pectenotoxin-1 and pectenotoxin-6

The metabolism of toxins that have accumulated in fish and shellfish is considered a detoxification process, as happens with pectenotoxins (PTXs) in the Japanese scallop Patinopecten yessoensis. PTXs are macrolactones that display hepatotoxicity in mice, principally by capping or sequestering actin, their molecular target. PTX-2, which is considered to be the parental compound, oxidizes progressively to PTX-1, PTX-3, and PTX-6 in the Japanese scallop. In this study, we observed that PTX-1, PTX-6, and PTX-9 induce dose-dependent damage in the actin cytoskeleton and in the viability of primary cultured rat hepatocytes. In Clone 9 rat hepatocytes, PTX-1 and PTX-9 also affect the morphology of cells, but surprisingly, PTX-6 induced no effect. In accordance with this lack of activity, the actin cytoskeleton of CaCo-2 cells, another epithelial cell line, is not affected by PTX-6. In conclusion, the order of cytotoxicity of the analogues is PTX-2 > PTX-1 > PTX-6 >PTX-9. From a structure-activity perspective, the increase in the level of oxidation of the PTX molecule on C-43 decreases its cytotoxicity. Furthermore, PTX-6 is not able to induce effects on immortal cells while retaining its toxicity against primary cultured cells, whereas PTX-9, a 7-S-isomer, is active in both cellular models. The different cytotoxicities exerted by PTX-6 on cell lines and primary cells could be determined by the presence of a carboxylic acid group on C43 of the PTX molecule.

Topics: Actins; Animals; Cell Line; Cell Survival; Cells, Cultured; Cytoskeleton; Cytotoxins; Furans; Hepatocytes; Lactones; Macrolides; Male; Marine Toxins; Oxidation-Reduction; Pectinidae; Pyrans; Rats; Rats, Sprague-Dawley

Conditions for the determination of lipophilic marine toxins, such as yessotoxins and pectenotoxins (PTX)-6, were investigated with capillary electrophoresis coupled to mass spectrometry (MS) with an electrospray ionization source. After optimization, a simple and MS compatible alkaline volatile buffer solution of ammonium acetate was selected as background electrolyte, with isopropanol/water (80/20, v/v) sheath liquid modified with ammonium acetate used at the electrospray ionization (ESI) source. Previously to capillary electrophoresis (CE) separations, the application of an on-line sample pre-concentration approach based on field-amplified sample stacking was accomplished to increase sensitivity. As a result, the limits of detection provided by capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) were 0.02 microg ml(-1) (0.01 microg g(-1)), which corresponded to 1.25 pg for yessotoxin and 0.25 microg ml(-1) (0.13 microg g(-1) and 13.25 pg on capillary) for PTX-6. Accuracy tests showed 97.7% recovery from spiked blank mussel samples that showed no significant matrix influence running under optimal conditions. Intermediate precision was close to 4% relative standard deviation (RSD) for the migration time, and an RSD of 7.5% for peak areas. The method was successfully applied to naturally contaminated seafood samples in which yessotoxins and pectenotoxins-6 were clearly determined. This work demonstrated the potential of CE-ESI-MS to be applied for a sensitive determination of lipophilic toxins from the marine environment as alternative to liquid chromatography-electrospray ionization-single quadrupole mass spectrometry (LC-ESI-MS) for this purpose.

Topics: Animals; Furans; Macrolides; Marine Toxins; Mollusk Venoms; Oxocins; Pyrans; Sensitivity and Specificity; Shellfish; Spain; Spectrometry, Mass, Electrospray Ionization