The ethanolic extract of bulbs of Cyrtanthus obliquus (L.f.) Ait yielded the new dinitrogenous alkaloid obliquine (1), 3S, 4aS, 11S, 10bS-3,4,4a, 13,11,5,6-heptahydro-5[2-(4-hydroxyphenyl)ethyl]-3-methoxy-13-methyl-[1,3-dioxolo[4,5-g]indolo[3,3a-c]-isoquinolin-12-one, together with the five known structures 11alpha-hydroxygalanthamine, 3-epimacronine, narcissidine, tazettihe and trisphaeridine. All structures were established using 1D and 2D NMR techniques and HREIMS. The alkaloids were tested for cytotoxicity against two mammalian cell lines and did not show activity at concentrations up to 100 mug/ml. (C) 2002 Elsevier Science Ltd. All rights reserved.