Carbazole alkaloids as new cell cycle inhibitor and apoptosis inducers from Clausena dunniana Levl

Carbazole alkaloids, 3-methylcarbazole (1), murrayafoline A (2), girinimbine (3), mahanimbine (4) and bicyclomahanimbine (5), were isolated for the first time from Clausena dunniana Levl. by bioassay-guided separation procedure and were identified by spectroscopic methods. Compounds 1 - 5 showed growth inhibitory activity (1, IC₅₀ 25 μg/ml) on human fibrosarcoma HT-1080 cells and cell cycle M-phase inhibitory (2, MIC 0.78 μg/ml) and apoptosis inducing (2, MIC 1.56 μg/ml; 3, MIC 25 μg/ml; 4, MIC 20 μg/ml; 5, MIC 30 μg/ml) activities on mouse tsFT210 cells, respectively, and 2 - 5 provided the first examples of carbazole alkaloids as new cell cycle inhibitors and apoptosis inducers.