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Abstract：
β-carboline alkaloids of the harmala group (HAlks)-a family of compounds with pharmacologic effects-can be found at trace levels (<25 μg kg-1 algae) in the edible invasive algae Undaria pinnatifida, known commonly as wakame. In this study, we present a simple and sensitive method to detect and quantify at low parts-per-trillion levels the six HAlks more frequently found in those plants. The method is based on on-line solid phase extraction capillary electrophoresis mass spectrometry using a C18 sorbent. First, the methodology was optimized and validated with standard solutions through the use of ultraviolet (UV) and mass spectrometry (MS) detection. Second, the optimized method for MS detection was applied to an analysis of the HAlks in U. pinnatifida extracts. The method achieved limits of detection between 2 and 77 pg mL-1 for standards, producing an analyte preconcentration of about 1000-times in comparison to CE-MS. Some matrix effects were observed for the complex wakame extracts, especially for the most polar HAlks (harmol and harmalol), which bear aromatic hydroxyl groups. Harmine, harmaline, and norharmane were not detected in the algal extracts, whereas harmane was found at 70 pg mL-1 (70 ng kg-1 dry algae). The results underscored that C18-SPE-CE-MS may be considered as a powerful method to detect trace levels of alkaloids and other bioactive small molecules in complex plant extracts.
摘要：
harmala组（HAlks）的β-咔啉生物碱-具有药理作用的化合物家族-可以在可食用的入侵藻类裙带菜中发现痕量水平（<25μgkg-1藻类），通常被称为裙带菜。在这项研究中,我们提出了一种简单而灵敏的方法来检测和量化在这些植物中更常见的六种HAlk。该方法基于使用C18吸附剂的在线固相萃取毛细管电泳质谱。首先,通过使用紫外（UV）和质谱（MS）检测，用标准溶液对方法进行了优化和验证。第二,优化的MS检测方法用于分析U.pinnatifida提取物中的HAlks。该方法对标准品的检出限在2至77pgmL-1之间，与CE-MS相比，产生约1000倍的分析物预浓缩。观察到复杂裙带菜提取物的一些基质效应，特别是对于极性最强的HAlks（Harmol和harmalol），带有芳香羟基。Harmine,Harmaline,在藻类提取物中没有检测到norharmane，而哈曼在70pgmL-1（70ngkg-1干藻）时被发现。结果强调，C18-SPE-CE-MS可能被认为是检测复杂植物提取物中痕量生物碱和其他生物活性小分子的有效方法。
