Glycosmisines A and B: isolation of two new carbazole–indole-type dimeric alkaloids from Glycosmis pentaphylla and an evaluation of their antiproliferative activities

Two unique carbazole–indole-type dimeric alkaloids, glycosmisines A (1) and B (2), have been isolated from the stems of Glycosmis pentaphylla and their structures are elucidated by 1D and 2D NMR analyses, and their cytotoxicity against the growth of three cancer cell lines (A549, HepG-2 and Huh-7 cells) in culture was investigated using an MTT assay. Compounds 1 and 2 exhibited significant levels of cytotoxicity against three human cancer cell lines, and these two compounds also induced apoptosis in the same cell lines, as evidenced by changes in the morphological features of cells treated with these compounds and their dose-dependent accumulation of a sub-G1 population.