Isolation of substances with antiproliferative and apoptosis-inducing activities against leukemia cells from the leaves of Zanthoxylum ailanthoides Sieb. & Zucc

Extraction of the leaves of Zanthoxylum ailanthoides Sieb. & Zucc. affords extracts and four isolated compounds which exhibit activities against leukemia cells. The chloroform-soluble fraction (ZAC) of the crude extract of this plant showed cytotoxic activity against human promyelocytic leukemia (HL-60) and myelomonocytic leukemia (WEHI-3) cells with IC50 values of 73.06 and 42.22 μg/mL, respectively. The active ZAC was further separated to yield pheophorbide-a methyl ester (1), pheophorbide-b methyl ester (2), 132-hydroxyl (132-S) pheophorbide-a methyl ester (3) and 132-hydroxyl (132-R) pheophorbide-b methyl ester (4) whose structures were confirmed by spectroscopic methods. Compounds 2–4 showed cytotoxic activities against both leukemia cells with IC50 value in the range of 46.76–79.43 nM, whereas compound 1 exhibited only weak cytotoxic activity. The extracts and compounds 1–4 also induced apoptosis and DNA damage in leukemia cells after treatment. The results suggested that the Z. ailanthoides is biologically active against leukemia cells.