Two separate commercial products of kratom [Mitragyna speciosa (Korth.) Havil. Rubiaceae] were used to generate reference standards of its indole and oxindole alkaloids. While kratom has been studied for over a century, the characterization data in the literature for many of the alkaloids are either incomplete or inconsistent with modern standards. As such, full ¹H and ¹³C NMR spectra, along with HRESIMS and ECD data, are reported for alkaloids 1–19. Of these, four new alkaloids (7, 11, 17, and 18) were characterized using 2D NMR data, and the absolute configurations of 7, 17, and 18 were established by comparison of experimental and calculated ECD spectra. The absolute configuration for the N(4)-oxide (11) was established by comparison of NMR and ECD spectra of its reduced product with those for compound 7. In total, 19 alkaloids were characterized, including the indole alkaloid mitragynine (1) and its diastereoisomers speciociliatine (2), speciogynine (3), and mitraciliatine (4); the indole alkaloid paynantheine (5) and its diastereoisomers isopaynantheine (6) and epiallo-isopaynantheine (7); the N(4)-oxides mitragynine-N(4)-oxide (8), speciociliatine-N(4)-oxide (9), isopaynantheine-N(4)-oxide (10), and epiallo-isopaynantheine-N(4)-oxide (11); the 9-hydroxylated oxindole alkaloids speciofoline (12), isorotundifoleine (13), and isospeciofoleine (14); and the 9-unsubstituted oxindoles corynoxine A (15), corynoxine B (16), 3-epirhynchophylline (17), 3-epicorynoxine B (18), and corynoxeine (19). With the ability to analyze the spectroscopic data of all of these compounds concomitantly, a decision tree was developed to differentiate these kratom alkaloids based on a few key chemical shifts in the ¹H and/or ¹³C NMR spectra.

中文翻译：

---

Kratom 的化学 [Mitragyna speciosa]：更新表征数据和方法以阐明吲哚和氧化吲哚生物碱。

kratom [ Mitragyna speciosa (Korth.) Havil. 的两种不同的商业产品。茜草科]用于生成其吲哚和羟吲哚生物碱的参考标准。虽然 kratom 已被研究了一个多世纪，但文献中许多生物碱的表征数据要么不完整，要么与现代标准不一致。因此，报告了生物碱1 – 19 的完整¹ H 和¹³ C NMR 谱以及 HRESIMS 和 ECD 数据。在这些中，四个新生物碱（7，11，17，和18），使用2D-NMR数据进行了表征，并的绝对构型7，图17和18是通过比较实验和计算的ECD光谱而建立的。N (4)-氧化物 ( 11 )的绝对构型是通过比较其还原产物的 NMR 和 ECD 谱与化合物7 的那些谱来确定的。共表征了19种生物碱，包括吲哚生物碱帽柱花碱( 1 )及其非对映异构体speciociliatine( 2 )、speciogynine( 3 )和mitraciliatine( 4 )；吲哚生物碱paynantheine ( 5 ) 及其非对映异构体isopaynantheine ( 6 ) 和epiallo-isopaynantheine ( 7 )；的N (4)-氧化物mitragynine- N (4)-氧化物 ( 8 )、特殊纤毛素- N (4)-氧化物 ( 9 )、isopaynantheine- N (4)-氧化物 ( 10 ) 和表烯基-isopaynantheine- N (4) )-氧化物 ( 11 ); 9-羟基化羟吲哚生物碱Speciofoline ( 12 )、isorotundifoleine ( 13 )和isospeciofoleine ( 14 )；和 9-未取代的羟吲哚类棒碱 A（15）、棒碱 B（16）、3-表旋茶碱（17）、3-表旋氧碱 B（18）和棒碱（19））。由于能够同时分析所有这些化合物的光谱数据，因此开发了一种决策树，以根据¹ H 和/或¹³ C NMR 光谱中的几个关键化学位移来区分这些 kratom 生物碱。