Lin Zongtao, Yang Ruinan, Guan Zheng, Chen Ailiang, Li Wei
Department of Pharmaceutical Sciences, College of Pharmacy, The University of Tennessee Health Science Center, Memphis, TN, 38163, United States.
Phytochem Anal. 2014 Nov-Dec;25(6):485-94. doi: 10.1002/pca.2517. Epub 2014 Apr 14.
As an essential medicine and tea source in many countries, Plumula Nelumbinis potentially exerts its major biological activities through its alkaloids. However, the activities of Plumula Nelumbinis are not fully understood due to the lack of studies on its chemical components.
To establish an ultra-performance liquid chromatography combined with diode-array detector (UPLC/DAD) method, coupled to an electrospray ionisation with quadrupole time-of-flight mass spectrometry (ESI/QTOF/MS) method, for the separation and identification of Plumula Nelumbinis alkaloids.
The eluant from an UPLC separation of an ethanol extract of Plumula Nelumbinis was directly infused into an ESI/QTOF/MS system. Both positive and negative ion modes of ESI with low and high collision energy (CE) were used to obtain sufficient MS information.
Twenty-one alkaloids were tentatively identified based on their chromatographic characteristics, UV spectra, exact mass, MS fragments and literature reports. They consist of six bis-1-benzyltetrahydroisoquinoline, eleven benzyltetrahydroisoquinoline (including two glycoalkaloids and two quaternary ammoniums), two aporphine, one proaporphine and one indole alkaloids. Eleven were identified in Plumula Nelumbinis for the first time and seven were first reported in Nelumbo nucifera Gaertn. Five compounds, namely norcoclaurine-4'-O-glucoside, norcoclaurine-6-O-glucoside, isolotusine, 6-demethyl-4-demethylN-methylcoclaurine and N-norisoliensinine, were characterised and proposed as new compounds.
The established UPLC/DAD - ESI/QTOF/MS method is efficient for systematic identification of the alkaloids in Plumula Nelumbinis extract.
莲子心作为许多国家的一味重要药材和茶叶来源，其主要生物活性可能通过生物碱发挥作用。然而，由于对其化学成分研究不足，莲子心的活性尚未完全明确。
建立超高效液相色谱结合二极管阵列检测器（UPLC/DAD）方法，并与电喷雾电离四极杆飞行时间质谱（ESI/QTOF/MS）方法联用，用于莲子心中生物碱的分离与鉴定。
将莲子心乙醇提取物经UPLC分离后的洗脱液直接注入ESI/QTOF/MS系统。采用低、高碰撞能量（CE）的ESI正、负离子模式，以获取充足的质谱信息。
根据色谱特征、紫外光谱、精确质量、质谱碎片及文献报道，初步鉴定出21种生物碱。它们包括6种双-1-苄基四氢异喹啉、11种苄基四氢异喹啉（包括2种糖生物碱和2种季铵盐）、2种阿朴啡、1种原阿朴啡和1种吲哚生物碱。其中11种为首次在莲子心中鉴定出，7种为首次在莲（Nelumbo nucifera Gaertn.）中报道。鉴定并提出5种化合物，即去甲乌药碱-4'-O-葡萄糖苷、去甲乌药碱-6-O-葡萄糖苷、异莲心碱、6-去甲基-4-去甲基-N-甲基乌药碱和N-去甲异荷叶碱为新化合物。
所建立的UPLC/DAD-ESI/QTOF/MS方法可有效用于莲子心提取物中生物碱的系统鉴定。
