Nineteen vobasinyl-ibogan-type bisindole alkaloids, including nine new compounds, taburnaemines A–I (1–9), were isolated from the twigs and leaves of Tabernaemontana corymbosa. The structures and absolute configurations of the new alkaloids were determined by a combination of MS, NMR, and ECD analyses. Alkaloids 1–5 contain a rare 1,3-oxazinane moiety in the vobasinyl unit, while 6 has an uncommon 1,3-oxazolidine moiety in the iboga unit. The absolute configurations of alkaloid 1 and the known alkaloid tabernaecorymbosine A (10) were confirmed by single-crystal X-ray diffraction analysis. All of the bisindole alkaloids, except 2 and 16′-decarbomethoxytabernaecorymbosine A (14), showed antiproliferative activity (IC₅₀ 2.6–9.8 μM) against several human cancer cell lines, including A-549, MDA-MB-231, MCF-7, KB, and P-glycoprotein-overexpressing multidrug-resistant KB cells. The preliminary structure–activity relationship correlations are also discussed.

中文翻译：

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Taburnaemines AI，塔贝娜塔伯菌的细胞毒性Vobasinyl-Iboga型双吲哚生物碱。

十九vobasinyl-ibogan型双吲哚生物碱，包括九个新化合物，taburnaemines A-I（1 - 9），从的树枝和叶子中分离狗牙花属伞房。通过结合MS，NMR和ECD分析确定了新生物碱的结构和绝对构型。生物碱1 – 5在vobasinyl单元中包含稀有的1,3-恶唑烷部分，而6在iboga单元中具有不常见的1,3-恶唑烷部分。通过单晶X射线衍射分析确认了生物碱1和已知的生物碱碳核糖核苷A（10）的绝对构型。除双吲哚以外的所有生物碱2和16'-decarbomethoxytabernaecorymbosine A（14）对多种人类癌细胞系（包括A-549，MDA-MB-231，MCF-7，KB和P-糖蛋白）表现出抗增殖活性（IC ₅₀ 2.6–9.8μM） -过表达耐多药的KB细胞。初步的结构-活动关系的相关性也进行了讨论。