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1.
Marine algal toxins of the okadaic acid (OA) group can occur as diol esters and sulfated diol esters in algae and as fatty acid esters in shellfish. Several of these ester forms have been identified, but the most common procedure for detecting OA group toxin esters is by measuring the increase in parent toxin after alkaline hydrolysis. Use of this alkaline hydrolysis method led to the discovery of high levels of conjugates of OA and dinophysistoxins-2 (DTX2) in seawater and of OA, DTX1, and DTX2 in blue mussel hepatopancreas (HP) from Fl?devigen, Norway, during a bloom of Dinophysis spp. In the water sample, a C 8-diol ester, a C 9-diol ester, and a previously undescribed C 8-triol ester of OA were characterized using HPLC-MS (2), -MS (3), and -MS (4) in combination with various derivatization procedures. Palmitic acid (16:0) ester derivatives of these diol/triol esters were found in mussel HP and characterized using HPLC-MS (2), -MS (3), and -MS (4). To the authors' knowledge, hybrid diol-fatty acid esters of OA have not been previously described. Mass spectral analysis showed the presence of two forms of hybrid esters: one with the fatty acid conjugated to the 7-OH of the OA moiety and the other with the fatty acid conjugated to the OH group in the "diol" moiety. In the water sample, the C 8-diol ester was the most abundant, whereas in the mussels, the 16:0-C 9-diol hybrid ester was most abundant, and only minor amounts of the 16:0-C 8-diol hybrid ester were detected, suggesting that C 8- and C 9-diol esters of OA may be metabolized differently in blue mussels. 7- O-acyl esters of OA, DTX1, and DTX2 are thought to contribute to shellfish toxicity by being hydrolyzed in the human stomach to the parent toxins, and the newly characterized hybrid esters are likely to contribute similarly.  相似文献   

2.
Pectenotoxins from marine dinoflagellates of the genus Dinophysis are rapidly hydrolyzed by many shellfish to give pectenotoxin-2 seco acid, which isomerizes to 7-epi-pectenotoxin-2 seco acid. Three series of fatty acid esters of pectenotoxin-2 seco acid (PTX-2 seco acid) and 7-epi-PTX-2 seco acid were detected by LC-MS analysis of extracts from blue mussels (Mytilus edulis) from Ireland. The locations of the fatty acid ester linkages were identified by a combination of LC-MSn in positive- and negative-ion modes, LC-MS analysis of the products from reaction of the esters with sodium periodate, and NMR analysis of purified samples of the two most abundant ester derivatives. The 37-O-acyl esters of PTX-2 seco acid were the most abundant, followed by the corresponding 11-O-acyl esters, accompanied by low levels of the 33-O-acyl esters. The most abundant fatty acid esters in the fractionated sample were, in order, the 16:0, 22:6, 14:0, 16:1, 18:4, and 20:5 fatty acids, although a wide array of other PTX-2 seco acid fatty acid esters were also present at low levels.  相似文献   

3.
Further studies on mussel samples from Galicia, Spain, have revealed the presence of okadaic acid (OA), dinophysistoxin 2 (DTX2), and the fatty acid acyl esters of both of these toxins as the "DTX3" complex. Measurements were performed with an improved in situ method for the formation of 9-anthryldiazomethane (ADAM) derivatives followed by liquid chromatography with fluorescence detection. Base hydrolysis of DTX3 toxins gave free OA and DTX2, which were determined following ADAM derivatization. Results were confirmed by liquid chromatography/mass spectrometry analyses, and in most of the samples, free DTX2 was the most abundant toxin. However, the OA/DTX2 ratio in the DTX3 conjugated form was different, with OA being the most abundant in all cases. This difference could be due to different rates of metabolism of OA and DTX2 to the acyl esters or due to contamination of the shellfish by the two toxins at different points in time, resulting in less acyl ester formation for one toxin versus the other. The second possibility would be reasonable if two different source organisms were producing the toxins.  相似文献   

4.
A liquid chromatographic (LC) method was compared with the AOAC mouse bioassay method (18.086-18.092) for determination of paralytic shellfish toxins in shellfish tissues. Shellfish samples were collected from Massachusetts coastal waters as part of a state surveillance program, and extracts of shellfish meat were analyzed for toxins by using both analytical methods. Overall correlation of the LC and bioassay methods is good (r = 0.943), but for samples with toxicities less than 100 micrograms saxitoxin/100 g shellfish meat, the correlation is significantly less (r = 0.531). Limits of detection are 10 micrograms saxitoxin/100 g shellfish meat and 40 micrograms saxitoxin/100 g shellfish meat for the LC and bioassay methods, respectively. Analytical capacity of the LC method is limited to 12 samples/person-day compared with 30 samples/person-day for the bioassay. Sampling capacity of the LC method could be increased by using a fluorescence detector with a wider response range, which would eliminate the need for dilution of concentrated samples.  相似文献   

5.
A liquid chromatographic method for quantitating paralytic shellfish poison toxins in shellfish has been developed in which the toxins are converted to fluorescent purines by prechromatographic oxidation under mildly basic conditions with hydrogen peroxide or periodate. The addition of ammonium formate to the periodate oxidation reaction greatly improved the yield of fluorescent derivatives for neosaxitoxin, gonyautoxin-1, B-2, and C-3 compared to the same reaction without ammonium formate. As little as 3-6 ng of each of the nonhydroxylated toxins and 7-12 ng of the hydroxylated compounds per gram of shellfish could be detected. Reversed-phase chromatography using ammonium formate in the mobile phase improved the chromatography of neosaxitoxin and B-2 compared to results obtained earlier. Because the oxidation products of neosaxitoxin and B-2 could not be separated, parent compounds were separated before oxidation by using an SPE-COOH ion exchange cartridge. The repeatability coefficient of variation for the oxidation reactions ranged from 3 to 8% for the peroxide reaction, and from 4 to 11% for the periodate reaction, depending upon the individual toxin determined and its concentration in the extract (0.04-0.55 micrograms/g). The method was compared to the mouse bioassay and the postcolumn oxidation method. In most cases, results were comparable.  相似文献   

6.
The analysis of shellfish extracts for the determination of paralytic shellfish poisoning (PSP) toxins by liquid chromatography with fluorescence detection repeatedly showed the presence of a compound suspected to interfere with gonyautoxin 4. The first aim of this study was to confirm by liquid chromatography coupled to tandem mass spectrometry that this compound was not gonyautoxin 4. The second part of this work was to improve a nonvolumetric C(18) solid-phase extraction (SPE) procedure to evaluate the removal of the interference associated with the recovery of PSP toxins. The cleanup procedure was modified into a volumetric SPE procedure and proved to efficiently and totally remove the interference while recovering from 78 to 85% of the PSP toxins available as commercial standards (saxitoxin, neosaxitoxin, gonyautoxins 1-4) and considered as major PSP toxins in human intoxication, with 85% recovery for gonyautoxin 4. The efficiency of this cleanup procedure was checked on shellfish extracts containing this interference and originating from France and Turkey.  相似文献   

7.
Pectenotoxins (PTXs) accumulate in shellfish feeding on dinoflagellates of the genus Dinophysis, so that humans can be exposed to these toxins through shellfish consumption. Some PTXs are toxic to experimental animals, whereas others are of much lower toxicity. Pectenotoxin-2, the most abundant PTX from most Dinophysis spp., is rapidly metabolized by most shellfish to a mixture of pectenotoxin-2 seco acid (2) and 7-epi-pectenotoxin-2 seco acid (1). A mixture of 1 and 2 was produced during purification of an extract from in vitro enzymatic hydrolysis of pectenotoxin-2. These were separated by preparative HPLC, and the structure of 1 was confirmed by one- and two-dimensional 1H and 13C NMR spectroscopy and LC-MS3 analyses. No toxic changes were recorded in mice injected intraperitoneally with 1 or 2 at a dose of 5000 microg/kg. PTX seco acids are therefore unlikely to be of consequence to human consumers at the concentrations found in contaminated shellfish.  相似文献   

8.
Canadian Total Diet Study composite samples collected from 1992 to 2004 (n = 151) were analyzed for a series of perfluorooctanesulfonamides that are likely breakdown products or manufacturing residuals associated with perfluorooctylsulfonyl phosphate esters. These esters have been incorporated into coatings for paper and paperboard used in food packaging. N-Ethylperfluorooctanesulfonamide (N-EtPFOSA), perfluorooctanesulfonamide, N,N-diethylperfluorooctanesulfonamide, N-methylperfluorooctanesulfonamide, and N,N-dimethylperfluorooctanesulfonamide were extracted using solvent extraction and quantified by gas chromatography-mass spectrometry. Perfluorooctanesulfonamides were detected in the picograms per gram to low nanograms per gram of wet weight range in all food groups tested-baked goods and candy, dairy, eggs, fast food, fish, meat, and foods to be prepared in packaging. The highest concentrations of total perfluorooctanesulfonamides were observed in fast food composites (from less than the method detection limit to 27300 pg/g of wet weight). Concentrations of N-EtPFOSA appeared to decrease over the sampling period (1992-2004) in French fries and other fast food composites; no such trend was apparent in freshwater fish, marine fish, and shellfish composites. A basic estimate of dietary exposure to perfluorooctanesulfonamides suggests that Canadians (>12 years old) are exposed to approximately 73 ng/person/day from these foods.  相似文献   

9.
We performed a neuroblastoma cell (Neuro2a) culture assay modified slightly from a method reported previously to provide a simple and sensitive evaluation of paralytic shellfish poisoning (PSP) toxicity in shellfish. The cell bioassay was just as sensitive for C-toxins as for gonyautoxins. The sensitivity of our cell bioassay was 4 times that of the current standard mouse bioassay. Using the cell bioassay, we evaluated PSP toxicity in 361 shellfish samples collected from Mikawa Bay and Ise Bay, Aichi Prefecture, Japan, from April 1999-March 2002. The results were compared with those obtained in a postcolumn derivatization liquid chromatographic analysis. PSP toxins were detected in 236/361 samples by both assays, and there was a fairly good correlation (r = 0.9001, n = 236, p < 0.001) between the results from the two assays. We applied this cell bioassay when short-necked clams in the bay turned poisonous in 2001. The chronological changes in PSP toxicity in the short-necked clams were analyzed and compared with those of the cell density of poisonous plankton (Alexandrium tamarense) occurring in the bay. The PSP toxicity in shellfish peaked 2 weeks after the cell density reached a maximum. We recommend using the cell bioassay for routine monitoring of PSP toxicity in shellfish living in natural marine environments.  相似文献   

10.
Diarrhetic shellfish poisoning (DSP) toxins pose a serious health risk for consumers of bivalves and other shellfish, as well as a huge economic burden for the bivalve-producing farmers. In this work, the aim was to utilize a solubilization-based protein-isolation method to produce a low-DSP toxin protein isolate from toxic blue mussels that are unsuitable for the whole shellfish market. A homogenate of whole mussel meat was solubilized at low pH (2.8) or high pH (11.1), followed by centrifugation and reprecipitation of the solubilized mussel proteins at the isoelectric pH. In a second centrifugation, precipitated proteins were collected. These processes resulted in 81 (acid solubilization) and 72% (alkaline solubilization) reduction in the initial DTX-1 toxin content of the mussel meat. No other DSP toxins were found in the protein isolates. Acid processing of mussel meat resulted in 50% reduction in the total lipid content, while alkaline treatment did not significantly affect the lipid content. The effect of citric acid and calcium chloride addition to the mussel meat-water homogenate on lipid and toxin content was also investigated. A poor correlation factor was surprisingly obtained between reductions in DTX-1 toxin and lipids in protein isolates from processed toxic mussels. Results from an analytical mass balance of the DTX-1 toxin during acid processing showed that 61% of this toxin ended up in the aqueous supernatant after the second centrifugation. The present study presents a promising alternative way of utilizing mussels for food production in periods when they are toxic.  相似文献   

11.
Fusarium toxins, Alternaria toxins, and ergot alkaloids represent common groups of mycotoxins that can be found in cereals grown under temperate climatic conditions. Because most of them are chemically and thermally stable, these toxic fungal secondary metabolites might be transferred from grains into the final products. To get information on the commensurate contamination of various cereal-based products collected from the Czech retail market in 2010, the occurrence of "traditional" mycotoxins such as groups of A and B trichothecenes and zearalenone, less routinely determined Alternaria toxins (alternariol, alternariol monomethyl ether and altenuene), ergot alkaloids (ergosine, ergocryptine, ergocristine, and ergocornine) and "emerging" mycotoxins (enniatins A, A1, B, and B1 and beauvericin) were monitored. In a total 116 samples derived from white flour and mixed flour, breakfast cereals, snacks, and flour, only trichothecenes A and B and enniatins were found. Deoxynivalenol was detected in 75% of samples with concentrations ranging from 13 to 594 μg/kg, but its masked form, deoxynivalenol-3-β-d-glucoside, has an even higher incidence of 80% of samples, and concentrations ranging between 5 and 72 μg/kg were detected. Nivalenol was found only in three samples at levels of 30 μg/kg. For enniatins, all of the samples investigated were contaminated with at least one of four target enniatins. Enniatin A was detected in 97% of samples (concentration range of 20-2532 μg/kg) followed by enniatin B with an incidence in 91% of the samples (concentration range of 13-941 μg/kg) and enniatin B1 with an incidence of 80% in the samples tested (concentration range of 8-785 μg/kg). Enniatin A1 was found only in 44% of samples at levels ranging between 8 and 851 μg/kg.  相似文献   

12.
A high pressure liquid chromatographic procedure is described for assay of toxins associated with paralytic shellfish poisoning (PSP). The method is applicable to saxitoxin, neosaxitoxin, gonyautoxins I through IV, and their sulfocarbamoyl derivatives. Toxins are separated on a bonded phase cyano column and detected by fluorescence following alkaline oxidation (NH+4 and periodic acid). The utility of the HPLC procedure for research and monitoring is discussed.  相似文献   

13.
The natural contamination of shellfish with diarrheic shellfish toxins (DSP) has important public health implications. To avoid the economic effects of toxic episodes on shellfish farmers and the related industry, research on artificial methods alternative to the natural detoxification of shellfish is needed. Because the usual thermal processes are not efficient, alternative technologies have to be studied. Here preliminary results are presented about the lability of the DSP toxin okadaic acid in a supercritical atmosphere of carbon dioxide with acetic acid. Most of the toxin is eliminated (up to 90%), and the biological activity against its target enzyme is also severely affected (up to 70% reduction). Detoxification of contaminated shellfish requires a partial dehydration, and the detoxification yield is lower than that obtained with free toxin. Mass spectrometry experiments suggest that acetylation of the toxin molecule is not the basis of the inactivating mechanism, but a conformational change is suggested. This is the first report of the use of supercritical fluids to inactivate toxins.  相似文献   

14.
Polybrominated diphenyl ethers (PBDEs) are used as flame retardants in a variety of materials, including synthetic polymers and textiles. Although these chemicals have been detected in environmental samples and human tissues, there is little information about human exposure to PBDEs through the diet. In the present study, we determined the concentrations of PBDEs in a number of food samples acquired in Catalonia (Spain) during 2000. The dietary intake of PBDEs was estimated for the general population living in this Spanish region. The highest PBDE concentrations were found in oils and fats, fish and shellfish, meat and meat products, and eggs, while the lowest levels corresponded to fruits, vegetables, and tubers. The dietary intake of PBDEs for an adult male was 97.3 ng/day (assuming not detected (ND) = (1)/(2) limit of detection (LOD)) or 81.9 ng/day (assuming ND = 0) The greatest contribution to these values corresponded to fish and shellfish, with approximately one-third of the total intake. TetraBDEs and pentaBDEs were the homologues showing the highest percentages of contribution to the sum of total PBDEs. The comparison of the current dietary intake with the suggested lowest observed adverse effect level value of 1 mg/kg/day for the most sensitive endpoints for toxic effects of PBDEs results in a safety factor over 5 orders of magnitude in relation to PBDE exposure from food.  相似文献   

15.
Ten paralytic shellfish toxins [saxitoxin, neosaxitoxin, B-1, B-2, gonyautoxin 1, 2, and 3 (i.e., GTX-1, GTX-2, and GTX-3), C-1, C-2, and C-3] were oxidized at room temperature under mildly basic conditions with hydrogen peroxide or periodic acid. The products were then analyzed by liquid chromatography (LC). The N-1-hydroxylated toxins (neosaxitoxin, B-2, GTX-1, and C-3) formed fluorescent products after periodate oxidation at ca pH 8.7, but did not form fluorescent derivatives with peroxide oxidation. The non-N-1-hydroxylated toxins (saxitoxin, B-1, GTX-2, GTX-3, C-1, and C-2) formed highly fluorescent derivatives with both peroxide and periodate oxidations. Individual toxins produced mainly single fluorescent peaks by reverse-phase LC. However, all GTX toxins eluted with the same retention time. Also, C-1 and C-2 eluted together, as did neosaxitoxin and B-2. The non-N-1-hydroxylated toxins could be detected in quantities as low as 20-50 pg/injection, while the N-1-hydroxy analogues could be detected at levels as low as 100-500 pg/injection. UV absorption and fluorescence emission spectra were similar for the oxidation products of all toxins examined (max. 333 +/- 2 nm absorption, 389 +/- 4 nm fluorescence emission).  相似文献   

16.
In this study, the concentrations of 15 perfluorinated compounds (PFCs) were analyzed in 30 water samples collected in Catalonia (Spain) at three stages of the drinking water treatment process in several water purification plants. In addition, the concentrations of 13 PFCs were determined in samples of fish and shellfish collected from coastal areas of Catalonia. The intake of PFCs through both pathways, drinking water intake and fish and shellfish consumption, was also estimated. In water samples, the highest mean concentrations corresponded to perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) (1.81 and 2.40 ng/L, respectively), whereas perfluorodecanosulfonate (PFDS) and perfluorotetradecanoic acid (PFTDA) were under their respective limits of detection in all analyzed samples. The results show that although the current treatment processes caused slight reductions in PFC concentrations, these processes did not mean significant changes in the amounts of PFCs already contained in the raw water. Among the analyzed PFCs in fish and shellfish, only seven compounds could be detected in at least one composite sample. PFOS showed the highest mean concentration (2.70 ng/g fw), being detected in all species with the exception of mussels. With regard to PFOA (mean, 0.074 ng/g fw), the highest concentrations were detected in prawn and hake (0.098 and 0.091 ng/g fw, respectively). The current exposure to PFCs through consumption of fish and shellfish indicates that it should not be of concern for the consumers. The amounts ingested are well below the recommended tolerable daily intakes, at least for those PFCs for which information is available.  相似文献   

17.
2- and 3-hydroxy fatty acids (2- and 3-OH-FAs) are bioactive substances reported in sphingolipids and bacteria. Little is known of their occurrence in food. For this reason, a method suitable for the determination of OH-FAs at trace levels in bovine milk fat was developed. OH-FAs (and conventional fatty acids in samples) were converted into methyl esters and the hydroxyl group was derivatized with pentafluorobenzoyl (PFBO) chloride to give PFBO- O-FA methyl esters. These derivatives with strong electron affinity were determined by gas chromatography interfaced to mass spectrometry using electron-capture negative ion in the selected ion monitoring mode (GC/ECNI-MS-SIM). This method proved to be highly sensitive and selective for PFBO-O-FA methyl esters. For the analysis of samples, two internal standards were used. For this purpose, 9,10-dideutero-2-OH-18:0 methyl ester (ISTD-1) from 2-OH-18:1(9 c) methyl ester as well as the ethyl ester of 3-PFBO-O-12:0 (ISTD-2) was synthesized. ISTD-1 served as a recovery standard whereas ISTD-2 was used for GC/MS measurements. The whole-sample cleanup consisted of accelerated solvent extraction of dry bovine milk, addition of ISTD 1, saponification, conversion of fatty acids into methyl esters by use of boron trifluoride, separation of the methyl esters of OH-FAs from nonsubstituted FAs on activated silica, conversion of OH-FAs methyl esters into PFBO-O-FA methyl esters, addition of ISTD-2, and measurement by GC/ECNI-MS-SIM. By this method, ten OH-FAs were quantified in bovine milk fat with high precision in the range from 0.02 +/- 0.00 to 4.49 +/- 0.29 mg/100 g of milk fat.  相似文献   

18.
The aim of the present work was to establish the limiting factors affecting the biosynthesis of volatile esters present in virgin olive oil (VOO). Oil volatile fractions of the main Spanish olive cultivars, Arbequina and Picual, were analyzed. It was observed that acetate esters were the most abundant class of volatile esters in the oils, in concordance with the high content of acetyl-CoA found in olive fruit, and that the content of C6 alcohols is limited for the synthesis of volatile esters during the production of VOO. Thus, the increase of C6 alcohol availability during VOO production produced a significant increase of the corresponding ester in the oils in both cultivars at two different maturity stages. However, the increase of acetyl-CoA availability had no effect on the VOO volatile fraction. The low synthesis of these C6 alcohols seems not to be due to a shortage of precursors or cofactors for alcohol dehydrogenase (ADH) activity because their increase during VOO production had no effect on the C6 alcohol levels. The experimental findings are compatible with a deactivation of ADH activity during olive oil production in the cultivars under study. In this sense, a strong inhibition of olive ADH activity by compounds present in the different tissues of olive fruit has been observed.  相似文献   

19.
This paper compares three different methods to determine faecal pollution in shellfish. Two of these are related to MPN (Most Probable Number) technique and the last one is a direct count. The different results which may be obtained using these different techniques are shown. The relevance that introduction of the intervalve water may have on the bacterial titres in shellfish is presented. The shellfish utilized in this work came from two locations situated in the same bay. Simultaneous analyses on flesh, intervalve water and shellfish growing water show the different microbial titre that these three elements may have at the same time.  相似文献   

20.
Azaspiracids are a group of lipophilic polyether toxins produced by the small dinoflagellate Azadinium spinosum. They may accumulate in shellfish and can result in illnesses when consumed by humans. Research into analytical methods, chemistry, metabolism, and toxicology of azaspiracids has been severely constrained by the scarcity of high-purity azaspiracids. Consequently, since their discovery in 1995, considerable efforts have been made to develop methods for the isolation of azaspiracids in sufficient amounts and purities for toxicological studies, in addition to the preparation of standard reference materials. A seven-step procedure was improved for the isolation of azaspiracids-1-3 (1, 2, and 3) increasing recoveries 2-fold as compared to previous methods and leading to isolation of sufficiently purified azaspiracid-6 (6) for structural determination by NMR spectroscopy. The procedure, which involved a series of partitioning and column chromatography steps, was performed on 500 g of Mytilus edulis hepatopancreas tissue containing ~14 mg of 1. Overall yields of 1 (52%), 2 (43%), 3 (43%), and 6 (38%) were good, and purities were confirmed by NMR spectroscopy. The structure of 6 was determined by one- and two-dimensional NMR spectroscopy and mass spectrometry. The stability of 6 relative to 1 was also assessed in three solvents in a short-term study that demonstrated the greatest stability in aqueous acetonitrile.  相似文献   

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