两类大戟二萜的高分辨ESI-MS/MS质谱裂解规律及诊断离子解析  

Analysis on Fragmentation Patterns and Diagnostic Ions of Two Types of Euphorbia Diterpenoid by High-resolution Tandem Mass Spectrometry

作　　者：王天山[1,2,3] 付子卓 蒋方龙 WANG Tian-shan;FU Zi-zhuo;JIANG Fang-long(Key Laboratory of Tropical Medicinal Resource Chemistry of Ministry of Education,Haikou 571199,China;Hainan Provincial Key Laboratory of Tropical Pharmaceutical Herb Chemistry,Haikou 571199,China;College of Chemistry and Chemical Engineering,Hainan Normal University,Haikou 571199,China)

机构地区：[1]热带药用资源化学教育部重点实验室,海南海口571199 [2]海南省热带药用植物化学重点实验室,海南海口571199 [3]海南师范大学化学与化工学院,海南海口571199

出　　处：《分析测试学报》2023年第2期141-149,共9页Journal of Instrumental Analysis

摘　　要：采用高分辨电喷雾串联质谱技术研究了15种大戟二萜的二级质谱裂解行为,总结了这些化合物的基本裂解规律并归纳了其诊断离子。所研究的二萜均为多酯类化合物,根据其二萜骨架的不同分为曼西烷型(化合物1~9)和前曼西烷型(化合物10~15)。研究结果发现,这些化合物先断裂酰氧基和/或脱水等得到二萜骨架离子,接着在骨架上发生裂解生成一系列特征的诊断离子,这些离子集中在m/z 200~320区域。化合物1~7的骨架离子为m/z 311(离子A)和m/z 293(离子B),化合物8~9的骨架离子为m/z 295(离子C)和m/z277(离子D),而化合物10~15的骨架离子为m/z 313(离子E)和m/z 295(离子F)。根据这些关键的诊断离子可以鉴别化合物的结构类型。此外,关键诊断离子丢失H_(2)O、HCHO、CO、C_(3)H_(4)和/或丙酮等中性分子,可分别证明前体离子存在羟基、四氢呋喃环、羰基、异丙烯基和/或CH3C(OH)CH3片段或官能团。上述诊断离子和特征的中性丢失既可表征这些化合物的化学结构,又有助于其它未知曼西烷型和前曼西烷型二萜的结构鉴定。Tandem mass spectrometry(MS/MS) generates fragmentation ions from quasi-molecular ions.Meanwhile,high-resolution mass spectrometry offers an accurate mass measurement,which is particularly suitable for the analysis of fragmentation pathways and structure identification of natural products.In this paper,fifteen natural compounds of Euphorbia diterpenoid,classified as myrsinane-type(1-9) and pemyrsinane-type(10-15) possessing chemical structural features of 5/7/6/3 and 5/7/6 ring fused system,were selected to analyze the basis of characteristic MS/MS fragmentation patterns.Experimental data indicated that diterpenoid backbone fragments were yielded by continuous acids,carboxylates elimination and dehydration upon higher-energy collision dissociation(HCD).Compounds 1-7 fragmented to yield backbone ions of m/z 311(ionA) and m/z 293(ionB),compounds 8 and 9 gave at m/z 295(ionC) and m/z 277(ionD),and similarly,compounds 10-15 showed them at m/z 313(ionE) and m/z 295(ion F).A series of diagnostic ions including backbone ions in the low mass region of m/z 200-320 were identified,which were associated with specific structural features.The neutral losses of H_(2)O,HCHO,CO,C_(3)H_(4)and/or acetone were the characteristic eliminations from the backbone precursor ions due to the presence of hydroxyl,THF(tetrahydrofuran) ring,carbonyl,isopropenyl and/or CH_(3)C(OH)CH_(3)units in the structures.The occurrence of key diagnostic ions and their fragmentation patterns could potentially permit the chemical structure determination and the identification for unknowns.

关 键 词：大戟二萜 曼西烷型 前曼西烷型 裂解规律 诊断离子 

分 类 号：O657.6[理学—分析化学] R282[理学—化学]