Alkaloids of Crinum x powellii “Album” (Amaryllidaceae) and their Topoisomerase Inhibitory Activity

The alkaloids lycorine, 1-O-acetyllycorine and ismine were isolated from the basic dichloromethane- soluble fraction of Crinum x powellii “Album” bulbs. The alkaloid structures were established by physical and spectroscopic analyses, including 1D NMR techniques and GCMS analysis. The three alkaloids are reported for the first time for this hybrid. Additionally, the three alkaloids isolated were tested against a mechanism-based bioassay utilizing genetically engineered mutants of the yeast Saccharomyces cerevisiae strains RAD+, RAD52Y and RS321 where lycorine was the only alkaloid that displayed moderate topoisomerase I inhibitory activity.