Schulze Birgit, Lauchli Ryan, Sonwa Mesmin Mekem, Schmidt Annika, Boland Wilhelm
Max Plank Institute for Chemical Ecology, 07745 Jena, Germany.
Anal Biochem. 2006 Jan 15;348(2):269-83. doi: 10.1016/j.ab.2005.10.021. Epub 2005 Nov 15.
A GC-MS-based method for the simultaneous quantification of common oxylipins along with labile and highly reactive compounds based on in situ derivatization with pentafluorobenzyl hydroxylamine to the corresponding O-2,3,4,5,6-pentafluorobenzyl oximes (PFB oximes) is presented. The approach covers oxo derivatives such as jasmonic acid (JA), 12-oxophytodienoic acid (OPDA), certain phytoprostanes, unsaturated oxo-acids, oxo-hydroxy acids, and aldehyde fragments from the polar head of fatty acids. In the positive electron impact-MS mode, the PFB oximes display characteristic fragment ions that greatly facilitate the identification of oxylipins in complex matrices. In addition, the fluorinated derivatives allow a highly selective and low-background analysis by negative chemical ionization. Besides showing the general value of the method for the identification of a broad range of oxylipins (18 examples), we also demonstrate sensitivity, linearity, and reproducibility for the quantification of JA, OPDA, 11-oxo-9-undecenoic acid, and 13-oxo-9,11-tridecadienoic acid. The efficiency of the method is demonstrated by differential profiling of these four oxylipins in lima bean leaves after mechanical wounding and feeding by the herbivore Spodoptera littoralis. Caterpillar feeding induced several oxylipins, whereas after wounding only the level of JA increased. The rapid in situ derivatization prevents the isomerization of cis-JA to trans-JA. The resting level of JA in lima beans showed an isomer ratio of 80:20 for trans/cis-JA. After wounding, de novo synthesis of JA alters the ratio to 20:80 in favor of the cis isomer.
本文介绍了一种基于气相色谱-质谱联用(GC-MS)的方法,该方法通过与五氟苄基羟胺原位衍生化,将常见的氧脂类以及不稳定和高反应性化合物同时定量为相应的O-2,3,4,5,6-五氟苄基肟(PFB肟)。该方法涵盖了氧代衍生物,如茉莉酸(JA)、12-氧代植物二烯酸(OPDA)、某些植物前列腺素、不饱和氧代酸、氧代羟基酸以及脂肪酸极性头部的醛片段。在正电子轰击质谱模式下,PFB肟显示出特征性碎片离子,极大地促进了复杂基质中氧脂类的鉴定。此外,氟化衍生物允许通过负化学电离进行高选择性和低背景分析。除了展示该方法在鉴定多种氧脂类(18个例子)方面的普遍价值外,我们还证明了对JA、OPDA、11-氧代-9-十一碳烯酸和13-氧代-9,11-十三碳二烯酸定量的灵敏度、线性和重现性。通过对机械损伤和食草动物斜纹夜蛾取食后的利马豆叶片中这四种氧脂类进行差异分析,证明了该方法的有效性。毛虫取食诱导了几种氧脂类,而受伤后只有JA水平升高。快速的原位衍生化可防止顺式JA异构化为反式JA。利马豆中JA的静息水平显示反式/顺式JA的异构体比例为80:20。受伤后,JA的从头合成将比例改变为20:80,有利于顺式异构体。