PDF(Pubmed)
Abstract：
Phytochemical investigation of the two Tabernaemontana species (Apocynaceae) T. peduncularis Wall. and T. divaricata (L.) R.Br. ex Roem. & Schult. indicated closely related biosynthetic pathways leading to lipophilic and hydrophilic alkaloids. In total, 18 specialized metabolites comprising indole-derived alkaloid aglycones, three oxindole-derived alkaloid glycosides, and two iridoid glucosides could be identified in the studied species. Among the alkaloids, the two Iboga-type alkaloids 3,7-coronaridine isoindolenine, coronaridine 3,4-iminium and a javaniside derivative bearing a glucuronic acid, named javanuronic acid, could be described by spectroscopic and spectrometric methods for the first time. A docking experiment using alpha-fold was performed to generate a protein model of the enzyme 7-deoxyloganetic acid glucosyl transferase. Performed bioassays exhibited a growth reduction of neonate Spodoptera littoralis larvae and reduced cell viability of HepG2 cells of the extracts containing Iboga alkaloids, whilst the javaniside derivatives containing hydrophilic fraction did not show any effects. These findings indicate a high flexibility in the formation of bioactive indole alkaloid aglycones by Tabernaemontana species and also evidence similar accumulation trends in both species as well as indicate that biosynthetic routes leading to oxindole alkaloids like javanisides are more widespread than reported. Furthermore, the incorporation of the three novel compounds into potential biosynthetic pathways is discussed.
摘要：
两种Tabernaemontana物种（夹竹桃科）的植物化学研究。和T.divaricata（L.)R.Br.前Roem.&舒特。表明密切相关的生物合成途径导致亲脂性和亲水性生物碱。总的来说,18种特化代谢物，包括吲哚衍生的生物碱苷元，三种羟吲哚衍生的生物碱糖苷，在所研究的物种中可以鉴定出两种环烯醚萜苷。在生物碱中，两种伊博加型生物碱3,7-异吲哚啉，Coronaridine3,4-亚胺和带有葡萄糖醛酸的javaniside衍生物，名为javanuronic酸,可以用光谱和光谱方法首次描述。进行使用α-倍的对接实验以产生酶7-脱氧甲苯磺酸葡萄糖基转移酶的蛋白质模型。进行的生物测定显示，新生斜纹夜蛾幼虫的生长减少，并且含有伊博加生物碱的提取物的HepG2细胞的细胞活力降低，而含有亲水部分的javaniside衍生物没有显示任何效果。这些发现表明，Tabernaemontana物种在形成生物活性吲哚生物碱苷元配基方面具有很高的灵活性，并且还证明了这两个物种的相似积累趋势，并表明导致诸如javanisides之类的oxindole生物碱的生物合成途径比报道的更为广泛。此外，讨论了将这三种新化合物掺入潜在的生物合成途径。
