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，蜂蜜曾被认为是欧洲人群暴露于吡咯里西啶生物碱（pyrrolizidine alkaloid, PA）的主要食物来源之一。然而，针对柏林零售市场采集的蜂蜜与茶叶样品开展的综合分析却显示，茶叶中吡咯里西啶生物碱的含量竟出人意料地偏高。本研究共分析了87份蜂蜜样品与274份茶叶样品，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，以及混合花草茶或果茶。茶叶样品中总吡咯里西啶生物碱浓度低于1微克每千克，而蜂蜜样品中总吡咯里西啶生物碱的平均浓度约为10微克每千克。此外，本研究还对药用植物原料开展了检测，以追溯茶叶中吡咯里西啶生物碱的来源。结果表明，茶叶样品中的吡咯里西啶生物碱大概率是因与产吡咯里西啶生物碱的植物一同采收而造成的污染。在部分案例中，例如茴香、八角或葛缕子，无法排除这些植物自身可合成吡咯里西啶生物碱的可能性。