From Corydalis lutea, (+)-bicuculline, (+)-adlumidine, (-)-corypalmine, (-)-isocorypalmine and isocorydine have been isolated, along with a new aporphine alkaloid, the structure of which has been deduced from 1H and 13C NMR spectroscopic and mass spectrometric evidence. The trivial name crabbine has been assigned to the new compound. © 1993.