New stephaoxocane alkaloids from Stephania longa

Three new stephaoxocane-type alkaloids, stephalonganines A-C (1-3), together with the known eletefine (4), were isolated from the whole plant of Stephania longa. Their structures were fully characterized spectroscopically, and the absolute configurations of the new alkaloids were assigned by comparison of their circular-dichroism (CD) data with those of 1,2-dihydrostephaoxocanine (5), in combination with 2D-NMR experiments.