Soybean extracts enriched with free isoflavones promote nitric oxide synthesis and affect the proliferation of breast adenocarcinoma cells

Although soybean isoflavones naturally accumulate in their conjugated forms, the beneficial effects on human health of soybean-containing foods have been credited to their aglycone forms. In the present study we analyzed the effects of a chemical agent, sodium nitroprusside (SNP), in eliciting the exudation of non-conjugated isoflavones from intact soybean seeds, embrionary axes and cotyledons. The isoflavones in the exudates were determined by high performance liquid chromatography and mass spectrometry. The effect of the exudates on the emission of nitric oxide (NO) and on the proliferation of breast carcinoma cells (MCF-7) was also evaluated. SNP elicitation increased the production of the aglycone forms dose- and time-dependently. Exudates of embrionary axes and cotyledons stimulated NO emission and showed biphasic effects on viability of MCF-7 cells. At lower concentrations both extracts presented proliferative effects (10-25%), and at higher concentrations inhibited (15%) cell proliferation. The biphasic effect might be due to the action of isoflavone aglycones in activating estrogen receptors which in turn stimulate the production of NO. Overall, the results suggest that soybean extracts enriched in isoflavone aglycones by elicitation with SNP could be exploited as a functional ingredient in the food industry.

Xylodiol from Xylopia langsdorfiana induces apoptosis in HL60 cells

An atisane diterpene was isolated from Xylopia langsdorfiana St. Hilaire & Tulasne, Annonaceae, leaves, ent-atisane-7α,16α-diol (xylodiol). Preliminary study showed that xylodiol was cytotoxic and induced differentiation on human leukemia cell lines. However, the molecular mechanisms of xylodiol-mediated cytotoxicity have not been fully defined. Thus, we investigated the anti-tumor effect of xylodiol in human leukemia HL60 cell line. Xylodiol induced apoptosis and necrosis. HL60 cells treated with xylodiol showed biochemical changes characteristic of apoptosis, including caspases-8, -9 and -3 activation and loss of mitochondrial transmembrane potential (∆ Ψm). However, there was a condensation rather than swelling of mitochondria. Moreover, the formation of condensed mitochondria and the loss of ∆ Ψm occurred downstream of caspase activation. Cyclosporine A did not protect HL60 cells from the cytotoxic effects of xylodiol, suggesting that the loss of ∆ Ψm is a late event in xylodiol-induced apoptosis. Oxidative stress was involved in xylodiol-induced apoptosis. Thus, we conclude that activated caspases cleave cellular proteins resulting in mitochondrial damage leading to mitochondrial condensation, loss of ∆ Ψm and ROS release from the mitochondria. ROS can further induce and maintain a collapse of ∆ Ψm leading to cellular damage through oxidation of lipids and proteins resulting in apoptotic cell death.