovata strain from the French Mediterranean coast has been reported to produce all the ovatoxins (OVTX-a to -f) and quite high levels of pPLTX (12 % of the total toxin content) [15]. The toxin scenario becomes even more complicated considering toxin profiles of Ostreopsis spp.…”

Chemical, molecular, and eco-toxicological investigation of Ostreopsis sp. from Cyprus Island: structural insights into four new ovatoxins by LC-HRMS/MS

“…In more detail, three of the analyzed strains produced some of the known ovatoxins (OVTX-a, OVTX-d, OVTX-e) and isobaric palytoxin, so far found only in O. cf. ovata strains [1,2,16,23,24,42]; the remaining strains produced four new ovatoxins (OVTX-i, OVTX-j 1 , OVTX-j 2 , and OVTX-k). They represent a new addition to the palytoxin group of toxins having the same carbon backbone as ovatoxin-a, all differing in an additional C 2 H 2 O 2 moiety and an unsaturation in the region C49-C52.…”

Toxicity and Growth Assessments of Three Thermophilic Benthic Dinoflagellates (Ostreopsis cf. ovata, Prorocentrum lima and Coolia monotis) Developing in the Southern Mediterranean Basin

“…The most extensive sanitary events occurred in Italy (2005–2006), Spain (2004), Algeria (2009) and France (2006–2009) [18]. O. ovata can form floating clusters at the seawater surface and releases marine aerosols, causing thereby respiratory problems and irritations [19]. It can produce palytoxin (PLTX) [20,21,22,23], ovatoxins (OVTXs) [24,25,26,27] and mascarenotoxins [28].…”