Methyleugenol (ME), a natural ingredient of several herbs and spices used in the human diet, is hepatocarcinogenic in rodents. Following metabolic activation to the reactive carbocation intermediate, ME can bind covalently to DNA, which is directly associated with its carcinogenicity. In this work, a non-invasive approach to determine ME exposure was established by monitoring the urinary N⁶-(methylisoeugenol-3′-yl)-2′-deoxyadenosine (ME-dA) adduct. The developed method entails liquid–liquid extraction enrichment of urinary ME-dA, incorporation of deuterated ME-dA as an internal standard, and analysis by liquid chromatography coupled tandem mass spectrometry. Male rats (10–12 weeks, 180–200 g) were treated (p.o.) with ME, and ME-dA was excreted in urine in a dose- and time-dependent manner. The non-invasive approach enabled us to successfully determine exposure to ME-containing herbs and spices. These results suggest that ME-dA can potentially serve as an effective biomarker of ME exposure in rats. It is expected that the developed approach of detecting urinary ME-dA will facilitate the investigation of ME carcinogenesis.

中文翻译：

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尿甲基丁香酚-脱氧腺苷加合物作为大鼠甲基丁香酚暴露的潜在生物标志物

甲基丁香酚（ME）是人类饮食中使用的几种草药和香料的天然成分，在啮齿动物中具有致肝癌作用。在代谢活化到反应性碳正离子中间体之后，ME可以与DNA共价结合，而DNA与其致癌性直接相关。在这项工作中，通过监测尿液中N ^6的含量，建立了一种确定ME暴露的非侵入性方法。-（甲基异丁香酚-3'-基）-2'-脱氧腺苷（ME-dA）加合物。所开发的方法包括尿液ME-dA的液-液萃取富集，氘代ME-dA的内标结合以及液相色谱-串联质谱分析。雄性大鼠（10-12周，180-200 g）用ME处理（po），ME-dA以剂量和时间依赖性方式排泄到尿液中。非侵入性方法使我们能够成功确定暴露于含ME的草药和香料。这些结果表明，ME-dA可以潜在地作为大鼠ME暴露的有效生物标志物。预期开发的检测尿ME-dA的方法将促进ME致癌作用的研究。