RATIONALE Natural products have been great sources for drug discovery. However, the structures of natural products are diverse and difficult to elucidate. Cordyceps militaris is a parasitic fungus which usually grows on host insects. The metabolites of C. militaris have been reported to act as chemotherapeutic agents. In this study, we aimed for the structural elucidation of specialized metabolites derived from C. militaris, and the metabolic impact in leukemia cells. METHODS We describe a liquid chromatography data-dependent mass spectrometric platform combining tandem mass analysis and molecular networking. Leukemia cells treated with C. militaris extract and control groups were visualized in terms of their metabolic profiles using Global Natural Product Social (GNPS) molecular networking. By this method, we were able to elucidate the structures of metabolites from medicinal fungus extracts and cancer cells and then to recognize their changes in a semi-quantitative manner. RESULTS Using C. militaris and leukemia cells as examples, we found that approximately 100 new ion species were present in the treated leukemia cells, suggesting a highly altered metabolic profile. Specifically, based on the tandem mass spectral similarity, we proposed that cordycepin, a key fungus-derived therapeutic agent known for its antitumor activity, was transformed into its methylthio form in leukemia cells. CONCLUSIONS The platform described provides an ability to investigate complex molecular interactions of natural products in mammalian cells. By incorporating tandem mass spectrometry and molecular networking, we were able to reveal the chemical modification of crude bioactive compounds, for example potential bioactive compounds which might be modified from cordycepin. We envision that such a mass spectrometry (MS)-based workflow, combined with other metabolomics platforms, would enable much wider applicability to cell biology and be of great potential to pharmacological study as well as drug discovery.

中文翻译：

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分子网络作为一种去复制策略，用于监测天然产物处理过的癌细胞的代谢产物。

理由天然产物一直是发现药物的重要来源。然而，天然产物的结构是多种多样的并且难以阐明。虫草是一种寄生真菌，通常在宿主昆虫上生长。据报道，曲霉的代谢产物起化学治疗剂的作用。在这项研究中，我们的目标是阐明源自C鱼的特殊代谢产物的结构，以及对白血病细胞的代谢影响。方法我们描述了结合串联质谱分析和分子网络的液相色谱数据相关质谱平台。使用全球自然产物社会（GNPS）分子网络，将经mil虫提取物和对照组治疗的白血病细胞的代谢谱可视化。通过这种方法，我们能够阐明药用真菌提取物和癌细胞的代谢物结构，然后以半定量的方式识别它们的变化。结果以游梭菌和白血病细胞为例，我们发现在处理过的白血病细胞中大约存在100种新的离子物种，这表明其代谢状况发生了很大变化。具体而言，基于串联质谱的相似性，我们提出了将以其抗肿瘤活性而闻名的关键真菌衍生治疗剂虫草素在白血病细胞中转化为甲硫基形式。结论所描述的平台提供了研究哺乳动物细胞中天然产物的复杂分子相互作用的能力。通过结合串联质谱和分子网络，我们能够揭示粗生物活性化合物的化学修饰，例如可能从虫草素中修饰的潜在生物活性化合物。我们设想，这种基于质谱（MS）的工作流程与其他代谢组学平台相结合，将使细胞生物学具有更广泛的适用性，并且对药理研究和药物发现具有巨大的潜力。