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 IC(50) values of 3.0 and 0.6 microM, respectively.
Two novel major alkaloids, deoxycalyciphylline B (1) and deoxyisocalyciphylline B (2) with a unique fused hexacyclic skeleton, together with a quite recently reported alkaloid calyciphylline B (3), were isolated from the stem of Daphniphyllum subverticillatum. Their structures were established by spectral methods and chemical evidence, especially 2D NMR techniques. The structure of 1 was further confirmed by a single-crystal X-ray diffraction determination.
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