Lumutinines A–D, Linearly Fused Macroline–Macroline and Macroline–Sarpagine Bisindoles from Alstonia macrophylla

Four new linearly fused bisindole alkaloids, lumutinines A–D (1–4), were isolated from the stem-bark extract of Alstonia macrophylla. Lumutinines A (1) and B (2) represent the first examples of linear, ring A/F-fused macroline–macroline-type bisindoles, while lumutinines C (3) and D (4) were constituted from the union of macroline and sarpagine moieties. A reinvestigation of the stereochemical assignment of alstoumerine (8) by NMR and X-ray diffraction analyses indicated that the configuration at C-16 and C-19 required revision.

本研究从大叶鸡骨常山（Alstonia macrophylla）的茎皮提取物中分离得到4种全新的线性稠合双吲哚生物碱，命名为lumutinines A~D（1~4）。其中lumutinines A（1）与B（2）为首例具有A/F环稠合结构的线性双马枯林型（macroline）双吲哚生物碱；而lumutinines C（3）与D（4）则由马枯林型（macroline）与蛇根精型（sarpagine）两个结构单元稠合而成。此外，本研究通过核磁共振（NMR）与X射线衍射（X-ray diffraction）分析，对alstoumerine（8）的立体化学归属进行了重新考察，结果表明其C-16与C-19位的构型需要修正。