Two new indole alkaloids from Emmenopterys henryi

Two new indole alkaloids, 5-oxodolichantoside (1) and deglycocadambine (2), were isolated from the twigs and leaves of Emmenopterys henryi, together with four known indole alkaloids and five known iridoids. The structures of the new compounds were elucidated on the basis of extensive spectroscopic analyses, including 1D- and 2D-NMR experiments, and confirmed by single-crystal X-ray diffraction studies. This is the first report on the isolation of indole alkaloids from this species. The indole alkaloids were evaluated for their cytotoxic activities against five human cancer lines.