Pyrrolizidine alkaloids are naturally occurring toxins produced by certain weeds that can, if accidentally co-harvested, contaminate plant-based food, feed, and herbal medicinal products. Focusing on herbal medicinal products, the presence of pyrrolizidine alkaloids is restricted by regulatory prescribed thresholds to assure patient safety. Among the multitude of different herbal active substances utilized in herbal medicinal products, the class of pharmaceutically effective essential oils is considered to exhibit a negligible contribution to pyrrolizidine alkaloid contamination. Within the present investigation, this hypothesis should be scientifically scrutinized. For this purpose, an experimental set-up was chosen that reproduces the typical manufacturing step of hydrodistillation. Essential oils of eucalyptus and lemon were selected exemplarily and spiked with 3 representative pyrrolizidine alkaloids (retrorsine, retrorsine-N-oxide, and lycopsamine), whereupon hydrodistillation was performed. Analysis of the resulting distillates by LC-MS/MS proved that artificially added pyrrolizidine alkaloids were removed completely. Moreover, quantitative pyrrolizidine alkaloid recovery in the aqueous phases was observed. Hence, it was experimentally confirmed that herbal medicinal products employing hydrodistilled essential oils of pharmaceutical quality are intrinsically free of pyrrolizidine alkaloids due to the particularities of their manufacturing process. Furthermore, it can be concluded from theoretical considerations that essential oils produced by cold pressing have a negligible risk of carrying pyrrolizidine alkaloid contamination. Our findings provide a strong indication that the requirement for analytical pyrrolizidine alkaloid testing of essential oils for pharmaceutical use should be fundamentally reconsidered.

中文翻译：

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通过其制造过程中的加氢蒸馏步骤从精油中定量去除吡咯里西啶生物碱

吡咯里西啶生物碱是由某些杂草产生的天然毒素，如果意外共同收获，会污染植物性食品、饲料和草药产品。专注于草药产品，吡咯里西啶生物碱的存在受到监管规定阈值的限制，以确保患者安全。在草药产品中使用的众多不同的草药活性物质中，药用有效精油类别被认为对吡咯里西啶生物碱污染的贡献可以忽略不计。在目前的调查中，应该对这一假设进行科学审查。为此，选择了一个实验装置，该装置重现了加氢蒸馏的典型制造步骤。示例性地选择桉树和柠檬精油，并添加 3 种代表性的吡咯里西啶生物碱（逆转录酶、逆转录酶-N-氧化物和番茄红素），然后进行加氢蒸馏。通过 LC-MS/MS 对所得馏出物的分析证明，人为添加的吡咯里西啶生物碱被完全去除。此外，观察到水相中吡咯里西啶生物碱的定量回收。因此，实验证实，由于其制造工艺的特殊性，采用药用水蒸馏精油的草药产品本质上不含吡咯里西啶生物碱。此外，从理论上可以得出结论，冷压生产的精油携带吡咯里西啶生物碱污染的风险可以忽略不计。我们的研究结果有力地表明，应该从根本上重新考虑对药用精油进行分析性吡咯里西啶生物碱测试的要求。