Hunzeylanines A-E, Five Bisindole Alkaloids Tethered with a Methylene Group from the Roots of .

Five novel bisindole alkaloids, hunzeylanines A-E (), with an unprecedented skeleton were isolated from the roots of . Compounds 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 was also proposed. Alkaloids and displayed moderate cytotoxicity toward three human cancer cell lines (MDA-MB-231, AV3, and Huh7).