Wageningen University and Research Centre, Laboratory of Food Microbiology, EV Wageningen, Netherlands.
Appl Environ Microbiol. 2010 Nov;76(22):7466-72. doi: 10.1128/AEM.01659-10. Epub 2010 Oct 1.
Bacillus cereus produces the emetic toxin cereulide, a cyclic dodecadepsipeptide that can act as a K(+) ionophore, dissipating the transmembrane potential in mitochondria of eukaryotic cells. Because pure cereulide has not been commercially available, cereulide content in food samples has been expressed in valinomycin equivalents, a highly similar cyclic potassium ionophore that is commercially available. This research tested the biological activity of synthetic cereulide and validated its use as a standard in the quantification of cereulide contents in food samples. The synthesis route consists of 10 steps that result in a high yield of synthetic cereulide that showed biological activity in the HEp-2 cell assay and the boar sperm motility assay. The activity is different in both methods, which may be attributed to differences in K(+) content of the test media used. Using cereulide or valinomycin as a standard to quantify cereulide based on liquid chromatography-mass spectrometry (LC-MS), the concentration determined with cereulide as a standard was on average 89.9% of the concentration determined using valinomycin as a standard. The recovery experiments using cereulide-spiked food products and acetonitrile as extraction solute showed that the LC-MS method with cereulide as a standard is a reliable and accurate method to quantify cereulide in food, because the recovery rate was close to 100% over a wide concentration range.
蜡样芽胞杆菌产生呕吐毒素cereulide，这是一种环状十二肽，可作为 K(+)离子载体，使真核细胞线粒体的跨膜电位耗散。由于纯 cereulide 尚未商业化，因此食品样品中的 cereulide 含量以 valinomycin 当量表示，valinomycin 是一种高度相似的商业可得的环状钾离子载体。本研究测试了合成 cereulide 的生物活性，并验证了其在食品样品中 cereulide 含量定量中的标准应用。合成路线由 10 步组成，得到了高收率的合成 cereulide，该化合物在 HEp-2 细胞测定和猪精子活力测定中具有生物活性。两种方法的活性不同，这可能归因于所用测试介质中 K(+)含量的差异。使用 cereulide 或 valinomycin 作为标准，基于液相色谱-质谱（LC-MS）定量 cereulide，使用 cereulide 作为标准确定的浓度平均为使用 valinomycin 作为标准确定的浓度的 89.9%。使用 cereulide 加标食品和乙腈作为提取溶剂的回收实验表明，以 cereulide 为标准的 LC-MS 方法是一种可靠且准确的定量食品中 cereulide 的方法，因为回收率在较宽的浓度范围内接近 100%。
