电喷雾三重四极杆串联质谱研究天然物中紫杉烷类物质的裂解规律

Fragmentation characteristics of taxanes in natural plants by electrospray ionization tandem mass spectrometry

采用三重四极杆串联质谱研究了7种典型6-8-6-4环紫杉烷二萜类物质的裂解规律,包括紫杉醇、巴卡廷III、10-脱乙酰基巴卡廷III、7-表-10-脱乙酰基紫杉醇、三尖杉宁碱、7-木糖苷紫杉醇、7-木糖基-10-脱乙酰基紫杉醇,分析了这7种目标物的质谱行为,并归属其裂解规律.研究表明:此类物质侧链与骨架连接处的C—O键易断裂,C—O键断裂后脱去骨架上的乙酸基(AcOH)和苯甲酰氧基(BzOH)官能团.在正离子模式下,6-8-6-4环紫杉烷二萜类物质的典型碎片离子(m/z)为:569,509,527,425,387,345,327±2;共同的侧链[Sc+H]+碎片离子(m/z)为:286,264,280,308;另外,也能得到一些中性丢失离子(m/z),如:122,60,18,36.

The triple-quadrupole tandem mass spectrometry （MS/MS） was used to study the structure of 6-8-6-4 cyclic taxane diterpenoids, including taxol, baccation Ⅲ, 7-epi-10-deacetyl baecation Ⅲ, 10-deycetyl taxol, taxol B, 7-xylosyl taxol and 10-deacetyl-7-xylosyl taxol. The fragment behaviors of these compounds were analyzed and their fragmentation rules were assigned. The results showed that the C--O bond of the side chain and taxane ring was easily cleaved, and subsequently the acid （AcOH） and benzoyloxy （BzOH） functional substituents on the diterpene skeleton tend to fragment. In the positive ion mode, the typical fragment ions of 6 8-6-4 taxane diterpenoids are （m/z）.. 569, 509, 527, 425, 387, 345, 3274-2; common side chain [Sc＋H]＋ fragment ions （m/z） are.. 286, 264, 280, 308. In addition, some neutral lost ions （m/z） ： 122, 60, 18, 36 were also obtained.