The stem and roots of Hornschuchia obliqua provided two new alkaloids, 4,5-didehydroguadiscine and demethoxyguadiscine. Four known alkaloids, roemerine, guadiscine, liriodenine and cleistopholine were also isolated. The structures of the novel compounds were elucidated by spectroscopic analysis, including 2D NMR and MS. (C) 2002 Elsevier Science B.V. All rights reserved.