The isolation and characterization of the major crystalline alkaloids of three Crinum species, C. defixum, C. scabrum, and C. latifolium, are reported. A new alkaloid, 5α-hydroxyhomolycorine (1) has been isolated from C. defixum. The latter plant also contains an alkaloid identified as 9-O-demethylhomolycorine which differs in physical properties from that previously reported for this compound. Evidence is provided for the structure of 9-0-demethylhomolycorine by 1H and 13C NMR studies. In the latter, the exploitation of long-range 1 H coupling in the 13C spectra of lactones in this series is found to be diagnostically useful in assigning aromatic substitution patterns. A survey of the CD spectra of lactone alkaloids of the benzopyrano[3, 4-g]indole system indicates that this technique can provide useful structural information. © 1985, American Chemical Society. All rights reserved.