基于LTQ-Orbitrap高分辨质谱的骆驼蓬子中生物碱类成分鉴定及裂解途径分析

采用高效液相色谱-质谱（HPLC-MSⁿ）法分析骆驼蓬子甲醇提取物中的生物碱类成分。在正离子模式下，采用C18色谱柱，以乙腈0.5%氨水溶液为流动相进行梯度洗脱，LTQ-Orbitrap线性离子阱高分辨质谱解析多级质谱数据，并对成分进行定性分析。结果表明，从骆驼蓬子甲醇提取物中共鉴定出20种生物碱类成分，其中鸭嘴花酮碱葡萄糖苷、3-羟基-去氢骆驼蓬碱和鸭嘴花碱糖苷为首次从骆驼蓬子中鉴定得到；同时对路因碱、四氢哈尔明、鸭嘴花碱糖苷的质谱裂解途径进行分析，推测出一系列去氢骆驼蓬碱衍生物的裂解规律。该方法可为骆驼蓬子的化学成分和质量控制提供理论基础，也可为类似结构化合物的质谱裂解规律研究提供方法参考。

Identification of Alkaloids in Seeds of Peganumharmala Linn. and Analysis of Their Fragmentation Pathways by LTQ-Orbitrap MS

The seed of Peganumharmala Linn. belonging to the family of Zygophyllaceae, is a perennial herb which grows in semi-arid condition, steppe area and sandy soil. In China, Peganumharmala as a folk medicine has been used since antiquity among the Uighur, Kazakh and Mongolia for the treatment of cold, asthma, malaria, rheumatism, lumbago and some skin diseases such as scabies. The content of total alkaloids in ripe seeds could reach as high as 6% mainly in the form of harmaline and harmine, which were the first isolated in the last century. The problem was that the type and content of the rest of the alkaloids in the seeds of Peganumharmala were unknown. The aim of this work was to identify chemical constituents in the methanolic extract found in Peganumharmala. The extract of seeds of Peganumharmala were analyzed using high performance liquid chromatography coupled with high-resolution mass spectrometry. Chromatographic separation was achieved on a C18 column with the mobile phase of acetonitril-water (0.5% ammonia water) and step gradient elution. The ESI-MS analysis was operated at the range of m/z 100-1 000 in positive ionization mode. High-resolution mass spectrometry techniques have proven to be a reliable tool for the structural elucidation of unknown compounds in complex samples. In this context, linear ion trap quadrupole-Orbitrap-mass spectrometry (LTQ-Orbitrap MS) provides single-stage mass analysis that supplies molecular weight information and multi-stage mass analysis (MSⁿ) that provides structural information. Moreover, accurate mass measurement of the product ions facilitates the elucidation of unknown compounds. A total of twenty-two compounds of seeds are identified from the methanolic extract in the seeds of Peganumharmala, such as 10 isoquinoline alkaloid and 10 quinazolone alkaloids, which are characterized in the methanolic extract，based on the accurate mass of molecular and product ions provided by LTQ-Orbitrap mass spectrometer. As far as we know, these compounds have been recognized in seeds of Peganumharmala for the first time, such as glycosides vasicine, glycosides pegamine, 3-hydroxylated harmine. The method is rapid and simple in the qualitative analysis of licorice using LC-LTQ-Orbitrap MS, which could prove to have a high sensitivity and the result is accurate and reliable. It is an effective method to provide chemical information concerning the constituents in herbal medicines, which could be helpful for the quality control and further phytochemical studies of seeds of Peganumharmala L.