Influence of grass pellet production on pyrrolizidine alkaloids occurring in <i>Senecio aquaticus</i>-infested grassland

1,2-Dehydro-pyrrolizidine alkaloids (PA) and their <i>N</i>-oxides (PANO) exhibit acute and chronic toxic effects on the liver and other organs and therefore are a hazard for animal and human health. In certain regions of Germany, an increasing spread of <i>Senecio</i> spp. (ragwort) on grassland and farmland areas has been observed during the last years leading to a PA/PANO-contamination of feed and food of animal and plant origin. This project was carried out to elucidate whether the process of grass pellet production applying hot air drying influences the content of PA and PANO. Samples of hay (<i>n</i> = 22) and grass pellets (<i>n</i> = 28) originated from naturally infested grassland (around 10% and 30% dominance of <i>Senecio aquaticus</i>) and from a trial plot with around 50% dominance. Grass pellets were prepared from grass originating from exactly the same plots as the hay samples. The samples were analysed by liquid chromatography-tandem mass spectrometry for PA/PANO typically produced by this weed. The results of the study revealed that PA/PANO levels (predominantly sum of senecionine, seneciphylline, erucifoline and their <i>N</i>-oxides) in hay ranged between 2.1 and 12.6 mg kg⁻¹ dry matter in samples with 10% and 30% dominance of <i>S. aquaticus</i>, respectively. Samples from the trial plot (50% dominance) had levels of up to 52.9 mg kg⁻¹. Notably, the hot air drying process during the production of grass pellets did not lead to a reduction of PA/PANO levels. Instead, the levels in grass pellets with 10% and 30% <i>S. aquaticus</i> ranged from 3.1 to 55.1 mg kg⁻¹. Grass pellets from the trial plot contained up to 96.8 mg kg⁻¹. In conclusion, hot air drying and grass pellet production did not affect PA/PANO contents in plant material and therefore, heat-dried products cannot be regarded as safe in view of the toxic potential of 1,2-dehydro-pyrrolizidine alkaloids.1,2-脱氢吡咯里西啶生物碱（1,2-Dehydro-pyrrolizidine alkaloids, PA）及其N-氧化物（PANO）对肝脏及其他脏器具有急慢性毒性，因此对动物与人类健康构成危害。近年间，德国部分地区的千里光属（Senecio spp.，俗称狗舌草）植物在草地与农田中的扩散态势愈发显著，导致其污染了来自动植物源的饲料与食品。本研究旨在探明采用热风干燥工艺制备草颗粒的过程，是否会对PA与PANO的含量产生影响。试验样品包括干草（n=22）与草颗粒（n=28），均采自自然侵染的草地（其中水生千里光[S. aquaticus]占比分别约为10%与30%）以及占比约50%的试验样地。草颗粒的原料草与对应干草样品的来源地块完全一致。研究人员采用液相色谱-串联质谱法，对该杂草典型产生的PA/PANO进行了分析检测。结果显示，在水生千里光占比10%与30%的干草样品中，PA/PANO水平（主要为千里光碱、千里光菲灵、欧千里光碱及其N-氧化物的总和）范围为2.1~12.6 mg·kg⁻¹干物质；而占比50%的试验样地采集的样品，其PA/PANO含量最高可达52.9 mg·kg⁻¹。值得注意的是，草颗粒生产过程中的热风干燥工艺并未导致PA/PANO含量降低，反而，水生千里光占比10%与30%的草颗粒样品中，PA/PANO含量范围为3.1~55.1 mg·kg⁻¹；来自试验样地的草颗粒样品含量最高可达96.8 mg·kg⁻¹。综上，热风干燥与草颗粒制备工艺并未改变植物材料中的PA/PANO含量，因此鉴于1,2-脱氢吡咯里西啶生物碱的毒性潜力，经热风干燥的产品不能被视为安全。