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Five novel bisindole alkaloids, hunzeylanines A-E (1-5), with an unprecedented skeleton were isolated from the roots of Hunteria zeylanica. Compounds 1-5 represent the first examples of akuammine-pleioarpamine-type bisindole alkaloids fused with a dihydropyran unit. Their structures including absolute configurations were established through comprehensive spectroscopic data analyses and computational calculation methods. The plausible biogenetic pathway of 1 was also proposed. Alkaloids 1 and 2 displayed moderate cytotoxicity toward three human cancer cell lines (MDA-MB-231, AV3, and Huh7).

In order to study the alkaloids from branches and leaves of Ervatamia hainanensis, silica gel, ODS, Sephadex LH-20 and HPLC chromatography were used to obtain six alkaloids from the branches and leaves of E. hainanensis with use of. Based on the physicochemical properties and spectral data, their structures were identified as 10-hydroxydemethylhirsuteine(1), 3R-hydroxycoronaridine(2), 3-(2-oxopropyl)coronaridine(3), pandine(4), 16-epi-vobasine(5), and 16-epi-vobasinic acid(6). Among them, compound 1 was a new monoterpenoid indole alkaloid, and compounds 5 and 6 were obtained from this plant for the first time.

Five novel bisindole alkaloids, hunzeylanines A-E (

Four new corynanthe-type alkaloids, meloslines C-F (1-4), together with four known ones (5-8) were isolated from the roots of Alstonia scholaris. Their structures including absolute configurations were elucidated by extensive spectroscopic analysis and electronic circular dichroism (ECD) calculation. Compounds 1 and 2 exhibited potent vasorelaxant activity on endothelium-intact renal arteries precontracted with KCl.

Three new monoterpenoid indole alkaloids, alstratines A–C (1–3), along with three known ones were isolated from Alstonia rostrata. Compound 2 is the first example of an akuammicine-type alkaloid possessing an unprecedented 6/5/6/5/6/5 hexacyclic ring system. The new structures including their absolute configurations were elucidated on the basis of comprehensive spectroscopic data analyses, computational calculation methods, and X-ray diffraction analysis. Compound 2 exhibited potent vasorelaxant activity with an EC50 value of 6.3 μM. In addition, compound 5 exhibited moderate acetylcholinesterase (AChE) inhibitory activity with an IC50 value of 26.8 μM.