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Identification and analysis of a mercapturic acid conjugate of indole-3-methyl isothiocyanate in the urine of humans who consumed cruciferous vegetables
Journal of Chromatography B ( IF 3 ) Pub Date : 2017-12-02 , DOI: 10.1016/j.jchromb.2017.12.001
Pramod Upadhyaya , Adam T. Zarth , Naomi Fujioka , Vincent A. Fritz , Stephen S. Hecht

Glucobrassicin, a quantitatively significant constituent of Brassica vegetables, gives rise to indole-3-carbinol (I3C) and its dimer di-indolylmethane (DIM) when the vegetables are chewed. I3C and DIM have been extensively studied with respect to their anti-carcinogenic properties. However, the presumed intermediate isothiocyanate in their formation, indole-3-methyl isothiocyanate (IMITC), has to our knowledge never been observed, despite the fact that isothiocyanates derived from cruciferous vegetables are known to have anti-carcinogenic properties. Therefore, we investigated the formation and presence in human urine of IMITC by analyzing for its N-acetylcysteine conjugate, IMITC-NAC, in order to gain a more complete understanding of the biochemical pathways leading to formation of I3C and DIM upon consumption of vegetables rich in glucobrassicin. Standard IMITC-NAC was synthesized and its structure confirmed by NMR and MS. IMITC-NAC was identified in extracts of Brussels sprouts chopped in the presence of N-acetylcysteine. An LC-ESI–MS/MS-SRM method for analysis of IMITC-NAC, with [13C,15N]IMITC-NAC as internal standard, was developed and validated. Then, ten subjects (7 females) consumed a salad of Brussels sprouts and cabbage (containing 100–500 μmol glucobrassicin) once daily for 3 days. Urine was collected at intervals up to 24 h after vegetable consumption. Levels of IMITC-NAC in the urine of these 10 subjects ranged from 0.2 to 30.2 pmol/mL urine. These results provide the first evidence for the presumed intermediacy of IMITC in the formation of I3C and DIM in humans who consumed Brussels sprouts and cabbage as a source of glucobrassicin.



中文翻译:

食用十字花科蔬菜的人尿中巯基吲哚-3-甲基异硫氰酸酯的巯基酸结合物的鉴定和分析

甘草素是芸苔属蔬菜中数量上重要的成分,当咀嚼蔬菜时会产生吲哚-3-甲醇(I3C)及其二聚体二吲哚基甲烷(DIM)。关于I3C和DIM的抗癌特性,已经进行了广泛的研究。然而,据我们所知,尽管已知已知来自十字花科蔬菜的异硫氰酸酯具有抗癌性,但据推测从未形成中间中间体异硫氰酸酯,即吲哚-3-甲基异硫氰酸酯(IMITC)。因此,我们通过分析IMITC的N来研究其在人尿中的形成和存在。-乙酰半胱氨酸缀合物IMITC-NAC,以便更全面地了解食用富含葡聚糖的蔬菜后导致I3C和DIM形成的生化途径。合成了标准的IMITC-NAC,并通过NMR和MS确证了其结构。在存在N-乙酰半胱氨酸的情况下切碎的布鲁塞尔芽菜提取物中鉴定出IMITC-NAC 。用于IMITC-NAC分析的LC-ESI-MS / MS-SRM方法,[ 13 C,15开发并验证了N] IMITC-NAC作为内部标准。然后,十名受试者(7名女性)每天吃一次布鲁塞尔芽菜和卷心菜的沙拉(包含100–500μmol葡糖溴素),持续3天。食用蔬菜后不超过24小时的时间间隔收集尿液。这10名受试者的尿液中的IMITC-NAC水平为0.2至30.2 pmol / mL尿液。这些结果为IMITC在食用布鲁塞尔芽甘蓝和卷心菜作为葡萄糖br素来源的人的I3C和DIM形成中推测的中间性提供了第一个证据。

更新日期:2017-12-02
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