环草石斛 Dendrobium loddigesii Rolfe是中药石斛的源植物之一，以茎入药，具有滋阴清热、益胃生津的功效。本文采用红外光谱法对不同产地、不同采收期的环草石斛分别进行分析比较。结果显示，不同产地环草石斛红外光谱中，1035，1051，1078，1156，1500，1511，1736 cm -1等附近峰的相对峰强皆有显著差异，表明不同产地环草石斛的多糖、酮、酯类等成分的组成和含量有明显差异。在二维相关红外光谱中，越南、云南、广西、贵州的环草石斛分别有7，8，8，9个自动峰，且广西环草石斛的最强峰在1220 cm -1附近，不同于其他三个产地样品（980 cm -1）。不同采收期环草石斛的红外光谱中，1034～1023 cm -1主强峰的波数，（1617±177;4）cm -1次强峰的波数以及1078（1076，1079）cm-1峰的有无，皆随季节呈现出明显的阶段性变化，显示了环草石斛生长过程中所含多糖、酮类等成分积累的阶段性变化规律。应用红外光谱法能较好把握环草石斛的生长状况，帮助全面了解其成分组成与含量变化，对环草石斛的合理开发与高效利用有重要意义。
Based on the LC-ESI/MSn technique, the four pairs of isomers of psoralen and isopsoralen, imperatorin and isoimperatorin, neohesperidin and hesperidin, naringin and narirutin were distinguished mainly by comparison of the relative abundances of their major fragment ions. Because of the effect of the hydrogen on the C8 of psoralen, the intensity of the fragment ion formed by the loss of CO2 was relatively increased. By comparing the abundance of the product ions formed by the loss of CO and 2CO, the isomers of psoralen and isopsoralen could be distinguished. This method can also be used to distinguish the isomers of imperatorin and isoimperatorin. Because of the different con- nected position between glucose and rhamnose, in the mass spectrum of neohesperidin, the relative abundances of ions at m/z 489 and 343 generated by the ring-cross cleavage of glycan were more than 10%, while in the mass spec- trum of hesperidin, they were all less than 1%. This approach can also be used to distinguish the isomers ofnaringin and narirutin. Although the fragmentation pathways were similar, according to the tiny difference of structure, the change of relative intensity of main fragment ions could be observed and it could be used to distinguish some isomers more accurately and quickly.
SUN Ming-qianLU Jian-qiuZHANG Hong-guiZHANG Qun-shuXIAO NanRui-yun
