Abstract: In this study, electrospray ionization mass spectrometry (ESI-MS) was used to analyze flavonoid C-glycosides isolated from lotus plumule. It was found that in negative ionization mode, flavonoid C-glycosides with hexose substitution experienced cross-ring cleavages of sugar moiety, characterized by loss of a series of neutral fragments (90 u, 120 u, 150 u) which distinguished markedly with flavonoid O-glycosides. Flavonoid O-glycosides with one hexose substitution lost sugar moiety (162 u) directly. Although the types of hexose could not be directly differentiated by MS method, it could be solved by means of liquid chromatography-mass spectrometry (LC-MS) due to their different retention times. For flavonoid O-diglycosides, main fragment ions were derived from the loss of sugar moiety (146 u, 162 u, 308 u) and the types and the linkage information of disaccharide could be differentiated by the fragment ions and its relative abundance in the MS spectra. Not only can differential MS fragmentation patterns of flavonoid C-glycosides and flavonoid O-glycosides be very helpful to the rapid identification of flavonoids from lotus plumule, but can also enable the better differentiation of isomers of flavonoids from lotus plumule.

Key words: lotus plumule, flavonoids, flavonoid C-glycosides, flavonoid O-glycosides, electrospray ionization mass spectrometry (ESI-MS), liquid chromatography-mass spectrometry (LC-MS)

摘要： 采用电喷雾质谱法(ESI-MS)，对从莲子心分离得到的碳苷类黄酮化合物进行质谱碎裂规律研究。结果表明，负离子模式下，六碳糖碳苷黄酮主要发生糖环裂解，通过丢失特征性的碎片(90 u、120 u、150 u)与氧苷黄酮区分；单糖取代的六碳醛糖氧苷黄酮直接丢失单糖部分(162 u)，六碳醛糖种类无法通过质谱区分，但由于它们在液相上的保留时间不同，可通过液相色谱-质谱(LC-MS)联用方法分离鉴定；二糖取代的氧苷黄酮主要碎片离子通过丢失糖部分(146 u、162 u、308 u)所得，二糖的种类及连接方式可通过质谱图上的碎片离子峰及其相对丰度辨别。莲子心中多种碳苷黄酮和氧苷黄酮质谱的不同裂解规律，不仅有助于莲子心黄酮化合物的快速鉴定，而且可以通过与液相色谱联用实现莲子心中同分异构体的快速区分。

关键词: 莲子心, 黄酮化合物, 碳苷黄酮, 氧苷黄酮, 电喷雾质谱(ESI-MS), 液相色谱-质谱(LC-MS)