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.