From the leaves of Buxus sempervirens has been isolated, in addition to known alkaloids, a new alkaloid, spirofornabuxine (1), and its structure was determined by NMR spectroscopic analysis. This new alkaloid can be considered as the first member of a new group of steroidal derivatives, the spirobuxus alkaloids. Its implication in the biosynthesis of other Buxus alkaloids is discussed. (C) 1997 Published by Elsevier Science Ltd.