Carbazole alkaloids from <i>Clausena emarginata</i> with their potential antiproliferative activities

<p>A phytochemical investigation on the stems and leaves of <i>Clausena emarginata</i> led to the isolation of a previously undescribed carbazole alkaloid, clausemargine A (<b>1</b>), together with 11 known analogues (<b>2–12</b>). The structure of <b>1</b> was elucidated by extensive spectroscopic methods and the known compounds were identified by comparisons with data reported in the literature. All known compounds (<b>2</b>–<b>12</b>) were isolated from <i>C. emarginata</i> 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 <i>in vitro</i>. Compounds <b>1</b>–<b>12</b> showed significant antiproliferative effects with IC₅₀ values ranging from 0.28 to 15.18 μM.