Claurailas A-D, Cytotoxic Carbazole Alkaloids from the Roots of Clausena harmandiana

Four new carbazole alkaloids, claurailas A-D (1-4), as well as 12 known carbazoles and three known coumarins were isolated from the roots of Clausena harmandiana. Heptaphylline (6) and 7-methoxyheptaphylline (7) showed strong cytotoxicity against NCI-H187 and KB cell lines with IC50 values ranging from 1.3 to 2.7 mu M. Compound 7 showed no cytotoxicity against Vero cells.