Characterization of a New Anticancer Agent, EAPB0203, and Its Main Metabolites: Nuclear Magnetic Resonance and Liquid Chromatography–Mass Spectrometry Studies
作者:Florian Lafaille、Bernard Banaigs、Nicolas Inguimbert、Christine Enjalbal、Pierre-Emmanuel Doulain、Pierre-Antoine Bonnet、Carine Masquefa、Françoise M.M. Bressolle
DOI:10.1021/ac3021483
日期:2012.11.20
The present study was conducted to assess the structures of the main unknown oxygenated metabolites of EAPB0203. The first step was to assign all the 1H and 13C NMR of both EAPB0203 and its demethylated metabolite (EAPB0202) to the corresponding atoms in their molecular structures and to elucidate the fragmentation pathways for the [M + H]+ ions of these compounds using high-resolution mass spectrometry (MS). MS/MS spectra showed that both protonated molecules possessing an even number of electrons were unexpectedly losing radicals such as H•, CH3•, or even C7H7• giving stable radical cations. In vitro metabolism studies were investigated in rat and dog liver microsomes and in the filamentous fungus Cunninghamella elegans. Structural elucidation of six oxygenated metabolites was performed based on the following: (i) their fragmentation pathways in liquid chromatography–MS/MS (LC-MS/MS) analyses; (ii) comparison of their changes in their molecular masses and fragment ions with those of the parent drugs; and (iii) the results of online H/D exchange experiments that provided additional evidence in differentiating hydoxylated metabolites from N-oxides. Structures of the metabolites were elucidated by LC-MS/MS and comparison with synthetic standards; structures of these standards were confirmed using one- and two-dimensional 1H NMR spectroscopies.
本研究旨在评估 EAPB0203 的主要未知含氧代谢物的结构。第一步是将 EAPB0203 及其去甲基化代谢物(EAPB0202)的所有 1H 和 13C NMR 归入其分子结构中的相应原子,并使用高分辨率质谱法(MS)阐明这些化合物的 [M + H]+ 离子的碎片路径。MS/MS 光谱显示,拥有偶数电子的质子化分子会意外地失去 H-、CH3- 甚至 C7H7- 等自由基,从而产生稳定的自由基阳离子。在大鼠和狗的肝脏微粒体以及丝状真菌 Cunninghamella elegans 中进行了体外代谢研究。根据以下几点对六种含氧代谢物进行了结构鉴定:(i) 它们在液相色谱-质谱/质谱(LC-MS/MS)分析中的碎片路径;(ii) 它们的分子质量和碎片离子变化与母体药物的分子质量和碎片离子变化的比较;以及 (iii) 在线 H/D 交换实验的结果,这些结果为区分氢氧基化代谢物和 N-氧化物提供了更多证据。代谢物的结构通过 LC-MS/MS 和与合成标准品的比较得以阐明;这些标准品的结构通过一维和二维 1H NMR 光谱得以确认。