Carbazole alkaloids from Clausena emarginata with their potential antiproliferative activities

A phytochemical investigation on the stems and leaves of Clausena emarginata led to the isolation of a previously undescribed carbazole alkaloid, clausemargine A (1), together with 11 known analogues (2-12). The structure of 1 was elucidated by extensive spectroscopic methods and the known compounds were identified by comparisons with data reported in the literature. All known compounds (2-12) were isolated from C. emarginata for the first time. All isolated compounds were evaluated for their their antiproliferative activities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 in vitro. Compounds 1-12 showed significant antiproliferative effects with IC₅₀ values ranging from 0.28 to 15.18 μM.