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Fifteen Amaryllidaceae alkaloids (1-15) were evaluated for their antiproliferative activities against six distinct cancer cell lines. Several of these natural products were found to have low micromolar antiproliferative potencies. The log P values of these compounds did not influence their observed activity. When active, the compounds displayed cytostatic, not cytotoxic activity, with the exception of pseudolycorine (3), which exhibited cytotoxic profiles. The active compounds showed similar efficacies toward cancer cells irrespective of whether the cell lines were responsive or resistant to proapoptotic stimuli. Altogether, the data from the present study revealed that lycorine (1), amarbellisine (6), haemanthamine (14), and haemanthidine (15) are potentially useful chemical scaffolds to generate further compounds to combat cancers associated with poor prognoses, especially those naturally resistant to apoptosis, such as glioblastoma, melanoma, non-small-cell lung, and metastatic cancers.

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, 5a-hydroxyhomolycorine (1) has been isolated from C. defixum. The latter plant also contains an alkaloid identified as 9-0-demethylhomolycorine which differs in physical properties from that previously reported for this compound. Evidence is provided for the structure of 9-0-demethylhomolycorine by ' H and 13C NMR studies. In the latter, the exploitation of long-range ' 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.The Crinum genus of the amaryllidaceae has a wide geographical distribution in the temperate and subtropical regions. The species C. defixum Ker-Gawl, C. latifolium L., and C. scabrum Herb. are indigenous to the Indian subcontinent. Several preliminary reports2 have established the presence of lycorine in each of these species and a more definitive study3 of C. defixum has shown the presence of caranine, crinamine, crinine, galanthamine, galanthine, haemanthamine, and hippeastrine from C. defixum grown in Holland.

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