Rauvolfia tetraphylla L. (family Apocynaceae), often referred to as the wild snakeroot plant, is an important medicinal plant and produces a number of indole alkaloids in its seeds and roots. The plant is often used as a substitute for Ravuolfia serpentine (L.) Benth. ex Kurz known commonly as the Indian snakeroot plant or sarphagandha in the preparation of Ayurvedic formulations for a range of diseases including hypertension. In this study, we examine the spatial localization of the various indole alkaloids in developing fruits and plants of R. tetraphylla using desorption electrospray ionization mass spectrometry imaging (DESI-MSI). A semi-quantitative analysis of the various indole alkaloids was performed using UPLC-ESI/MS. DESI-MS images showed that the distribution of ajmalcine, yohimbine, demethyl serpentine and mitoridine are largely localized in the fruit coat while that for ajmaline is restricted to mesocarp of the fruit. At a whole plant level, the ESI-MS intensities of many of the ions were highest in the roots and lesser in the shoot region. Within the root tissue, except sarpagine and ajmalcine, all other indole alkaloids occurred in the epidermal and cortex tissues. In leaves, only serpentine, ajmalcine, reserpiline and yohimbine were present. Serpentine was restricted to the petiolar region of leaves. Principal component analysis based on the presence of the indole alkaloids, clearly separated the four tissues (stem, leaves, root and fruits) into distinct clusters. In summary, the DESI-MSI results indicated a clear tissue localization of the various indole alkaloids, in fruits, leaves and roots of R. tetraphylla. While it is not clear of how such localization is attained, we discuss the possible pathways of indole alkaloid biosynthesis and translocation during fruit and seedling development in R. tetraphylla. We also briefly discuss the functional significance of the spatial patterns in distribution of metabolites.

中文翻译：

---

使用解吸电喷雾电离 (DESI) 质谱成像对 Rauvolfia tetraphylla L. 的代谢物进行 UPLC 和 ESI-MS 分析及其空间定位

Rauvolfia tetraphylla L.（夹竹桃科），通常被称为野生蛇根植物，是一种重要的药用植物，在其种子和根中产生多种吲哚生物碱。该植物通常用作 Ravuolfia serpentine (L.) Benth 的替代品。ex Kurz 通常被称为印度蛇根植物或 sarphagandha，用于制备治疗包括高血压在内的一系列疾病的阿育吠陀制剂。在这项研究中，我们使用解吸电喷雾电离质谱成像 (DESI-MSI) 检查了各种吲哚生物碱在四叶草果实和植物发育中的空间定位。使用 UPLC-ESI/MS 对各种吲哚生物碱进行了半定量分析。DESI-MS 图像显示 ajmalcine、育亨宾、demethyl serpentine 和mitoridine 主要集中在果皮中，而ajmaline 则仅限于果实的中果皮。在整个植物水平上，许多离子的 ESI-MS 强度在根部最高，在地上部较低。在根组织内，除沙巴碱和阿马辛外，所有其他吲哚生物碱均存在于表皮和皮质组织中。在叶子中，仅存在蛇纹石、ajmalcine、利血匹林和育亨宾。蛇纹石仅限于叶的叶柄区域。基于吲哚生物碱存在的主成分分析清楚地将四种组织（茎、叶、根和果实）分成不同的簇。总之，DESI-MSI 结果表明各种吲哚生物碱在四叶树的果实、叶子和根中有清晰的组织定位。虽然不清楚这种定位是如何实现的，但我们讨论了四叶草果实和幼苗发育过程中吲哚生物碱生物合成和易位的可能途径。我们还简要讨论了空间模式在代谢物分布中的功能意义。