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 thetreatment of cancer.Aim of the study: In the present study we have investigated the effects of Ziziphus jujube extracts (ZEs) onbreast cancer.Materials and methods: We evaluated the effects of increasing concentrations of ZEs on ER positive MCF-7 and ER negative SKBR3 breast cancer cell proliferation using MTT assays. Apoptosis was analyzed byevaluating the involvement of some pro-apoptotic proteins, including Bax, Bad, Bid and PARP cleavageby immunoblotting analysis. Moreover, the effects of ZEs treatment on apoptosis were tested by bothDNA 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)positive MCF-7 (IC50 values of 14.42, 7.64, 1.69 g/mL) and ER negative SKBR3 (IC50 values of 14.06,6.21, 3.70 g/mL) human breast cancer cells. Remarkably, ZEs did not affect cell viability of both normalhuman fibroblasts BJ1-hTERT and nonmalignant breast epithelial MCF-10A cells. Treatment with ZEsinduced cell death by apoptosis in both malignant breast cells. We found that the most effective extractsZE2 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 breastcancer in Traditional Chinese Medicine.