Kleinenkuhnen Niklas, Büchel Felix, Gerlich Silke C, Kopriva Stanislav, Metzger Sabine
MS-Platform, Cluster of Excellence on Plant Sciences, Botanical Institute (CEPLAS), University of Cologne, Cologne, Germany.
Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Cologne, Germany.
Front Plant Sci. 2019 Jul 5;10:885. doi: 10.3389/fpls.2019.00885. eCollection 2019.
Sulfur is present in plants in a large range of essential primary metabolites, as well as in numerous natural products. Many of these secondary metabolites contain sulfur in the oxidized form of organic sulfate. However, except of glucosinolates, very little is known about other classes of such sulfated metabolites, mainly because of lack of specific and quantitative analytical methods. We developed an LC-MS method to analyze sulfated flavonoids, a group of sulfated secondary metabolites prominent, e.g., in plants of the genus . The method uses a linear gradient of methanol/formic acid in water on a Restek Raptor C Core-Shell column for separation of the compounds. The sulfated flavonoids are detected by mass spectrometry (MS) in a negative mode, using a neutral loss of 80 Da after a collision induced dissociation. With this method we were also able to quantify the sulfated flavonoids. We could detect all (mono)sulfated flavonoids described before in plus a number of new ones, such as isorhamnetin-sulfate-glycoside. In addition, we showed that sulfated flavonoids represent a substantial sulfur pool in , larger than the thiols glutathione and cysteine. The individual species possess different sulfated flavonoids, but there is no correlation between the qualitative pattern and type of photosynthesis. Similar to other sulfur-containing secondary compounds, the concentration of sulfated flavonoids in leaves is reduced by sulfur starvation. The new LC-MS method will enable qualitative and quantitative detection of these secondary metabolites in plants as a pre-requisite to addressing their functions.
硫存在于植物中大量必需的初级代谢产物以及众多天然产物中。这些次级代谢产物中的许多都含有有机硫酸盐氧化形式的硫。然而，除了硫代葡萄糖苷外，对于其他此类硫酸化代谢物的类别知之甚少，主要是因为缺乏特异性和定量分析方法。我们开发了一种液相色谱 - 质谱法来分析硫酸化黄酮类化合物，这是一类突出的硫酸化次级代谢产物，例如在某属植物中。该方法在Restek Raptor C核壳柱上使用水相中甲醇/甲酸的线性梯度来分离化合物。硫酸化黄酮类化合物通过质谱（MS）在负离子模式下进行检测，采用碰撞诱导解离后80 Da的中性丢失。通过这种方法，我们还能够对硫酸化黄酮类化合物进行定量。我们能够检测到之前在某植物中描述的所有（单）硫酸化黄酮类化合物以及一些新的化合物，如异鼠李素 - 硫酸 - 糖苷。此外，我们表明硫酸化黄酮类化合物在某植物中代表了一个大量的硫库，比硫醇谷胱甘肽和半胱氨酸更大。各个物种具有不同的硫酸化黄酮类化合物，但定性模式与光合作用类型之间没有相关性。与其他含硫次级化合物类似，硫饥饿会降低叶片中硫酸化黄酮类化合物的浓度。这种新的液相色谱 - 质谱法将能够对植物中的这些次级代谢产物进行定性和定量检测，作为研究其功能的先决条件。
