Magnolia dealbata seeds extract exert cytotoxic and chemopreventive effects on MDA-MB231 breast cancer cells

Context: Cancer prevention remains a high priority for the scientific world. Magnolia dealbata Zucc (Magnoliaceae), a Mexican endemic species, is used for the empirical treatment of cancer. Objective: To evaluate the cytotoxic and cancer chemopreventive effects of an ethanol extract of Magnolia dealbata seeds (MDE). Materials and methods: The cytotoxic effect of MDE, at concentrations ranging from 1 to 200 mu g/ ml, on human cancer cells and human nontumorigenic cells was evaluated using the MTT assay for 48 h. The apoptotic activities of MDE 25 mu g/ml on MDA-MB231 breast cancer cells were evaluated using the TUNEL assay and the detection of caspase 3 using immunofluorescence analysis for 48 h, each. The chemopreventive effect was evaluated by administrating different doses of MDE, between 1 and 50 mg/kg, injected intraperitoneally daily into athymic mice which were implanted with MDA-MB231 cells during 28 days. The growth and weight of tumors were measured. Results: MDE showed cytotoxic effects on MDA-MB231 cells (IC50 = 25 mu g/ml) and exerted pro-apoptotic activities as determined by DNA fragmentation in MDA-MB231 cells. MDE 25 mg/ml also induces the activation of caspase 3 in MDA-MB231 cells. These results suggest that Magnolia dealbata may be an optimal source of the bioactive compounds: honokiol (HK) and magnolol (MG). MDE 50 mg/kg i. p. exerted chemopreventive effects by inhibiting the growth of MDA-MB231 tumor by 75% in athymic mice, compared to the control group. Conclusions: MDE exerts cytotoxic, apoptotic and chemopreventive activities on MDA-MB231 human cancer cells.