The alkaloid complex of the leaves, stems, seeds, and seed pods of Merendera raddeana Rgl. (family Liliaceae) has been investigated. A number of known tropolone alkaloids and their photochemical isomers have been isolated together with the homoaporphine bases merenderine, kreysiginine, and O-methyl-kreysiginine and their N-oxides, which have not been described in the literature. One of them (merenderine N-oxide) has been characterized by its physical constants and has been investigated by IR, PMR, and mass-spectral methods. By a study of the PMR spectrum of the fraction of neutral alkaloids from the leaves of the plant it has been established that it consists mainly of a mixture of equal amounts of colchicine and cornigerine. © 1991 Plenum Publishing Corporation.