Browsing by Subject "LC-MS/MS"
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Combined oral toxicity of azaspiracid-1 and yessotoxin in female NMRI mice(Elsevier, 2011)For many years, the presence of yessotoxins (YTXs) in shellfish has contributed to the outcome of the traditional mouse bioassay and has on many occasions caused closure of shellfisheries. Since YTXs do not appear to cause diarrhoea in man and exert low oral toxicity in animal experiments, it has been suggested that they should be removed from regulation. Before doing so, it is important to determine whether the oral toxicity of YTXs is enhanced when present together with shellfish toxins known to cause damage to the gastrointestinal tract. Consequently, mice were given high doses of YTX, at 1 or 5 mg/kg body weight, either alone or together with azaspiracid-1 (AZA1) at 200 μg/kg. The latter has been shown to induce damage to the small intestine at this level. The combined exposure caused no clinical effects, and no pathological changes were observed in internal organs. These results correspond well with the very low levels of YTX detected in internal organs by means of LCMS/MS and ELISA after dosing. Indeed, the very low absorption of YTX when given alone remained largely unchanged when YTX was administered in combination with AZA1. Thus, the oral toxicity of YTX is not enhanced in the presence of sub-lethal levels of AZA1.
Production and Isolation of Azaspiracid-1 and -2 from Azadinium spinosum Culture in Pilot Scale Photobioreactors(MPDI Publishing, 2012)Azaspiracid (AZA) poisoning has been reported following consumption of contaminated shellfish, and is of human health concern. Hence, it is important to have sustainable amounts of the causative toxins available for toxicological studies and for instrument calibration in monitoring programs, without having to rely on natural toxin events. Continuous pilot scale culturing was carried out to evaluate the feasibility of AZA production using Azadinium spinosum cultures. Algae were harvested using tangential flow filtration or continuous centrifugation. AZAs were extracted using solid phase extraction (SPE) procedures, and subsequently purified. When coupling two stirred photobioreactors in series, cell concentrations reached 190,000 and 210,000 cell•mL−1 at steady state in bioreactors 1 and 2, respectively. The AZA cell quota decreased as the dilution rate increased from 0.15 to 0.3 day−1, with optimum toxin production at 0.25 day−1. After optimization, SPE procedures allowed for the recovery of 79 ± 9% of AZAs. The preparative isolation procedure previously developed for shellfish was optimized for algal extracts, such that only four steps were necessary to obtain purified AZA1 and -2. A purification efficiency of more than 70% was achieved, and isolation from 1200 L of culture yielded 9.3 mg of AZA1 and 2.2 mg of AZA2 of >95% purity. This work demonstrated the feasibility of sustainably producing AZA1 and -2 from A. spinosum cultures.
Quantitative analysis of azaspiracids in Azadinium spinosum cultures(Springer, 2012)Azaspiracids (AZAs) are secondary metabolites of Azadinium spinosum that can accumulate in shellfish and cause food poisoning when consumed. We describe here an analytical procedure for the determination of AZAs in cultures of A. spinosum with a focus on the formation of AZA methyl esters as artefacts during extraction and sample pre-treatment. A. spinosum cells were collected from bioreactor cultures using centrifugation or filtration. Different extraction procedures were evaluated for formation of methyl ester artefacts, yield, and matrix effects. Filtration of cultures using glass-fibre filters led to increased formation of methyl esters, and centrifugation is recommended for recovery of cells. The extraction solvent (methanol (MeOH), acetone, and acetonitrile (MeCN)) did not significantly affect the yield of AZAs as long as the organic content was 80% or higher. However, the use of MeOH as extraction solvent led to increased formation of methyl esters. AZA1 recovery over two successive extractions was 100% at the 95% confidence level for acetone and MeOH. In standard-addition experiments, no significant matrix effects were observed in extracts of A. spinosum or Azadinium obesum up to a sample size of 4.5 × 109 μm3. Moreover, experiments carried out to clarify the formation and structure of methylated AZA analogues led to the description of two AZA methyl esters and to the correction of the chemical structures of AZAs29–32.