Identification of bioactive constituents of Ziziphus jujube fruit extracts exerting antiproliferative and apoptotic effects in human breast cancer cells

Ethnopharmacological relevance: Ziziphus extracts have been used in Traditional Chinese Medicine for the treatment of cancer. Aim of the study: In the present study we have investigated the effects of Ziziphus jujube extracts (ZEs) on breast cancer. Materials and methods: We evaluated the effects of increasing concentrations of ZEs on ER alpha positive MCF-7 and ER alpha negative SKBR3 breast cancer cell proliferation using MTT assays. Apoptosis was analyzed by evaluating the involvement of some pro-apoptotic proteins, including Bax, Bad, Bid and PARP cleavage by immunoblotting analysis. Moreover, the effects of ZEs treatment on apoptosis were tested by both DNA fragmentation and terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) staining. By using chromatographic techniques, we identified the constituents of the effective extracts. Results: ZE1, ZE2, and ZE4 exerted significant antiproliferative effects on estrogen receptor alpha (ER alpha) positive MCF-7 (IC50 values of 14.42, 7.64, 1.69 mu g/mL) and ER alpha negative SKBR3 (IC50 values of 14.06, 6.21, 3.70 mu g/mL) human breast cancer cells. Remarkably, ZEs did not affect cell viability of both normal human fibroblasts BJ1-hTERT and nonmalignant breast epithelial MCF-10A cells. Treatment with ZEs induced cell death by apoptosis in both malignant breast cells. We found that the most effective extracts ZE2 and ZE4 shared a number of triterpenic acids, already known for their anticancer activities. Conclusions: Our data provide a rational base for the use of Ziziphus extracts in the treatment of breast cancer in Traditional Chinese Medicine. (C) 2012 Elsevier Ireland Ltd. All rights reserved.