Cimicifoetones A and B, Dimeric Prenylindole Alkaloids as Black Pigments of Cimicifuga foetida.

Zhou, Chang ‐ Xin; Yu, Yu ‐ E; Sheng, Rong; Mo, Jian ‐ Xia; Huang, Min; Ouyang, Liang; Gan, Li ‐ She

Two dimeric prenylindole alkaloids with a unique indole-benzoindolequinone skeleton, cimicifoetones A ( 1) and B ( 2), were isolated as black pigments from the rhizomes of Cimicifuga foetida. The structures were elucidated by spectroscopic methods including HRMS and 2D NMR, as well as single-crystal X-ray diffraction and computational chemical modeling techniques. Cimicifoetones A and B represented the first examples of dimeric indole alkaloids generated through [4 2] Diels-Alder cycloaddition between the prenyl side chain in one 3-prenylindole and the aromatic ring in another. The two compounds showed promising anti-proliferative activity on seven tumor cell lines with IC50 values in the range of 1.36-21.09 μ m. Flow cytometric and western blot analysis revealed that compound 2 induced cell apoptosis via death receptor-mediated extrinsic and mitochondrial-mediated intrinsic pathways.

INDOLE alkaloids; DIMERS; BUGBANE; PIGMENTS; QUINONE; CRYSTAL structure

Chemistry - An Asian Journal, 2017, Vol 12, Issue 12, p1277

1861-4728

Academic Journal

10.1002/asia.201700348