穗花杉双黄酮罗伯斯特双黄酮质谱裂解特征研究

Fragmentation pathways of amentoflavone and robustaflavone using ESI-MS

采用负离子检测模式下的电喷雾多级串联质谱(ESI-MS)方法对穗花杉双黄酮和罗伯斯特双黄酮的质谱行为进行研究,讨论C3′—C8″与C3′—C6″连接的双黄酮类化合物结构特征与质谱裂解行为之间的异同。实验结果表明:2种C—C连接的双黄酮类化合物在相同的质谱条件下均可以在C环发生0,4键断裂,生成质荷比m/z=375的碎片离子。此离子峰为C—C连接的双黄酮类化合物共有的特征离子峰;但是由于C—C连接位置的不同,这一对同分异构体的裂解途径也存在着明显差异。C3′—C6″连接的罗伯斯特双黄酮,由于空间构型的影响,在质谱条件下,C4′位的羟基更易于与C5″或者C7″位上的羟基发生分子内脱水,生成丰度响应值较高的碎片离子m/z为519和309。这2个碎片离子是罗伯斯特双黄酮的特征碎片离子,可用于区分穗花杉双黄酮和罗伯斯特双黄酮。

Amentoflavone and robustaflavone were investigated by negative ion electrospray ionization tandem mass spectrometry（ESI-MS）.The relationship between their structural features and the corresponding characteristic ions fragmentation behavior was discussed.The results show that bi-flavonoid linkage of C3′-C8″and C3′-C6″ has the same fragmentation pathways.Under the condition of bi-flavonoid linkage,the bond of C-ring breaks at 0,4 positions,and then gives the principal fragment ion at m/z=375 by losing of neutral species.For amentoflavone and robustaflavone,the positions at m/z=375 in MS spectrum may belong to the characteristic fragment ion.However,there are different fragmentation pathways because of the difference of the position of C-C linkage between amentoflavone and robustaflavone.C3′-C6″linkage may induce the changes in stereostructure.The dehydration will be easy between C4′-OH and C5″-OH or C4′-OH and C7″′-OH.For robustaflavone,the m/z=519 and m/z=309 are the characteristic ions,which may be used to distinguish between amentoflavone and robustaflavone.