Daphniyunnines A−E, Alkaloids from Daphniphyllum yunnanense

The first chemical study on the stems and leaves of Daphniphyllum yunnanense led to the isolation of five new alkaloids, daphniyunnines A−E (1−5). Daphniyunnines B−E (2−5) are four unusual C-22 nor-Daphniphyllum alkaloids. The structures of these alkaloids were characterized by spectroscopic methods, especially 2D NMR techniques. A single-crystal X-ray diffraction analysis was used to confirm the structure of 1. Daphniyunnine D (4) showed cytotoxicity against two tumor cell lines, P-388 and A-549, with IC50 values of 3.0 and 0.6 μM, respectively