From the epigeal part of Petilium raddeana have been isolated the known alkaloids edpetiline and edpetine and the new base petisidinone with mp 217-219°C, [α]D 0° (c 0.169; chloroform), C27H39NO3 (I). When the known alkaloid petisidine was oxidized, a product identical with petisidinone (I) was obtained. Thus, the structure of (I) has been established as 26,23-nitrilocholestane-3,6,22-trione. Details of the IR, PMR, and mass spectra of (I) are given. © 1987 Plenum Publishing Corporation.