Determination of pyrrolizidine alkaloids in tea, herbal drugs and honey

Honey was previously considered to be one of the main food sources of human pyrrolizidine alkaloid (PA) exposure in Europe. However, comprehensive analyses of honey and tea sampled in the Berlin retail market revealed unexpected high PA amounts in teas. This study comprised the analysis of 87 honey as well as 274 tea samples including black, green, rooibos, melissa, peppermint, chamomile, fennel, nettle, and mixed herbal tea or fruit tea. Total PA concentrations in tea ranged from −1, while a mean value of about 10 µg kg−1 was found in honey samples. Additionally, herbal drugs were investigated to identify the source of PA in teas. Results suggest that PA in tea samples are most likely a contamination caused by co-harvesting of PA-producing plants. In some cases such as fennel, anise or caraway, it cannot be excluded that these plants are able to produce PA themselves.

此前，蜂蜜被认为是欧洲人群接触吡咯里西啶生物碱（pyrrolizidine alkaloid，PA）的主要食物来源之一。然而，对柏林零售市场采集的蜂蜜与茶叶样本开展的全面分析显示，茶叶中的PA含量竟出乎意料地高。本研究共分析了87份蜂蜜样本与274份茶叶样本，茶叶样本涵盖红茶、绿茶、路易波士茶、香蜂草茶、薄荷茶、洋甘菊茶、茴香茶、荨麻茶以及混合花草茶与果茶。茶叶的PA总浓度范围为−1，而蜂蜜样本的PA平均浓度约为10 μg·kg⁻¹。此外，本研究还对草本药材开展了检测，以溯源茶叶中PA的来源。研究结果表明，茶叶样本中的PA极有可能是由产PA植物与目标作物混收造成的污染。在部分案例中，比如茴香、八角或葛缕子，无法排除这些植物自身能够合成PA的可能性。